JP6776574B2 - measuring device - Google Patents

Description

The present invention relates to a measuring device and a measuring method capable of suppressing heat transfer from a measurement target such as a combustion chamber of an internal combustion engine to the measuring device due to radiation or convection.

In a measuring device that measures the combustion state in the cylinder of an internal combustion engine, there are many parts that have a relatively high temperature such as a combustion chamber that is the measurement target, and at the time of measurement, between the measurement target and the measurement device. Even if a gap is provided, heat may be transferred from the measurement target to the measuring device due to radiation or convection, and the sensor portion of the measuring device may become hot and damaged.

In this regard, in an optical sensor that measures temperature and pressure in a combustion engine, the temperature at which an optical fiber (wavewave means) located in front of the optical sensor is surrounded by a metal such as copper or other heat conductive metal. By providing a descent means to radiate the heat of the optical fiber or by providing a spacer formed of a hollow tube through which the beam emitted from the optical fiber is transmitted, the low temperature side where the sensor is located from the high temperature side end where the measurement target is located. An optical sensor that reduces heat to the end has been proposed (see, for example, Patent Document 1).

Japanese Patent No. 5628044

However, in a hollow tube, although the amount of heat transfer due to heat convection or heat conduction can be reduced, the amount of heat transfer due to radiant heat (radiant heat) cannot be reduced, and the measurement target has a large amount of radiant heat at high temperature. There is a problem that the heat from the source cannot be sufficiently prevented from reaching the sensor.

An object of the present invention is to provide a measuring device and a measuring method capable of reducing the amount of heat transferred to the sensor of the measuring device for measuring the temperature and concentration of a relatively high temperature object to be measured and extending the life of the sensor. There is.

The measuring device of the present invention for achieving the above object reduces the radiant heat transmitted from the measuring object to the sensor between the measuring object and the sensor that detects the physical quantity indicating the state of the measuring object. A heat quantity reduction mechanism is provided, and the heat transfer amount reduction mechanism is composed of a tubular body. Inside the tubular body, from one end face of the axial end face of the cylinder facing the measurement target side, the said The measuring device is characterized in that a glass layer is provided in order toward the other end face facing the sensor side, a space portion filled with a rare gas or a vacuum space portion, and a glass layer .

Regarding this sensor, when measuring by receiving infrared rays or electromagnetic waves, it means the receiving part, but in order to measure the temperature and the concentration of gas components, terahertz waves etc. are transmitted to the measurement target. When the reflected wave or the scattered wave is received and measured, not only the receiving unit but also the transmitting unit is included.

According to this configuration, by providing a heat transfer amount reduction mechanism that reduces radiant heat, it is possible to measure the temperature of relatively high temperature parts such as internal combustion engines and the internal gas concentration, and prevent failures due to the heat of the sensor. You will be able to do it while.

Further, in the above measuring device, the heat transfer amount reducing mechanism includes a heat absorbing portion that absorbs radiant heat, a heat reflecting portion that reflects radiant heat, a space portion that excludes an air layer, and further. , A heat radiating unit that dissipates heat absorbed by the heat absorbing unit may be provided.

More specifically, in the above measuring device, the heat transfer amount reducing mechanism is composed of a tubular body, and a space filled with a glass layer and a rare gas in order from the front to the rear inside the tubular body. It is configured so that a glass layer is provided with a portion or a vacuum space portion.

According to this configuration, by providing a glass layer, this glass layer is used as a heat absorbing portion, a coating layer is provided on the surface of the glass layer and a heat reflecting portion is provided on the upper surface thereof, or a front glass layer and a rear glass layer are provided. The space between the glass layers can be used as a space portion, and a heat absorbing portion, a heat reflecting portion, a space portion excluding the air layer, a heat radiating portion, and the like can be easily provided compactly.

Further, in the above measuring device, if it is configured as a measuring device for measuring a physical quantity indicating the state inside the combustion chamber of the internal combustion engine, the inside of the exhaust manifold, or the inside of the exhaust pipe, the temperature of the internal combustion engine becomes high. The state of the inside of the combustion chamber, the inside of the exhaust manifold, or the inside of the exhaust pipe can be accurately measured while protecting the sensor.

According to the measuring device and the measuring method of the present invention, the amount of heat transferred to the sensor of the measuring device for measuring the temperature and concentration of a relatively high temperature object to be measured can be reduced, and the life of the sensor can be extended.

It is a figure which shows typically the structure of the measuring apparatus of 1st Embodiment which concerns on this invention. It is a figure which shows typically the structure of the measuring apparatus of 2nd Embodiment which concerns on this invention. It is a figure which shows typically the structure of the measuring apparatus of the 3rd Embodiment which concerns on this invention. It is a figure which shows typically the arrangement of a glass layer and a coat layer, and the state of the incident, transmission, and reflection of electromagnetic waves. It is a figure which shows typically the arrangement of a glass layer, a coat layer and a dielectric multilayer film, and the state of the incident and reflection of an electromagnetic wave. It is a figure which shows typically the relationship of arrangement of the transmission part, the receiving part, and the combustion chamber of the measurement target in the 1st Embodiment which concerns on this invention. It is a figure which shows typically the relationship between the arrangement of the transmitting part, the receiving part, and the combustion chamber of the measurement target in the comparative example which does not have a heat transfer amount reduction mechanism. FIG. 5 is a diagram schematically showing the transfer of radiant heat from the combustion chamber to the transmitting unit and the receiving unit in the comparative example of FIG. 7. Prediction results when there is an air layer between the transmitting part and the combustion chamber and between the receiving part and the combustion chamber, experimental results when there is an air layer, and prediction results when there is no air layer. It is a figure which shows the relationship of the value of the ratio of the temperature and the signal intensity which shows typically.

Hereinafter, the measuring device and the measuring method according to the embodiment of the present invention will be described with reference to the drawings. In the embodiment described below, the inside of the combustion chamber of the internal combustion engine is taken as an example for measurement, the temperature and the concentration of the gas component are taken as an example for the physical quantity to be measured, and the temperature and the gas component are used as terahertz waves. The present invention is not limited to these, and the present invention is not limited to these, for example, measuring the temperature and the concentration of gas components inside the exhaust manifold of an internal combustion engine, the inside of an exhaust pipe, and the like. It can also be applied to a measuring device such as a radiation thermometer that measures a temperature in a non-contact manner.

The sensor referred to here refers to the receiving unit when measuring by receiving an electromagnetic wave or the like, but as shown in FIG. 6, for measuring the temperature and the concentration of gas components from the transmitting unit 10. An electromagnetic wave Wm such as a terahertz wave (0.02 THz (terahertz) to 30 THz) is transmitted to the combustion chamber 3, and the reflected wave or scattered wave is received by the receiving unit 30 to receive the temperature and gas inside the combustion chamber 3. When measuring the concentration of a component, not only the receiving unit 30 but also the transmitting unit 10 is included in the sensor referred to here.

As shown in FIG. 7, in the prior art, when measuring the state of the combustion chamber 3 of the internal combustion engine, the transmitting unit 10 and the receiving unit 30 of the measuring device sandwich an air layer at a position away from the combustion chamber 3. The measurement signal (electromagnetic wave: here, terahertz wave) that has passed through the inside of the combustion chamber 3 reaches the receiving unit 30, and the measurement signal is analyzed to analyze the physical and chemical inside of the combustion chamber 3. Detect the target situation. In this case, as shown in FIG. 8, the radiant heat H generated from the combustion chamber 3 may reach the transmitting unit 10 and the receiving unit 30, and the transmitting unit 10 and the receiving unit 30 may be destroyed by heat.

On the other hand, in the present invention, as shown in FIG. 6, the measuring device 1 of the first embodiment of the present invention determines the state of the combustion chamber (measurement target) 3 of the internal combustion engine and the state of the combustion chamber 3. Heat transfer amount reduction mechanism 20 that reduces radiant heat H transmitted from the combustion chamber 3 to the transmitter 10 between the transmitter (sensor) 10 that transmits terahertz waves to detect the physical quantity such as the temperature and gas component shown. It is said that the configuration is provided. Further, the heat transfer amount reducing mechanism 20 for reducing the radiant heat H transmitted from the combustion chamber 3 to the receiving unit 30 is provided between the receiving unit (sensor) 30 that receives the terahertz wave. Since the same heat transfer amount reducing mechanism 20 provided in the transmitting unit 10 and the receiving unit 30 can be used, the heat transfer amount reducing mechanism 20 provided in the receiving unit 30 will be described below. The heat transfer amount reduction mechanism 20 provided in 10 can also exert the same effect with the same configuration.

In the present invention, the transmitting unit 10 and the receiving unit 30 as shown in FIG. 6 face each other and receive the measurement signal from the transmitting unit 10 that has passed through the inside of the combustion chamber 3 to be measured by the receiving unit 30. Not only the measuring device 1, but also the transmitting direction of the transmitting unit 10 and the receiving direction of the receiving unit 30 intersect, and the receiving unit 30 transmits the scattered wave generated by the measurement signal colliding with the substance inside the measurement target. It can also be applied to a measuring device for receiving, a measuring device in which the transmitting unit 10 and the receiving unit 30 are on the same side, and the receiving unit 30 receives a reflected signal of a measurement signal transmitted from the transmitting unit 10 to a measurement target. ..

Then, as shown in FIG. 1, the heat transfer amount reducing mechanism 20 of the measuring device 1 of the first embodiment is composed of a cylindrical body having a cylinder 21, and is inside the cylinder 21 of the cylindrical body. The glass layers 22 and the space 23 are alternately provided from the front of the combustion chamber 3 side to the rear of the receiving unit 30 side, and the glass layer 22 is provided immediately before the sensor substrate 31 of the receiving unit 30. It is assumed that the configuration is provided.

Heat absorption is performed by mixing a heat absorbing substance such as graphite or soot, which is similar to a black body, into the glass layer 22 provided between the combustion chamber 3 and the sensor substrate 31 of the receiving unit 30. A part can be formed, and these heat absorbing substances absorb electromagnetic waves (for example, infrared rays: about 1 μm to 1 mm in wavelength) Whi, which is radiant heat H, store heat in the glass layer 22, and radiant heat H behind. It is possible to prevent the electromagnetic wave Why from reaching. With this configuration, the heat transfer amount reduction mechanism 20 is provided with a heat absorption unit 22 that absorbs radiant heat H.

Further, as shown in FIG. 1, the frontmost coat layer 22a is provided on the most combustion chamber 3 side of the glass layer 22, and the surface of the frontmost coat layer 22a is coated with a coating that reflects electromagnetic waves Whi, which is radiant heat H. Provide. Further, as shown in FIGS. 1 and 4, the surface 22bf of the coating layer 22b in front of the glass layer 22 in the middle and the rear of the cylinder 21, and the coating layer 22b and the glass layer 22 behind the glass layer 22. A coating that reflects the electromagnetic wave Why of the radiant heat H is provided on the interface 22s.

When this measuring device 1 is used for measuring the combustion chamber 3, as shown in FIG. 1, a through hole 3b serving as a window leading into the combustion chamber 3 is provided on the peripheral wall 3a surrounding the combustion chamber 3 to provide the measuring device. The inlet side of 1 is inserted into the through hole 3b so that the combustion gas comes into contact with it. That is, the cylinder 21 is inserted into the through hole 3b opened in the wall surface 3a of the combustion chamber 3, and the glass layer 22 on the combustion chamber 3 side comes into contact with the combustion gas of the combustion chamber 3. It should be noted that the front surface of the glass layer 22 in contact with the combustion gas is the frontmost in the case where the coat layer 22a may be damaged by heating due to exposure to a substance having a particularly high temperature such as combustion gas. The coat layer 22a may not be provided.

Further, as shown in FIG. 5, the interface surface 22s where the glass layer 22 and the coat layer 22b are in contact with each other is a mirror surface in order to easily reflect the electromagnetic wave Why and to easily form the coat layer 22b. The finish is preferable, and for example, the surface roughness is preferably 10 μm or less in terms of JIS arithmetic average roughness (center line average roughness) Ra.

Further, as one of the structures for reflecting the electromagnetic wave Why, there is a coating that reflects or absorbs radiant heat (infrared wavelength). In this coating, special transmittance / reflectance wavelength characteristics can be created by appropriately selecting a plurality of materials and film thicknesses having different refractive indexes. In other words, by using this coating, a specific wavelength can be used as the center wavelength of the design, and only the wavelength longer than that wavelength can be passed or reflected in the opposite direction, and only the specific wavelength can be transmitted. It can be a structure that can be used. Further, a gold thin film coat can be used as the heat reflecting portion.

As shown in FIG. 4, this reflecting coating reflects the electromagnetic wave Whr, which is a part of the electromagnetic wave Why that becomes the radiant heat H, and measures while preventing the electromagnetic wave Whi from reaching the sensor substrate 31 of the receiving unit 30. It is possible to reach the sensor substrate 31 by passing a necessary electromagnetic wave Wm such as a terahertz wave of a signal for use. By providing the coating on the surfaces of the coat layers 22a and 22b on the surface of the glass layer 22 in this way, a heat reflecting portion that reflects the radiant heat H can be configured in the heat transfer amount reducing mechanism 20.

When a part of the electromagnetic wave Wm of the terahertz wave (0.02 THz (terahertz) to 30 THz: about 0.01 m to 15 mm in wavelength) is used for the measurement, the frequency band of the reflected electromagnetic wave Whr is measured. The frequency band excluding the electromagnetic wave Wm of the terahertz wave for use. The selection of the frequency band of the reflected electromagnetic wave Whr and the frequency band of the transmitted electromagnetic wave Wm is controlled by the thickness of the glass layer 22, the materials of the coat layers 22a and 22b, the thickness, the composition of the coating that reflects or absorbs radiant heat, and the like. can do.

Then, a space portion 23 is provided between the glass layer 22 and the glass layer 22, and in this space portion 23, a rare gas-based gas Ga such as argon (Ar), which is difficult to absorb such as an electromagnetic wave W, is sealed. The air layer is eliminated by diluting the amount of air by creating a vacuum. With this configuration, it is possible to prevent the electromagnetic wave Wm irradiating the combustion chamber 3 from being attenuated by the air layer and weakening the measurement signal received by the receiving unit 30. As a result, the attenuation of the measurement signal can be reduced, so that the signal strength reaching the sensor substrate 31 can be maintained high, and the deterioration of the detection accuracy can be prevented. When a vacuum is used, the air layer can be eliminated and heat transfer due to convection inside the space 23 can be prevented.

Further, the heat transfer amount reduction mechanism 20 is configured by providing a heat radiating portion that dissipates heat absorbed by the glass layer 22 which is a heat absorbing portion around the glass layer 22. In the measuring device 1 of the first embodiment shown in FIG. 1, the heat radiating portion radiates heat to the outside by using a heat radiating plate 24 having a fin structure provided around the tubular body 21. Further, in the measuring device 1A of the second embodiment shown in FIG. 2, the heat radiating portion uses a heat pipe 25 provided inside the cylinder 21 to transfer heat to a low temperature portion of the cylinder 21. Heat is transferred to the outside.

Further, in the measuring device 1B of the third embodiment shown in FIG. 3, a flow path 26 is formed inside the cylinder 21 so that the rare gas Ga circulates in the space portion 23, and the inlet side flow is formed in the flow path 26. The path 26a and the outlet side flow path 26b are connected to each other, and the rare gas Ga is introduced into the space portion 23 from the inlet side flow path 26a via the flow path 26 to cool the glass layer 22. After that, the rare gas Ga heated by the heat of the glass layer 22 is led out from the outlet side flow path 26b to the outside of the space portion 23 via the flow path 26, and is rare outside this with a cooling device (not shown) or the like. Cool the gas Ga. Then, the cooled rare gas Ga whose temperature has been lowered is put into the flow path 26 from the inlet side flow path 26a again and circulated. Instead of this rare gas Ga, polyethylene or the like that melts and becomes fluid due to temperature rise can also be used.

With the configuration including the heat radiating portions 24, 25, 26, the glass layer 22 which is a heat absorbing portion that has absorbed the radiant heat H can be cooled and the heat of the glass layer 22 can be dissipated, so that heat is accumulated in the glass layer 22. Therefore, it is possible to prevent the temperature from rising and to prevent the heat of the glass layer 22 from being transferred to the sensor substrate 31.

That is, in the measuring devices 1, 1A and 1B, the heat transfer amount reducing mechanisms 20, 20A and 20B are formed of a tubular body, and the glass layers are sequentially formed inside the tubular body 21 forming the tubular body from the front to the rear. The space portion 23 filled with the rare gas Ga, the space portion 23 in the vacuum, and the glass layer 22 are provided. In addition, in FIGS. 1 to 3, there are three glass layers 22 and two space portions 23 between them.

According to this configuration, by providing the glass layer 22, the glass layer 22 is used as a heat absorbing portion, or the coating layers 22a and 22b are provided on the surface of the glass layer 22, and the heat reflecting portion (heat reflecting portion) is provided on the upper surface of the coating layer. (Coating) can be provided, and the space portion 23 can be provided between the front glass layer 22 and the rear glass layer 22, so that the heat absorbing portion 22 and the heat reflecting portion 22 can be easily provided. The space portion 23 excluding the 22bf and 22s air layers, the heat radiating portions 24, 25, 26 and the like can be provided compactly.

That is, these prevent the radiant heat H from reaching the receiving unit 30 in the measuring devices 1, 1A and 1B that sense the measurement target that becomes relatively hot, such as inside the combustion chamber 3 of the internal combustion engine, and transmit the heat. It is possible to provide a mechanism capable of protecting the unit 10 and the receiving unit 30 from heat and improving the detection accuracy without reducing the measurement signal reaching the receiving unit 30.

Further, in these measuring devices 1, 1A and 1B, the inside of the combustion chamber 3 of the internal combustion engine, the inside of the exhaust manifold (not shown) of the internal combustion engine, or the inside of the exhaust pipe (not shown) of the internal combustion engine. When the sensor board 31 is configured to measure physical quantities such as the temperature indicating the state and the concentration of the gas component, the state inside the combustion chamber 3 of the internal combustion engine, the inside of the exhaust manifold, and the inside of the exhaust pipe becomes high. While protecting, the condition of the internal combustion engine can be measured accurately.

Next, the measurement method according to the embodiment of the present invention will be described. This measuring method is a measuring method for detecting physical quantities such as temperature and concentration of gas components indicating the state of the combustion chamber (measurement target) 3, and is a receiving unit for detecting the physical quantities indicating the states of the combustion chamber 3 and the combustion chamber 3. This method is characterized in that the radiant heat H transmitted from the combustion chamber 3 to the receiving unit 30 is reduced by the heat transfer amount reducing mechanisms 20, 20A, and 20B provided between the sensor and the sensor 30.

Further, in this measuring method, the heat absorbing unit 22 provided in the heat transfer amount reducing mechanisms 20, 20A, 20B for absorbing the radiant heat H absorbs the radiant heat H to prevent the radiant heat H from being transmitted to the receiving unit 30. Or, the heat reflecting portions 22bf and 22s that reflect the radiant heat H reflect the radiant heat H to prevent the radiant heat H from being transmitted to the receiving portion 30, and the space portion 23 that excludes the air layer is provided by the air layer. It is possible to prevent the electromagnetic wave Wm radiating to the combustion chamber 3 from being attenuated and weakening the measurement signal received by the receiving unit 30. Further, the heat radiating units 24, 25, and 26 dissipate the heat absorbed by the heat absorbing unit 22 to prevent the temperature rise of the heat absorbing unit 22, and the heat absorbed by the heat absorbing unit 22 is transferred to the receiving unit 30. Prevent it from being transmitted.

According to the measuring devices 1, 1A, 1B and the measuring method according to the embodiment of the present invention having the above configuration, the heat transfer amount reducing mechanisms 20, 20A and 20B for reducing the radiant heat H allow the internal combustion engine and the like to have a relatively high temperature. It becomes possible to measure the temperature of the portion to be formed, the internal gas concentration, and the like while preventing the transmitter 10 and the receiver 30 from being damaged by heat.

That is, as shown in FIGS. 7 and 8, an air layer exists because a gap is provided between the measurement target (detection target) such as the combustion chamber 3 and the transmission unit 10 and the reception unit 30. Radiant heat H and convection heat are transmitted to the transmitting unit 10 and the receiving unit 30 by radiation (radiation) and convection in this air layer, and the measurement signal is reduced by the time the measurement signal reaches the receiving unit 30 by this air layer. In some cases, or not shown, the radiant heat H applied to the sensor of the receiving unit 30 is reduced as compared with the case where a protective cover for protecting the receiving unit 30 from heat is provided in front of the receiving unit 30 to weaken the detection signal. Further, by eliminating the air layer, the measurement signal input to the receiving unit 30 can be maintained in a strong state, and the measurement accuracy (detection accuracy) can be improved. Therefore, the state of the measurement target such as the combustion chamber 3 of the internal combustion engine can be detected more accurately. Further, by reducing the heat applied to the receiving unit 30, the life of the receiving unit 30 can be extended.

As shown in FIG. 9, the presence of a gap (air layer) between the sensor and the combustion chamber causes attenuation of the signal strength. The horizontal axis of FIG. 9 shows the temperature, and the vertical axis shows the value of the ratio of the signal intensity to the reference state. A of FIG. 9 shows a prediction result (calculated value) when there is a gap between the receiving unit 30 and the measurement target, and B of FIG. 9 shows a gap when there is a gap between the receiving unit 30 and the measurement target. The experimental result is shown, and C in FIG. 9 shows the prediction result (calculated value) when there is no gap between the receiving unit 30 and the measurement target. At the same distance, there is a large difference in the value of the signal intensity ratio between the prediction result A with a gap and the prediction result C without a gap, in order to suppress the effect of making the value of the signal intensity ratio in the air layer difficult to detect. It can be seen that it is necessary to prevent the presence of a gap, that is, an air layer.

1,1A, 1B measuring device 3 Combustion chamber (measurement target)
3a Peripheral wall of combustion chamber 3b Through hole 10 Transmitter (sensor)
20 Heat transfer reduction mechanism 21 Cylindrical 22 Glass layer (heat absorption part)
22a Frontmost coat layer (heat reflecting part)
22b Coat layer 22bf Surface of coat layer (heat reflection part)
22s Interface between coat layer and glass layer 23 Space 24 Heat dissipation plate (heat dissipation)
25 Heat pipe (heat dissipation part)
26 Flow path (heat dissipation part)
26a Inlet side flow path (heat dissipation part)
26b Outlet side flow path (heat dissipation part)
30 Receiver (sensor)
31 Sensor board (sensor)
Ga Rare gas H Radiant heat W Electromagnetic wave Why Electromagnetic wave that is greatly involved in radiant heat Whr Reflected electromagnetic wave Wm Electromagnetic wave for measurement

Claims (6)

A heat transfer amount reduction mechanism for reducing radiant heat transmitted from the measurement target to the sensor is provided between the measurement target and a sensor that detects a physical quantity indicating the state of the measurement target .
The heat transfer amount reduction mechanism is composed of a tubular body, and inside the tubular body, from one end face of the axial end face of the cylinder facing the measurement target side to the other end face facing the sensor side. A measuring device characterized in that a glass layer is provided in this order, a space portion filled with a rare gas or a vacuum space portion, and a glass layer . The measuring device according to claim 1, wherein the heat transfer amount reducing mechanism includes a heat absorbing unit that absorbs radiant heat. The measuring device according to claim 1 or 2, wherein the heat transfer amount reducing mechanism includes a heat reflecting portion that reflects radiant heat. The measuring device according to any one of claims 1 to 3 , wherein the heat transfer amount reducing mechanism includes a space portion from which an air layer is excluded. The measuring device according to claim 2 , wherein the heat transfer amount reducing mechanism includes a heat radiating unit that dissipates heat absorbed by the heat absorbing unit. The measuring device according to any one of claims 1 to 5 , wherein a physical quantity indicating a state inside a combustion chamber of an internal combustion engine, an inside of an exhaust manifold, or an inside of an exhaust pipe is measured.

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