JP2014009615A - Sensor-protective structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor-protective structure that has low flow resistance to gas flowing in a passage and catches water droplets of condensed water from the upstream toward a sensor to remove them.SOLUTION: A sensor-protective structure 10 includes a passage 20, a sensor 30, and a guide 40. The passage 20 allows intake air or exhaust air of an internal combustion engine 1 to circulate. The sensor 30 is installed on an attaching part 21 prepared on a wall 20A of the passage 20 and projects toward the inside of the passage 20, and a detection part 31 faces inside the passage 20. The guide 40 includes a central part 41 and a fold-back part 42, a base 40A is fixed to the upstream of the attaching part 21, and a tip 40B is inclined to the downstream of the passage 20. The central part 41 forms a roof 411 projecting to the upstream of the passage 20, from the base 40A to the tip 40B. The fold-back part 42 is arranged on both sides of the central part 41 from the base 40A to the tip 40B, and forms a side ditch 421 which is hollow to the downstream of the passage 20.

Description

  The present invention relates to a protection structure for a sensor disposed in an exhaust passage of an internal combustion engine.

  There is an internal combustion engine in which oxygen or the like is detected by a sensor provided in an exhaust passage, and a fuel injection amount and an intake air amount are controlled based on the detection result. The sensor installed in the exhaust passage includes a detection element, a heater for activating the detection element, and a cover that covers the detection element. The cover has a vent so that the detection element contacts the exhaust gas. This sensor may be installed in the vicinity of the intake manifold in order to optimize combustion in a so-called dual loop EGR (exhaust gas recirculation) system.

  In the case of a dual loop EGR system, depending on the temperature and humidity of the outside air and operating conditions, the water vapor in the intake gas is cooled and condensed in the intercooler to become condensed water. The condensed water flows along the inner wall of the intake passage or is scattered on the flow of intake gas. If condensed water adheres to the detection element that has become high temperature, the detection element may be damaged by thermal shock. For this reason, a cover is attached to the outer periphery of the detection element to prevent the condensed water from adhering. However, condensed water may enter through the vents.

  According to the water-reduction structure for a sensor described in Patent Document 1, a rectifying plate for rectifying a part of exhaust gas at an acute angle with respect to the sensor is provided upstream of the sensor installed in the exhaust pipe. I have. The current plate is attached in the form of a curtain plate from the side where the sensor is installed, and extends obliquely toward the downstream side.

JP 2007-321593 A

  The rectifying plate installed in Patent Document 1 changes the airflow inside the exhaust pipe in a direction away from the sensor. At this time, since the rectifying plate is installed in the form of a curtain plate, the flow cross-sectional area of the exhaust pipe is narrowed to generate flow resistance, and a reduced pressure region is formed on the downstream side, thus flying. Easy to entrain water drops. As a result, the water droplets that have flowed to the lower edge (tip) of the current plate and the water droplets passing through the lower edge are blown up toward the downstream side of the current plate, that is, the upper side where the sensor is attached. The sensor will be wetted to a higher range than the lower end.

  Further, the rectifying plate has a water conduit portion at the tip portion for guiding the collected and collected condensed water in the radial direction of the exhaust pipe. The water conduit portion extends in a direction substantially perpendicularly crossing the gas flow in the exhaust pipe. Since the gas flows through the exhaust pipe at a flow velocity at which condensed water droplets fly, the condensed water accumulated in the water conduit located at the downstream end of the rectifying plate may spill out with the force of the gas. This spilled condensed water may be caught by a gas in a decompression region downstream of the rectifying plate, that is, wet the sensor at a position higher than the rectifying plate.

  Therefore, the present invention provides a protection structure for a sensor that captures and eliminates water droplets of condensed water that have a small flow resistance with respect to a gas flowing in a passage and come from the upstream toward the sensor.

  A sensor protection structure according to an embodiment of the present invention includes a passage, a sensor, and a guide. The passage circulates intake or exhaust of the internal combustion engine. The sensor is installed in a mounting portion prepared on the wall of the passage, protrudes toward the inside of the passage, and the detection portion faces the passage. The guide includes a central portion and a return portion, the base portion is fixed upstream of the attachment portion, and the tip portion is inclined downstream of the passage. The central part forms a ridge protruding toward the upstream of the passage from the base to the tip. The return portions are disposed on both sides of the central portion from the base portion to the tip portion, and form side grooves that are recessed toward the downstream of the passage.

  At this time, the central portion has a width larger than the width of the sensor having the center line in the direction in which the sensor protrudes when viewed from the upstream side of the passage. Alternatively, the outer surface of the return portion is formed so as to move away from the sensor as it goes downstream of the passage. Alternatively, the downstream edge of the return portion is formed at an acute angle. Alternatively, the ridge at the center is projected upstream from the upstream end of the return portion. When the sensor has a vent hole on the outer periphery, the guide has a size that at least hides the vent hole when viewed from the upstream side of the passage. Further, the return portion of the tip portion may be formed so as to be at least the same distance from the inner wall of the passage where the attachment portion and the base portion are disposed in the radial direction of the passage with respect to the central portion of the tip portion. . Further, the downstream end of the tip may extend to the downstream side of the center of the sensor.

  According to the protection structure of the sensor of the present invention, the base is fixed upstream of the mounting portion on which the sensor is installed, and the guide is tilted downstream. This guide has a central part formed from the base part to the tip part with the ridge protruding upstream, and a return part that is arranged on both sides of the central part from the base part to the tip part and forms a side groove recessed downstream. ing. Since the tip of the guide is inclined downstream, the flow resistance is small with respect to the gas flowing in the passage. In addition, the condensed water flowing from the upstream along the passage is captured by the guide, whether it is condensed water flowing along the inner wall of the passage or condensed water flying on the gas flowing through the passage. Be collected. The collected condensed water is collected in the side groove by the gas flowing through the passage. Further, since the tip of the guide is inclined downstream with respect to the base, the guide flows along the side groove from the base to the tip and is discharged. In this way, water droplets of condensed water coming from the upstream toward the sensor are surely captured and eliminated. According to this protective structure, since the flow resistance of the guide is small, it is difficult to form a decompression region downstream of the guide, and therefore, condensed water is not caught in the projection region of the guide in the downstream direction. That is, since the guide is positioned upstream of the sensor, the sensor can be protected from getting wet with condensed water.

  According to the protection structure of the invention in which the central portion of the guide has a width larger than the width of the sensor centered on the direction in which the sensor protrudes when viewed from the upstream side of the passage, the condensed water discharged from the side groove of the return portion is The sensor is not wetted because it is discharged to pass through the side of the sensor.

  According to the protective structure of the invention in which the outer surface of the return portion is formed so as to move away from the sensor as it goes downstream of the passage, the condensate flowing out from the side groove of the guide is positively detected by the gas hitting the outer surface of the return portion. It is possible to drain away from the direction.

  According to the protection structure of the invention in which the edge on the downstream side of the return portion is formed at an acute angle, it is difficult to generate turbulent flow downstream of the guide, and water drainage on the edge on the downstream side of the return portion is improved. Since the direction in which condensed water is discharged from the guide is stable, it is easy to protect the sensor from getting wet.

  According to the protection structure of the invention in which the ridge of the central portion protrudes upstream from the upstream end of the return portion, even if there is a lot of moisture in the gas flowing through the passage and a lot of condensed water is generated, the condensed water is surely Therefore, the condensed water is not discharged from the range of the central portion of the front end portion of the guide.

  According to the protection structure of the invention in which the sensor has a vent hole on the outer periphery, and the guide is formed so as to hide at least the vent hole when viewed from the upstream side of the passage, the guide having the minimum size as the protection structure By doing so, the flow resistance of the guide to the gas flowing in the passage can be minimized.

  According to the protective structure of the invention, the return portion of the tip portion of the guide is separated from the inner wall of the passage where the mounting portion and the base portion are disposed in the radial direction of the passage by at least the same distance from the central portion of the tip portion. The end face of the tip is arranged in a direction along the flow direction of the passage. Therefore, the flow resistance at the tip of the guide is reduced, and the direction of discharging condensed water from the side groove of the tip is stabilized.

  According to the protection structure of the invention in which the downstream end of the guide tip extends to the downstream side from the center of the sensor, the condensed water discharged from the side groove at the tip of the guide is reliably downstream from the center of the sensor. Be guided to.

The schematic diagram which shows an internal combustion engine provided with the protection structure of the sensor of 1st Embodiment. The perspective view which looked at the protection structure of the sensor of FIG. 1 from the inner side of the channel | path. The front view which looked at the protection structure of FIG. 2 from the upstream. The side view of the protection structure of FIG. The figure seen from the direction perpendicular | vertical to the end surface of the front-end | tip part of the guide of FIG. The top view which looked at the protection structure of FIG. 2 from the center of the channel | path. The top view which looked at the protection structure of the sensor of 2nd Embodiment from the center of the channel | path. The perspective view which looked at the protection structure of the sensor of 3rd Embodiment from the inner side of the channel | path. The side view of the protection structure of FIG. The perspective view which looked at the protection structure of the sensor of 4th Embodiment from the inner side of the channel | path. The side view of the protection structure of FIG.

  A sensor protection structure 10 according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic view of an internal combustion engine to which the sensor protection structure 10 is applied. The internal combustion engine 1 shown in FIG. 1 includes an intake passage 12 communicating with the engine 11 and an exhaust passage 13 extending from the engine 11, and a supercharger 14 is installed between the intake passage 12 and the exhaust passage 13. The intake passage 12 has a flow sensor 121 upstream of the supercharger 14, and an intercooler 122 and an oxygen sensor (so-called A / F (Air Fuel retio) sensor) 123 downstream of the supercharger 14. ing. Further, the exhaust passage 13 has an oxygen sensor 132 downstream of the catalyst 131. The supercharger 14 is a so-called turbocharger, and includes a turbine disposed in the exhaust passage 13 and a compressor disposed in the intake passage 12. The internal combustion engine 1 employs a so-called dual loop EGR (Exhaust Gas Recircuration) system.

  The oxygen sensor 123 is installed in the vicinity (upstream) of the intake manifold 113 connected to the intake port 111 in order to optimize combustion in the dual loop EGR system. The dual loop EGR system has a high pressure EGR passage 161 and a low pressure EGR passage 162 which are one form of the exhaust gas recirculation passage. The high pressure EGR passage 161 communicates the exhaust passage 13 between the exhaust port 112 of the engine 11 and the supercharger 14 to the intake passage 12 between the intercooler 122 and the intake port 111. The low pressure EGR passage 162 allows the exhaust passage 13 downstream of the supercharger 14 to communicate with the intake passage 12 upstream of the supercharger 14.

  The high pressure EGR passage 161 includes a high pressure EGR valve 163 at an end portion on the intake passage 12 side, and the low pressure EGR passage 162 includes a low pressure EGR valve 164 at an end portion on the intake passage 12 side. When the high pressure EGR valve 163 and the low pressure EGR valve 164 are opened, part of the exhaust gas is recirculated by the high pressure EGR passage 161 and the low pressure EGR passage 162, respectively. By performing the exhaust gas recirculation, moisture (water vapor) in the exhaust gas also enters the intake gas, so that the amount of moisture (water vapor) in the intake gas increases. Further, the amount of moisture in the exhaust gas is increased by burning the intake gas having an increased amount of moisture.

  In the internal combustion engine 1 in this embodiment, the condensed water generated when the water vapor in the intake gas is cooled by the intercooler and the condensed water generated when the water vapor in the exhaust gas is cooled in the exhaust passage 13 are: The protection structure 10 is provided so as not to adhere to the sensors installed in the intake passage 12 and the exhaust passage 13, respectively. The protection structure 10 of the first embodiment is shown in FIGS.

  As shown in FIG. 2, the sensor protection structure 10 includes at least a passage 20, a sensor 30, and a guide 40. The passage 20 is a passage through which intake air or exhaust gas from the internal combustion engine 1 circulates. In the first embodiment, the passage 20 is the intake passage 12 and the exhaust passage 13. The sensor 30 is, for example, the above-described oxygen sensor 123, which is installed in the attachment portion 21 prepared on the wall 20A of the passage 20, protrudes toward the inside of the passage 20, and the detection portion 31 faces the passage. Yes. As shown in FIGS. 2 and 4, the detection unit 31 is covered with a cover 32, and has a vent hole 33 communicating the inside and the outside of the cover 32 on the outer periphery. The position of the vent hole 33 may be slightly different depending on the type of sensor 30 and installation conditions.

  As shown in FIGS. 2 to 6, the guide 40 includes a central portion 41 and a return portion 42, the base portion 40 </ b> A is fixed upstream of the attachment portion 21, and the distal end portion 40 </ b> B is inclined downstream of the passage 20. That is, the angle formed by the guide 40 with respect to the inner wall 20B of the downstream passage 20 from the point where the base portion 40A is fixed is an acute angle. As shown in FIGS. 5 and 6, the central portion 41 forms a ridge 411 that protrudes upstream of the passage 20 from the base portion 40 </ b> A to the distal end portion 40 </ b> B. The return portions 42 are disposed on both sides of the central portion 41 from the base portion 40 </ b> A to the distal end portion 40 </ b> B, and form side grooves 421 that are recessed toward the passage 20.

  As shown in FIG. 3, the central portion 41 of the guide 40 has a width G1 larger than the width S of the sensor 30 with the direction in which the sensor 30 protrudes as a center line 30A when viewed from the upstream side of the passage 20. Yes. As shown in FIGS. 3, 5, and 6, the outer surface 422 of the return portion 42 is further away from the sensor 30 as it goes downstream of the passage 20. The downstream edge 423 and the upstream edge 424 of the return portion 42 are each formed at an acute angle. Further, the ridge 411 of the central portion 41 protrudes upstream from the edge 424 at the upstream end of the return portion 42.

  The guide 40 is large enough to hide at least the vent hole 33 of the sensor 30 when viewed from the upstream side of the passage 20. In the first embodiment, the guide 40 is large enough to cover the sensor 30 as shown in FIGS. 3 and 4. That is, it protrudes larger than the sensor 30 in the radial direction of the passage 20 from the inner wall 20 </ b> B of the passage 20. The end face 40C of the tip 40B of the guide 40 in the first embodiment is formed along a plane orthogonal to a line extending from the base 40A to the tip 40B of the guide 40 as shown in FIG. . FIG. 5 shows a state in which the protective structure 10 is viewed along a line extending from the base portion 40A toward the distal end portion 40B. When the passage 20 is arranged almost horizontally and the mounting portion 21 of the sensor 30 is prepared near the top, as shown in FIGS. 3 and 4, the ridge 411 of the central portion 41 of the distal end portion 40B of the guide 40 is the lowest. Become.

  The sensor protection structure 10 configured as described above is formed in the condensed water W and the passage 20 that are transmitted from the upstream side of the sensor 30 along the inner wall 20B of the passage 20 as shown in FIGS. Any of the condensed water W flying on the flowing gas is captured by the guide 40 installed upstream of the sensor 30, collected in the side groove 421, and discharged from the tip 40B. The guide 40 has a small flow resistance against the gas flowing through the passage 20 because the tip end portion 40B is inclined toward the downstream side. Moreover, since the return part 42 is provided in the both sides of the center part 41, and the side groove | channel 421 is formed, the condensed water W caught in the middle of the guide 40, ie, the part from the base 40A to the front-end | tip part 40B, remains as it is. It flows along the side groove 421 to the tip 40B without going around to the back side of the guide 40. Since the edge 423 on the downstream side of the return portion 42 is formed at an acute angle, the condensate W is easily cut off, and the condensate W is not caught on the downstream side of the guide 40. Further, since the outer surface 422 of the return portion 42 is formed so as to move away from the sensor 30 as it goes downstream, the condensed water W is blown away in a direction that actively leaves the sensor 30.

  Since the sensor 30 is hidden in the projection area of the guide 40 in the flow direction of the passage 20, the condensed water W is not directly applied. Further, since the collected condensed water W is discharged from the side groove 421 on the tip end portion 40B side, the collected condensed water W is not indirectly related to the sensor 30. Thus, the protection structure 10 protects the sensor 30 from getting wet with the condensed water W.

  The sensor protection structure 10 according to the second to fourth embodiments will be described below. The configuration having the same function as the sensor protection structure 10 of the first embodiment will be described with the same reference numerals as the configuration of the first embodiment in each embodiment, and the detailed description will be given in the first embodiment. Consider the corresponding description. Moreover, since the whole structure of the internal combustion engine 1 and the place where the sensor 30 is installed are as shown in FIG. 1, these are also taken into consideration when necessary in each embodiment.

  A sensor protection structure 10 according to a second embodiment of the present invention will be described with reference to FIG. The outer surface 422 of the return portion 42 of the guide 40 in the protection structure 10 of the second embodiment is formed along the flow of gas flowing in the passage, that is, in parallel with each other. Other points are the same as those of the protective structure 10 in the first embodiment.

  According to the sensor protection structure 10 configured as described above, the maximum width G2 of the guide 40 having the center line 30A as the direction in which the sensor 30 protrudes with respect to the flow direction of the passage 20 is the same as that of the first embodiment. When the guide 40 is the same, the condensed water in the guide 40 in the second embodiment is more able to flow along the side groove 421.

  A sensor protection structure 10 according to a third embodiment of the present invention will be described with reference to FIGS. The guide 40 in the protection structure 10 of the third embodiment has a distal end portion 40B with respect to the central portion 41 of the distal end portion 40B in the radial direction of the passage 20 from the inner wall 20B of the passage 20 where the mounting portion 21 and the base portion 40A are arranged. Are at least the same distance apart. That is, as shown in FIGS. 8 and 9, when the mounting portion 21 of the sensor 30 is provided near the top of the passage 20 extending substantially horizontally, the end face 40C of the tip 40B of the guide 40 is along the flow direction of the passage. In this case, it is formed almost horizontally. The configuration other than the above may be the protective structure 10 in the first embodiment or the protective structure 10 in the second embodiment.

  In the protection structure 10 configured as described above, the condensed water W captured by the guide 40 flows along the side groove 421 toward the distal end portion 40B. The condensed water W that has reached the tip 40B flows out from the side groove 421 to the end face 40C, and is discharged from the downstream edge 423 of the return portion 42, particularly in this case, the most downstream point 425. As shown in FIG. 9, the most downstream point 425 is closer to the direction in which the sensor 30 protrudes from the attachment portion 21 of the passage 20 than the ridge 411 of the central portion 41 of the distal end portion 40 </ b> B and the distal end of the sensor 30. is seperated. Therefore, the condensed water W that has been pushed off the surface of the guide 40 by the gas flowing in the passage 20 is surely drained at the most downstream point 425. Further, since the end face 40C is formed along the gas flow, it is difficult to cause a turbulence such that the gas flow is wound downstream of the guide 40 at the distal end portion 40B.

  A sensor protection structure 10 according to a fourth embodiment of the present invention will be described with reference to FIGS. 10 and 11. In the case of the fourth embodiment, as shown in FIG. 11, the end face 40C of the tip 40B of the guide 40 is formed along the gas flow in the passage 20, that is, as in the case of the third embodiment. In the radial direction of the passage 20 from the inner wall 20B of the passage 20 where the mounting portion 21 is disposed, the return portion 42 of the tip portion 40B is separated from the central portion 41 of the tip portion 40B by at least the same distance.

  And the guide 40 in the protection structure 10 of 4th Embodiment has a magnitude | size which hides the ventilation hole 33 of the sensor 30 at least seeing from the upstream of the channel | path 20. FIG. In this case, the end surface 40C of the distal end portion 40B of the guide 40 extends to a position H away from the inner wall 20B rather than the farthest portion of the vent hole 33 farthest from the inner wall 20B of the passage 20. As shown in FIGS. 10 and 11, the position H is closer to the inner wall 20 </ b> B than the tip of the sensor 30.

  Further, in the case of the protection structure 10 of the fourth embodiment, the guide 40 is moved as far as possible from the sensor 30 with a distance that does not allow the condensed water W flowing to the tip 40 </ b> B of the guide 40 to move to the cover 32 of the sensor 30. It is a close arrangement. In the case of the fourth embodiment, as shown in FIG. 11, the downstream edge 423 of the return portion 42, that is, the most downstream point 425 in the distal end portion 40 </ b> B of the guide 40 extends to the downstream side of the center line 30 </ b> A of the sensor 30. ing.

  With this configuration, the condensed water W drained from the most downstream point 425 of the guide 40 is discharged to the downstream side of the sensor 30. In addition, since the size of the guide 40 is limited to such an extent that the vent hole 33 of the sensor 30 is hidden, the flow resistance to the gas flowing through the passage 20 is smaller than in other embodiments.

  In the third and fourth embodiments, the central portion 41 and the return portion 42 of the distal end portion 40B of the guide 40 are disposed at substantially the same distance in the radial direction of the passage 20 from the inner wall 20B of the passage 20. On the other hand, the return portion 42 may be formed so as to be separated from the central portion 41, that is, downstream from the upstream of the end surface 40C of the tip portion 40B is separated from the inner wall 20B. In the first embodiment, the end surface 40C of the distal end portion 40B of the guide 40 is formed downstream, so that the outer side surface 422 of the return portion 42 of the guide 40 is formed so as to be separated from each other toward the downstream side of the passage 20. Condensed water W is discharged in a direction of actively leaving the sensor 30 by being formed so as to be away from the attachment portion 21 as it goes.

  In each embodiment, the cross-sectional shape of the central portion 41 of the guide 40 perpendicular to the center line 30A of the sensor 30 is V-shaped, and the overall cross-sectional shape including the return portion 42 is W-shaped. It is not limited to this. The central portion 41 may be U-shaped or parabolic.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 10 ... Protection structure, 20 ... Passage (12 ... Intake passage, 13 ... Exhaust passage), 20A ... Wall, 20B ... Inner wall, 21 ... Mounting part, 30 ... Sensor (123 ... Oxygen sensor), 30A ... Center line, 31 ... detection section, 33 ... vent, 40A guide, 40A ... base, 40B ... tip, 41 ... center, 411 ... ridge, 42 ... return section, 421 ... side groove, 422 ... outer surface, 423 ... (downstream) edge, 424 ... (upstream edge), 425 ... most downstream point, S ... (sensor) width, G1 ... (central part) width, G2 ... (guide) maximum width, W ... condensate.

Claims (8)

A passage through which intake air or exhaust gas from the internal combustion engine flows;
A sensor that is installed in a mounting portion prepared on the wall of the passage and projects toward the inside of the passage, and a detection unit faces the passage;
A central portion that forms a ridge projecting upstream from the passage from the base portion to the distal end portion, and a side groove that is disposed on both sides of the central portion from the base portion to the distal end portion and that is recessed toward the downstream side of the passage. A protective structure for a sensor, comprising: a return portion to be formed, the base portion being fixed upstream of the attachment portion, and the tip portion being inclined toward the downstream side of the passage. 2. The protection structure of a sensor according to claim 1, wherein the central portion has a width larger than a width of the sensor having a center line in a direction in which the sensor protrudes when viewed from the upstream of the passage. 3. The sensor protection structure according to claim 1, wherein an outer surface of the return portion is moved away from the sensor as it goes downstream of the passage. 4. The sensor protective structure according to any one of claims 1 to 3, wherein the downstream edge of the return portion is formed at an acute angle. The sensor ridge structure according to any one of claims 1 to 4, wherein the ridge of the central portion protrudes upstream from the upstream end of the return portion. The sensor has a vent on the outer periphery,
6. The sensor protection structure according to claim 1, wherein the guide has a size that at least hides the vent hole when viewed from an upstream side of the passage. 7. The return portion of the distal end portion is at least the same distance from the inner wall of the passage where the attachment portion and the base portion are disposed in the radial direction of the passage with respect to the central portion of the distal end portion. The sensor protective structure according to any one of claims 1 to 6. The sensor protection structure according to any one of claims 1 to 7, wherein a downstream end of the tip portion extends to a downstream side of a center line of the sensor.

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