Internal combustion engine piston temperature wireless real-time measurement system and installation method

Abstract

The invention discloses a thermocouple suitable for measuring the temperature of a piston of an internal combustion engine, the thermocouple comprises a thermocouple wire and an armored sleeve, the armored sleeve comprises a large head end and a small head end, and the large head end is installed on a high-temperature gas side. The pressure of high-temperature fuel gas in the piston is borne through the middle face of the large head end and the small head end, the sealing effect is achieved, and the high-temperature fuel gas is prevented from jumping out of a gap between the piston and the thermocouple. The invention further discloses an installation method of the thermocouple suitable for measuring the temperature of the piston of the internal combustion engine, different installation modes are selected according to the positions of the temperature measuring points of the piston for the integral piston, the protective sleeve is arranged between the piston top and the piston skirt for the combined piston, and the extension line of the thermocouple penetrates through the protective sleeve. And reliable and stable work of the thermocouple in a high-temperature and high-pressure severe environment is ensured.

Description

Technical Field

[0001] The invention patent relates to the technical field of engines and testing related technologies, and more specifically, to a method for measuring the temperature of an internal combustion engine piston. Background Art

[0002] An internal combustion engine is a power device that converts thermal energy into mechanical energy. It has a compact structure, high output power, and is stable and reliable. It is a mobile power device with the highest thermal efficiency and is widely used in various fields such as vehicles and ships. In an internal combustion engine, the piston, as a "heart" component, plays a key role in heat-to-work conversion, flow field organization, and combustion organization. However, the working conditions of the piston are very harsh. It is in direct contact with high-temperature combustion gas (2500K) and is subjected to the coupling of alternating thermal stress and alternating mechanical stress. It is prone to mechanical failures such as ablation, cracking, and cylinder pulling. Measuring the piston temperature is an important basis for evaluating its thermal load and reliability.

[0003] Temperature measurement can be mainly divided into two categories: contact temperature measurement and non-contact temperature measurement. Although non-contact temperature measurement has a fast response speed and can measure the complete temperature field of the piston top surface, it is affected by the radiation of flames and carbon smoke, and its measurement error is large; and it is limited by the size of the equipment and cannot be used normally in a small space. For the temperature measurement of the piston top surface, it is better to choose contact temperature measurement, among which thermocouples are the best choice.

[0004] Regarding the problem of measuring the temperature of the internal combustion engine piston, how to design the structure of the thermocouple and how to install the thermocouple on a piston that reciprocates at high speed and has a narrow installation space to ensure its reliable and stable operation in the harsh environment of high temperature and high pressure has become a difficult point. Summary of the invention

[0005] In view of the defects or improvement needs of the prior art, the present invention provides a thermocouple and arrangement scheme suitable for piston temperature measurement, which aims to ensure measurement reliability and stability and provide basic data for the study of combustion and heat transfer problems in engine cylinders.

[0006] The wireless real-time temperature measurement system for the internal combustion engine piston includes a wireless signal transmitter located below the piston pin seat in the cylinder, a data receiving antenna located below the cylinder liner, and a wireless signal receiver located outside the cylinder. The temperature sensor senses the temperature of the piston surface to be measured, converts the temperature signal into a voltage signal to be measured, and transmits the measured voltage signal to the wireless signal transmitter in the cylinder. The data transmitting antenna transmits the temperature of the point to be measured, the cold end temperature and other signals to the data receiving antenna through 433MHz wireless communication. The data receiving antenna transmits the data to the wireless signal receiver outside the cylinder, and transmits it to the host computer by wire, and finally completes the real-time display of the temperature data in the host computer.

[0007] According to one aspect of the present invention, a thermocouple suitable for measuring the temperature of an internal combustion engine piston is provided, comprising a thermocouple wire and an armored sleeve, wherein the armored sleeve comprises a large end and a small end, and the large end is installed on the high-temperature fuel gas side. The pressure of the high-temperature fuel gas in the piston is borne by the intermediate surface between the large end and the small end, and at the same time, a sealing effect is played to prevent the high-temperature fuel gas from escaping from the gap between the piston and the thermocouple.

[0008] Furthermore, the armor sleeve is in a stepped or conical shape. When the stepped shape is adopted, the pressure of the high-temperature gas in the piston is borne by the intermediate shaft shoulders at the large head end and the small head end to perform sealing.

[0009] Furthermore, for the combined piston, the circumferential surface of the big end is a threaded structure or a smooth structure, and for the integral piston, the circumferential surface of the big end is a smooth structure. The thermocouple with a threaded structure on the circumferential surface of the big end is fixedly connected to the piston through the thread, which has better sealing performance and is not easy to fall out during the movement of the piston; the thermocouple with a smooth structure on the circumferential surface of the big end is installed by pressing, and does not need to be rotated and tightened during the installation process, avoiding the entanglement and damage of the thermocouple extension wire, which is suitable for the integral piston.

[0010] Furthermore, the armor sleeve is made of the same material as the piston, thereby ensuring that the thermal conductivity of the armor sleeve and the piston to be measured is consistent, thereby reducing measurement errors.

[0011] Furthermore, the thermocouple is a shell-connected thermocouple, and the wall thickness of the end face of the armor sleeve is determined by the material of the thermocouple armor sleeve. The minimum wall thickness of the end face of the steel armor sleeve is 0.5 mm, and the minimum wall thickness of the end face of the aluminum armor sleeve is 1 mm. This wall thickness can prevent the high-pressure gas on the top of the piston from causing the collapse of the protective sleeve, and at the same time avoid a large deviation between the measuring point and the point to be measured on the top of the piston, resulting in reduced measurement accuracy.

[0012] Furthermore, the top surface shape of the armored sleeve should not destroy the original surface structure of the piston to be tested, so as to avoid changes in the combustion performance of the internal combustion engine caused by changes in the shape and structure of the piston top after the armored thermocouple is installed in the piston.

[0013] Furthermore, since the thermocouple is repeatedly flushed in the oil channel, in order to ensure the reliability of the thermocouple structure, the tensile strength between the thermocouple temperature measuring junction and the armor sleeve is greater than 20N during processing to prevent the connection between the thermocouple temperature measuring junction and the armor sleeve from falling off.

[0014] Furthermore, when installing the thermocouple, it is necessary to apply high temperature resistant ceramic glue on the surface of the armor sleeve in advance, and then install the thermocouple. On the one hand, it prevents the thermocouple from flying out due to inertia when the piston moves at high speed, and on the other hand, the ceramic glue also ensures a certain sealing effect to prevent high temperature gas from escaping through the gap between the armor sleeve and the piston installation hole.

[0015] To achieve the above-mentioned purpose, according to another aspect of the present invention, a thermocouple installation method suitable for piston temperature measurement is also provided, characterized in that a thermocouple installation hole is processed on the piston surface, the thermocouple is installed on the piston surface, and the thermocouple extension wire enters the interior of the piston from the top of the piston and is connected to the wireless signal transmitter in the cylinder.

[0016] For integral pistons, when the temperature sensor measuring point can avoid the oil channel hole, the thermocouple can be directly connected to the piston by machining a long mounting hole that matches the thermocouple armor sleeve structure, thereby preventing the thermocouple from extending into the oil channel and affecting the flow of lubricating oil, and at the same time preventing the thermocouple from falling off and other electrical faults caused by the oscillating environment of the lubricating oil in the oil channel. When the temperature sensor cannot avoid the thermocouple measuring point of the oil channel hole, such as the piston ring land measuring point, the thermocouple extension wire is allowed to enter the oil channel by machining a short mounting hole, and a plug hole is machined near the thermocouple measuring point. The thermocouple extension wire is routed in the oil channel hole and led out from the plug hole.

[0017] For the combined piston, the thermocouple extension line passes through the oil hole and enters the inner oscillation cavity from the outer oscillation cavity of the piston. A protective sleeve is installed between the piston top and the piston skirt. After the thermocouple extension line enters the sleeve from the piston top, it is led out from the piston skirt.

[0018] Specifically, the thermocouple extension line is arranged on the wall of the oscillation chamber and fixed with high temperature resistant epoxy resin glue to avoid damage to the thermocouple due to piston vibration and lubricating oil scouring.

[0019] Furthermore, in order to smoothly lead the thermocouple extension wire from the piston top to the piston skirt and avoid damage to the thermocouple due to piston vibration and lubricating oil scouring, a protective sleeve is provided between the piston top and the piston skirt, and the thermocouple extension wire passes through the protective sleeve.

[0020] Specifically, the protective sleeve is composed of a top thread, a middle sleeve, a bottom thread and a retaining ring.

[0021] Furthermore, a threaded hole is processed at the teardrop-shaped protrusion on the top of the piston, the top of the protective sleeve is threadedly connected to the top of the piston, a tripod fixing bracket is installed on the piston skirt, a mounting hole is processed in the middle of the tripod fixing bracket, the bottom of the protective sleeve is threadedly connected to the middle of the tripod fixing bracket, and the three legs of the tripod fixing bracket are connected to the piston skirt. Through the tripod fixing bracket, the lateral impact on the protective sleeve will be transferred to the connection of the piston skirt, thereby improving the impact resistance of the protective sleeve.

[0022] In addition, the protective sleeve can be designed to be an external thread structure, and the thermocouple extension wire passes through the protective sleeve. A threaded hole is processed on the outside of the oscillation cavity in the piston skirt to match the external thread of the protective sleeve, thereby fixing the protective sleeve. This method is simple to process, but it has high requirements on the coaxiality of the thermocouple extension wire and the sleeve.

[0023] In general, compared with the prior art, the above technical solution conceived by the present invention provides a thermocouple suitable for piston temperature measurement and an installation method for transient temperature measurement, which mainly has the following beneficial effects:

[0024] (1) A thermocouple suitable for measuring piston temperature is proposed, comprising a thermocouple wire and an armored sleeve, wherein the armored sleeve comprises a large end and a small end, and the large end is installed on the high-temperature gas side. The pressure of the high-temperature gas in the piston is borne by the middle surface between the large end and the small end, and at the same time, it plays a sealing role to prevent the high-temperature gas from escaping from the gap between the piston and the thermocouple.

[0025] (2) A method for installing a thermocouple suitable for measuring the temperature of an internal combustion engine piston. Different installation methods and matching tooling are proposed according to different piston types, ensuring that the thermocouple can work stably and reliably in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the working principle diagram of the internal combustion engine piston temperature measurement system;

[0027] Figure 2 Schematic diagram of the stepped armored thermocouple structure;

[0028] Figure 3 This is a schematic diagram of the installation method of the integral piston thermocouple avoiding the oil channel hole;

[0029] Figure 4 It is a schematic diagram of the installation method of the integral piston thermocouple which cannot avoid the oil passage hole;

[0030] Figure 5 This is a schematic diagram of the layout of the combined piston thermocouple extension line;

[0031] Figure 6 This is a schematic diagram of the protective sleeve structure of the first embodiment of the present invention;

[0032] Figure 7 This is a schematic diagram of the structure of a tripod fixing bracket according to the first embodiment of the present invention;

[0033] Figure 8 This is a schematic diagram of the installation of a combined piston thermocouple according to the first embodiment of the present invention;

[0034] Fig. 9 This is a schematic diagram of the protective sleeve structure of the second embodiment of the present invention;

[0035] Fig.10 This is a schematic diagram of the installation of a combined piston thermocouple according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. In the present invention, the terms "first", "second", etc. (if any) in the present invention and the accompanying drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0037] Wireless real-time measurement system for internal combustion engine piston temperature. The system works as follows Figure 1 As shown. The wireless real-time temperature measurement system for the internal combustion engine piston includes a wireless signal transmitter located below the piston pin seat in the cylinder, a data receiving antenna located below the cylinder liner, and a wireless signal receiver located outside the cylinder. The temperature sensor senses the temperature of the piston surface to be measured, converts the temperature signal into a voltage signal to be measured, and transmits the measured voltage signal to the wireless signal transmitter in the cylinder. The data transmitting antenna transmits the temperature of the point to be measured, the cold end temperature and other signals to the data receiving antenna through 433MHz wireless communication. The data receiving antenna transmits the data to the wireless signal receiver outside the cylinder, and transmits it to the host computer by wire, and finally completes the real-time display of the temperature data in the host computer.

[0038] A thermocouple suitable for measuring the temperature of an internal combustion engine piston comprises a thermocouple wire and an armored sleeve, wherein the armored sleeve comprises a large end and a small end, and the large end is installed on the high-temperature gas side. The pressure of the high-temperature gas in the piston is borne by the middle surface between the large end and the small end, and at the same time, it plays a sealing role to prevent the high-temperature gas from escaping from the gap between the piston and the thermocouple. The armored sleeve is stepped or conical. The thermocouple used for piston temperature measurement adopts a shell-connected thermocouple, and the wall thickness of the end face of the armored sleeve is determined by the material of the thermocouple armored sleeve. The minimum wall thickness of the end face of the steel armored sleeve is 0.5mm, and the minimum wall thickness of the end face of the aluminum armored sleeve is 1mm. The wall thickness can prevent the high-pressure gas on the top surface of the piston from causing the collapse of the protective sleeve, and at the same time avoid a large deviation between the measuring point and the point to be measured on the top surface of the piston, resulting in a reduction in measurement accuracy. Its structure is as follows Figure 2 shown.

[0039] Thermocouples with a threaded structure on the circumferential surface of the large head are fixedly connected to the piston through threads, which has better sealing performance and the thermocouple is not easy to fall out during the movement of the piston; thermocouples with a smooth structure on the circumferential surface of the large head are installed by pressing, and do not need to be rotated and tightened during installation, avoiding entanglement and damage of the thermocouple extension wire.

[0040] For integral pistons, the preferred solution is to avoid the oil passage hole. By machining a long stepped hole, the thermocouple can directly reach the inside of the piston. The installation method is as follows Figure 3This prevents the thermocouple from directly reaching the inside of the piston, thereby preventing the thermocouple from extending into the oil passage to affect the flow of the lubricating oil, and also prevents the thermocouple from falling off and causing electrical faults such as vibration of the lubricating oil in the oil passage.

[0041] For integral pistons, when the temperature sensor cannot avoid the thermocouple measuring point of the oil channel hole, such as the piston ring land measuring point, a short step hole is processed to allow the thermocouple extension line to enter the oil channel, and a plug hole is processed near the thermocouple measuring point. The thermocouple extension line is routed in the oil channel hole and led out from the plug hole. The installation method is as follows: Figure 4 shown.

[0042] For the combined piston, the thermocouple extension line passes through the oil hole and enters the inner oscillation cavity from the outer oscillation cavity of the piston. A protective sleeve is installed between the piston top and the piston skirt. The thermocouple extension line enters the sleeve from the piston top and is led out from the piston skirt. The thermocouple extension line is arranged close to the wall of the oscillation cavity and fixed with high-temperature resistant epoxy resin glue to avoid damage to the thermocouple due to piston oscillation and lubricating oil scouring. The extension line is arranged as follows: Figure 5 shown.

[0043] For the combined piston, in order to smoothly lead the thermocouple extension wire from the piston top to the piston skirt and avoid damage to the thermocouple due to piston vibration and lubricating oil scouring, a protective sleeve is arranged between the piston top and the piston skirt, and the thermocouple extension wire passes through the protective sleeve.

[0044] There are two types of protective sleeve structures and their corresponding installation methods. Specific embodiment one:

[0046] The first protective sleeve structure is as follows Figure 6 As shown in the figure, the protective sleeve is composed of a top thread, an intermediate sleeve, a bottom thread and a retaining ring. Furthermore, a threaded hole is processed at the teardrop-shaped protrusion on the top of the piston to fix the top thread of the protective sleeve to the top of the piston. A tripod fixing bracket is installed on the piston skirt. The structure of the tripod fixing bracket is as follows: Figure 7 As shown, the three legs of the tripod fixing bracket are connected to the piston skirt, and the middle of the bracket is connected to the bottom thread of the protective sleeve, thereby completing the fixing of the protective sleeve. Figure 8 Through the tripod fixing bracket, the lateral impact on the protective sleeve will be transferred to the three screws on the piston skirt, thus ensuring the impact resistance of the sleeve. Specific embodiment 2:

[0048] The second type of protective sleeve structure is an external thread structure, such as Fig. 9 As shown, the thermocouple extension line passes through the protective sleeve. Specifically, a threaded hole is processed on the outer side of the oscillation cavity in the piston skirt to match the outer thread of the protective sleeve, so as to fix the protective sleeve. Fig.10This method is simple to process, but it has very high requirements on the coaxiality of the extension wire and the sleeve.

[0049] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thermocouple suitable for measuring the temperature of an internal combustion engine piston, characterized in that: It comprises a thermocouple wire and an armored sleeve, and is characterized in that the armored sleeve comprises a large head end and a small head end, and the large head end is installed on the high-temperature fuel gas side.

2. A thermocouple suitable for measuring the temperature of an internal combustion engine piston according to claim 1, characterized in that: For a combined piston, the circumferential surface of the big end is a threaded structure or a smooth structure, and for an integral piston, the circumferential surface of the big end is a smooth structure.

3. A thermocouple suitable for measuring the temperature of an internal combustion engine piston according to claim 1, characterized in that: The armor sleeve is made of the same material as the piston to be tested.

4. A thermocouple suitable for measuring the temperature of an internal combustion engine piston according to claim 1, characterized in that: The thermocouple is a shell-connected thermocouple. The wall thickness of the end face of the armored sleeve is determined by the material of the armored sleeve. The minimum wall thickness of the end face of the steel armored sleeve is 0.5mm, and the minimum wall thickness of the end face of the aluminum armored sleeve is 1mm.

5. A thermocouple suitable for measuring the temperature of an internal combustion engine piston according to claim 1, characterized in that: The end face shape of the armored sleeve should not destroy the original surface shape of the piston to be tested.

6. The method for installing a thermocouple suitable for measuring the temperature of an internal combustion engine piston as claimed in claim 1, characterized in that: The method comprises the following steps: machining a thermocouple mounting hole on the piston surface, mounting the thermocouple on the piston surface, extending the thermocouple wire from the piston top into the piston interior and connecting to a wireless signal transmitter in the cylinder.

7. A method for installing a thermocouple suitable for measuring the temperature of an internal combustion engine piston according to claim 6, characterized in that: For the integral piston, according to the position of the piston temperature measurement point, when the thermocouple can avoid the oil channel hole, a long mounting hole is processed on the piston so that the thermocouple extension line can directly reach the inside of the piston; when the thermocouple cannot avoid the oil channel hole, a short mounting hole is processed on the piston so that the thermocouple extension line can enter the oil channel, and a plug hole is processed at the oil channel outlet position of the thermocouple extension line. The thermocouple extension line passes through the oil channel hole and is led out from the plug hole.

8. A method for installing a thermocouple suitable for measuring the temperature of an internal combustion engine piston according to claim 6, characterized in that: For the combined piston, the thermocouple extension line passes through the oil hole, enters the inner oscillation cavity from the outer oscillation cavity of the piston, then enters the protective sleeve arranged between the piston top and the piston skirt, and finally leads out from the piston skirt.

9. A method for installing a thermocouple suitable for measuring the temperature of an internal combustion engine piston according to claim 8, characterized in that: It also includes the following steps: the protective sleeve includes a top thread, a middle sleeve, a bottom thread and a retaining ring, a threaded hole is processed at the water drop-shaped protrusion on the top of the piston, the top thread of the protective sleeve is connected to the top of the piston, a tripod fixing bracket is installed on the piston skirt, a mounting hole is processed in the middle of the tripod fixing bracket, the bottom thread of the protective sleeve is connected to the middle of the tripod fixing bracket, and the three legs of the tripod fixing bracket are connected to the piston skirt.

10. A method for installing a thermocouple suitable for measuring the temperature of an internal combustion engine piston according to claim 8, characterized in that In, The protective sleeve is an external thread structure, and a threaded hole is processed on the outer side of the oscillation cavity in the piston skirt. The protective sleeve is connected to the piston skirt through threads.

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