JP6623925B2 - Arrangement structure of exhaust gas sensor - Google Patents

Description

  The present invention relates to an arrangement structure of an exhaust gas sensor.

  In automobiles, it is obligatory to monitor the control status of exhaust gas with an on-board computer. As an item to be monitored, for example, a deterioration state of a catalyst for purifying exhaust gas is cited (see Patent Document 1). In Patent Literature 1, oxygen sensors are provided before and after the catalyst, respectively, and it is determined whether or not the catalyst has deteriorated based on the output values of these two oxygen sensors.

  Specifically, the number of times of output inversion between rich leans of two oxygen sensors is used. For example, when the catalyst is normal and can sufficiently adsorb oxygen, the number of output reversals of the downstream oxygen sensor approaches zero. For this reason, the ratio of the output reversal frequency of the upstream oxygen sensor to the downstream is increased. On the other hand, when the catalyst is deteriorated and the oxygen adsorption capacity is reduced, the number of output reversals of the downstream oxygen sensor approaches the number of output reversals of the upstream oxygen sensor. For this reason, the ratio of the number of output reversals of the upstream oxygen sensor to the downstream is reduced. Therefore, when the above ratio falls below a predetermined value, it can be determined that the catalyst has deteriorated.

JP-A-2003-206784

  By the way, when determining deterioration of a catalyst in a motorcycle, it is difficult to arrange the two oxygen sensors before and after the catalyst while ensuring detection accuracy due to restrictions on the structure and layout of the exhaust pipe and muffler.

  The present invention has been made in view of the above, and an object of the present invention is to provide an arrangement structure of an exhaust gas sensor in which an exhaust gas sensor can be arranged before and after a catalyst without deteriorating detection accuracy.

An arrangement structure of an exhaust gas sensor according to the present invention includes a catalyst for purifying exhaust gas of an engine, an exhaust gas sensor for detecting an exhaust gas component of the engine, and an exhaust control valve for adjusting a flow rate of the exhaust gas downstream of the catalyst. When, wherein the catalyst is disposed below the body frame for suspending the engine behind the engine case, the exhaust gas sensor, before and after the body frame, is arranged so as to sandwich the catalyst, the catalyst An upstream sensor provided on the upstream side of the catalyst, and a downstream sensor provided on the downstream side of the catalyst, wherein the upstream sensor and the downstream sensor are biased to one side in the vehicle width direction. The exhaust control valve is arranged on the downstream side of the downstream sensor so as to be biased toward the other side in the vehicle width direction .

According to this configuration, since the catalyst is arranged below the body frame, the exhaust gas sensor can be arranged close to the catalyst before and after the body frame. In particular, by disposing the exhaust gas sensor in a relatively extra space behind the body frame, the exhaust gas sensor can be brought closer to the catalyst. As a result, the detection accuracy of the exhaust gas sensor does not deteriorate. Further, since the upstream sensor and the downstream sensor are arranged to be biased to one side, the wiring of the upstream sensor and the downstream sensor can be easily arranged. Further, since the exhaust control valve is arranged on the opposite side to the exhaust gas sensor, it is possible to prevent the peripheral configuration of the exhaust control valve from interfering with the exhaust gas sensor (particularly, the downstream sensor), and the layout of the exhaust gas sensor is reduced. Easier to do.

  Further, in the arrangement structure of the exhaust gas sensor according to the present invention, it is preferable that the catalyst is disposed at a center in a vehicle width direction, and the downstream sensor is attached to a catalyst case that accommodates the catalyst. According to this configuration, by attaching the downstream sensor to the catalyst case, the downstream sensor can be brought closer to the catalyst. Further, since the catalyst is arranged at the center in the vehicle width direction, the exhaust gas sensor can be protected from flying stones and the like.

  Further, the arrangement structure of the exhaust gas sensor according to the present invention further includes a side stand configured to be swingable between a support position for supporting the vehicle and a storage position, and when the side stand is in the storage position. Preferably, the downstream sensor overlaps the side stand in a side view. According to this configuration, when the side stand is at the storage position, the side of the downstream sensor is hidden by the side stand. As a result, the downstream sensor can be protected from flying stones and the like. Further, a cover for protecting the downstream sensor can be omitted, and the configuration can be simplified.

  Further, the arrangement structure of the exhaust gas sensor according to the present invention further includes an exhaust pipe connected to an upstream side of the catalyst, and an oil pan provided at a lower part of the engine case, wherein the oil pan has a vehicle width. It is preferable that the exhaust pipe has a recess on one side in the direction, the exhaust pipe is arranged along the recess, and the upstream sensor is attached to the exhaust pipe so as to fit in the recess. According to this configuration, since the upstream sensor is housed in the recess, it is possible to prevent the upstream sensor from projecting from the oil pan. As a result, the downstream sensor can be protected, and the influence on the appearance can be suppressed.

Further, another arrangement structure of the exhaust gas sensor according to the present invention includes a catalyst for purifying an exhaust gas of an engine, an exhaust gas sensor for detecting an exhaust gas component of the engine, and adjusting a flow rate of the exhaust gas downstream of the catalyst. An exhaust control valve, wherein the catalyst is disposed below a body frame that suspends the engine behind an engine case, and the exhaust gas sensors are disposed so as to sandwich the catalyst before and after the body frame. An upstream sensor provided on the upstream side of the catalyst, and a downstream sensor provided on the downstream side of the catalyst, wherein the upstream sensor is arranged biased to one side in the vehicle width direction, The downstream sensor is arranged to be biased on the other side in the vehicle width direction, and the exhaust control valve is arranged on the other side in the vehicle width direction on the downstream side of the downstream sensor. And wherein the Rukoto. According to this configuration, by disposing the downstream sensor and the exhaust control valve on the same side (the other side in the vehicle width direction), the downstream sensor and the exhaust control valve can be disposed together, and Is improved. In addition, the downstream sensor can be protected by a cover that protects the exhaust control valve, and the configuration can be simplified.

  Preferably, the arrangement structure of the exhaust gas sensor according to the present invention further includes an under cowl that covers a lower front part of the engine, and the downstream sensor is covered with the under cowl. According to this configuration, since the downstream sensor is covered with the under cowl, the downstream sensor can be protected from flying stones or the like by the under cowl.

  According to the present invention, the exhaust gas sensors can be arranged before and after the catalyst without deteriorating the detection accuracy.

FIG. 1 is a left side view showing a schematic configuration of a motorcycle to which an arrangement structure of an exhaust gas sensor according to the present embodiment is applied. FIG. 1 is a right side view showing a schematic configuration of a motorcycle to which an arrangement structure of an exhaust gas sensor according to the present embodiment is applied. FIG. 2 is a left side view showing a configuration around the engine of the motorcycle according to the present embodiment. FIG. 2 is a top view illustrating a configuration around an exhaust pipe of the engine according to the present embodiment. FIG. 2 is a bottom view showing a configuration around an exhaust pipe of the engine according to the present embodiment. FIG. 6 is a schematic sectional view taken along line AA of FIG. 5. It is a top view which shows the arrangement structure of the exhaust gas sensor concerning a modification. It is a bottom view which shows the arrangement structure of the exhaust gas sensor concerning a modification.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, an example in which the arrangement structure of the exhaust gas sensor according to the present invention is applied to a motorcycle of a sports type will be described, but the application target can be changed without being limited to this. For example, the arrangement structure of the exhaust gas sensor according to the present invention may be applied to other types of motorcycles, buggy-type motorcycles, motorcycles, and the like. In addition, as for the direction, the front of the vehicle is indicated by an arrow FR, and the rear of the vehicle is indicated by an arrow RE. In the following drawings, some components are omitted for convenience of explanation.

  With reference to FIGS. 1 to 3, a schematic configuration of a motorcycle to which the arrangement structure of the exhaust gas sensor according to the present embodiment is applied will be described. FIG. 1 is a left side view showing a schematic configuration of a motorcycle to which the arrangement structure of the exhaust gas sensor according to the present embodiment is applied. FIG. 2 is a right side view showing a schematic configuration of a motorcycle to which the arrangement structure of the exhaust gas sensor according to the present embodiment is applied. FIG. 3 is a left side view showing the configuration around the engine of the motorcycle according to the present embodiment.

  As shown in FIGS. 1 to 3, the motorcycle 1 is configured by suspending an engine 3 on a body frame 2 on which components such as a power unit and an electrical system are mounted. The engine 3 is, for example, a parallel four-cylinder engine. The engine 3 is configured by attaching a cylinder head 31 and a cylinder head cover 32 to an upper part of an engine case 30 in which a crankshaft (not shown) and the like are accommodated. An oil pan 33 is provided below the engine case 30.

  The vehicle body frame 2 is a twin-spar type frame formed by casting aluminum, and is configured so that the engine 3 is suspended as described above to obtain rigidity as a whole vehicle body. The vehicle body frame 2 has a shape that extends from the front to the rear as a whole and curves downward at the rear end side.

  Specifically, the vehicle body frame 2 includes a head frame 21 that branches from the head pipe 20 rearward and bifurcates to the left and right, a pair of left and right tank rails 22 that extend diagonally downward from the head frame 21 toward the rear of the vehicle body, And a body frame 23 extending downward from the rear end of the rail 22.

  The head frame 21 has a pair of left and right bracket portions 21a protruding downward, and supports the front side (cylinder head 31) of the engine 3 with the bracket portions 21a. The tank rail 22 is formed in a cylindrical shape having a hollow cross-sectional shape. The fuel tank 10 is disposed above the tank rail 22.

  The body frame 23 is configured by connecting upper and lower end portions of a pair of frame portions 23a extending downward from the rear end of each tank rail 22 in the vehicle width direction. At the upper and lower ends of the body frame 23, the rear side of the engine 3 (the rear part of the engine case 30) is supported. A swing arm pivot 23b for swingably supporting the swing arm 11 is formed at a substantially central portion in the vertical direction of the body frame 23.

  At the upper end of the body frame 23, a seat rail (not shown) extending rearward and upward and a back stay 24 are provided. The seat rail is provided with a rider seat 12 and a pillion seat 13 connected to the fuel tank 10.

  Various covers as a vehicle body exterior are mounted on the vehicle body frame 2 and the engine 3 configured as described above. Specifically, the front half of the vehicle body is covered by the front cowl 40, and the side surface of the vehicle body is covered by the side cowl 41. Further, the seat rail is covered by the rear cowl 42, and the front lower part of the engine 3 is covered by the under cowl 43.

  A pair of right and left front forks 50 is steerably supported by the head pipe 20 via a steering shaft (not shown). A front wheel 51 is rotatably supported at a lower portion of the front fork 50, and a portion above the front wheel 51 is covered by a front fender 52.

  The swing arm 11 extends rearward from the swing arm pivot 23b. A rear suspension 53 is provided between the swing arm 11 and the body frame 23. One end of the rear suspension 53 is supported on the upper end side of the body frame 23, and the other end is supported below the front side of the swing arm 11 via the rear suspension link 54. A rear wheel 55 is rotatably supported at the rear end of the swing arm 11. The upper part of the rear wheel 55 is covered by a rear fender 56 provided at the rear of the rear cowl 42.

  At the lower end of the left body frame 23, a side stand 14 that supports the vehicle is provided. The side stand 14 extends in a rod shape from the lower end of the body frame 23 as a base end, and is configured to be swingable about the base end as a fulcrum. Specifically, the side stand 14 is configured to be swingable between a support position for supporting the vehicle and a storage position. In FIG. 3, the solid line portion is in the storage position, and the two-dot chain line portion is in the support position.

  Further, an exhaust pipe 6 and a muffler 7 are connected to each exhaust port of the cylinder head 31 as an exhaust system. A plurality of exhaust pipes 6 (four in the present embodiment) extend downward from each exhaust port, and are bent rearward in front of and below the engine 3 to be integrated into one. At the downstream end of the exhaust pipe 6, a catalyst 8 for purifying exhaust gas is provided.

  The catalyst 8 is formed of, for example, a three-way catalyst, and is housed in a cylindrical catalyst case 80. The catalyst 8 converts pollutants (carbon monoxide, hydrocarbons, nitrogen oxides, etc.) in the exhaust gas into harmless substances (carbon dioxide, water, nitrogen, etc.). The muffler 7 is connected to the downstream side of the catalyst 8 via a connection pipe 70. Exhaust gas generated by combustion of the engine 3 is purified by a catalyst 8 through an exhaust pipe 6. After the exhaust noise is reduced by the muffler 7, the exhaust gas is discharged outside.

  As will be described in detail later, exhaust gas sensors 9 for detecting exhaust gas components of the engine and determining deterioration of the catalyst 8 are arranged before and after the catalyst 8. Specifically, the exhaust gas sensor 9 includes an upstream sensor 90 provided on the front side (upstream side) of the catalyst 8 and a downstream sensor 91 provided on the rear side (downstream side) of the catalyst 8. The exhaust gas sensor 9 is composed of, for example, a zirconia oxygen sensor, and the output (current value) changes according to the oxygen concentration in the exhaust gas. The current value is output to the ECU 15 (Electronic Control Unit). Note that the exhaust gas sensor 9 is not limited to the oxygen sensor, and may be, for example, an air-fuel ratio sensor.

  The ECU 15 performs overall control of various operations in the motorcycle 1. The ECU 15 is configured by a processor, a memory, and the like that execute various processes in the motorcycle 1. The memory is configured by a storage medium such as a ROM (Read Only Memory) and a RAM (Random Access Memory) depending on the application. The memory stores a control program for controlling each part of the motorcycle 1 and the like. Particularly, in the present embodiment, the ECU 15 determines the deterioration of the catalyst 8 based on the output of the exhaust gas sensor 9. Specifically, the determination is made based on the ratio of the number of times of output reversal between the rich lean of the upstream sensor 90 and the downstream sensor 91. In addition, in order to determine the deterioration of the catalyst 8, not only the case where the ratio of the number of times of output reversal is used, but also the output difference between the upstream sensor 90 and the downstream sensor 91 may be used.

  As described above, in an exhaust system of a motorcycle, it is required to monitor a deterioration state of a catalyst as an exhaust gas purifying device. In order to determine the deterioration of the catalyst, it is necessary to install exhaust gas sensors upstream and downstream of the catalyst.

  For example, it has been conventionally practiced to detect the oxygen concentration in the exhaust gas with an exhaust gas sensor (oxygen sensor) provided on the upstream side of the catalyst and control the air-fuel ratio. However, if an exhaust gas sensor is to be arranged downstream of the catalyst for the purpose of determining the deterioration of the catalyst, the exhaust gas sensor is moved closer to the downstream side of the catalyst while securing a predetermined detection accuracy due to a limitation of a layout peculiar to a motorcycle. It was difficult.

  In this regard, in the case of a four-wheeled motor vehicle, the catalyst can be arranged in a place where there is enough space, such as in an engine room, so that the arrangement and protection of the exhaust gas sensor are easy. On the other hand, in a motorcycle, a catalyst is often disposed in a chamber or a muffler, and it is structurally difficult to dispose a downstream sensor close to the catalyst. Further, even when the catalyst is disposed in the middle of the exhaust pipe, the exhaust pipe and peripheral components are often close to each other, and it is difficult to secure a space for disposing the exhaust gas sensor. Furthermore, since the exhaust system of the motorcycle is exposed to the outside, it may be assumed that the temperature of the catalyst is apt to decrease and it is not possible to appropriately obtain a sensor output, for example, in winter or during rainy weather. In addition, protection of the exhaust gas sensor also poses a problem.

  For example, when a catalyst is provided in a chamber or a muffler, it is conceivable to secure a space for disposing an exhaust gas sensor by making the outer wall concave. However, as a result of the reduction in the volume of the chamber and the muffler, there is a possibility that the original functions (output increase and noise reduction) may be affected. Although it is conceivable to arrange the catalyst itself on the front side of the vehicle, it is not very practical because it is difficult to secure a space for arranging the catalyst in the first place and a large design change is required. Furthermore, various problems occur, such as heat damage due to the catalyst as a heat source approaching the rider, a decrease in output, a method of protecting the exhaust gas sensor, and deterioration of appearance and design.

  Therefore, the present inventor has arrived at the present invention by focusing on a limited space below the engine 3 in the motorcycle 1 of the sports type. Specifically, in the present embodiment, the catalyst 8 is disposed below the body frame 23 that suspends the engine 3 behind the engine case 30, and the two exhaust gas sensors 9 ( The upstream sensor 90 and the downstream sensor 91) are arranged.

  According to this configuration, since the catalyst 8 is disposed below the body frame 23, the exhaust gas sensor 9 can be disposed close to the catalyst 8 before and after the body frame 23. In particular, by arranging the downstream sensor 91 in a relatively roomy space behind the body frame 23, the downstream sensor 91 can be brought closer to the catalyst 8. By disposing the downstream sensor 91 immediately after the catalyst 8, the purified exhaust gas directly contacts the downstream sensor 91 without being diffused. As a result, an output can be obtained stably and the detection accuracy of the exhaust gas sensor 9 is not impaired. As described above, by effectively utilizing the space below the engine 3, the exhaust gas sensor 9 can be disposed without requiring a significant design change and without affecting the appearance and design. Further, by providing the catalyst 8 near the engine 3, it is possible to suppress a decrease in the temperature of the catalyst 8, and to suppress the deterioration of the exhaust gas purification effect and the influence on the sensor output. .

  Next, the exhaust system according to the present embodiment will be described in detail with reference to FIGS. FIG. 4 is a top view showing the peripheral configuration of the exhaust pipe of the engine according to the present embodiment. FIG. 5 is a bottom view showing the configuration around the exhaust pipe of the engine according to the present embodiment. FIG. 6 is a schematic sectional view taken along the line AA of FIG.

  As shown in FIGS. 3 to 5, in the exhaust system according to the present embodiment, the exhaust pipe 6 includes exhaust pipes 6 a to 6 d extending downward from exhaust ports of the cylinder head 31 and a first collecting pipe 60 a. , 60b and the second collecting pipe 61. Specifically, as shown in FIG. 4, the exhaust pipes 6a, 6b, 6c, and 6d are arranged from the right side in the vehicle width direction. The exhaust pipes 6a and 6d on the outside in the vehicle width direction are connected by a connection pipe 62 extending in the vehicle width direction. The exhaust pipes 6b and 6c on the inner side in the vehicle width direction are connected by a connecting pipe (not shown).

  The four exhaust pipes 6 a-6 d are bent rearward below the front of the engine case 30. The two right exhaust pipes 6a, 6b are connected to a first collecting pipe 60a and are integrated into one, and the two left exhaust pipes 6c, 6d are connected to a first collecting pipe 60b and are integrated into one. Can be The first collecting pipes 60a and 60b extend rearward, respectively, and are connected to the second collecting pipe 61 to be combined into one.

  The catalyst 8 housed in the catalyst case 80 is connected to the rear end of the second collecting pipe 61. The catalyst 8 is arranged in the catalyst case 80 to be slightly biased toward the front side. The catalyst case 80 extends rearward so as to cross from the left side to the right side with respect to the center line C in the vehicle width direction of the vehicle, and is slightly bent rightward so as to avoid the rear suspension link 54. A connection pipe 70 connecting the muffler 7 is connected to the rear end of the catalyst case 80 on the right side of the center line C. The connection pipe 70 extends rearward and upward.

  As described above, the exhaust gas sensors 9 are arranged before and after the catalyst 8. The exhaust gas sensor 9 is formed in a columnar shape having a predetermined length. One end of the exhaust gas sensor 9 is a detection unit, and a wiring (not shown) is connected to the other end. Specifically, the upstream sensor 90 is attached to the rear end of the second collecting pipe 61 such that one end penetrates into the second collecting pipe 61. The downstream sensor 91 is attached immediately after the catalyst 8 such that one end thereof penetrates into the catalyst case 80.

  In particular, as shown in FIGS. 4 and 5, the exhaust pipes 6 (the first collective pipes 60 a and 60 b and the second collective pipe 61) that pass below the engine 3 are distributed to the left with respect to the center line C of the vehicle. Is established. Further, the upstream sensor 90 and the downstream sensor 91 are also arranged to be deviated leftward with respect to the center line C of the vehicle, and the other end is directed to the upper left (outward in the vehicle width direction). By arranging the two exhaust gas sensors 9 collectively on one side, it is possible to facilitate wiring of the upstream sensor 90 and the downstream sensor 91.

  In addition, since the catalyst 8 is disposed on the center line C of the vehicle and the downstream sensor 91 is attached to the catalyst case 80, the downstream sensor 91 can be disposed close to the catalyst 8. In particular, since the catalyst 8 is disposed at the center in the vehicle width direction, the exhaust gas sensor 9 can be disposed inside the entire width of the vehicle, and the upstream sensor 90 and the downstream sensor 91 are protected from flying stones. Can be.

  In particular, as shown in FIG. 5, the upstream sensor 90 and the downstream sensor 91 are accommodated within the left and right widths of the oil pan 33 and the swing arm 11. This also allows the exhaust gas sensor 9 to be disposed before and after the catalyst without increasing the vehicle width, and the exhaust gas sensor 9 can be protected. Further, the downstream sensor 91 is disposed between the engine case 30 (the oil pan 33) and the rear suspension 53 (the rear suspension link 54) in the front-rear direction. For this reason, in addition to being able to protect the downstream sensor 91, the downstream sensor 91 can be brought closer to the engine 3, which is a heat source. Therefore, the downstream sensor 91 can be warmed, and the detection accuracy of the exhaust gas can be increased.

  Further, as shown in FIG. 3, the downstream sensor 91 overlaps the side stand 14 in a side view when the side stand 14 is at the storage position. Therefore, the side (left side) of the downstream sensor is hidden by the side stand 14. As a result, the downstream sensor 91 can be protected from flying stones or the like during traveling. Further, a cover for protecting the downstream sensor 91 can be omitted, and the configuration can be simplified.

  An exhaust control valve 71 for adjusting the flow rate of the exhaust gas is provided inside the connecting pipe 70. The exhaust control valve 71 is arranged to be deviated to the right with respect to the center line C of the vehicle. By arranging the exhaust control valve 71 on the side opposite to the exhaust gas sensor 9 in this way, it is possible to prevent the peripheral configuration of the exhaust control valve 71 from interfering with the downstream sensor 91, and 9 becomes easier to layout.

  As shown in FIG. 6, below the engine case 30 (see FIG. 3), the oil pan 33 has a leftward recess 33a. Then, the second collecting pipe 61 is disposed along the recess 33a, and the upstream sensor 90 is disposed so as to fit in the recess 33a. Therefore, the other end of the upstream sensor 90 can be prevented from protruding from the oil pan 33 in the vehicle width direction. As a result, it is possible to protect the upstream sensor 90 and suppress the influence on the appearance. Further, since the exhaust pipes 6 (the first collecting pipes 60a, 60b and the second collecting pipe 61) are arranged along the recesses 33a of the oil pan 33, the upstream of the exhaust pipe 6, which is considered to have a relatively high temperature. The upstream sensor 90 can be arranged on the side. As a result, the upstream sensor 90 can be warmed, and the detection accuracy of the exhaust gas can be increased.

  Note that the present invention is not limited to the above embodiment, and can be implemented with various modifications. In the above embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited thereto, and can be appropriately changed within a range in which the effects of the present invention are exhibited. In addition, the present invention can be appropriately modified and implemented without departing from the scope of the object of the present invention.

  For example, in the embodiment described above, the upstream sensor 90 is arranged immediately before the catalyst 8, but the present invention is not limited to this configuration. The upstream sensor 90 may be arranged at any position on the upstream side of the catalyst 8, and may be arranged, for example, in front of the engine case 30.

  Further, in the above-described embodiment, the configuration is provided with the single catalyst 8, but the configuration is not limited to this. The catalyst 8 may be composed of a plurality of catalysts. For example, the catalyst 8 may be provided in each of the first collecting pipes 60a and 60b, and the exhaust gas sensors 9 may be arranged before and after each catalyst 8.

  In the above-described embodiment, the other ends of the upstream sensor 90 and the downstream sensor 91 are directed outward in the vehicle width direction. However, the present invention is not limited to this configuration. The other ends of the upstream sensor 90 and the downstream sensor 91 may be directed inward in the vehicle width direction, for example.

  Further, in the above-described embodiment, the upstream sensor 90 and the downstream sensor 91 are arranged to be deviated to the left in the vehicle width direction, but the present invention is not limited to this configuration. For example, the arrangement structure of the exhaust gas sensor shown in FIGS. 7 and 8 may be adopted. FIG. 7 is a top view illustrating an arrangement structure of an exhaust gas sensor according to a modification. FIG. 8 is a bottom view showing an arrangement structure of an exhaust gas sensor according to a modification.

  The modification shown in FIGS. 7 and 8 is different from the present embodiment in that the downstream sensor 91 is arranged to be deviated rightward with respect to the center line of the vehicle. In this case, since the downstream sensor 91 and the exhaust control valve 71 are both arranged on the right side, the downstream sensor 91 and the exhaust control valve 71 can be arranged together, and the assembling property is improved. Further, the downstream sensor 91 can be protected by a cover (not shown) for protecting the exhaust control valve 71, and the configuration can be simplified. In this case, as shown in FIG. 2, the downstream sensor 91 is covered with the under cowl 43, so that the under cowl 43 can protect the downstream sensor 91 from flying stones or the like. Further, a cover for protecting the downstream sensor 91 can be omitted, and the configuration can be simplified.

  As shown in FIG. 8, the upstream sensor 90 and the downstream sensor 91 are accommodated in the left and right widths of the oil pan 33 and the swing arm 11. Thus, the exhaust gas sensor 9 can be arranged before and after the catalyst without increasing the vehicle width, and the exhaust gas sensor 9 can be protected. Further, the downstream sensor 91 is disposed between the engine case 30 (the oil pan 33) and the rear suspension 53 (the rear suspension link 54) in the front-rear direction. For this reason, in addition to being able to protect the downstream sensor 91, the downstream sensor 91 can be brought closer to the engine 3, which is a heat source. Therefore, the downstream sensor 91 can be warmed, and the detection accuracy of the exhaust gas can be increased.

  As described above, the present invention has an effect that the exhaust gas sensor can be arranged before and after the catalyst without deteriorating the detection accuracy, and is particularly useful for an arrangement structure of the exhaust gas sensor.

Reference Signs List 1 motorcycle 14 side stand 23 body frame 3 engine 30 engine case 33 oil pan 33a recess 43 under cowl 6 exhaust pipe 71 exhaust control valve 8 catalyst 80 catalyst case 9 exhaust gas sensor 90 upstream sensor 91 downstream sensor

Claims (6)

A catalyst for purifying the exhaust gas of the engine,
An exhaust gas sensor that detects an exhaust gas component of the engine;
An exhaust control valve that adjusts the flow rate of exhaust gas downstream of the catalyst ,
The catalyst is disposed below a body frame that suspends the engine behind the engine case,
The exhaust gas sensor is disposed before and after the body frame so as to sandwich the catalyst, and has an upstream sensor provided on the upstream side of the catalyst, and a downstream sensor provided on the downstream side of the catalyst. ,
The upstream sensor and the downstream sensor are arranged to be biased to one side in the vehicle width direction,
The arrangement of the exhaust gas sensor, wherein the exhaust control valve is arranged on the downstream side of the downstream sensor so as to be biased toward the other side in the vehicle width direction . The catalyst is disposed at the center in the vehicle width direction,
The arrangement structure of an exhaust gas sensor according to claim 1 , wherein the downstream sensor is attached to a catalyst case containing the catalyst. A supporting position for supporting the vehicle, and a side stand configured to be swingable between a storage position,
3. The exhaust gas sensor arrangement according to claim 2 , wherein when the side stand is in the storage position, the downstream sensor overlaps the side stand in a side view. 4. An exhaust pipe connected to the upstream side of the catalyst,
An oil pan provided at a lower part of the engine case,
The oil pan has a recess on one side in the vehicle width direction,
The exhaust pipe is disposed along the recess,
The exhaust gas sensor arrangement according to any one of claims 1 to 3 , wherein the upstream sensor is attached to the exhaust pipe so as to fit in the recess. A catalyst for purifying the exhaust gas of the engine,
An exhaust gas sensor that detects an exhaust gas component of the engine;
An exhaust control valve that adjusts the flow rate of exhaust gas downstream of the catalyst,
The catalyst is disposed below a body frame that suspends the engine behind the engine case,
The exhaust gas sensor is disposed so as to sandwich the catalyst before and after the body frame, and has an upstream sensor provided on the upstream side of the catalyst, and a downstream sensor provided on the downstream side of the catalyst. ,
The upstream sensor is arranged to be biased to one side in the vehicle width direction,
The downstream sensor is arranged to be biased to the other side in the vehicle width direction,
The arrangement of the exhaust gas sensor, wherein the exhaust control valve is disposed on the other side in the vehicle width direction on the downstream side of the downstream side sensor. An under cowl covering the front and lower part of the engine is further provided,
The arrangement structure of the exhaust gas sensor according to claim 5 , wherein the downstream sensor is covered with the under cowl.

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