JP2021148724A - Measurement device for high temperature portion of engine - Google Patents

Abstract

To reduce measurement cost by reducing measurement accuracy and responsiveness within a permissible range, relating to a device for measuring the temperature of a high temperature portion such as a combustion chamber.SOLUTION: A measurement device 1 is composed of a holder body 2 and a cap 3 provided at the distal end of the holder body, with a sensor housing unit 13 formed at the distal end of the bolder body 2 while the sensor housing unit 13 is opened forward. The cap 3 is composed of a cylindrical body 17 and an end plate 18. The end plate 18 is made of a metal such as copper, having high thermal conductivity, and is close to or in contact with the distal end face of a temperature sensor 12. The temperature sensor 12 is repeatedly usable since it is not exposed to a combustion gas. The end plate 18 has high thermal conductivity, therefore the temperature can be measured accurately and with good responsiveness even by an indirect measurement method by correcting an actual measured value. Running costs can be significantly reduced since an expensive temperature sensor is repeatedly usable.SELECTED DRAWING: Figure 1

Description

The present invention relates to an apparatus that is mounted on a cylinder head, a cylinder block, or the like of a gasoline engine or a diesel engine to measure the temperature of a high temperature portion such as a combustion chamber.

In a reciprocating engine, knowing the temperature (or temperature change) in the combustion chamber (inside the cylinder) at the time of combustion is indispensable for analyzing the combustion state and making improvements. For example, in order to suppress heat dissipation from the combustion chamber composed of the cylinder block and the cylinder head (and piston), it has been proposed to provide a heat shield film on the inner surface of the combustion chamber. In order to confirm, it is indispensable to grasp the temperature of the inner surface (wall surface) of the combustion chamber.

As described above, there is a strong demand for the technology for measuring the temperature inside the cylinder of the engine, and the technology for measuring the temperature inside the cylinder has been proposed to meet this demand. As an example, Patent Document 1 discloses a temperature sensor mounted in a measurement hole provided in a cylinder. This temperature sensor has a structure in which a detection element portion and a temperature compensation element portion are arranged on the tip surface of the sensor body, and the detection element portion detects the temperature from the intensity of infrared rays.

Japanese Unexamined Patent Publication No. 4-310829

Since the temperature sensor of Patent Document 1 is a kind of contact type and directly detects the temperature inside the cylinder, it is considered to be excellent in measurement accuracy and responsiveness. It is also thought to be effective in detecting the wall temperature of the combustion chamber. However, in Patent Document 1, since the detection element is exposed to the combustion chamber and is directly exposed to the high-temperature combustion gas, it is presumed that it is difficult to use it repeatedly.

Regarding engines, research on lean burn has been conducted by each manufacturer and institution from the viewpoint of improving thermal efficiency and detoxifying exhaust gas, and temperature sensors have been used as essential items for combustion state analysis. The reality is that expensive temperature sensors are thrown away, so there has been a demand for technology that can measure the temperature inside the cylinder at low cost.

The present invention meets such a demand, and an object of the present invention is to provide a measuring device having excellent durability while suppressing a decrease in temperature measurement accuracy and responsiveness within an acceptable range.

The present invention relates to a device for measuring the temperature of a high temperature part of an engine, and this device is
"A holder body that is inserted into a measurement hole made in an engine component and a cap that is attached to the holder body from the tip side are provided, and a temperature sensor arranged at the tip of the holder body is provided. It is held by the cap so that it cannot be pulled out. "
It has a basic structure.

And in the above basic configuration
"The cap is composed of a cylinder attached to the main body by screwing or other means and an end plate provided at the tip of the cylinder, and at least the end plate has a thermal conductivity equal to or higher than that of copper. It is made of a metal plate with a conductivity, and the end plate of the cap is set to be in close contact with or in contact with the tip surface of the temperature sensor. "
It has the feature.

In the present invention, the holder body may be made of steel such as stainless steel or ceramic. On the other hand, the cap can be entirely made of a material with high heat conductivity such as copper, but from the viewpoint of strength, the cylinder is made of stainless steel and the tip is made of a highly heat transfer metal plate such as copper. It is preferable to fix the end plate by welding or the like.

The end plate may be any metal material having high heat transfer property that instantly transfers the heat inside the cylinder to the temperature sensor and having a strength that can withstand the pressure inside the cylinder, and copper is preferable from the viewpoint of cost and strength. However, silver, gold, or alloys thereof (including copper alloys) can also be used.

In the present invention, a sensor accommodating portion for stably holding the temperature sensor is required, but the sensor accommodating portion may be formed on the holder body or the cap. Alternatively, it can be formed so as to straddle both the holder body and the cap.

As a usage mode of the measuring device, for example, when measuring the temperature of the wall surface of the combustion chamber, it may be attached to the cylinder head or the cylinder block so that the end plate of the cap is substantially flush with the wall surface of the combustion chamber, and combustion is performed. When detecting the internal temperature of the chamber, the end plate may be projected toward the inside of the combustion chamber. Further, the temperature measuring device of the present invention can be attached to an exhaust system and used for measuring the temperature of exhaust gas.

The device of the present invention is an indirect measurement method in which the temperature is detected by a temperature sensor via the heat of the end plate, but since the end plate has extremely high thermal conductivity, the temperature (heat) of the combustion chamber or the like can be instantly and accurately measured. Can be transmitted to the temperature sensor. Therefore, the temperature can be measured with the same high accuracy and responsiveness as when the element portion of the temperature sensor is exposed to the combustion chamber or the like by back calculation.

Therefore, for example, when it is used for temperature measurement of a combustion chamber, the temperature change from intake to exhaust can be measured with high accuracy and responsiveness as an actual numerical value. This can greatly accelerate the analysis of combustion and lead to improvement. Since the temperature sensor is not exposed to the combustion gas, it can be used repeatedly. Therefore, in-cylinder temperature measurement with excellent accuracy and responsiveness can be realized at low cost.

Depending on the thickness of the end plate, the amount of heat transferred from the end plate to the temperature sensor may decrease slightly. In this case, the actual temperature and the measured temperature in the device of the present application can be calculated back. The deviation rate may be detected and the measured temperature may be corrected based on this deviation rate.

In the view which shows the measuring apparatus, (A) is a cross-sectional view which shows the mounting state, (B) is a side view seen from the direction orthogonal to the axis, (C) is a vertical sectional side view of 1st Embodiment in a separated state. Is. It is a vertical sectional side view in the built-in state of 1st Embodiment. It is a longitudinal side view of the second embodiment. It is a longitudinal side view of the third embodiment. It is a longitudinal side view of the 4th embodiment.

(1). First Embodiment Next, an embodiment of the present invention will be described with reference to the drawings. First, the first embodiment shown in FIGS. 1 and 2 will be described. The appearance of the measuring device 1 is shown in FIGS. 1 (A) and 1 (B). The measuring device 1 includes a circular and elongated rod-shaped holder main body 2 and a cap 3 attached to the tip thereof. In the present embodiment, as shown in FIG. 1 (A), the measuring device 1 is provided on the cylinder head 4. It is attached to the hole 5.

FIG. 1A is a cross-sectional view taken along a plane that is orthogonal to the crank axis direction and passes through the cylinder bore axis, and the measurement hole 5 is opened in a recess 6 formed in the cylinder head 4 to be a measuring device. 1 is arranged so that the tip surface of the cap 3 is substantially the same as the wall surface (inner peripheral surface) 7 of the recess 6.

Specifically, while the female screw is formed at the base of the measurement hole 5, the male screw portion 8 is formed at the base end of the holder body 2, and the male screw portion 8 is used as the female screw of the measurement hole 5. While being screwed in, it is held at a predetermined depth by the locknut 9.

In FIG. 1A, reference numeral 10 is an intake port, reference numeral 11 is an exhaust port, and reference numeral 11a is an ignition hole for mounting a spark plug. The illustrated cylinder head 4 is a lower portion of a type in which the upper and lower parts are separated, and the cam shaft is rotatably held by an upper portion fixed to the upper surface of the illustrated cylinder head 4.

Needless to say, the arrangement mode of the measuring device 1 can be arbitrarily set according to the purpose of measurement. For example, the measuring device 1 can be arranged at a plurality of locations on the inner peripheral portion of the recess 6, and may be arranged on the upper surface of the recess 6 in addition to or instead of the inner peripheral surface of the cavity 6. It is also possible to do. It is also possible to arrange it at one place or a plurality of places on the outer peripheral portion of the cylinder block (not shown).

The holder body 2 is made of stainless steel and is formed to be hollow, and a sensor accommodating portion 13 for accommodating the temperature sensor 12 is formed to open forward on the tip side. The sensor accommodating portion 13 includes a bottom surface 13a for positioning the temperature sensor 12, and the cable 14 provided on the temperature sensor 12 is pulled out from the center hole 15 formed in the holder main body 2.

The portion of the holder body 2 where the sensor storage portion 13 is provided is set to a small diameter, and a male screw 16 is formed on the outer peripheral surface of the small diameter portion. On the other hand, the cap 3 is composed of a tubular body 17 having a female screw screwed into the male screw 16 of the sensor housing portion 13 and an end plate 18 fixed to the tip thereof by welding, and the tubular body 17 is attached to the holder body 2. When fully screwed into the male screw 16, the end plate 18 is set so as to be in close contact with or in contact with the tip surface of the temperature sensor 12.

The tubular body 17 constituting the cap 3 is made of stainless steel, while the end plate 18 is made of copper, and both are integrally joined by fiber laser welding. Therefore, by setting the outer diameter of the end plate 18 to be smaller than the outer diameter of the tubular body 17, a welding step portion is formed on the outside of the outer circumference of the end plate 18. The thickness of the end plate 18 is preferably as thin as possible while ensuring strength. When the outer diameter of the holder body 2 is about 3 mm, it can be said that the thickness of the end plate 18 may be about 0.3 mm. Therefore, it is possible to punch a thin copper plate into a circle.

FIG. 2 shows the usage state of the measuring device 1. The heat generated by the combustion of fuel is transferred to the temperature sensor 12 via the end plate 18, and the temperature sensor 12 detects the heat of the end plate 18. However, since the copper constituting the end plate 18 has extremely high thermal conductivity, the cylinder The temperature inside can be detected accurately and with good responsiveness. That is, although it is an indirect measurement method, it is possible to realize the same measurement accuracy and measurement speed as when the temperature sensor 12 is exposed in the cylinder.

The temperature sensor 12 is protected by the cap 3, and the element (thermocouple) provided in the temperature sensor 12 is not exposed to the high-pressure combustion gas, so that the temperature sensor 12 can be used repeatedly. Therefore, as compared with the conventional disposable method, the running cost of measurement can be significantly reduced without degrading the measurement accuracy.

Note that FIG. 2 shows a state in which the heat shield film 19 is formed on the inner surface of the combustion chamber. Then, the effect of the heat shield film 19 can be confirmed by arranging the measuring device 1 so that the outer surface of the end plate 18 is flush with the inner surface of the combustion chamber. Since the temperature of the combustion chamber differs depending on the location, a plurality of measuring devices 1 are used to accurately know the temperature distribution. However, the measuring device 1 of the present embodiment is expensive because the temperature sensor 12 can be used repeatedly. The measurement cost can be significantly reduced while using the temperature sensor 12.

(2). Other Embodiments Next, the following embodiments of FIG. 3 will be described. The second embodiment shown in FIG. 3 is a modification of the first embodiment, and the depth of the sensor housing portion 13 is made slightly deeper than that of the first embodiment, and the bottom surface 13a of the sensor housing portion 13 is heat-resistant. A ring-shaped gasket 20 having elasticity is arranged. In this embodiment, since the end plate 18 can be brought into close contact with the tip surface of the temperature sensor 12 by utilizing the elasticity of the gasket 20, it can be said that the measurement accuracy and responsiveness of the temperature sensor 12 can be further improved.

In the third embodiment shown in FIG. 4, an inward flange 21 for holding the outer peripheral portion of the end plate 18 is formed at the tip of the tubular body 17, and the end plate 18 is held and fixed to the tip surface of the sensor housing portion 13 with the flange 21. doing. In this embodiment, since the welding process can be eliminated, it can be said that the cost can be further reduced.

In the fourth embodiment shown in FIG. 5, the sensor accommodating portion 13 is formed in the cap 3 screwed into the holder body 2, and the end plate 18 is forcibly fitted to the tip end portion of the tubular body 17 in the cap 3. .. That is, while the small diameter portion 17a is formed at the tip of the tubular body 17, the tubular portion 18a is integrally formed with the end plate 18, and the tubular portion 18a is fitted to the small diameter portion 17a of the tubular body 17 by press fitting. There is. The end plate 18 can also be fixed to the tip surface of the tubular body 17 by welding as in the first embodiment.

In the embodiment of FIG. 5, the entire sensor accommodating portion 13 is formed on the cap 3, but the sensor accommodating portion 13 may be formed so as to straddle both the holder main body 2 and the cap 3.

Although the embodiments of the present invention have been described above, the present invention can be embodied in various ways. For example, as a means for fixing the holder body to a member such as a cylinder head or a cylinder block, a flange may be formed at the base end of the holder body and the flange may be fixed to the cylinder head or the cylinder block with screws. It is possible. The end plate can also be fixed to the cylinder by clad welding or resistance welding. Further, the measuring device of the present invention can also be used to measure the temperature of exhaust gas by attaching it to an exhaust system member such as a catalyst case.

The present invention can be embodied in an engine temperature measuring device. Therefore, it can be used industrially.

1 Measuring device 2 Holder body 3 Cap 4 Cylinder head 5 Measuring hole 12 Temperature sensor 13 Sensor storage 13a Bottom surface 15 Center hole 16 Male screw 17 Cylinder body (female screw cylinder)
18 End plate

Claims (1)

A holder body inserted into a measurement hole made in a component of the engine and a cap attached to the holder body from the tip side are provided, and a temperature sensor arranged at the tip end portion of the holder body is described. It is a configuration that is held by a cap so that it cannot be pulled out.
The cap is composed of a cylinder attached to the main body by screwing or other means and an end plate provided at the tip of the cylinder, and at least the end plate has a thermal conductivity equal to or higher than that of copper. The end plate of the cap is set to be in close contact with or in contact with the tip surface of the temperature sensor.
High temperature part measuring device of engine.

Images