JP2007154676A - Sensor cleaning device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor cleaning device of an engine capable of removing deposits deposited on an intake temperature sensor. <P>SOLUTION: An engine 12 comprises an EGR device 15 and the intake temperature sensor 44 installed in an intake pipe 13. The sensor cleaning device comprises a compressed air supply source 19, a compressed air supply passage 46, an injection nozzle 25, and a control means 18. The compressed air supply passage 46 connects the compressed air supply source 19 to the injection nozzle 25. The injection nozzle 25 can inject the compressed air supplied from the compressed air supply source 45 to an intake temperature sensor 44. The control means 18 operates an opening/closing valve 47 only for a predetermined time when the operation of the engine 12 is stopped to jet the compressed air to the intake temperature sensor 44. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sensor cleaning device used for cleaning an engine having an intake air temperature sensor or the like.

  A vehicle having an EGR (Exhaust Gas Recirculation) device that suppresses generation of nitrogen oxides (NOx) is known. In this vehicle, an EGR passage that communicates the exhaust passage and the intake passage is provided, and EGR gas that is part of the exhaust gas is returned to the intake system via the EGR passage. By mixing EGR gas into the air-fuel mixture, the combustion temperature is lowered to suppress the generation of nitrogen oxides. In the case of the vehicle, it is provided with two intake temperature sensors provided in the intake passages upstream and downstream of the EGR passage and confirming the operation state of the EGR device, and control means for receiving a signal from the intake air temperature sensor. By comparing the temperatures of the two intake temperature sensors, it can be determined whether or not the EGR gas is flowing normally.

  An engine having a PCV (Positive Crankcase Ventilation) device that prevents blow-by gas that is unburned gas from being released into the atmosphere is also known. In the PCV device, blow-by gas is purified by returning the blow-by gas to the intake passage and re-combusting it in the combustion chamber of the engine. When this blow-by gas is discharged from the crankcase of the engine, the oil content is removed by a breather device or the like, but the remaining engine oil remains in the gas as oil mist and reaches the intake passage without being completely removed. Sometimes.

There is also known an oxygen concentration sensor for detecting the oxygen concentration in exhaust gas. This oxygen concentration sensor includes a sensor element, a protective tube that covers the sensor element, and a compressed air injection device for blowing off carbon adhering to the inside of the protective tube. The compressed air injection device periodically sends compressed air into the protective tube. A jet of compressed air prevents carbon adhering to the sensor element or the like from being blown off, thereby preventing the responsiveness of the sensor element from deteriorating (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 64-48664

  In the case of a vehicle that employs an EGR device and a PCV device, carbon contained in the EGR gas and the oil mist may mix and adhere to the intake air temperature sensor as a deposit. Due to this deposit, there is a problem that the intake air temperature sensor cannot sense the intake air temperature after the introduction of EGR gas.

  In order to remove the deposit, it is conceivable to apply the compressed air injection device of the oxygen concentration sensor described in Patent Document 1 to the intake air temperature sensor. However, in the case of the intake air temperature sensor using the compressed air injection device, since the compressed air is periodically injected during the engine operation, the temperature of the intake air temperature sensor decreases during the engine operation, and actually the EGR Although the gas is flowing, there is a problem that the control means erroneously determines that the EGR gas is not flowing.

  An object of the present invention is to provide an engine sensor cleaning device capable of removing deposits accumulated on an intake air temperature sensor while maintaining an accurate EGR gas determination function during engine operation.

  The sensor cleaning device for an engine according to the present invention includes an EGR device that recirculates exhaust gas to the intake passage through an EGR passage that communicates the exhaust passage and the intake passage, and a connection portion between the EGR passage and the intake passage. In an engine having an intake air temperature sensor provided in the intake passage on the downstream side, a compressed air supply source and a compression provided in the intake passage and supplied from the compressed air supply source via the compressed air supply passage An injection nozzle for injecting air toward the intake air temperature sensor, an on-off valve provided in the compressed air supply passage, and the on-off valve are operated only for a predetermined time when the engine is stopped, and the intake nozzle Control means for injecting compressed air toward the temperature sensor.

  In the engine sensor cleaning device according to another aspect of the present invention, the injection nozzle injects the compressed air from an oblique direction toward the intake temperature sensor from the downstream side in the intake passage with respect to the intake temperature sensor. To do.

  According to the present invention, deposits accumulated on the intake air temperature sensor can be removed by the compressed air injected from the injection nozzle while the engine is stopped, so that the detection accuracy of the intake air temperature sensor does not decrease when the engine is operated. The intake air temperature after the introduction of EGR gas can be detected with high accuracy. Further, the control means drives the on-off valve only for a predetermined time when the engine is stopped to inject compressed air toward the intake air temperature sensor. For this reason, it can be avoided that the compressed air is injected during the operation of the intake air temperature sensor and the temperature of the intake air temperature sensor is lowered, and an erroneous determination that the EGR device has failed can be prevented.

  Below, with reference to FIGS. 1-5, Embodiment of the vehicle to which the sensor cleaning apparatus of the engine of this invention is applied is described.

  FIG. 1 is a diagram schematically showing a part of a vehicle. As shown in FIG. 1, the vehicle 11 includes an engine 12. The engine 12 is a diesel engine including an intercooler turbo (not shown), for example. The engine 12 includes an engine body 20, an intake pipe 13 that is an intake passage, an exhaust pipe 14 that is an exhaust passage, an EGR device (Exhaust Gas Recirculation) 15 that connects the intake pipe 13 and the exhaust pipe 14, and blow-by gas. A PCV (Positive Crankcase Ventilation) device (not shown) for returning the air to the intake pipe 13 is provided.

  Further, the vehicle 11 includes an engine ECU 18 (Electronic control unit) that is a control means, an air tank 19 that is a compressed air supply source, and the like.

  The engine body 20 includes a combustion chamber 12A communicating with the intake pipe 13 and the exhaust pipe 14, an intake valve 12B provided between the combustion chamber 12A and the intake pipe 13, and a space between the combustion chamber 12A and the exhaust pipe 14. And an exhaust valve 12C. The intake pipe 13 is provided with an injection nozzle 25 that forms part of a sensor cleaning device described later.

  Air sucked through an air cleaner (not shown) and blow-by gas discharged from the engine 12 flow into the intake pipe 13. The blow-by gas is introduced into the intake pipe 13 by the PCV device, but contains an oil component (oil mist) that could not be removed.

  The engine ECU 18 is composed of a microcomputer that performs electronic control of the engine 12 and its peripheral devices. The air tank 19 that is a compressed air supply source stores therein compressed air compressed at a pressure of, for example, about 8 atmospheres. The air tank 19 supplies compressed air to an air suspension and an air brake (not shown). The air tank 19 supplies compressed air to the injection nozzle 25 via the on-off valve 47 described below.

  Further, an accelerator position sensor 26, a water temperature sensor 27 that measures the water temperature of the cooling water 30 of the engine 12, and an engine speed sensor 28 that measures the rotational speed of the engine 12 are connected to the engine ECU 18 via a signal line 29. ing.

  The EGR device 15 includes an EGR pipe 33 that is an EGR passage communicating the intake pipe 13 and the exhaust pipe 14, an EGR cooler 34 provided in the middle of the EGR pipe 33, and an EGR valve mechanism 35 that adjusts the flow rate of EGR gas. And have. A connection portion 36 for guiding EGR gas into the intake pipe 13 is provided at a connection portion between the EGR pipe 33 and the intake pipe 13. The EGR device 15 recirculates the exhaust gas to the intake pipe 13 via the EGR pipe 33. The EGR cooler 34 can circulate cooling water inside.

  The EGR valve mechanism 35 includes a lift mechanism 37 for adjusting the flow rate of the EGR gas, three pipes 40 for supplying compressed air to the lift mechanism 37, and three pieces that are connected to the air tank 19 and open and close each pipe 40. The solenoid valve 38 is provided. Each solenoid valve 38 is controlled by the engine ECU 18 via an output line 39 extending from the engine ECU 18. The engine ECU 18 can operate the lift amount of the lift mechanism 37 by adjusting the amount of compressed air flowing into the pipe 40 via each solenoid valve 38. By operating the lift amount of the lift mechanism 37, the flow rate of the EGR gas can be adjusted.

  The engine 12 includes a first intake air temperature sensor 43 and a second intake air temperature sensor 44. The first intake air temperature sensor 43 is provided in the intake pipe 13 at a position upstream from the connection point 36. The second intake air temperature sensor 44 is provided in the intake pipe 13 at a position downstream from the connection point 36. The first intake air temperature sensor 43 and the second intake air temperature sensor 44 are each connected to the engine ECU 18 via a signal line 48.

  The sensor cleaning device includes an injection nozzle 25 that injects compressed air to the second intake air temperature sensor 44, a supply unit 45 that supplies the compressed air to the injection nozzle 25, an engine ECU 18, an air tank 19, and the like.

  The presence / absence of EGR gas is determined using the temperature sensing signal sensed by the first intake air temperature sensor 43 and the temperature sensing signal sensed by the second intake air temperature sensor 44. That is, since the EGR gas that is a part of the exhaust gas has a higher temperature than the air (fresh air) that passes through the intake pipe 13, the second intake temperature sensor 44 is used when the EGR gas flows. A temperature higher than the intake air temperature sensor 43 can be sensed. Using this temperature difference, the engine ECU 18 detects a failure in the EGR device 15 by determining whether or not the EGR gas is flowing normally.

  As shown in FIG. 1, the supply means 45 has a compressed air pipe 46 that is a compressed air passage that connects the injection nozzle 25 and the air tank 19, and an on-off valve 47 disposed in the middle of the compressed air pipe 46. is doing. The on-off valve 47 is driven by a solenoid, and its opening / closing is controlled by the engine ECU 18.

  As shown in FIG. 2, the second intake air temperature sensor 44 includes a sensing portion 51 at the tip, a base portion 52 having a threaded groove on the peripheral surface, and a second intake air temperature sensor 44 disposed between the base portion 52 and the intake pipe 13. 1 gasket 53. The signal line 48 is accommodated in the base 52. The sensing unit 51 can sense the temperature of the EGR gas inside the intake pipe 13 in contact with the EGR gas.

  On the other hand, the intake pipe 13 is provided with a screw hole 55 having a female screw complementary to the base portion 52. When the second intake air temperature sensor 44 is fixed to the intake pipe 13, the second intake air temperature sensor 44 is screwed into the screw hole 55 and fixed through the first gasket 53. The first gasket 53 maintains the airtightness inside the intake pipe 13.

  The injection nozzle 25 is disposed downstream of the position where the second intake temperature sensor 44 is provided and inside the intake pipe 13. The injection nozzle 25 includes a bolt portion 57 that penetrates the intake pipe 13, a nozzle portion 58 that is provided at one end of the bolt portion 57 and that injects compressed air, a nut member 59 that is screwed into the other end of the bolt portion 57, and a bolt And a second gasket 60 disposed between the portion 57 and the intake pipe 13. A flow path 57 </ b> A through which compressed air flows is provided inside the bolt part 57.

  On the other hand, the intake pipe 13 is formed with a through hole 61 in which a female screw complementary to the bolt portion 57 is formed. When the injection nozzle 25 is fixed to the intake pipe 13, the injection nozzle 25 is screwed into the through hole 61 and fixed to the intake pipe 13 via the second gasket 60. The airtightness inside the intake pipe 13 is maintained by the second gasket 60.

  The tip of the nozzle portion 58 is bent obliquely from the downstream side of the intake air toward the second intake air temperature sensor 44 with respect to the second intake air temperature sensor 44. The nozzle portion 58 injects the compressed air obliquely with respect to the axis X of the second intake air temperature sensor 44 toward the downstream surface 44 </ b> A of the second intake air temperature sensor 44. The downstream surface 44A refers to a portion of the entire peripheral surface of the second intake air temperature sensor 44 that is located downstream in the intake air flow direction. Further, in order to direct the nozzle hole of the nozzle portion 58 toward the second intake air temperature sensor 44, positioning alignment marks 62 are provided on the injection nozzle 25 side and the intake pipe 13 side.

  Next, the deposit actually deposited on the second intake air temperature sensor 44 will be described with reference to FIGS. 3 is a view of the second intake air temperature sensor 44 as viewed from the side of the intake pipe 13, and FIG. 4 is a view of the second intake air temperature sensor 44 as viewed from the front end side. As shown in FIGS. 3 and 4, when the travel distance of the vehicle becomes longer, deposits deposited by mixing the oil mist and carbon in the EGR gas adhere to the second intake air temperature sensor 44 as deposits 67. To do.

  The deposit 67 includes a deposit 67A attached to the front end surface of the second intake air temperature sensor 44 and a deposit 67B attached to the peripheral surface of the second intake air temperature sensor 44. A large amount of the deposit 67 is attached to the surface 44A on the downstream side of the second intake air temperature sensor 44 with respect to the flow direction of the intake air.

  With reference to FIG. 5, the flow of the purge which is injection of compressed air is demonstrated. In the vehicle 11 of this embodiment, a purge operation is performed under the control of the engine ECU 18. Hereinafter, each step of the purge flow will be described.

  In the first step S11, the engine 12 needs to be stopped. In this purge flow, the compressed air is injected every time the engine 12 of the vehicle 11 is stopped. Even if the operation of the engine 12 is stopped, the engine ECU 18 is kept energized by the in-vehicle battery for a certain period of time.

  In step S12, the engine ECU 18 confirms that the rotational speed of the engine 12 is zero. If the rotational speed is correctly zero, the process proceeds to the next step S13. If the rotational speed is not zero, the rotational speed is measured again after a predetermined time.

  In step S13, the engine ECU 18 instructs the on-off valve 47 of the supply means 45 to take a compressed air injection standby state. In the subsequent step S14, the engine ECU 18 causes the injection nozzle 25 to perform a purge after a predetermined time has elapsed in the timer measurement. The purge is performed twice. Each purge is performed by, for example, injecting compressed air for 0.5 seconds. The second purge is performed, for example, after 1 second has elapsed after the completion of the first purge.

  Due to this purge, high-pressure compressed air is injected as shown by a two-dot chain line in FIG. 2, and a deposit 67A on the front end surface of the second intake air temperature sensor 44 and a deposit 67B on the peripheral surface of the second intake air temperature sensor 44 are obtained. And are removed. In this case, of the deposit 67B attached to the peripheral surface of the second intake air temperature sensor 44, the one attached to the downstream surface 44A is efficiently removed.

  In step S15, it is confirmed whether or not purging has been performed twice. When the purge is performed twice, the deposit 67 removal process is completed. If the purge has not been performed twice, the on / off valve 47 of the supply means 45 is instructed to perform another purge.

  The above is the embodiment of the vehicle 11 to which the engine sensor cleaning device is applied. According to the present embodiment, the deposit 67 adhering to the second intake air temperature sensor 44 can be removed by purging that is injection of compressed air. Thus, the engine ECU 18 can accurately determine whether or not the EGR device 15 has failed without lowering the EGR gas sensing accuracy of the second intake air temperature sensor 44. Further, since this purge is performed in a state where the engine 12 is stopped, the temperature of the second intake air temperature sensor 44 does not decrease, and the engine ECU 18 erroneously determines that the EGR device 15 has failed. Can be prevented.

  Further, while the engine 12 is being driven, the flow of intake air changes significantly in the intake pipe 13 due to the influence of an intercooler turbo or the like. In this embodiment, since the purge is performed when the operation of the engine 12 is stopped, the compressed air can be reliably injected to the deposit 67 without being influenced by the flow of intake air. In addition, since the alignment marks 62 for positioning are provided on the injection nozzle 25 side and the intake pipe 13 side, the direction of the nozzle hole of the nozzle portion 58 can be easily matched to the second intake temperature sensor 44. Therefore, the compressed air can be reliably injected into the deposit 67 accumulated in the second intake air temperature sensor 44.

  In particular, in this embodiment, a purge is performed every time the driver finishes driving, and this can be removed before the deposit 67 is fixed to the sensing unit 51. Further, the injection nozzle 25 injects compressed air toward the downstream surface 44 </ b> A of the second intake air temperature sensor 44. Thereby, the deposit 67 can be removed mainly on the downstream surface 44A where the deposit 67 is likely to be deposited.

  The injection nozzle 25 injects compressed air obliquely from the downstream side of the intake pipe 13 with respect to the second intake temperature sensor 44. Therefore, the compressed air is injected obliquely with respect to the axis X of the second intake air temperature sensor 44, and the deposit 67A attached to the tip surface of the second intake air temperature sensor 44 and the second intake air temperature. Deposit 67B adhering to the peripheral surface of sensor 44 can be efficiently removed.

  The supply means 45 is configured to share the air tank 19 as a compressed air supply source. For this reason, it is not necessary to provide an air tank separately, and the vehicle 11 and the sensor cleaning device can be simply configured. In addition, since the compressed air is purged twice, the deposit 67 deposited on the second intake air temperature sensor 44 is blown off by the first purge, and further the second purge purges in the vicinity of the second intake air temperature sensor 44. It is possible to move away the deposit 67 that has fluttered to the second intake air temperature sensor 44, and to sufficiently remove the deposit 67 deposited on the second intake air temperature sensor 44.

  Further, since the purge is performed twice in a short time of 0.5 seconds, the deposit 67 can be effectively removed while minimizing the amount of compressed air used.

  In the present embodiment, the supply means 45 is provided with an on-off valve 47 to switch on and off the injection of compressed air. However, an engine ECU 18 that is a control means is provided with a solenoid valve in the injection nozzle 25. The opening / closing of the solenoid valve may be controlled by In addition, the injection nozzle 25 is provided at the connection portion between the compressed air pipe 46 and the intake pipe 13, but this connection portion is configured as a simple opening so that the compressed air pipe 46 and the intake pipe 13 communicate with each other. It may be.

1 is a schematic view of a part of a vehicle including an engine sensor cleaning device of the present invention. Sectional drawing of the 2nd intake-air-temperature sensor vicinity of the vehicle shown by FIG. FIG. 3 is a side view showing a state in which deposits are accumulated on the second intake air temperature sensor shown in FIG. 2. The top view which looked at the state which the deposit accumulated on the 2nd intake-air temperature sensor shown by FIG. 2 from the front end side of the sensor. The flowchart which shows each process of the purge performed with respect to the 2nd intake air temperature sensor shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Vehicle 12 ... Engine 13 ... Intake pipe 14 ... Exhaust pipe 15 ... EGR apparatus 16 ... Removal mechanism 18 ... Engine ECU
19 ... Air tank (Compressed air supply source)
25 ... Injection nozzle 43 ... First intake temperature sensor 44 ... Second intake temperature sensor 44A ... Downstream end 45 ... Supply means 46 ... Compressed air pipe 47 ... Open / close valve 67 ... Deposit

Claims (2)

An EGR device that recirculates exhaust gas to the intake passage via an EGR passage communicating the exhaust passage and the intake passage;
In an engine having an intake air temperature sensor provided in the intake passage downstream of a connection portion between the EGR passage and the intake passage,
A compressed air source;
An injection nozzle that is disposed in the intake passage and injects compressed air supplied from the compressed air supply source through the compressed air supply passage toward the intake air temperature sensor;
An on-off valve provided in the compressed air supply passage;
An engine sensor cleaning device comprising: control means for operating the on-off valve only for a predetermined time when the engine is stopped and injecting compressed air from the injection nozzle toward the intake air temperature sensor.   2. The engine sensor according to claim 1, wherein the injection nozzle injects the compressed air from an oblique direction toward the intake air temperature sensor from a downstream side of the intake air passage with respect to the intake air temperature sensor. Cleaning device.

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