Piston frictional resistance testing system

Abstract

The invention provides a piston frictional resistance testing system which comprises a power supply assembly, a displacement sensor and an oscilloscope. The power supply assembly drives a piston of the compressor to move through electric energy. The displacement sensor is a non-contact sensor and is used for measuring the displacement of the piston in the movement process of the piston. The oscilloscope is used for collecting the displacement amount of the displacement sensor and forming an oscillogram of time and displacement values. Displacement values of the piston in the compression process and the expansion process are compared through an oscillogram, when the displacement values of the expansion process and the compression process are consistent, friction between the piston and the air cylinder is avoided, when the displacement values of the expansion process and the compression process are inconsistent, friction exists between the piston and the air cylinder, and the larger the deviation value is, the larger the friction force is. According to the piston frictional resistance testing system provided by the invention, the displacement sensor is a non-contact sensor, and the displacement sensor does not need to be mounted on the piston, so that the mounting difficulty of the piston frictional resistance testing system is reduced, and the stress of the piston is not influenced.

Description

Technical Field

[0001] The invention relates to the technical field of compressor detection equipment, and in particular to a piston friction resistance testing system. Background Art

[0002] The pulse tube refrigerator uses a linear compressor to drive refrigeration. The compressor drives the piston along the cylinder through an AC power supply to do work. The refrigerator piston is supported by a leaf spring. Under normal circumstances, the piston and cylinder are coaxial and sealed by a micron-level gap. When there is an angle between the axis of the piston and the cylinder, additional oblique friction will be generated between the piston and the cylinder, causing wear of the piston and cylinder, affecting the life and reliability of the refrigerator. Therefore, it is very important to detect whether there is friction in the operation of the piston to improve the reliability of the refrigerator.

[0003] The movement of the piston includes compression and expansion. If there is no friction between the piston and the cylinder during the movement, the force on the piston is the same during the compression and expansion process, and the displacement is also the same during the compression and expansion process. If there is friction between the piston and the cylinder during the movement, the force on the piston is inconsistent during the compression and expansion process, resulting in inconsistent displacement of the piston during the compression and expansion process.

[0004] At present, a displacement sensor is usually arranged on the piston to detect the displacement of the piston. By obtaining and observing the displacement data of the piston, it is determined whether there is friction between the piston and the cylinder. This detection method requires the displacement sensor to be installed on the piston. The installation and measurement of the displacement sensor is complicated and may affect the force on the piston. Summary of the invention

[0005] The present invention provides a piston friction resistance testing system, which is used to solve the problem that in the prior art, a displacement sensor is installed on a piston to detect the displacement of the piston, resulting in complex installation of the displacement sensor and being set on the piston, which affects the force applied to the piston. The system achieves the effect of using a non-contact displacement sensor instead of a contact sensor to detect the displacement of the piston.

[0006] The present invention provides a piston friction resistance testing system, comprising:

[0007] A power supply assembly, the power supply assembly is used to supply power to a piston of the compressor to drive the piston to reciprocate in the cylinder;

[0008] A displacement sensor, wherein the displacement sensor is a non-contact sensor and is used to measure the displacement of the piston;

[0009] An oscilloscope is connected to the displacement sensor, and is used to collect displacement data of the displacement sensor and form a waveform diagram of time and displacement value.

[0010] According to the piston friction resistance testing system provided by the present invention, the power supply component includes a power supply and an AC controller, and the power supply supplies power to the piston of the compressor through the AC controller.

[0011] According to the piston friction resistance testing system provided by the present invention, the AC controller includes a frequency control module and a voltage control module.

[0012] According to the piston friction resistance testing system provided by the present invention, when the power supply is a DC power supply, the AC power controller further includes an inverter, and the inverter is used to convert DC power into AC power.

[0013] According to the piston friction resistance testing system provided by the present invention, the frequency of the alternating current output by the frequency control module is 0.001 Hz to 0.01 Hz.

[0014] According to the piston friction resistance testing system provided by the present invention, the voltage peak value of the alternating current output by the voltage control module is 10V to 15V.

[0015] According to the piston friction resistance testing system provided by the present invention, the displacement sensor is a laser displacement sensor, a magneto-inductive displacement sensor, an inductive displacement sensor or a capacitive displacement sensor.

[0016] According to the piston friction resistance testing system provided by the present invention, when the displacement sensor is a laser displacement sensor, a detection window is further provided on the compressor, and the light of the laser displacement sensor is emitted to the piston through the detection window.

[0017] According to the piston friction resistance testing system provided by the present invention, a sealing plate is provided on the detection window, and the sealing plate is made of a transparent material.

[0018] According to the piston friction resistance testing system provided by the present invention, the sealing plate is a glass plate.

[0019] The piston friction resistance test system provided by the present invention includes a power supply component, a displacement sensor and an oscilloscope. The power supply component drives the piston of the compressor to reciprocate by electric energy. The displacement sensor is a non-contact sensor, and during the reciprocating motion of the piston, the displacement sensor is used to measure the displacement of the piston. The oscilloscope is used to collect the displacement of the displacement sensor and form a waveform diagram of time and displacement value. By observing the waveform diagram, it is compared whether the displacement values ​​of the piston in the compression process and the expansion process are consistent. When the displacement values ​​of the expansion process are consistent with the compression process, it means that there is no friction between the piston and the cylinder. When the displacement values ​​of the expansion process and the compression process are inconsistent, it means that there is friction between the piston and the cylinder, and the larger the deviation value, the greater the friction force. In the piston friction resistance test system provided by the present invention, the displacement sensor uses a non-contact sensor, and there is no need to install the displacement sensor on the piston, which reduces the difficulty of installing the piston friction resistance test system and does not affect the force on the piston. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of the piston friction resistance testing system provided by the present invention;

[0022] Figure 2 This is a force analysis diagram of the piston provided by the present invention during the compression process;

[0023] Figure 3 This is a force analysis diagram of the piston provided by the present invention during the expansion process.

[0024] Reference numerals:

[0025] 110: power supply; 120: AC power controller; 200: laser displacement sensor; 300: oscilloscope; 410: piston; 420: cylinder body; 500: detection window. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the embodiments of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0028] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0030] Combine the following Figure 1 to Figure 3 It should be understood that the following description is only an illustrative embodiment of the present invention and does not constitute a limitation on the present invention.

[0031] An embodiment of the present invention provides a piston friction resistance testing system, including a power supply component, a displacement sensor and an oscilloscope 300 .

[0032] The power supply assembly is used to supply power to the piston 410 of the compressor to drive the piston 410 to reciprocate in the cylinder 420. The displacement sensor is a non-contact sensor. The displacement sensor can be arranged on one side of the compressor and is used to detect the displacement of the piston 410 in the compressor. The oscilloscope 300 is connected to the displacement sensor in communication, and the oscilloscope 300 is used to collect displacement data of the displacement sensor and automatically draw a waveform diagram of time and displacement value.

[0033] See also Figure 2 , the piston 410 is in the compression process, that is, the piston 410 moves to the right in the figure. If there is a friction force f1 between the piston 410 and the cylinder body 420 at this time, the piston 410 is subjected to the left friction force f1 and the left elastic force F of the leaf spring when moving. k At this time, the driving force F on the piston 410 is e1 =F k +f1.

[0034] See also Figure 3 , the piston 410 is in the process of expansion, that is, the piston 410 moves to the left in the figure. If there is a friction force f2 between the piston 410 and the cylinder 420 at this time, the piston 410 is subjected to the rightward friction force f2 and the rightward driving force F e2 , at this time Fe2+f2=F k .

[0035] When the friction force of the piston 410 does not exist during the compression process, F e1 =F k .

[0036] When the friction force of the piston 410 does not exist during the expansion process, Fe2=F k .

[0037] Obviously, when there is friction between the piston 410 and the cylinder 420, the forces on the piston 410 during the compression process and the expansion process are different, and therefore, the displacements during the compression process and the expansion process are also different. When there is no friction between the piston 410 and the cylinder 420, the forces on the piston 410 during the compression process and the expansion process are the same, and therefore, the displacements during the compression process and the expansion process are the same.

[0038] In this way, the displacement value of the displacement sensor can be collected by the oscilloscope 300, and a waveform diagram of time and displacement value can be formed. By observing the waveform diagram, it can be known whether the displacement values ​​of the piston 410 in the compression process and the expansion process are the same. If they are the same, it means that there is no friction during the movement. If they are different, it means that there is friction during the movement.

[0039] In some embodiments of the present invention, the power supply assembly may include a power supply 110 and an AC controller 120 , and the power supply 110 supplies power to the piston 410 of the compressor through the AC controller 120 .

[0040] The power source 110 can be direct current or alternating current. If the power source 110 is direct current, the alternating current controller 120 is required to first convert the direct current into alternating current, and then adjust the frequency and voltage peak of the alternating current. If the power source 110 is alternating current, the frequency and voltage peak of the alternating current are directly adjusted. Finally, the adjusted alternating current is used to control the reciprocating motion of the piston 410.

[0041] Specifically, when the power supply 110 outputs AC power, the AC power controller 120 may only include a frequency control module and a voltage control module, wherein the frequency control module is used to adjust the frequency of the AC power, and the voltage control module is used to adjust the voltage peak of the AC power.

[0042] When the current output by the power supply 110 is direct current, in addition to the frequency control module and the voltage control module, an inverter is also required in the AC controller 120 to first convert the direct current into alternating current. Afterwards, the frequency of the converted alternating current is adjusted through the frequency control module, and the voltage is adjusted through the voltage control module.

[0043] In the prior art, different DC voltages are usually applied to the piston 410 of the compressor, and a displacement sensor is arranged on the piston 410 for measurement. This measurement method obtains limited data points and cannot detect the overall operation process of the piston 410, and the displacement sensor installation and measurement are complicated. This application uses AC power to drive the piston 410 to move when performing friction resistance detection on the piston 410, and the piston 410 of the compressor in the pulse tube refrigerator is also driven by AC power, achieving a comprehensive test close to the actual operating state of the piston 410.

[0044] In some embodiments of the present invention, the frequency of the AC power output after passing through the frequency control module can be any value between 0.001 Hz and 0.01 Hz. The gap between the piston 410 and the cylinder is very small. If the piston 410 runs too fast, gas force will be generated to do work, affecting the accuracy of the friction resistance measurement. Therefore, a very low frequency drive is required, for example, the frequency can be 0.005 Hz, to ensure that the piston 410 is not affected by the gas force and to achieve the actual operation state test of the piston 410.

[0045] In some embodiments of the present invention, after the alternating current passes through the voltage control module, the voltage peak is adjusted to a value between 10 V and 15 V. The voltage peak can be determined according to the stroke of the piston 410 .

[0046] In some embodiments of the present invention, the displacement sensor may be a laser displacement sensor 200 , a magneto-inductive displacement sensor, an inductive displacement sensor, or a capacitive displacement sensor. Any non-contact displacement sensor may be used to measure the displacement value of the piston 410 .

[0047] In a specific embodiment, the displacement sensor may be a laser displacement sensor 200, and a detection window 500 may be provided on the compressor, and the light of the laser sensor may be emitted toward the piston 410 through the detection window 500. In a further embodiment, a sealing plate may be provided on the detection window 500, and the sealing plate may be made of a transparent material, such as a glass plate.

[0048] The light beam emitted by the laser is focused by a converging lens and then incident vertically onto the surface of the piston 410 through a glass plate. The receiving lens of the laser displacement sensor 200 receives the reflected light and images it on the photosensitive surface of the photodetector. When the measured surface moves, causing the reflected light point to move along the reflected light axis, the image point on the photodetector will also be displaced. The actual displacement of the object can be obtained through the relationship between the actual displacement and the image point displacement. In the present invention, the measured parameter is the displacement of the compressor piston 410. The incident light passes through the converging lens and is incident on the end face of the piston 410. The displacement of the compressor piston 410 can be calculated by the displacement change of the detector photosensitive surface.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A piston friction resistance testing system, characterized in that: include: a power supply assembly, the power supply assembly being used to supply power to a piston (410) of the compressor so as to drive the piston (410) to reciprocate in a cylinder (420); A displacement sensor, wherein the displacement sensor is a non-contact sensor and is used to measure the displacement of the piston (410); An oscilloscope (300), the oscilloscope (300) being connected to the displacement sensor, the oscilloscope (300) being used to collect displacement data of the displacement sensor and form a waveform diagram of time and displacement value.

2. The piston friction resistance testing system according to claim 1, characterized in that: The power supply component comprises a power supply (110) and an AC controller (120), and the power supply (110) supplies power to the piston (410) of the compressor through the AC controller (120).

3. The piston friction resistance testing system according to claim 2, characterized in that: The AC power controller (120) comprises a frequency control module and a voltage control module.

4. The piston friction resistance testing system according to claim 3, characterized in that: When the power source (110) is a direct current power source, the alternating current controller (120) further comprises an inverter, and the inverter is used to convert direct current into alternating current.

5. The piston friction resistance testing system according to claim 3 or 4, characterized in that: The frequency of the alternating current output by the frequency control module is 0.001 Hz to 0.01 Hz.

6. The piston friction resistance testing system according to claim 3 or 4, characterized in that: The voltage peak value of the alternating current output by the voltage control module is 10V to 15V.

7. The piston friction resistance testing system according to claim 1, characterized in that: The displacement sensor is a laser displacement sensor (200), a magneto-inductive displacement sensor, an inductive displacement sensor or a capacitive displacement sensor.

8. The piston friction resistance testing system according to claim 7, characterized in that: When the displacement sensor is the laser displacement sensor (200), a detection window (500) is also provided on the compressor, and light from the laser displacement sensor (200) is emitted toward the piston (410) through the detection window (500).

9. The piston friction resistance testing system according to claim 8, characterized in that: The detection window (500) is provided with a sealing plate, and the sealing plate is made of a transparent material.

10. The piston friction resistance testing system according to claim 9, characterized in that: The sealing plate is a glass plate.

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