JP2016133326A - Vacuum degree estimation system of double-tube system, internal combustion engine, and vacuum degree estimation method of double-tube structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum degree estimation system of a double-tube structure, an internal combustion engine, and a vacuum degree estimation method of the double-tube structure which can easily determine a vacuum degree of a vacuum state in a double-tube structure which creates a vacuum state between an outer tube and an inner tube of the double-tube in which a fluid can be made to flow.SOLUTION: A vacuum degree estimation system 10 of a double-tube structure creates a vacuum state between an outer tube 21 and an inner tube 22 of a double-tube 20 in which a fluid is made to flow inside an inner tube 22, and includes: temperature measurement means 31 for measuring a temperature T of a fluid made to flow in the inner part of the inner tube 21; and vacuum degree estimation means 32 for estimating a temperature difference ΔT between an inlet side temperature Ti and an outlet side temperature To of the double-tube structure of the fluid measured by this temperature measurement means 31 or estimating the degree of vacuum from the outlet side temperature To of this fluid.SELECTED DRAWING: Figure 1

Description

  The present invention maintains a heat insulation property of a double pipe structure in a double pipe structure in which a space between an outer pipe and an inner pipe of a double pipe used for a heat insulation structure such as an exhaust system pipe of an internal combustion engine is in a vacuum state. The present invention relates to a double-pipe structure vacuum degree estimation system, an internal combustion engine, and a double-pipe structure vacuum degree estimation method that can easily estimate a vacuum degree in a double pipe for maintenance.

  In order to purify exhaust gas components such as NOx in the exhaust gas, the engine is provided with an exhaust gas purification device including a catalyst as a post-processing device. In order to keep the catalyst at an activation temperature or higher, an exhaust pipe It is necessary to prevent the exhaust gas flowing in the interior from being cooled by heat radiation from the inside.

  As one of the means for preventing the cooling of the exhaust gas, for example, in at least one of the exhaust gas treatment device of the engine and the exhaust passage leading to the exhaust gas treatment device, the exterior is formed in a double structure having an inner wall and an outer wall. A gas absorbent that absorbs the replacement gas and a radiant heat shielding plate are installed between the inner wall and the outer wall of the double structure, and the replacement gas that has replaced the air in the double pipe structure is absorbed by the gas absorbent. There has been proposed an exhaust gas treatment device and a heat insulation structure of an exhaust passage which are relatively simple and have a high heat insulation capability and prevent a temperature drop due to heat radiation by evacuating the inside of the tube (see, for example, Patent Document 1).

  This double pipe structure has good heat retention, but there is a problem that the degree of vacuum gradually decreases between the inner wall and the outer wall of the double pipe structure. For example, an outer tube portion including an inner tube portion and an outer tube portion fitted on the inner tube portion in a state where a gap is formed between the inner tube portion and the inner tube portion. The two outer tube members to be connected are hermetically connected using a joint with a suction port interposed between the two outer tube members, and a vacuum valve is provided at the suction port of the joint with a suction port. Accordingly, a double pipe structure has been proposed in which a vacuum valve is opened and air in the gap is sucked and exhausted by a vacuum pump so that the inside of the gap can be brought into a desired reduced pressure state (see, for example, Patent Document 2). ).

  The degree of vacuum between the outer tube and the inner tube of this double pipe structure is such that, in an internal combustion engine or the like mounted on a vehicle, the heat insulation performance of the double pipe structure, and hence the exhaust gas purification in the exhaust gas purification device. Since it is directly related to performance, it is an important item in terms of maintenance. However, when the degree of vacuum of this double tube structure is always measured with a pressure gauge, it is necessary to attach a pressure gauge, and there is a problem that the number of parts, wiring, and mounting man-hours increase.

  On the other hand, in the exhaust gas purification device, the exhaust gas temperature is temporarily increased in order to burn and remove PM (fine particles) collected by the fine particle collection device for recovering the purification ability of the exhaust gas purification device. Forcibly regenerating PM or forcibly regenerating NOx in order to regenerate the NOx occlusion power in the NOx occlusion reduction catalyst is performed, for example, forcibly regenerating NOx, and the inlet of the exhaust gas purification device is used for these regeneration controls. Is provided with a temperature sensor for measuring the temperature of the exhaust gas.

JP 2002-349259 A JP 2012-77786 A

  The present invention has been made in view of the above, and an object of the present invention is to provide a double-pipe structure in which a fluid is caused to flow inside the inner tube by making a vacuum between the outer tube and the inner tube of the double tube. It is an object of the present invention to provide a double-pipe structure vacuum degree estimation system, an internal combustion engine, and a double-pipe structure vacuum degree estimation method that can easily determine the vacuum degree of the vacuum state.

  In order to achieve the above object, a double pipe structure vacuum degree estimation system according to the present invention is a double pipe that places a vacuum between an outer pipe and an inner pipe of a double pipe and allows fluid to flow inside the inner pipe. A double-pipe structure vacuum degree estimation system for determining a vacuum degree of a vacuum state in a structure, a temperature measuring means for measuring a temperature of a fluid flowing in the inner pipe, and a fluid measured by the temperature measuring means The double pipe structure is provided with a vacuum degree estimating means for estimating a vacuum degree from the temperature difference between the inlet side temperature and the outlet side temperature of the double pipe structure or the outlet side temperature of the fluid.

  According to this configuration, the vacuum state between the outer tube and the inner tube of the double pipe is changed by the change in the amount of heat radiated or received by the double pipe, that is, the change in the temperature of the fluid flowing inside the inner pipe. Since the determination is made, the degree of vacuum can be estimated with a relatively strong and inexpensive sensor called a temperature sensor.

  In general, the environment outside the outer pipe is little changed, or parameters such as the outside air temperature that represent the environmental state can be measured. Therefore, the inlet of the fluid flowing inside the inner pipe based on the parameter indicating the environmental state is measured. The relationship of the degree of vacuum with respect to the temperature difference between the side temperature and the outlet side temperature is prepared in advance in a database such as map data, and the degree of vacuum can be estimated by referring to this database from the temperature difference.

  In particular, when the temperature of the fluid on the inlet side of the double pipe can be predicted or calculated in advance, only the outlet side temperature can be used for heat dissipation or heat reception of the double pipe, and the heat transfer state of the double pipe can be understood. From this, the degree of vacuum can be estimated. Usually, the relationship between the outlet side temperature and the degree of vacuum is prepared in advance in a database such as map data, and the degree of vacuum can be estimated from the outlet side temperature with reference to this database.

  In the above-described double pipe structure vacuum degree estimation system, the double pipe is disposed in an exhaust gas passage on the upstream side of an exhaust gas purification device for purifying exhaust gas of an internal combustion engine, and the temperature measuring means includes When it is configured with a temperature sensor that measures the temperature of the exhaust gas disposed on the inlet side of the exhaust gas purification device, the exhaust gas purification device is usually used to recover the purification capability of the exhaust gas purification device. A temperature sensor that measures the temperature of exhaust gas is arranged at the inlet of the exhaust gas purification device for controlling the forced regeneration of PM in the particulate collection device and NOx forced regeneration in the NOx storage reduction catalyst. Thus, the degree of vacuum can be estimated.

  In the above-described double pipe structure vacuum degree estimation system, if a check valve is provided in the vacuum pipe for vacuuming between the outer pipe and the inner pipe of the double pipe, the degree of vacuum is lowered. However, when the air pressure between the outer and inner pipes of the double pipe is high, just connect an external pipe connected to the vacuum pump or vacuum tank to the vacuum pipe to restore the degree of vacuum. Therefore, vacuuming can be performed between the outer pipe and the inner pipe, and the degree of vacuum can be maintained by the check valve just by removing the external pipe, so maintenance can be simplified. Man-hours can be reduced.

  In order to achieve the above object, an internal combustion engine according to the present invention provides the temperature of exhaust gas discharged from a cylinder of the internal combustion engine in the purification capability recovery control of the exhaust gas purification device, and the degree of vacuum of the double pipe structure. The estimation system is configured to control according to the estimated degree of vacuum.

  According to this configuration, even when the degree of vacuum of the double pipe structure changes due to secular change and the temperature of the exhaust gas on the outlet side of the double pipe structure decreases, in the purification capacity recovery control, The exhaust gas temperature exhausted from the cylinder can be raised to maintain the exhaust gas temperature necessary for recovery of the purification capacity, so the exhaust gas purification performance is good in response to changes in the vacuum degree of the double-pipe structure. Can be maintained in a state.

  In the internal combustion engine, when the degree of vacuum estimated by the degree-of-vacuum estimation unit is equal to or lower than a preset degree of vacuum, an alarm for prompting evacuation of the double-pipe structure is provided. Since the driver who has received the alarm can perform maintenance at an inspection factory or the like before the exhaust gas purification performance deteriorates, the exhaust gas purification performance can be maintained in a good state.

  In order to achieve the above object, the method for estimating the degree of vacuum of a double pipe structure according to the present invention is a double pipe that places a vacuum between an outer pipe and an inner pipe of a double pipe and allows a fluid to flow inside the inner pipe. A method of estimating the degree of vacuum of a double-pipe structure for determining the degree of vacuum in a vacuum state in the structure, wherein the temperature of the fluid flowing through the inner pipe is measured, and the inlet side temperature and outlet of the double-pipe structure In this method, the degree of vacuum is determined from the temperature difference between the side temperatures or the fluid outlet side temperature. According to this method, an effect similar to that of the double-pipe structure vacuum degree estimation system can be obtained.

  According to the double-pipe structure vacuum degree estimation system, the internal combustion engine, and the double-pipe structure vacuum degree estimation method of the present invention, the vacuum state between the outer pipe and the inner pipe of the double pipe is changed to the double pipe structure. Judgment is based on changes in the amount of heat radiated or received by the pipe, that is, changes in the temperature of the fluid flowing inside the inner pipe, so that the degree of vacuum can be estimated with a relatively strong and inexpensive sensor called a temperature sensor. become.

It is a figure which shows typically the structure of the vacuum degree estimation system of the double pipe structure of embodiment which concerns on this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a double-pipe structure vacuum degree estimation system, an internal combustion engine, and a double-pipe structure vacuum degree estimation method according to embodiments of the present invention will be described with reference to the drawings. In addition, the internal combustion engine of embodiment which concerns on this invention is an internal combustion engine provided with the vacuum degree estimation system of the double pipe structure of embodiment which concerns on this invention.

  As shown in FIG. 1, the double pipe structure vacuum degree estimation system 10 according to the embodiment of the present invention places a vacuum between the outer tube 21 and the inner tube 22 of the double tube 20, and This is a system for determining the degree of vacuum in a vacuum state in a double-pipe structure in which fluid flows inside. This double-pipe structure vacuum degree estimation system 10 measures the temperature T of the fluid flowing inside the inner pipe 22. The temperature difference ΔT (= Ti−To) between the inlet side temperature Ti and the outlet side temperature To of the fluid double tube structure measured by the measuring means 31 and the temperature measuring means 31, or the outlet side temperature To of this fluid The vacuum degree estimating means 32 for estimating the vacuum degree is provided.

  Further, in this double pipe structure vacuum degree estimation system 10, the double pipe 20 is disposed in the exhaust gas passage 2 on the upstream side of the exhaust gas purification device 3 for purifying the exhaust gas of the internal combustion engine, and the temperature measuring means 31 is an inlet side temperature sensor 31a for measuring the temperature Ti of the exhaust gas on the inlet side of the double pipe 20, and the temperature To of the exhaust gas on the outlet side of the double pipe 20, that is, the inlet side of the exhaust gas purification device 3. It comprises an outlet side temperature sensor 31b that measures the above.

  Normally, the exhaust gas purifying device 3 is exhausted for controlling the forced PM regeneration in the particulate collection device and the NOx forced regeneration in the NOx occlusion reduction type catalyst for recovering the purifying ability of the exhaust gas purifying device 3. Since the temperature sensor for measuring the temperature of the exhaust gas is arranged at the inlet of the gas purification device 3, this can be used as the outlet side temperature sensor 31b for estimating the degree of vacuum.

  Further, a check valve 24 is provided in a vacuuming pipe 23 for evacuating the space between the outer pipe 21 and the inner pipe 22 of the double pipe 20. As a result, when the degree of vacuum is reduced and the air pressure between the outer tube 21 and the inner tube 22 of the double pipe 20 is increased, a vacuum pump or a vacuum pump 23 is provided for recovering the degree of vacuum. Vacuum connection between the outer pipe 21 and the inner pipe 22 can be performed simply by connecting the external pipe 40 connected to the vacuum tank, and the degree of vacuum can be maintained by the check valve 24 simply by removing the external pipe 40. become able to. Therefore, maintenance can be simplified and man-hours can be reduced.

  In the internal combustion engine according to the embodiment of the present invention, the temperature Tg of the exhaust gas discharged from the cylinder of the internal combustion engine in the purification capacity recovery control of the exhaust gas purification device 3 is used as the degree of vacuum estimation system having a double pipe structure. 10 is configured to control according to the estimated degree of vacuum.

  As a result, even when the degree of vacuum of the double-pipe structure changes due to secular change and the temperature To of the exhaust gas on the outlet side of the double-pipe structure decreases, in the purification capacity recovery control, from the cylinder The exhaust gas temperature Tg can be raised to maintain the exhaust gas temperature necessary for recovery of the purification capacity, so the exhaust gas purification performance is in good condition in response to changes in the vacuum degree of the double-pipe structure. Can be maintained.

  In addition, when the degree of vacuum estimated by the double-pipe structure vacuum degree estimation system 10 is equal to or lower than a preset degree of vacuum, an alarm that prompts evacuation of the double-pipe structure is provided. As a result, the driver who received this warning is urged to perform maintenance at an inspection factory, etc., so the exhaust gas purification performance can be maintained before the deterioration of the exhaust gas purification performance, so the vacuum can be restored. The exhaust gas purification performance of the exhaust gas purification device 3 can be maintained in a good state.

  Next, the vacuum degree estimation method for the double tube structure according to the embodiment of the present invention will be described. In this method, the space between the outer tube 21 and the inner tube 22 of the double tube 20 is evacuated, and the degree of vacuum in the double tube structure in which a fluid flows inside the inner tube 22 is determined. In this method, the temperature T of the fluid flowing inside the inner tube 22 is measured, and the temperature difference ΔT between the inlet side temperature Ti and the outlet side temperature To of the fluid double tube structure, or the fluid The degree of vacuum is determined from the outlet side temperature To.

  According to the double-pipe structure vacuum degree estimation system 10, the engine 20, and the double-pipe structure vacuum degree estimation method configured as described above, generally, there is little change in the environment outside the outer pipe 21, Since parameters such as the outside air temperature representing the environmental state can be measured, the degree of vacuum with respect to the temperature difference ΔT between the inlet side temperature Ti and the outlet side temperature To of the fluid flowing in the inner tube 22 based on the parameters indicating the environmental state. This relationship can be prepared in advance in a database such as map data, and the degree of vacuum can be estimated from this temperature difference ΔT with reference to this database.

  In particular, when the temperature Ti of the fluid on the inlet side of the double pipe 20 can be predicted or calculated in advance, the amount of heat released or received by the double pipe 20 can be obtained only by the outlet side temperature To. The heat state is known, and the degree of vacuum can be estimated from this. Usually, the relationship between the outlet side temperature To and the degree of vacuum is prepared in advance in a database such as map data, and the degree of vacuum can be estimated from the outlet side temperature To by referring to this database.

  Accordingly, the vacuum state between the outer tube 21 and the inner tube 22 of the double tube 20 is caused by a change in the amount of heat radiated or received by the double tube 20, that is, a change in the temperature of the fluid flowing inside the inner tube 22. Therefore, it is possible to estimate the degree of vacuum with a relatively strong and inexpensive sensor such as the temperature sensors 31a and 31b.

10 Double pipe structure vacuum degree estimation system 20 Double pipe 21 Outer pipe 22 Inner pipe 23 Vacuum pulling pipe 24 Check valve 30 Control device 31 Temperature measuring means 31a Inlet side temperature sensor 31b Outlet side temperature sensor 32 Vacuum degree estimating means 40 External piping Ti Inlet side temperature To Outlet side temperature

Claims (6)

A double-pipe structure vacuum degree estimation system for determining a vacuum degree in a double-pipe structure in which a vacuum state is established between an outer pipe and an inner pipe of a double pipe and a fluid flows inside the inner pipe. ,
Temperature measuring means for measuring the temperature of the fluid flowing through the inner pipe;
It was equipped with a vacuum degree estimation means for estimating the degree of vacuum from the temperature difference between the inlet side temperature and the outlet side temperature of the double pipe structure of the fluid measured by this temperature measuring means, or the outlet side temperature of this fluid. This is a double-pipe structure vacuum degree estimation system.   The double pipe is disposed in an exhaust gas passage upstream of an exhaust gas purification device for purifying exhaust gas of an internal combustion engine, and the temperature measuring means is provided for exhaust gas disposed on the inlet side of the exhaust gas purification device. The double-pipe structure vacuum degree estimation system according to claim 1, comprising a temperature sensor for measuring temperature.   The double pipe structure vacuum degree estimation system according to claim 1 or 2, wherein a check valve is provided in a vacuum drawing pipe for evacuating a space between the outer pipe and the inner pipe of the double pipe.   The temperature of the exhaust gas discharged from the cylinder of the internal combustion engine in the purification capacity recovery control of the exhaust gas purification device is a double-pipe structure vacuum degree estimation system according to any one of claims 2 and 3. An internal combustion engine controlled according to an estimated degree of vacuum.   The internal combustion engine according to claim 4, wherein when the degree of vacuum estimated by the degree-of-vacuum estimation means becomes equal to or lower than a preset degree of vacuum, an alarm is issued to urge the double pipe structure to be evacuated. A method for estimating the degree of vacuum of a double tube structure in which a vacuum state is determined in a double tube structure in which a vacuum is created between an outer tube and an inner tube of a double tube, and a fluid flows inside the inner tube. ,
The temperature of the fluid flowing inside the inner pipe is measured, and the degree of vacuum is determined from the temperature difference between the inlet side temperature and the outlet side temperature of the fluid in the double pipe structure or the outlet side temperature of the fluid. A method for estimating the degree of vacuum of a double tube structure.

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