JP7649354B1 - Exhaust system - Google Patents

Abstract

An exhaust device capable of maintaining the temperature of a sensor at an appropriate temperature even when the sensor is attached to a combustion gas passage disposed inside a muffler.
[Solution] In an exhaust system (30) having a sensor (80) for detecting a specific component contained in combustion gas (G), a boss (54) for supporting the sensor (80) is attached via a support member (53) attached to an outer shell member (47) constituting a passage for the combustion gas (G). A catalytic device (42) for purifying the combustion gas (G) is provided, and the sensor (80) is disposed in a member connected immediately downstream of and immediately after the catalytic device (42) in the flow path of the combustion gas (G). The outer shell member (47) is tapered toward the downstream side of the flow path of the combustion gas (G), so that the surface of the sensor (80) is inclined in a side view.
[Selection diagram] Figure 9

Description

The present invention relates to an exhaust system, and in particular to an exhaust system equipped with a sensor that detects the concentration of a specific component contained in the combustion gas of an internal combustion engine.

Conventionally, exhaust devices have been known in which a sensor that detects the concentration of a specific component contained in the combustion gas of an internal combustion engine is disposed so that the detection portion is exposed within the combustion gas passage.

Patent Document 1 discloses a configuration in which a cylindrical boss for supporting a cylindrical oxygen sensor in an exhaust system for a motorcycle is attached directly to an opening in the combustion gas passage.

JP 2017-214904 A

However, in the configuration of Patent Document 1, the boss that supports the sensor is attached directly to the combustion gas passage, so the temperature of the combustion gas passage is easily transmitted to the sensor via the boss, and there is an issue that the temperature of the sensor is likely to become high if an attempt is made to place the sensor inside the muffler where it is not easily exposed to the wind from traveling.

The object of the present invention is to provide an exhaust system that solves the problems of the conventional technology and can suppress the temperature rise of the sensor even when the sensor is installed inside the muffler.

To achieve the above object, the present invention has a first feature in that, in an exhaust system (30) having a sensor (80) that detects a specific component contained in combustion gas (G), a boss (54) that supports the sensor (80) is attached via a support member (53) attached to an outer shell member (47) that forms the passage for the combustion gas (G).

The second feature is that the device is equipped with a catalytic device (42) that purifies the combustion gas (G), and the sensor (80) is disposed in a member connected immediately downstream of and to the catalytic device (42) in the flow path of the combustion gas (G).

The third feature is that the outer shell member (47) is a tapered tube whose surface is inclined when viewed from the side of the sensor (80) by narrowing in diameter toward the downstream side of the flow path of the combustion gas (G).

The exhaust system (30) is attached to the body of a saddle-type vehicle (1), and the saddle-type vehicle (1) has a functional part (27) located in front of the sensor (80), and the functional part (27) covers at least a portion of the sensor (80) when viewed from the front of the vehicle body, which is a fourth feature.

The fifth feature is that a wind receiving member (51) is provided around the sensor (80) and is inclined so that the rear side of the vehicle body is positioned further outward in the vehicle width direction than the front side of the vehicle body.

The sixth feature is that, in a side view of the vehicle body, the sensor (80) is disposed on the inside in the vehicle width direction of a side stand (24) attached to the body of the saddle-type vehicle (1).

The seventh feature is that the boss (54) is attached via the support member (53) so that the boss (54) is disposed at a position spaced radially outward from the opening (48) formed in the outer shell member (47).

Furthermore, the eighth feature is that the boss (54) is attached to a first support member (52) that is attached to the support member (53).

According to the first feature, in an exhaust system (30) having a sensor (80) that detects a specific component contained in the combustion gas (G), the boss (54) that supports the sensor (80) is attached via a support member (53) attached to the outer shell member (47) that forms the passage for the combustion gas (G), so that the temperature of the outer shell member is less likely to be transmitted to the boss and the sensor compared to a configuration in which the boss is directly attached to the outer shell member that forms the passage for the combustion gas. This makes it possible to prevent the temperature of the sensor from becoming too high, even when the sensor is disposed inside the muffler.

According to the second feature, a catalytic device (42) that purifies the combustion gas (G) is provided, and the sensor (80) is disposed in a member that is connected downstream and immediately after the catalytic device (42) in the flow path of the combustion gas (G). By disposing the sensor immediately after the catalytic device, it is possible to improve the detection accuracy of a specific component of the combustion gas.

According to the third feature, the outer shell member (47) is a tapered tube whose surface is inclined in a side view of the sensor (80) as the diameter of the outer shell member (47) decreases toward the downstream side of the flow path of the combustion gas (G). Therefore, compared to a configuration in which the surface of the outer shell member is oriented horizontally, for example, it is possible to arrange the sensor closer to the center of the outer shell member, thereby saving space.

According to the fourth feature, the exhaust device (30) is attached to the body of a saddle-type vehicle (1), and the saddle-type vehicle (1) has a functional part (27) located in front of the sensor (80), and the functional part (27) covers at least a portion of the sensor (80) when viewed from the front of the vehicle body, so that it is possible to protect the sensor from stone chips and the like that occur from the front when the saddle-type vehicle is traveling.

According to the fifth feature, a wind-receiving member (51) is provided around the sensor (80) and is inclined so that the rear side of the vehicle body is positioned more outward in the vehicle width direction than the front side of the vehicle body. By receiving the wind from the vehicle while it is traveling, the cooling effect of the sensor can be further improved.

According to the sixth feature, the sensor (80) is disposed on the vehicle widthwise inner side of the side stand (24) attached to the body of the saddle-type vehicle (1) when viewed from the side of the vehicle body, so that the sensor can be protected from stones and the like thrown from the side of the vehicle body.

According to the seventh feature, by attaching the boss (54) via the support member (53), the boss (54) is disposed at a position spaced radially outward from the opening (48) formed in the outer shell member (47). Since the boss does not come into direct contact with the opening provided in the outer shell member, heat from the outer shell member is less likely to be transferred to the sensor, and the temperature of the sensor can be prevented from becoming too high.

According to the eighth feature, the boss (54) is attached to the first support member (52) which is attached to the support member (53), which further prevents the temperature of the sensor from becoming too high.

1 is a right side view of a motorcycle to which an exhaust device according to an embodiment of the present invention is applied. FIG. FIG. 2 is a partially enlarged left side view of the motorcycle with exterior parts removed. FIG. 4 is a cross-sectional view taken along line VV in FIG. 3. 6 is a cross-sectional view taken along line VI-VI of FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 4. FIG. 8 is a partially enlarged view of FIG. 7 . 4 is a cross-sectional view showing the sensor attachment portion as viewed from the side of the sensor. FIG.

The preferred embodiment of the present invention will now be described in detail with reference to the drawings. Fig. 1 is a right side view of a motorcycle 1 to which an exhaust device 30 according to one embodiment of the present invention is applied. Fig. 2 is a left side view of the motorcycle 1. The motorcycle 1 is a straddle-type vehicle that travels by transmitting the driving force of a power unit P, which is an integral combination of an internal combustion engine and a transmission, to a rear wheel WR via a drive chain 18.

A head pipe F1 that rotatably supports a steering stem (not shown) is provided at the front end of a pair of left and right main frames F2 that make up the vehicle body frame F. A top bridge 9 and a bottom bridge 5 that support a pair of left and right front forks 2 are fixed to the upper and lower ends of the steering stem, respectively.

A front wheel WF is rotatably supported on the lower end of the front fork 2. A front fender 3 that covers the upper part of the front wheel WF is attached to the front fork 2. A pair of left and right steering handlebars 10 are attached to the upper part of the top bridge 9. A front cowl 6 that supports a headlight 4 is disposed in front of the head pipe F1. A windscreen 8 and a pair of left and right rearview mirrors 7 are attached to the upper part of the front cowl 6. A pair of left and right side cowls 23 are connected to the lower part of the front cowl 6, and an under cowl 22 that covers the lower part of the power unit P is connected to the lower end of the side cowls 23.

A fuel tank 11 is disposed on top of the main frame F2. A pivot frame F3 supporting a pivot 21 that pivotally supports a swing arm 19 is connected to the rear end of the main frame F2, which extends rearward and downward from the head pipe F1. Step holders 28 supporting step bars 20 on which the rider places his or her feet are attached to positions toward the lower side of the pivot frame F3. A side stand 24 that supports the vehicle body in a tilted state to the left is rotatably attached to the lower end of the pivot frame F3 on the left side in the vehicle width direction. A power unit P to which an exhaust device 30 is attached is suspended below the main frame F2 and in front of the pivot frame F3.

The swing arm 19, which rotatably supports the rear wheel WR, is suspended from the main frame F2 at a position toward the front by the rear cushion 12. A rear frame F4 is fixed to the rear end of the main frame F2, extending rearward and upward and supporting a seat 13 on which a passenger sits and a rear cowl 15 in which a taillight unit 16 is embedded. In addition, a pair of left and right tandem step holders 14 and a rear fender 17 that covers the upper part of the rear wheel WR are attached to the rear frame F4.

The exhaust system 30 has a muffler 31 located below the step bar 20. A muffler protector 32 is attached to the right side of the muffler 31 in the vehicle width direction. A sensor attachment section 50 is provided on the left side of the muffler 31 in the vehicle width direction, to which a sensor 80 that detects the concentration of a specific component contained in the combustion gas is attached. The sensor attachment section 50 is disposed at a position on the inside of the side stand 24 in the vehicle width direction, thereby protecting the sensor from stone chips and the like from the side of the vehicle body.

Figure 3 is a partially enlarged left side view of motorcycle 1 with exterior parts removed. Also, Figure 4 is a left side view of exhaust device 30. The same reference numerals as above indicate the same or equivalent parts. Exhaust device 30 is composed of four exhaust pipes 33 connected to cylinder head 29 of the internal combustion engine, a collector 34 connected to the rear of exhaust pipes 33, a catalyst storage section 35 connected to the rear of collector 34, a muffler 31 connected to the rear of catalyst collector 35, and an exhaust pipe 40 protruding from the rear of muffler 31.

The sensor mounting section 50, which is provided on the left side of the muffler 31 in the vehicle width direction, is composed of a wind receiving member 51 that receives wind from the front as the vehicle travels, and a first support member 52 that is circular when viewed from the front and faces through an opening provided in the wind receiving member 51.

A cylindrical oil filter 26 is attached to the front of the crankcase 25 that supports the cylinder head 29, and an oil pan 27 for storing oil is attached to the lower end of the crankcase 25. A sensor 80 that detects the concentration of a specific component contained in the combustion gas G is attached to a sensor mounting portion 50 provided on the muffler 31. A harness 81 that outputs a sensor signal extends forward from the upper end of the approximately cylindrical sensor 80. The sensor 80 can be, for example, an O2 sensor or LAF sensor that detects oxygen concentration, or an SO2 sensor that detects nitrogen dioxide concentration.

The catalyst storage section 35 contains a cylindrical catalyst device 42. The mounting hole 82 into which the sensor 80 is screwed is provided in a member connected immediately downstream of the catalyst device 42. Inside the muffler 31, a first pipe 36 connected to the rear of the catalyst device 42, a second pipe 37 having a punching pipe 38, and a third pipe 39 connected to the exhaust pipe 40 are arranged, and together with multiple partition walls (not shown), an expansion chamber that expands the combustion gas G is formed.

The combustion gas G discharged from the exhaust port provided in the cylinder head 29 passes through the exhaust pipe 33, the collector section 34, the catalyst storage section 35, the muffler 31, and the exhaust pipe 40 and is discharged to the rear of the vehicle body.

Figure 5 is a cross-sectional view taken along line V-V in Figure 3. The same reference numerals as above indicate the same or equivalent parts. The catalyst device 42 housed in the catalyst housing 35 is configured by housing a cylindrical honeycomb core 43 in a cylindrical outer tube 44. The honeycomb core 43 is a metal foil made of overlapping flat and corrugated foils carrying a catalyst such as platinum, which is wound multiple times to form a honeycomb structure.

The catalytic converter 42 is housed in a heat insulating tube 46 that constitutes the catalyst housing 35, with a case member 45 wound around the outer cylinder 44. The wind receiving member 51, which is made of a thin metal plate, has a protruding portion 51a at its rear end that projects to the left in the vehicle width direction, and is disposed at an angle so that the rear side of the vehicle body is positioned further outward in the vehicle width direction than the front side of the vehicle body. This makes it easier for the wind receiving member 51 to receive the wind while the vehicle is traveling, improving the cooling effect of the sensor 80.

Figure 6 is a cross-sectional view taken along line VI-VI in Figure 3. The same reference numerals as above indicate the same or equivalent parts. The oil pan 27 attached to the lower end of the crankcase 25 is positioned so that its downward protrusion is offset to the left in the vehicle width direction from the center of the vehicle body. In a front view of the vehicle body, the four exhaust pipes 33 are arranged side by side along the inclined surface that slopes upward to the left in the figure on the right side of the oil pan 27 in the vehicle width direction. A collector section 34 connected to the rear of the exhaust pipes 33 curves to the left in the vehicle width direction behind the oil pan 27 and is connected to the front of the muffler 31.

When viewed from the front of the vehicle, the sensor 80 is disposed in a position that is slightly visible from the right-upward inclined surface on the left side of the oil pan 27 in the vehicle width direction. This makes it possible to protect the sensor 80 from stone chips and the like from the front while ensuring the cooling effect of the wind generated by the wind receiving member 51.

Figure 7 is a cross-sectional view taken along line VII-VII in Figure 4. Figure 8 is an enlarged view of a portion of Figure 7, and Figure 9 is a cross-sectional view showing the sensor mounting portion 50 as viewed from the side of the sensor 80. The same reference numerals as above indicate the same or equivalent parts. The sensor 80 is attached to a tapered tube 47, which serves as an outer shell member connected to the rear of the catalytic converter 42, and is disposed downstream of and immediately behind the catalytic converter 42. This improves the accuracy of detection of a specific component contained in the combustion gas G.

In this embodiment, the cylindrical boss 54 to which the sensor 80 is screwed is not directly attached to the tapered tube 47, but is attached to the first support member 52 via the second support member 53 attached to the tapered tube 47. With this configuration, the boss 54 does not come into direct contact with the second support member 53, so that the temperature of the sensor 80 can be prevented from becoming too high. In the axial direction of the sensor 80, the first support member 52 is fixed to the upper edge of the second support member 53, the boss 54 is attached to the first support member 52, and the wind receiving member 51 is fixed to the upper edge of the first support member 52. The periphery of the wind receiving member 51 is attached to an opening provided in the heat shield 49 that forms the outer shell of the muffler 31. Note that attaching the boss 54 via the second support member 53 is not limited to the case where the first support member 52 to which the boss 54 is attached is attached to the second support member 53 as in this embodiment, but also includes the case where the boss 54 is directly attached to the second support member 53.

In this embodiment, by attaching the boss 54 via the second support member 53, the boss 54 is disposed at a position spaced radially outward from the opening 48 formed in the tapered tube 47. This prevents the boss 54 from directly contacting the edge of the opening 48 of the tapered tube 47, making it difficult for heat from the tapered tube 47 to be transmitted to the sensor 80, and thus making it possible to suppress a rise in temperature of the sensor 80.

A connecting member 47a is attached to the upstream end of the tapered tube 47 for connecting to the outer tube 42 of the catalytic converter 42. The outer shell member is composed of the tapered tube 47 and the connecting member 47a. As shown in FIG. 9, the diameter of the tapered tube 47 decreases toward the downstream side, so that the surface of the sensor 80 is shaped to slope downward toward the rear in a side view of the sensor 80. This makes it possible to position the sensor 80 closer to the center of the tapered tube 47, for example, and reduce the amount of upward protrusion of the sensor 80 in the figure, compared to a configuration in which the surface of the tapered member 47 is oriented horizontally in the figure.

As described above, in the exhaust device 30 according to the present invention, in the exhaust device 30 having the sensor 80 that detects a specific component contained in the combustion gas G, the boss 54 supporting the sensor 80 is attached to the first support member 52 via the second support member 53 attached to the tapered tube 47 that constitutes the passage of the combustion gas G. This makes it possible to make it difficult for the temperature of the tapered tube 47 to be transmitted to the boss 54 and the sensor 80, compared to a configuration in which the boss 54 supporting the sensor 80 is directly attached to the passage of the combustion gas G. This makes it possible to prevent the temperature of the sensor 80 from becoming too high, even when the sensor 80 is disposed inside the muffler 51.

The shape of the motorcycle, the structure of the exhaust system, the internal structure of the muffler, the shape of the oil pan, the shape and structure of the sensor, the number and arrangement of the sensors, the shape and structure of the wind receiving member and the first support member, the shape and structure of the second support member, the mounting position of the second support member, the shape and structure of the tapered tube, the shape and structure of the catalytic converter, etc. are not limited to the above embodiment and can be modified in various ways. The exhaust system according to the present invention can be applied to various vehicles, such as saddle-type three-wheeled and four-wheeled vehicles, and three-wheeled and four-wheeled vehicles having a passenger compartment, as well as motorcycles.

Reference Signs List 1...Motorcycle (saddle-type vehicle), 24...Side stand, 27...Oil pan (functional part), 30...Exhaust device, 31...Muffler, 42...Catalyst device, 47...Outer shell member, 51...Wind-receiving member, 52...First support member, 53...Second support member (support member), 54...Boss, 80...Sensor, G...Combustion gas

Claims (7)

In an exhaust system (30) having a sensor (80) for detecting a predetermined component contained in a combustion gas (G),
a cylindrical boss (54) supporting the sensor (80) is attached via a second support member (53) attached to an outer shell member (47) that constitutes a passage for the combustion gas (G);
The boss (54) is attached to a first support member (52) that is attached to the second support member (53) . A catalytic converter (42) for purifying the combustion gas (G),
2. The exhaust system of claim 1, wherein the sensor (80) is disposed on a member connected immediately downstream of and to the catalytic device (42) in a flow path of the combustion gas (G). The exhaust device according to claim 1 or 2, wherein the outer shell member (47) is a tapered pipe whose surface is inclined in a side view of the sensor (80) by decreasing in diameter toward the downstream side of the flow path of the combustion gas (G). The exhaust device (30) is attached to a body of a saddle-type vehicle (1),
The saddle-type vehicle (1) has a functional component (27) located in front of the sensor (80),
The exhaust system according to claim 1 or 2, wherein the functional component (27) covers at least a portion of the sensor (80) when seen from the front of the vehicle body. The exhaust system according to claim 4, wherein the sensor (80) is disposed on the inner side in the vehicle width direction of a side stand (24) attached to the body of the saddle-type vehicle (1) when viewed from the side of the vehicle body. The exhaust device according to claim 1 or 2, wherein the boss (54) is attached via the support member (53) so that the boss (54) is disposed at a position spaced radially outward from the opening (48) formed in the outer shell member (47). The first support member (52) supports an outer surface of the boss (54) by an inner surface of a circular hole formed in the first support member (52),
3. The exhaust system according to claim 1, wherein the boss (54) is in contact only with the first support member (52) and is not in direct contact with the second support member (53).

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