Pulse flame thermal shock quantitative test system of pressure sensor

Abstract

The invention discloses a pulse flame thermal shock quantitative test system of a pressure sensor, which comprises a detection box, a thermal shock temperature adjusting mechanism, a thermal shock frequency adjusting mechanism, a thermal shock temperature sensor, a flame burner, a gas supply system, a temperature detection unit and a pressure adjusting system, a rotary disc of the thermal shock frequency adjusting mechanism is located between a to-be-detected pressure sensor and a flame burner, a flame guide hole is formed in the rotary disc and used for switching a detection position and a non-detection position at fixed frequency, and when the detection position is located, the flame guide hole is located under the to-be-detected pressure sensor and a thermal shock temperature sensor and guides flames of the flame burner under the flame guide hole to the to-be-detected pressure sensor and the thermal shock temperature sensor; the test system can reproduce a cylinder pressure environment to carry out a thermal shock test on a sensor to be tested, provides a thermal impact force up to 2000 DEG C through the flame burner, and can simulate a plurality of thermal shock temperatures through adjustment of the thermal shock temperature adjustment mechanism. The real simulation working environment comprehensively tests and comprehensively evaluates the thermal shock error and the temperature self-compensation capability of the sensor to be tested.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor performance detection, and specifically refers to a pulse flame thermal shock quantitative test system for a pressure sensor. Background Art

[0002] Traditional piezoelectric combustion pressure sensors use the longitudinal piezoelectric effect, and their piezoelectric material is a disc-shaped quartz crystal. The advantages of this type of sensor are simple structure and simple and mature technology. It includes a central quartz crystal, a polytetrafluoroethylene insulating lining, and an elastic sleeve from the inside out. Due to the rapid change of the in-cylinder temperature, the internal and external expansion amounts of the quartz crystal and the metal elastic sleeve are different, causing the pre-tightening force to change, resulting in a thermal shock effect in the piezoelectric pressure sensor, bringing an additional output (temperature drift) caused by temperature, making the collected expansion pressure waveform distorted or even drop below the absolute zero value, as Figure 3 shown, and the distortion continues until the exhaust stroke.

[0003] There are three methods to eliminate temperature drift: 1. Set a copper or aluminum temperature compensation sheet in the middle of the quartz crystal to make the internal and external expansion amounts the same. Since thermal expansion is not linear, the temperature compensation range of this method is ≤80°C; 2. Isolate the flame thermal shock by setting a pressure measurement hole with a certain length between the sensor and the bottom surface of the cylinder head. Since the pressure waveform collected by the pressure sensor is superimposed with small oscillation waves of a certain frequency, it affects the fine analysis of the internal combustion engine combustion process; 3. Optimize the structure of the quartz crystal, the design of its elastic sleeve, and the pre-tightening technology to reduce its detection error under thermal shock; this requires quantitative testing and calibration of the thermal shock of the pressure sensor, and comprehensive evaluation of its thermal compensation ability under thermal shock;

[0004] In the prior art, the test method of thermal shock is relatively arbitrary. Simply put the pressure sensor into high-temperature liquid for detection, and the frequency of thermal shock cannot be controlled; another example is the patent 202220462277.6, a pressure sensor resistance to instantaneous high-temperature shock test device, which can solve the problem of thermal shock frequency control through a turntable. However, since it uses an infrared tube to heat a constant temperature plate to provide heat source, and the highest thermal shock temperature in the cylinder reaches more than 2000°C, it is difficult for the infrared tube heating to reach this temperature. In addition, the test environment of this test device is an atmospheric pressure environment, while the internal combustion engine is a variable-pressure combustion system, and the cylinder is a variable-pressure environment. This test method cannot directly reflect and evaluate the detection error of the pressure sensor under thermal shock at various cylinder pressures. It only collects the thermal shock test data under atmospheric pressure and cannot accurately and comprehensively evaluate the temperature compensation ability of the cylinder pressure sensor in a variable cylinder pressure environment, and cannot provide comprehensive data support for the optimization of the sensor structure and assembly. Summary of the Invention

[0005] The object of the present invention is to overcome the defects in the prior art and provide a quantitative test system for pulsed flame thermal shock of a pressure sensor for measuring the temperature compensation ability of a combustion pressure sensor in an internal combustion engine, so as to overcome one or more problems caused by the limitations and defects of the related art to a certain extent.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A quantitative test system for pulsed flame thermal shock of a pressure sensor, comprising a detection box, a thermal shock temperature adjustment mechanism, a thermal shock frequency adjustment mechanism, a thermal shock temperature sensor, a flame burner, a gas supply system, a temperature detection unit, and a pressure adjustment system; wherein,

[0008] A test hole for setting the pressure sensor to be tested is provided at the top of the detection box, and a temperature detection unit is arranged inside the detection box for detecting the ambient temperature inside the box. The detection box is connected to the pressure adjustment system for detecting and automatically adjusting the ambient pressure inside the box;

[0009] The flame burner is arranged directly below the test hole, and gas is input into it by the gas supply system. The thermal shock temperature sensor is located beside the pressure sensor to be tested. The flame burner is arranged on the thermal shock temperature adjustment mechanism for lifting and adjusting the height position of the flame burner according to the temperature signal of the thermal shock temperature sensor;

[0010] The thermal shock frequency adjustment mechanism includes a turntable. The turntable is arranged between the pressure sensor to be tested and the flame burner. A flame guiding hole is vertically penetrated through the turntable. The turntable rotates to switch the detection position and the non-detection position at a fixed frequency. In the non-detection position, the turntable blocks the flame between the pressure sensor to be tested and the flame burner. In the detection position, the flame guiding hole is located directly below the pressure sensor to be tested and the thermal shock temperature sensor for guiding the flame of the flame burner directly below to the pressure sensor to be tested and the thermal shock temperature sensor.

[0011] Further, the pressure adjustment system includes a constant pressure valve and a booster pump. An air inlet interface is provided on the side wall of the detection box. The constant pressure valve and the air inlet interface are respectively arranged near two opposite box corners of the detection box. The booster pump inflates and pressurizes the detection box through the air inlet interface. The constant pressure valve is a constant pressure exhaust integrated valve with a built-in pressure gauge and adjustable pressure relief pressure.

[0012] Furthermore, the thermal shock frequency adjustment mechanism further includes a driving motor and a driving shaft. The driving motor is arranged on the top of the detection box and is connected to the turntable through the driving shaft. A cooling water jacket is arranged on the top of the detection box. The middle part of the cooling water jacket is a bearing installation hole, and the bearing of the driving shaft is arranged in the bearing installation hole.

[0013] Further, the gas supply system delivers a mixture of natural gas and air at a constant flow rate.

[0014] Furthermore, there is a separation distance between the upper plane of the turntable and the detection end face of the pressure sensor to be measured. The upper plane of the turntable is provided with a heat-conducting convex platform protruding upward, and the heat-conducting convex platform extends upward close to the detection end face of the pressure sensor to be measured. The flame guiding hole vertically penetrates the heat-conducting convex platform.

[0015] Furthermore, the flame guiding hole is in the shape of an arc-shaped waist hole concentric with the rotation center of the turntable, its radian angle is 4°-6°, and its width is adapted to the end diameter of the detection end of the pressure sensor to be measured.

[0016] Furthermore, there are at least 2 heat-conducting convex platforms, which are evenly distributed annularly around the rotation center of the turntable.

[0017] Compared with the prior art, the pulse flame thermal shock quantitative test system of the pressure sensor of the present invention has the following beneficial effects:

[0018] This test system can reproduce the cylinder pressure environment to conduct a thermal shock test on the sensor to be measured. Through the flame burner, a thermal shock force of up to 2000°C can be provided. Under the adjustment of the thermal shock temperature adjustment mechanism, the thermal shock force at multiple thermal shock temperatures can be simulated. Thus, the working environment can be truly simulated to comprehensively test and comprehensively evaluate the thermal shock error and temperature self-compensation ability of the sensor to be measured, providing data support for optimizing the quartz crystal structure design, elastic sleeve design and its pre-tightening technology of the pressure sensor. Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of the quantitative test system of the present invention;

[0020] Figure 2 is Figure 1 a schematic structural diagram of the turntable in

[0021] Figure 3 is the detected pressure curve of each crankshaft angle under the in-cylinder thermal shock of the pressure sensor.

[0022] In the figure: 1. Constant pressure valve; 2. Cooling water jacket; 3. Driving motor; 4. Pressure sensor to be measured; 5. Turntable; 51. Heat-conducting convex platform; 52. Flame guiding hole; 6. Flame burner; 7. Lifting platform; 8. Screw jack; 9. Base frame; 10. Air inlet interface; 11. Detection box; 12. Thermal shock temperature sensor. Specific Embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings of the embodiments of the present invention. Obviously, the described embodiments are only the best embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] This embodiment provides a quantitative test system for pulsed flame thermal shock of a pressure sensor. As Figure 1 - Figure 2 shown, the detection box 11 should have sufficient internal space to form a test environment that can simulate the in-cylinder environment inside it, reducing the fluctuations in the environmental temperature and pressure of its internal space caused by combustion. The flame burner 6 and the thermal shock temperature adjustment mechanism are arranged inside the detection box 11. The driving source of the thermal shock temperature adjustment mechanism is a screw jack 8, which is installed on the base frame 9. The flame burner 6 is seated on the lifting platform 7 of the screw jack 8; the flame burner 6 is connected to the gas supply system outside the detection box 11. The gas supply system includes a premixing unit (not shown in the figure) and a constant-flow delivery unit (not shown in the figure). The premixing unit sets a mixer to premix natural gas and air in a certain proportion, and adapts to the pressure environment through the constant-flow delivery unit, and delivers the constant-flow mixed gas to the flame burner 6; a remote control igniter is built in the flame burner 6;

[0025] A test hole for threadedly installing the pressure sensor 4 to be measured is provided at the top of the detection box 11. The flame center of the flame burner 6 is concentric with the test hole and is located directly below it; the thermal shock temperature sensor 12 is arranged at the inner top of the detection box 11 and is located beside the pressure sensor 4 to be measured. Before thermal shock detection, the flame temperature of the flame burner 6 is detected to guide the lifting adjustment of the thermal shock temperature adjustment mechanism;

[0026] A thermal shock frequency adjustment mechanism is provided at the top of the detection box 11. The thermal shock frequency adjustment mechanism includes a driving motor 3, a driving shaft and a turntable 5. The driving motor 3 is installed outside the top of the detection box 11. The driving shaft passes through the top plate of the detection box 11 and is provided with an end seal for end face sealing. The turntable 5 is installed at the lower end of the driving shaft and is located between the pressure sensor 4 to be measured and the flame burner 6. At least one flame guiding hole 52 is vertically and throughly opened on the turntable 5. The driving motor 3 drives the turntable 5 to rotate at a constant speed, switching the detection position and the non-detection position at a fixed frequency to generate instantaneous high-temperature shocks; at the detection position, the flame guiding hole 52 is located directly below the pressure sensor 4 to be measured and the thermal shock temperature sensor 12, and is located directly above the flame burner 6. At this time, the flame of the flame burner 6 can be guided to the pressure sensor 4 to be measured and the thermal shock temperature sensor 12 through the flame guiding hole 52; at the non-detection position, the turntable 5 blocks the flame between the pressure sensor 4 to be measured and the flame burner 6. In order to prevent the relevant accessories from being baked at high temperature by the flame for a long time, the lower plane of the turntable 5 is wrapped with a heat-insulating fiberglass layer. In addition, a cooling water jacket 2 is provided at the top of the detection box 11. Cooling circulating water is introduced into the cooling water jacket 2. A bearing installation hole is provided in the middle of the cooling water jacket 2. The bearing of the driving shaft is installed in the bearing installation hole to cool the bearing and the supporting section of the driving shaft, ensuring the stable performance of the end seal, the bearing and the driving motor 3;

[0027] The pressure test environment inside the detection box 11 is maintained by a pressure regulation system. The pressure regulation system includes a constant pressure valve 1 and a booster pump. An air inlet interface 10 is provided on the side wall of the detection box 11. The air inlet interface 10 is connected to a booster gas path outside the detection box 11. An electromagnetic main valve, a check valve, a pressure stabilizing valve, and a booster pump are provided on the booster gas path. To avoid the influence of pressure fluctuations during the pressure stabilizing process, the constant pressure valve 1 and the air inlet interface 10 are respectively arranged near two opposite box corners of the detection box 11. The constant pressure valve 1 can set the stabilized pressure inside the detection box 11. It is a constant pressure exhaust integrated valve with a built-in pressure gauge, which can automatically exhaust pressure to control the pressure inside the box. The constant pressure valve 1 feeds back the actual pressure inside the detection box 11;

[0028] In addition, considering that long-term testing will cause the temperature inside the detection box 11 to be too high, a temperature detection unit is arranged inside the detection box 11 for temperature monitoring. When the test environment temperature is too high, the test is stopped, and the pressure regulation system is started for ventilation and cooling.

[0029] In this embodiment, as a further technical solution, the pressure sensor 4 to be measured can detect the air pressure inside the detection box 11 in real time. To avoid the slit effect at non-detection positions and improve the test accuracy, there is a separation distance between the upper plane of the turntable 5 and the detection end face of the pressure sensor 4 to be measured. A heat conduction boss 51 is convexly arranged on the upper plane of the turntable 5. The heat conduction boss 51 extends upward close to the detection end face of the pressure sensor 4 to be measured. There are at least 2 heat conduction bosses 51, which are annularly and evenly distributed around the rotation center of the turntable 5. A flame guiding hole 52 is vertically penetrated through the heat conduction boss 51.

[0030] In this embodiment, as a further technical solution, under high-frequency switching, the thermal shock needs to have a certain duration. Therefore, the flame guiding hole 52 is set in the shape of an arc waist hole, which is concentric with the rotation center of the turntable 5, and the radian angle is 4° - 6°. Its width is adapted to the end diameter of the detection end of the pressure sensor 4 to be measured. During the detection position, both the pressure sensor 4 to be measured and the thermal shock temperature sensor 12 are located directly above the flame guiding hole 52.

[0031] The test method of this test system is as follows:

[0032] First, the design of the test points comprehensively considers the power stroke and exhaust stroke under multiple working conditions, and at least includes the highest rotational speed, the highest pressure point, and the highest thermal shock temperature point;

[0033] Secondly, install the pressure sensor 4 to be measured and conduct debugging. The debugging includes the generation of the pressure in the test environment and the debugging of the thermal shock temperature.

[0034] Pressure debugging: Set the pressure relief pressure of the constant pressure valve 1, and start the pressure regulation system to pressurize to the preset pressure of the test point;

[0035] Thermal shock temperature debugging: The turntable 5 stops at the detection position. Start the gas supply system to deliver the mixed gas at a constant flow rate, ignite the flame burner 6, and the thermal shock temperature sensor 12 collects the flame temperature in real time. According to the thermal shock temperature of the test point, the thermal shock temperature adjustment mechanism adjusts the height of the flame burner 6 up and down;

[0036] Next, conduct a thermal shock force test. Set the rotation speed of the turntable 5 according to the thermal shock frequency under the rotational speed condition. The thermal shock frequency is 10 Hz - 50 Hz. Start the turntable 5 to rotate, collect the thermal shock pressure signal at the detection position and the actual pressure signal at the non-detection position, and obtain the pressure data of the pressure sensor 4 to be measured at this test point;

[0037] Obtain comprehensive evaluation data that can comprehensively evaluate the temperature compensation ability of the pressure sensor 4 to be measured according to the above test method; During the test, pay attention to monitoring and maintaining the environmental temperature and environmental pressure in the detection box 11. When the environmental temperature reaches 200 °C, start the pressure regulation system for low-flow air exchange until the environmental temperature returns to the controllable environmental temperature; When the environmental pressure fluctuation reaches 2%, if it fluctuates upward, the constant pressure valve 1 automatically relieves pressure. If it fluctuates downward, stop the machine for inspection and start the pressure regulation system to adjust the pressure.

[0038] The orientation words such as "upper", "lower", "side", "end", "bottom", "inner", "outer", etc. mentioned in this article are based on Figure 1 - Figure 2 the orientation or positional relationship shown in the corresponding drawings in

[0039] These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation;

[0040] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pulse flame thermal shock quantitative test system for a pressure sensor, characterized in that: It includes a detection box, a thermal shock temperature adjustment mechanism, a thermal shock frequency adjustment mechanism, a thermal shock temperature sensor, a flame burner, a gas supply system, a temperature detection unit and a pressure adjustment system; wherein, The top of the detection box is provided with a test hole for setting the pressure sensor to be tested, the temperature detection unit is provided inside the detection box for detecting the ambient temperature inside the box, and the detection box is connected to the pressure regulating system for regulating the ambient pressure inside the box; The flame burner is arranged directly below the test hole, and gas is inputted into the flame burner by the gas supply system. The thermal shock temperature sensor is located beside the pressure sensor to be tested. The flame burner is located on the thermal shock temperature adjustment mechanism, and is used to adjust the height position of the flame burner according to the temperature signal of the thermal shock temperature sensor. The thermal shock frequency adjustment mechanism includes a turntable, which is arranged between the pressure sensor to be tested and the flame burner. A flame guide hole is vertically opened on the turntable. The turntable rotates at a fixed frequency to switch between the detection position and the non-detection position. When in the non-detection position, the turntable is blocked between the pressure sensor to be tested and the flame of the flame burner. When in the detection position, the flame guide hole is located directly below the pressure sensor to be tested and the thermal shock temperature sensor, and is used to guide the flame of the flame burner directly below it to the pressure sensor to be tested and the thermal shock temperature sensor.

2. The pulse flame thermal shock quantitative testing system for pressure sensors according to claim 1, characterized in that: The pressure regulating system includes a constant pressure valve and a booster pump. An air inlet interface is provided on the side wall of the detection box. The constant pressure valve and the air inlet interface are respectively arranged near two opposite box corners of the detection box. The booster pump inflates and pressurizes the detection box through the air inlet interface. The constant pressure valve is a constant pressure exhaust integrated valve with a built-in pressure gauge and adjustable pressure relief pressure.

3. The pulse flame thermal shock quantitative testing system for pressure sensors according to claim 2, characterized in that: The thermal shock frequency adjustment mechanism also includes a driving motor and a driving shaft. The driving motor is arranged on the top of the detection box and is connected to the turntable through the driving shaft. A cooling water jacket is arranged on the top of the detection box. The middle part of the cooling water jacket is a bearing mounting hole. The bearing of the driving shaft is arranged in the bearing mounting hole.

4. The pulse flame thermal shock quantitative testing system for pressure sensors according to claim 1, characterized in that: The gas supply system delivers a mixture of natural gas and air at a constant flow rate.

5. The pulse flame thermal shock quantitative testing system for pressure sensors according to claim 1, characterized in that: There is a standoff distance between the upper plane of the turntable and the detection end face of the pressure sensor to be tested. A heat-conducting boss is protruded from the upper plane of the turntable. The heat-conducting boss extends upward close to the detection end face of the pressure sensor to be tested, and the flame guide hole vertically penetrates the heat-conducting boss.

6. The pulse flame thermal shock quantitative testing system for pressure sensors according to claim 5, characterized in that: The flame guide hole is in the shape of an arc-shaped waist hole concentric with the rotation center of the turntable, with an arc angle of 4°-6°, and a width that is adapted to the end diameter of the detection end of the pressure sensor to be tested.

7. The pulse flame thermal shock quantitative testing system for pressure sensors according to claim 6, characterized in that: There are at least two heat-conducting bosses, which are evenly distributed in a ring shape around the rotation center of the turntable.

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