CN105136319A - Fixing device for diesel engine waste heat recovery system temperature measuring thermocouple - Google Patents

Abstract

The invention discloses a fixing device for a temperature-measuring thermocouple of a waste heat recovery system of a diesel engine. There is an internal thread in the small diameter hole of the stepped through hole, and an internal thread is opened in the large diameter hole of the stepped through hole. There are multiple layers of circular PTFE pads. One end of a support bolt is threaded into the large diameter hole of the stepped through hole and the end of the support bolt is pressed on the PTFE pad. There are intermediate mounting holes arranged coaxially with each other, the intermediate mounting holes are used to pass through the sensor thermocouple wire, and there are multiple fluid holes for fluid passage on the side wall of the protective cover, and the intermediate mounting holes between the fluid holes and the protective cover interlinked. This unit holds fine wire thermocouple sensors well.

Description

Fixing device for temperature measuring thermocouple in waste heat recovery system of diesel engine

technical field

The present invention relates to a thermocouple temperature sensor, and mainly relates to a filament thermocouple temperature sensor.

Background technique

As one of the seven basic physical quantities in the International System of Units, temperature is a basic parameter that needs to be measured and monitored in many experiments. In the field of thermal energy and power engineering, the measurement of temperature in the research of combustion process, flow process, heat and mass transfer process is even more essential. And in some experiments, it is necessary to measure the temperature change in real time. For example, when recovering waste heat from a diesel engine, it is necessary to know the exhaust temperature of the engine under different working conditions. This requires the temperature sensor to have better dynamic response performance, so the temperature sensor The thermal inertia should be as small as possible, ie the volume of the measuring part of the sensor should be as small as possible. The volume of the measurement part of the filament thermocouple temperature sensor is very small, so its dynamic performance is also good, so it is most commonly used in temperature measurement.

Thermocouples are widely used to measure temperature. Compared with other temperature measuring instruments, thermocouples have many advantages: (1) The measurement range is wide, and its temperature measurement lower limit can reach -250 ° C. Thermocouples made of some special materials , the upper limit of its temperature measurement can reach 2800 ℃, and it has high precision. (2) Long-distance multi-point detection can be realized, which is convenient for centralized control, digital display and automatic recording. (3) It can be made into a small-sized thermocouple with small thermal inertia, which is suitable for fast dynamic measurement, point temperature measurement and surface temperature measurement. Especially for the filament thermocouple, the diameter of the filament is less than 1mm, so its temperature measurement performance, especially the dynamic performance, is better. The premise of using the thermocouple correctly is to install the thermocouple correctly. If the installation is not correct, the temperature value obtained will be incorrect, and even the thermocouple temperature sensor will be damaged during use. However, the filament thermocouples currently available on the market do not have installation and fixing devices, so the installation and fixation of the filament thermocouples is an urgent problem to be solved.

The structure of the commonly used filament thermocouple mainly includes two parts: plug-in connector and thermocouple wire. According to the structure of the filament thermocouple, the following problems should be paid attention to during the use of the filament thermocouple: (1) Fixation, because the thermocouple wire is very thin and cannot provide support, so the installation device should be able to support and fix the entire filament during installation Thermocouple sensor. (2) Heat insulation. Since the upper part of the filament thermocouple is a plug-in connector, the material is generally plastic materials such as nylon, so heat insulation should be paid attention to during use to avoid burning the upper plug-in connector at high temperature. (3) Sealing, for the temperature measurement of high temperature, high pressure and high speed fluid, its sealing should be guaranteed to prevent the leakage of fluid. (4) Protection of thermocouple wires. The diameter of thermocouple wires is generally less than 1mm, which is easy to break, so it should have sufficient mechanical strength when used. Therefore, the above-mentioned problems should be considered when designing the installation device of the filament thermocouple.

Contents of the invention

The purpose of the present invention is to solve the installation problem of the filament thermocouple temperature sensor, and provide a fixing device for the temperature measuring thermocouple of the diesel engine waste heat recovery system that can fix the thermocouple temperature sensor, seal well and protect the thermocouple wire.

The present invention is a fixing device for a temperature measuring thermocouple of a waste heat recovery system of a diesel engine, which includes a connecting bolt, and a cylindrical sleeve is threaded on the connecting bolt, and the cylindrical sleeve is used to connect with the device under test , there is a stepped through hole along the axis direction in the middle of the connecting bolt, an internal thread is opened in the small diameter hole of the stepped through hole, and an internal thread is opened in the large diameter hole of the stepped through hole And the inner wall of the bottom section of the large-diameter hole is a smooth section, one end of a protective sleeve is screwed to the small-diameter hole of the stepped through-hole, and a multi-layer circular PTFE pad is installed at the bottom of the large-diameter hole of the stepped through-hole. The outer wall of the circular PTFE pad is in contact with the smooth section of the large-diameter hole and the diameter of the large-diameter hole of the connecting bolt matches the diameter of the circular PTFE pad. One end of a support bolt is threaded in the stepped through hole and the end of the support bolt is pressed on the PTFE pad, the top of the support bolt is used to fix the connector of the thermocouple sensor, and the middle of the support bolt, PTFE pad and the protective sleeve are all There are intermediate installation holes arranged coaxially with each other, and the intermediate installation holes are used to pass through the sensor thermocouple wires. There are a plurality of fluid holes for fluid to pass through on the side wall of the protective sheath. The fluid The hole communicates with the middle installation hole of the protective cover.

The present invention has the following advantages:

(1) The filament thermocouple sensor can be well fixed, the cylindrical sleeve is directly welded on the device under test, and rigid connections such as threads are adopted between various parts, which solves the problem that the thermocouple wire cannot be supported by force, and can be well fixed sensor.

(2) Good sealing performance. The double sealing effect of connecting bolts and PTFE pads not only prevents the measured fluid from leaking from the installation hole, but also prevents the measured fluid from leaking from the protective sleeve.

(3) It can protect the thermocouple sensor very well. The sealant on the upper part of the support bolt can play a good heat insulation effect and prevent the plug-in connector of the sensor from being burned by high temperature; the protective sleeve can withstand the impact of the measured fluid and avoid The thermocouple wire is subjected to the impact of the measured fluid, which causes damage to the thermocouple wire.

(4) Easy disassembly and assembly. The main parts of the device are connected together by bolts, so the installation and disassembly of the sensor are very convenient.

(5) The insertion depth is adjustable. By changing the thickness of the PTFE gasket and the screw-in depth of the connecting bolt and the cylindrical sleeve, the insertion depth of the thermocouple wire can be adjusted within a wide range.

Description of drawings

1 is a schematic diagram of the overall structure of the fixing device of the temperature measuring thermocouple of the diesel engine waste heat recovery system of the present invention;

Fig. 2 is the sectional view of the cylindrical sleeve in the device shown in Fig. 1;

Fig. 3 is the sectional view of the connecting bolt in the device shown in Fig. 1;

Fig. 4 is the sectional view of the support bolt in the device shown in Fig. 1;

Fig. 5 is the sectional view of the protective cover in the device shown in Fig. 1;

FIG. 6 is a schematic diagram of the use of the device shown in FIG. 1 .

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in the accompanying drawings, the fixing device of the temperature measuring thermocouple of the diesel engine waste heat recovery system of the present invention includes a connecting bolt 3, and a cylindrical sleeve 7 is threaded on the connecting bolt 3, and the cylindrical sleeve 7 is used to connect with the device under test. A stepped through hole is opened in the middle of the connecting bolt 3 along the axis direction, and an internal thread is opened in the small diameter hole of the stepped through hole. There is an internal thread in the large diameter hole of the hole and the inner wall of the bottom section of the large diameter hole is a smooth section (the smooth section is used to install the PTFE pad, no thread is provided here), one end of a protective sleeve 5 is connected to the stepped through hole The small-diameter hole is threaded, and a multi-layer circular PTFE pad 6 is installed at the bottom of the large-diameter hole in the stepped through hole. The outer wall of the circular PTFE pad is in contact with the smooth section of the large-diameter hole and the connecting bolts The diameter of the large-diameter hole coincides with the diameter of the circular PTFE pad. One end of a support bolt 2 is threaded in the large-diameter hole of the stepped through hole and the end of the support bolt is pressed on the PTFE pad 6. The top of the support bolt 2 is used to fix the connector of the thermocouple sensor. In the middle of the support bolt 2, the PTFE pad 6 and the protective sleeve 5, there are middle installation holes arranged coaxially with each other. The middle installation hole is used to pass through the thermocouple wire of the sensor, and a plurality of fluid holes for fluid passage are opened on the side wall of the protective sheath, and the fluid holes communicate with the middle installation hole of the protective sheath.

The functions and effects of each part of the device are as follows: the device mainly includes five parts: (1) The structure of the cylindrical sleeve with internal thread is shown in Figure 2. The cylindrical sleeve and the device under test are connected together by welding. The cylindrical sleeve mainly plays the role of fixing and positioning, determines the installation position of the filament thermocouple sensor, and fixes the sensor on the equipment under test. (2) The structure of the connecting bolt is shown in Figure 3. The connecting bolt is connected with the support bolt through the inner threaded hole inside, and connected with the protective sleeve through the threaded hole at the bottom. The connecting bolt mainly plays a connecting role and a certain sealing effect. The main part of the entire installation device is connected into a whole through the connecting bolt, and the connecting bolt plays a certain sealing role by combining with the internal thread of the cylindrical sleeve. (3) The structure of the supporting bolt is shown in Figure 4. The supporting bolt is threadedly connected with the internal threaded hole of the connecting bolt through the external thread, so as to be fixed on the connecting bolt. The connector for the filament thermocouple sensor can be fixed on top of the support bolt with a high temperature resistant sealant. The supporting bolt mainly plays the role of supporting the whole filament thermocouple sensor. (4) The structure of the protective cover is shown in FIG. 5 . The main function of the protective sleeve is to protect the thermocouple wire. The thermocouple wire is very thin and its mechanical strength is very small. In order to avoid the damage of the thermocouple wire caused by the impact of the high-speed fluid on the thermocouple wire, it is necessary to install a protective sleeve around the thermocouple wire. . At the same time, in order to measure the temperature value accurately, the protective cover is covered with fluid holes formed by machining, which can make the fluid fully contact with the thermocouple wire, so that the obtained value is accurate. (5) The PTFE pad mainly plays a sealing role. The PTFE gasket is placed in the internal threaded hole of the connecting bolt and above the protective sleeve, which can prevent the measured fluid from leaking from above the protective sleeve, so that the entire installation device has a good seal.

PTFE pad is a hard, compact, easy-to-form three-dimensional space, acid-resistant, alkali-resistant, corrosion-resistant, and able to withstand high temperatures of about 250 ° C for installation and connection. Moreover, it can also compensate and balance errors caused by defects, machining, rigid deformation, installation dislocation, etc., balance the uneven preload, and effectively solve the leakage problem of various facilities under complex conditions. The invention adopts a circular PTFE gasket whose diameter is equivalent to that of the inner threaded hole of the connecting bolt, and there is a middle installation hole in the center of the gasket through which the thermocouple wire can pass. In addition, a multi-layer gasket is placed in the inner threaded hole of the connecting bolt, which can effectively prevent the measured fluid from leaking through the hole above the protective sleeve. As the support bolts are continuously tightened, the support bolts continue to press the gasket, and the middle mounting hole in the center of the gasket is also continuously tightened until the middle mounting hole is completely attached to the thermocouple wire, so that the middle mounting hole can only make the thermocouple The wire passes through, which can effectively prevent the measured fluid from leaking through the middle installation hole on the PTFE pad. The double sealing function of the PTFE gasket makes the whole installation device have excellent sealing performance.

The installation and use method of the device of the present invention is as follows: (1) at first determine the installation position of the sensor on the measured pipeline 4, after the sensor is positioned, drill a suitable hole on the measured pipeline 4, and then the cylindrical sleeve 7 is welded on on the pipe being measured. (2) Pass the thermocouple wire of the thermocouple temperature sensor 1 through the middle installation hole inside the support bolt 2, adjust the distance between the plug-in connector on the upper part of the filament thermocouple sensor 1 and the upper part of the support bolt, and use high temperature resistant, insulating The hot sealant bonds the connector to the support bolt 2 . (3) Place the sealing PTFE gasket 6 with a suitable thickness in the threaded hole inside the connecting bolt 3, make the thermocouple wire pass through the middle mounting hole in the center of the gasket, and then screw the support bolt 2 into the connecting bolt 3 threaded holes, and press the PTFE gasket tightly. (4) Pass the thermocouple wire through the protective sleeve 5, and screw the protective sleeve 5 into the small-diameter hole of the stepped hole at the bottom of the connecting bolt 3, so that the filament thermocouple sensor and the installation device are connected as a whole . (5) Finally, the entire device is fixed on the measured device by connecting the external thread of the bolt 3 and the internal thread of the cylindrical sleeve 7 to complete the installation of the filament thermocouple sensor.

The installation position and insertion depth of the filament thermocouple sensor will affect the accuracy of the measurement data. When the correct installation position is selected, the insertion depth of the sensor needs to be adjusted. The invention can adjust the position of the effective part of the thermocouple wire in the measured fluid in two ways to improve the accuracy of the measurement data. (1) By changing the number of layers of the PTFE gasket, changing the depth of the support bolt screwed into the connecting bolt, thereby adjusting the position of the thermocouple wire in the measured fluid. (2) Adjust the position of the thermocouple wire in the measured fluid by changing the depth of the connecting bolt screwed into the cylindrical sleeve. These two height adjustment methods can adjust the position of the thermocouple wire in the measured fluid within a wide range, so that the installation device of the present invention can be applied to pipes with different diameters and measured devices with different sizes.

The invention provides a reliable technical solution for the device to solve the problems of fixing, heat insulation and sealing in the installation process of the filament thermocouple sensor, protection of the thermocouple wire in the use process, and position adjustment of the sensor.

Claims (1)

1. the stationary installation of diesel residual heat recovery system temperature thermocouple, it is characterized in that: it comprises coupling bolt, on described coupling bolt, threaded connecting sleeve has a cylindrical sleeves, described cylindrical sleeves is used for being connected with tested device device, ladder hole is had in the axial direction in the middle of described coupling bolt, internal thread is had in the small diameter bore of described ladder hole, internal thread is had and the hole inner bottom part section inwall of large diameter hole is smooth section in the large diameter hole of described ladder hole, one end of a protective sleeve is threaded with the small diameter bore of ladder hole, at the large diameter hole inner bottom part of ladder hole, multi-layer circular phenyl tetrafluoride pad is installed, circular phenyl tetrafluoride pad outer wall contact with the smooth section of large diameter hole coordinate and the diameter of the large diameter hole of described coupling bolt and circular phenyl tetrafluoride pad diameter identical, in the large diameter hole that the threaded one end of a carrying bolt is connected to described ladder hole and the end of carrying bolt is by being pressed on phenyl tetrafluoride pad, the top of described carrying bolt is used for the connector of stationary heat thermocouple sensor, at described carrying bolt, the centre of phenyl tetrafluoride pad and protective sleeve all has the middle mounting hole of line setting coaxially to each other, described middle mounting hole is used for through sensor thermocouple silk, described protective sleeve sidewall has multiple fluid bore passed through for fluid, the middle mounting hole of described fluid bore and protective sleeve connects.