Shaft system torsional vibration testing device of reciprocating compressor

Abstract

The invention belongs to the technical field of testing devices, and particularly relates to a torsional vibration testing device for a shaft system of a reciprocating compressor. The invention provides a reciprocating compressor shaft system torsional vibration testing device. The reciprocating compressor shaft system torsional vibration testing device comprises a connecting assembly, a fixing assembly and a photoelectric encoder. The connecting assembly comprises a guide rod and a coupling, the coupling is arranged on the guide rod, and the coupling is connected with the photoelectric encoder; the fixing assembly comprises a first fixing disc and a second fixing disc, the first fixing disc and the second fixing disc are connected through a plurality of positioning rods, the coupler is arranged between the first fixing disc and the second fixing disc, the photoelectric encoder is arranged on the first fixing disc, and the photoelectric encoder is arranged on the second fixing disc. The first fixing disc is arranged between the coupler and the photoelectric encoder. The pulse signal of the device is slightly influenced by the external environment, the sensor mounting precision is high, and the rotating speed of the detected piece can be accurately detected.

Description

Technical Field

[0001] This application belongs to the technical field of testing devices, and particularly relates to a torsional vibration testing device for a reciprocating compressor shafting. Background Art

[0002] Torsional vibration is the calculation of the influence degree of the excitation frequency of the transmission system on the natural frequency, reflecting the degree of danger of resonance (resonance) in the system. It is mainly related to the moment of inertia and torsional stiffness of each component of the system, that is, related to the structural dimensions of the equipment. It is not the vibration during actual operation. During the working process, since the crankshaft of the compressor needs to convert its rotational motion into the reciprocating motion of the piston and transmit the power to drive the driven components connected to it. During the above process, the crankshaft needs to bear torsional fatigue loads. In order to understand the anti-torsional performance of the crankshaft and prevent the torsional angle of the crankshaft from being too large, a torsional vibration testing device is generally used to test the crankshaft.

[0003] In the prior art, a typical detection method is the magnetoelectric measurement method, and its principle is as Figure 1 shown. It mainly consists of a stator (permanent magnet), a toothed disk rotor, and a coil. When the toothed disk rotor rotates, if its teeth are opposite to the stator, then the air gap is the smallest at this time, and the magnetic flux passing through the coil is the largest (the first state, please refer to Figure 1 ); if its slots are opposite to the stator, then the air gap is the largest at this time, and the magnetic flux passing through the coil is the smallest (the second state, please refer to Figure 2 ). In this way, when the stator is stationary and the rotor rotates one tooth, the magnetic reluctance of the magnetic circuit changes once due to the concave and convex parts of the teeth, and the magnetic flux passing through the coil changes once, and an induced electromotive force is generated in the coil. Therefore, the change frequency f {Hz} of the induced electromotive force is equal to the product of the measured rotational speed n {r / s} and the number of teeth N {1 / r} on the gear rotor.

[0004] However, since the basic principle of detection in the prior art is to form a voltage signal through the change of the magnetic flux in the coil and then obtain a pulse signal, and the change amount of the magnetic flux is easily interfered by the electromagnetic field, resulting in amplitude modulation of the collected pulse signal, thus causing errors in the pulses formed by the toothed disk, and even the phenomenon of pulse signal loss, affecting the detection result. In addition, due to the limited number of teeth of the toothed disk rotor, for some compressors with high rotational speeds, it is difficult for the number of pulses to meet the test requirements, and accurate rotational speed signals cannot be collected. At the same time, no matter which detection technology is used, the sensor installation problem needs to be considered. Summary of the Invention

[0005] Based on the fact that the basic principle of detection in the prior art is to form a voltage signal through the change of magnetic flux in a coil, and then obtain a pulse signal. However, the change amount of magnetic flux is easily interfered by the electromagnetic field, causing amplitude modulation of the collected pulse signal, resulting in errors in the pulses formed by the toothed disk, and even the phenomenon of pulse signal loss, which affects the detection result. In addition, due to the limited number of teeth of the toothed disk rotor, for some compressors with high rotational speeds, it is difficult for the number of pulses to meet the test requirements, and accurate rotational speed signals cannot be collected. At the same time, no matter which detection technology is adopted, the installation problem of the sensor needs to be considered. Therefore, the present application provides a torsional vibration test device for the shafting of a reciprocating compressor.

[0006] In order to overcome the above technical problems, the present application provides a torsional vibration test device for the shafting of a reciprocating compressor, including a connecting component, a fixing component, and an optoelectronic encoder; The connecting component includes a guide rod and a coupling. The coupling is arranged on the guide rod, and the coupling is connected to the optoelectronic encoder; The fixing component includes a first fixing disk and a second fixing disk. The first fixing disk and the second fixing disk are connected by a plurality of positioning rods. The coupling is arranged between the first fixing disk and the second fixing disk. The optoelectronic encoder is arranged on the first fixing disk, and the first fixing disk is arranged between the coupling and the optoelectronic encoder.

[0007] Optionally, one end of the guide rod is provided with an external thread, a through hole is provided on the second fixing disk, an internal thread is provided in the through hole, the aperture of the through hole is adapted to the outer diameter of the guide rod, and the guide rod passes through the through hole and is threadedly connected to the coupling.

[0008] Optionally, the positioning rod is a thin cylinder, and the number of the thin cylinders is 3 or 4. The first fixing disk and the second fixing disk are fixedly connected by the thin cylinders.

[0009] Optionally, the optoelectronic encoder includes a shaft and a bearing seat. The coupling is connected to the shaft, and the bearing seat is fixedly connected to the first fixing disk.

[0010] Optionally, the optoelectronic encoder includes a code disk and a photosensitive element group. The code disk includes a transparent area and a non-transparent area. The photosensitive element group includes a silicon photocell and a photosensitive transistor.

[0011] Optionally, both the first fixing disk and the second fixing disk are disks.

[0012] Optionally, the guide rod is connected to the crankshaft of the measured part, and the second fixing disk is fixedly connected to the crankcase of the measured part.

[0013] Optionally, the first fixing plate and the photoelectric encoder are connected in the form of counterbored holes.

[0014] Compared with the prior art, the beneficial effects of the reciprocating compressor shafting torsional vibration testing device provided by the present application are as follows: The reciprocating compressor shafting torsional vibration testing device provided by the present application uses a photoelectric encoder. By using a photoelectric sensor to emit and receive optical signals, the frequency of the light source is modulated, with strong anti-interference ability, greatly reducing the influence of the external environment on the pulse signal. At the same time, through the fixation of the fixing component, the photoelectric encoder can be aligned with the crankshaft and the guide rod of the measured part. Then, a coupling is used to connect the guide rod and the photoelectric encoder in the middle, solving the alignment problem between the photoelectric encoder and the crankshaft of the measured part, ensuring that the rotation signal of the crankshaft of the measured part can be accurately transmitted, and improving the detection accuracy. The pulse signal of this device is less affected by the external environment, and the installation accuracy of the sensor is high, enabling more accurate detection of the rotational speed of the measured part. Description of the Drawings

[0015] Figure 1 is a schematic diagram of the prior art magnetoelectric speed sensor and the toothed disk rotor in the first state; Figure 2 is a schematic diagram of the prior art magnetoelectric speed sensor and the toothed disk rotor in the second state; Figure 3 is a schematic structural diagram of the reciprocating compressor shafting torsional vibration testing device of the present application; Figure 4 is a schematic cross-sectional diagram of the reciprocating compressor shafting torsional vibration testing device of the present application; Figure 5 is a brief schematic block diagram of the signal processing process of the photoelectric encoder of the present application.

[0016] In the figures: 1 - photoelectric encoder, 2 - guide rod, 3 - coupling, 4 - first fixing plate, 5 - second fixing plate, 6 - positioning rod, 7 - shaft, 8 - bearing housing, 9 - code disk, 10 - photosensitive element group, 11 - crankshaft of the measured part, 12 - crankcase of the measured part, 13 - light source. Detailed Embodiments

[0017] Hereinafter, specific embodiments of the present application will be described in detail with reference to the accompanying drawings. According to these detailed descriptions, those skilled in the art can clearly understand the present application and can implement the present application. Without violating the principles of the present application, the features in different embodiments can be combined to obtain new implementation manners, or some features in certain embodiments can be replaced to obtain other preferred implementation manners.

[0018] Reducing the influence of the external environment on the pulse signal, improving the installation accuracy of the sensor, and enhancing the detection accuracy are the goals to be achieved.

[0019] An optical encoder, also known as a handwheel pulse generator, abbreviated as a handwheel, is a sensor that converts the mechanical geometric displacement of the output shaft into pulses or digital quantities through photoelectric conversion. It is mainly applied to various numerical control devices and is currently the most widely used sensor. The optical encoder mainly consists of a grating disk and a photoelectric detection device. In the servo system, the grating disk is coaxial with the motor, causing the rotation of the motor to drive the rotation of the grating disk, and then the photoelectric detection device outputs a number of pulse signals. The rotational speed of the current motor can be calculated based on the number of pulses per second of this signal. The code disk of the optical encoder outputs two optical codes with a 90-degree phase difference. The rotation direction of the motor can be determined based on the change in the state of the two-channel output optical codes.

[0020] A coupling is a mechanical part used to connect two shafts (the driving shaft and the driven shaft) in different mechanisms to rotate together to transmit torque. In high-speed and heavy-duty power transmission, some couplings also have the functions of buffering, vibration reduction, and improving the dynamic performance of the shafting. The coupling consists of two halves, which are respectively connected to the driving shaft and the driven shaft. Generally, most prime movers are connected to the working machine with the help of a coupling.

[0021] See Figures 3 to 5 , this application provides a torsional vibration test device, including a connection component, a fixing component, and an optical encoder 1; The connection component includes a guide rod 2 and a coupling 3. The coupling 3 is arranged on the guide rod 2, and the coupling 3 is connected to the optical encoder 1; The fixing component includes a first fixing disk 4 and a second fixing disk 5. The first fixing disk 4 and the second fixing disk 5 are connected by a number of positioning rods 6. The coupling 3 is arranged between the first fixing disk 4 and the second fixing disk 5. The optical encoder 1 is arranged on the first fixing disk 4, and the first fixing disk 4 is arranged between the coupling 3 and the optical encoder 1.

[0022] The optical encoder 1 here is an incremental optical encoder.

[0023] During the working process, the compressor is driven by a driving mechanism (usually a motor or an internal combustion engine) to rotate its crankshaft, and then drives the piston to reciprocate, and transmits the power to drive the driven components connected to it to move. However, during the reciprocating motion of the piston, its moving speed is constantly changing, so the torsional force borne by the crankshaft is also constantly changing. The change in the force will inevitably cause a change in the moving speed of the crankshaft and the generation of vibration. This application is set to accurately understand the change amount of the moving speed of the crankshaft during the working process.

[0024] As Figure 3 and Figure 4 shown, in the torsional vibration test device for the reciprocating compressor shafting provided by the present application, the photoelectric encoder 1 moves together with the guide rod 2 and the component to be detected, i.e., the crankshaft 11. If the rotational speed of the component to be detected, i.e., the crankshaft 11, remains constant, the time required to rotate through the same angle is the same, or in other words, the ratio of the time required to rotate through two different angles to the two angles is the same. According to the above principle, the amplitude of the rotational speed of the component under test under certain conditions can be measured, and it can be determined whether the measured amplitude falls within the required range.

[0025] During the test, first, the crankshaft 11 of the component to be detected is connected to the guide rod 2, then the second fixing plate 5 with external threads is screwed into the threaded hole coaxial with the crankshaft 11 on the crankcase 12 of the component under test, then the coupling 3 is placed in the space surrounded by three thin cylinders, immediately afterwards, the first fixing plate 4 is connected to the three thin cylinders, and finally, the end of the guide rod 2 without threads is connected to the photoelectric encoder 1 through the coupling 3. In this way, after starting the machine, the rotational motion of the crankshaft 11 of the component under test can be coaxially transmitted to the photoelectric encoder 1.

[0026] Further, one end of the guide rod 2 is provided with external threads, the second fixing plate 5 is provided with a through hole, an internal thread is provided in the through hole, the aperture of the through hole is adapted to the outer diameter of the guide rod 2, and the guide rod 2 passes through the through hole and is threadedly connected to the coupling 3.

[0027] One end of the guide rod 2 is provided with external threads for fixedly connecting with the crankshaft 11 of the component to be detected, and the other end is without threads for connecting with the photoelectric encoder 1 through the coupling 3. The guide rod 2 should be long enough to meet the requirement of extending out of the crankcase 12 of the component under test and connecting with the coupling 3.

[0028] A threaded through hole coaxial with the crankshaft 11 of the component to be detected is opened on the crankcase 12 of the component under test, so as to realize threaded fixed connection with the second fixing plate 5 with external threads in the middle, thereby ensuring that the second fixing plate 5 with external threads is coaxial with the crankshaft 11 of the component to be detected. A smooth through hole is opened in the center of the second fixing plate 5, and its diameter is larger than the maximum diameter when the guide rod 2 passes through the through hole, so as to facilitate the guide rod 2 to pass through the through hole without contact.

[0029] Further, the positioning rod 6 is a thin cylinder, the number of the thin cylinders is 3 or 4, and the first fixing plate 4 and the second fixing plate 5 are fixedly connected through the thin cylinders.

[0030] Axially, the coupling 3 is surrounded between multiple thin cylinders, and the end faces of the coupling 3 are surrounded between the first fixing plate 4 and the second fixing plate 5. Threaded holes are provided at both ends of the thin cylinders to facilitate the fixed connection between the first fixing plate 4 and the second fixing plate 5. The geometric dimensions of each thin cylinder are the same, and their axes are all parallel to the axis of the crankshaft 11 of the workpiece to be detected, so as to ensure that the first fixing plate 4 and the second fixing plate 5 are parallel to each other. The holes on the first fixing plate 4 and the second fixing plate 5 for connecting with the thin cylinders are all in the form of counterbored holes, and are drilled on the same circumference to ensure that the first fixing plate 4 and the second fixing plate 5 are coaxial, thereby ensuring that the shaft 7 of the photoelectric encoder 1 is coaxial with the crankshaft 11 of the workpiece to be detected.

[0031] Further, the photoelectric encoder 1 includes a shaft 7 and a bearing housing 8. The coupling 3 is connected to the shaft 7, and the bearing housing 8 is fixedly connected to the first fixing plate 4.

[0032] The second fixing plate 5 is fixedly connected to the bearing housing 8 of the photoelectric encoder 1 by threads.

[0033] Further, the photoelectric encoder 1 includes a code disk 9 and a photosensitive element group 10. The code disk 9 includes a transparent area and a non-transparent area, and the photosensitive element group 10 includes a silicon photocell and a photosensitive transistor.

[0034] One end of the guide rod 2 without threads is connected to the photoelectric encoder 1 through the coupling 3. In this way, after starting up, the rotational movement of the crankshaft 11 of the workpiece to be detected can be coaxially transmitted to the photoelectric encoder 1, thereby driving the code disk 9 to rotate. When the code disk 9 rotates through a transparent area, a change in light and darkness occurs once, and a change in the electrical signal is generated by the photosensitive element 10. Therefore, its change frequency f {Hz} is equal to the product of the measured rotational speed n {r / s} and the number of transparent areas N {1 / r} on each turn of the code track.

[0035] Further, the first fixing plate 4 is a disk, and the second fixing plate 5 is a disk.

[0036] Further, the guide rod 2 is connected to the crankshaft 11 of the workpiece to be detected, and the second fixing plate 5 is fixedly connected to the crankcase 12 of the workpiece to be detected.

[0037] Further, the first fixing plate 4 and the photoelectric encoder 1 are connected in the form of counterbored holes.

[0038] The holes on the first fixing plate 4 for connecting with the photoelectric encoder 1 are in the form of counterbored holes, so as not to interfere with the installation of the coupling 3.

[0039] The code disk 9 moves together with the guide rod 2 and the component to be detected, the crankshaft 11. If the rotational speed of the component to be detected, the crankshaft 11, remains constant, then the time required to rotate through the same angle is the same. Or rather, the ratio of the time required to rotate through two different angles to the difference between the two angles is the same. According to the above principle, the amplitude of the rotational speed of the component under test under certain conditions can be measured, and it can be determined whether the measured amplitude falls within the required range.

[0040] Before the test, the second fixed disk 5 is connected to the positioning rod 6, and the first fixed disk 4 is connected to the bearing housing 8 of the photoelectric encoder 1. During the test, first, the component to be detected (the compressor crankshaft 11) is connected to the guide rod 2, then the second fixed disk 5 with external threads is screwed into the threaded hole on the compressor crankcase that is coaxial with the crankshaft 11 of the component under test. Next, the coupling 3 is placed into the space enclosed by three thin cylinders. Immediately afterwards, the first fixed disk 4 is connected to the three thin cylinders. Finally, the end of the guide rod 2 without threads is connected to the shaft 7 of the incremental photoelectric encoder 1 through the coupling 3. In this way, after starting the machine, the rotational motion of the crankshaft 11 of the component under test can be coaxially transmitted to the shaft 7 of the photoelectric encoder 1, thereby driving the code disk 9 to rotate. The light emitted by the light source 13 (usually a light-emitting diode, which is a type of photoelectric sensor) fixed on the bearing housing 8 of the incremental photoelectric encoder 1 is angle-encoded through the transparent and opaque regions on the code disk 9 and then enters the photosensitive elements (mostly silicon photocells and phototransistors) 10. The photosensitive element group 10 gives a coded signal corresponding to the angular displacement of the code disk.

[0041] Next, a brief description will be given of the characteristics of the code disk of the incremental photoelectric encoder and the signal processing process.

[0042] The incremental photoelectric encoder 1 is provided with two circles of transparent slits with equal angular pitches on the code disk 9. The distance between adjacent transparent slits in the inner and outer circles is staggered by half a slit width, which is used to determine the forward and reverse rotations of the rotating machinery. In addition, at a certain radial position outside the inner and outer circles, a transparent slit is also opened, which is used to indicate the zero position reference for one full rotation of the rotating machinery.

[0043] Please refer to Figure 5 , Figure 5 which is a brief schematic block diagram of the signal processing process of the incremental photoelectric encoder 1.

[0044] The output signals of the photosensitive elements a and b corresponding to the outer and inner circles of the code disk 9 are amplified and shaped to generate rectangular pulses Pa and Pb, which are respectively connected to the D terminal and the C terminal of the D flip-flop. The D flip-flop is triggered at the rising edge of the C pulse (i.e., Pb). When rotating forward, the photosensitive element a senses light earlier than the photosensitive element b, that is, the pulse Pa leads the pulse Pb by 90°. The output terminal Q of the D flip-flop is "1", making the addition and subtraction control line of the reversible counter at a high potential, and the counter performs addition counting. At the same time, Pa and Pb also output a pulse P through the AND gate Y, which is sent to the counting input terminal of the reversible counter through the delay circuit, and the counter performs addition counting. When rotating in reverse, the pulse P2 leads the pulse P1 by 90°. The output terminal Q of the D flip-flop is "0", and the counter performs subtraction counting.

[0045] The reciprocating compressor shafting torsional vibration test device provided by this application uses an optoelectronic encoder 1. The optoelectronic sensor emits and receives optical signals, and the frequency of the light source is modulated, with strong anti-interference ability, greatly reducing the influence of the external environment on the pulse signal. At the same time, through the fixation of the fixing component, the optoelectronic encoder 1 can be centered with the crankshaft 11 of the measured part and the guide rod 2. Then, the guide rod 2 and the optoelectronic encoder 1 are connected through a coupling 3, solving the centering problem between the optoelectronic encoder 1 and the crankshaft 11 of the measured part, ensuring that the rotation signal of the crankshaft 11 of the measured part can be accurately transmitted, and improving the detection accuracy. The pulse signal of this device is less affected by the external environment, and the installation accuracy of the sensor is high, and it can accurately detect the rotational speed of the measured part.

[0046] Although the present application has been described above with reference to specific embodiments, those skilled in the art should understand that many modifications can be made to the configuration and details disclosed in the present application within the principles and scope disclosed in the present application. The protection scope of the present application is determined by the appended claims, and the claims are intended to cover all modifications included in the technical features or scope of the claims.

Claims

1. A torsional vibration test device for a reciprocating compressor shafting, characterized in that: It includes a connecting component, a fixing component and an optical encoder (1); The connecting component includes a guide rod (2) and a coupling (3). The coupling (3) is arranged on the guide rod (2), and the coupling (3) is connected to the optical encoder (1); The fixing component includes a first fixing disk (4) and a second fixing disk (5). The first fixing disk (4) and the second fixing disk (5) are connected by a plurality of positioning rods (6). The coupling (3) is arranged between the first fixing disk (4) and the second fixing disk (5). The optical encoder (1) is arranged on the first fixing disk (4), and the first fixing disk (4) is arranged between the coupling (3) and the optical encoder (1); The optical encoder (1) includes a code disk (9) and a photosensitive element group (10). The code disk (9) includes a transparent area and a non-transparent area. The photosensitive element group (10) includes a silicon photocell and a photosensitive transistor.

2. The torsional vibration test device for the reciprocating compressor shafting according to claim 1, wherein: One end of the guide rod (2) is provided with an external thread. A through hole is provided on the second fixing disk (5). An internal thread is provided in the through hole. The aperture of the through hole is adapted to the outer diameter of the guide rod (2). The guide rod (2) passes through the through hole and is threadedly connected to the coupling (3).

3. The torsional vibration test device for the reciprocating compressor shafting according to claim 1, characterized in that: The positioning rod (6) is a thin cylinder. The number of the thin cylinders is 3 or 4. The first fixing disk (4) and the second fixing disk (5) are fixedly connected by the thin cylinders.

4. The torsional vibration test device for the reciprocating compressor shafting according to claim 1, characterized in that: The optical encoder (1) includes a shaft (7) and a bearing seat (8). The coupling (3) is connected to the shaft (7), and the bearing seat (8) is fixedly connected to the first fixing disk (4).

5. The torsional vibration test device for the reciprocating compressor shafting according to any one of claims 1 to 4, characterized in that: Both the first fixing disk (4) and the second fixing disk (5) are disks.

6. The torsional vibration test device for the reciprocating compressor shafting according to claim 5, characterized in that: The guide rod (2) is connected to the crankshaft (11) of the measured part, and the second fixing disk (5) is fixedly connected to the crankcase (12) of the measured part.

7. The torsional vibration test device for the reciprocating compressor shafting according to claim 6, characterized in that: The first fixing disk (4) and the optical encoder (1) are connected in the form of a countersunk hole.

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