瑞典专利SE538461C2 Vibration sensor in a portable vibration meter

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专利摘要:
12 SUMMARY A vibration detector suitable for field use and associated systems and procedures are described. A representative apparatus includes a vibration sensor that is in contact with a vibrating structure. The vibration sensor can be in contact with vibration isolators to eliminate frequencies at the operator's hand. In some embodiments, a contact force between the vibration sensor and the vibrating structure can be measured, for example using contact resistors. Since the sensitivity of the vibration sensor may be a function of the contact force, the vibration amplitude measurements can be adjusted for a known contact force to improve the accuracy of the vibration amplitude measurement. Publication figure: Fig. 2
公开号:SE538461C2
申请号:SE1450279
申请日:2014-03-12
公开日:2016-07-12
发明作者:Richer Paul
申请人:Fluke Corp；
IPC主号:

专利说明:

VIBRATION SENSOR IN A PORTABLE VIBRATION METER Technical field The present technology generally relates to vibration meters and associated systems and procedures.
Background Vibration can be an important consideration when designing, testing and maintaining machinery. For example, significant vibration levels may indicate defective construction or an obstructing machine failure. The presence of unexpected frequency peaks in a vibrating structure may indicate non-linear interactions among the natural frequencies of the subassemblies, which may cause premature machine failure. In some applications, detection of a single increase in vibration amplitude is a trigger for initiating maintenance and / or service of equipment.
Vibration detection is often performed in the field by attaching one or more accelerometers, or other vibration sensors, to the rotating machinery, or some other vibrating structure. Vibration sensors provide output signals that can be used to determine vibration amplitude and vibration frequency. It is known that the contact between the vibration sensor and the vibrating structure can be improved by placing the fixed vibration sensors (ie the accelerometers) firmly on the rotating machinery. By firmly attaching the vibration sensor, the transmission of vibrations from the vibrating structure to the sensor is generally improved. However, such a firm attachment may not be possible, or at least not practical, with hand-held vibration meters as being preferred for field use. In the field, a hand-held vibration detector is typically kept in contact with rotating machinery instead of hand for measuring the vibrations.
Figure 1 is a plan view of a conventional vibration meter 100. In operation, a single reading pen 3 of the vibration meter 100 is in contact with a vibrating structure 5. the vibrations are transmitted through the reading pen 3 to an accelerometer 2 inside a housing 4. When subjected to vibrations, the accelerometer 2 produces an output signal to be transmitted to electronics inside the unit 100 via lines 6. The unit 100 then determines the vibration amplitude / frequency based on the signal coming from the accelerometer. The output (ie the amplitude and frequency of the vibration) can be displayed using a single screen 7. However, such a conventional device is sensitive to the pre-contact quality between the device and the vibrating structure. The accuracy of the vibration sensor reading in a handheld device therefore remains a problem.
Brief Description of the Figures Many aspects of the present description may be better understood by reference to the following figures. The components in the figures are not necessarily to scale. The emphasis is instead on clearly illustrating the principles of the present description. In the figures, further reference numerals corresponding to corresponding parts are denoted throughout the various views.
Figure 1 is a plan view of a hand-held vibration meter in accordance with the prior art.
Figure 2 is a plan view of a handheld vibration meter in accordance with an embodiment of the technology described herein.
Figure 3A is an exploded view of a handheld vibration meter in accordance with an embodiment of the technology described herein.
Figure 3B is an isometric view of a force sensor assembly in accordance with an embodiment of the technology described herein.
Figure 4 is a graph of a sensitivity of the vibration sensor as a function of frequency.
Figure 5 is a schematic diagram of the output linearization of the pre-vibration sensor in accordance with an embodiment of the technology described herein.
Detailed Description Specific details of several embodiments of representative vibration meters and the associated method of vibration measurements are described below. In some embodiments of the present technology, the vibration meter is a hand-held device which is in contact with a vibrating structure (for example a rotating machinery) and which measures vibrations of the vibrating structure. The vibration meter may also include a force sensor for measuring a force between the vibration sensor and the vibrating equipment. The force measurement can be used to improve the accuracy of the vibration reading (for example amplitude and frequency), since the output from the vibration sensor generally changes the intensity of the contact force between the vibration meter and the vibrating structure. In some embodiments, therefore, the output of the vibration sensor may be combined with the force reading to provide evenly adjusted output that automatically takes into account the contact force of additional input from the user. Furthermore, one or more vibration isolators may be in contact with the vibration sensor for filtering the noise created by instability or shaking of the operator's hand, which would appear as low frequency vibrations at the output of the vibration sensor if it had not been filtered. One skilled in the art will also appreciate that the technology may have additional embodiments and that the technology may be practiced without several of the details of the embodiments described below with reference to Figures 2-5.
Figure 2 illustrates a vibration meter 200 in accordance with embodiments of the technology described herein. The vibration meter 200 has a housing 70 which may be made of molded plastic or other suitable materials. In operation, the vibration meter 200 may be hand-held against a vibrating structure 5 so that a vibration sensor 10 is in contact with the vibrating structure. In other embodiments of the technology, the vibration sensor may be in contact with the vibrating structure 5 through an intermediate element (not shown) which transmits vibrations from that vibrating structure to the vibration sensor. The vibration sensor 10 can be protected from mechanical or environmental damage by a jacket 25 which may be made of rubberized press material, metal, textile material, or other suitable materials. In some embodiments, the vibration sensor 10 may have a tip 11 that is harder than the rest of the vibration sensor 10 to improve the contact between the vibration sensor 10 and the vibrating structure 5. One skilled in the art would be aware of many examples of vibration sensors, including, for example, accelerometers. The vibration sensor 10 is connected to signal processing electronics (not shown in Figure 2) inside the housing 70. The signal processing electronics can determine the amplitudes and frequencies of the vibration based on the output of the vibration sensor 10. For example, the amplitude of the vibration can be determined by integrating the signal 10 (e.g. twice. One skilled in the art would know many methods for numerically counting electronically integrating a vibration sensor signal to determine the corresponding displacement of the vibrating structure during measurement. Command buttons 80 and a monitor 90 may be used to select and display the vibration frequencies and vibration amplitudes corresponding to the vibrating structure. As discussed in detail with reference to Figures 3A-5 below, the low frequency noise can be filtered from the vibration sensor 10. The signal from the low frequency noise can be further processed together with the signal from the force sensor to give a more accurate vibration reading.
Figure 3A shows an exploded view of the vibration meter 200 arranged in accordance with embodiments of the technology described herein. Starting in the upper right corner of the figure, the vibration sensor jacket 25 may at least partially accommodate the vibration sensor 10 for environmental or mechanical damage protection. In addition, in at least some embodiments, the vibration sensor 10 may at least partially be in contact with vibration isolators 16, 20. With conventional handheld vibration meters, the vibration of the operator's hand can be transmitted to the vibration sensor 10 and may be misinterpreted as being generated by the vibrating structure itself. (eg less than about 50 Hz). In at least some embodiments of the inventive technology, the vibration isolators 16, 20 may filter out these low frequencies before they reach the vibration sensor 10. The vibration isolators 16,20 may be made of a rubber-like material or other material which dampens vibrations of the vibration sensor 10 for the frequencies of interest. The rubber-like material can, for example, be selected based on known frequency damping properties. The vibration isolators 16 and 20 may be 17 and 21, respectively, for a more stable engagement with the vibration sensor10. An output signal from the vibration sensor can be transmitted through a single cable 11 to an interface panel 61 and further to signal processing electronics (not shown).
The vibration meter 200 may also include a force sensor 30. When the vibration meter 200 presses against the vibrating structure (not shown), the contact force is transmitted from the vibration sensor 10 to the force sensor 30, which is explained in more detail with reference to Figure 3B below. The force sensor can be supported by a structure, for example a combination of a load hub 65, a load rule 55 and a load rule bracket 50, for retaining the force sensor. Screws 70 can engage receiving receiving holes 26 to keep the parts of the vibration meter 200 in contact.
Figure 3B shows an isometric view of the force sensor 30 located between a pad 45 and a piston 40. One skilled in the art would be aware of multi-force sensors available on the market, such as inclusive load meters and layered force resistance sensors. A piston 40 having a substantially flat first surface 41 can transmit contact force from the vibration sensor to the force sensor 30, which can be slid between the piston 40 and the pad 45. In some embodiments, the force sensor 30 may be preloaded to pre-process its output within the sensitivity range. The preload can be achieved, for example, by pressing the piston 40 against the force sensor 30 carried by the elastic pad 45 on the opposite side. At high load, the force sensor 30 changes its electrical resistance. This change in resistance, corresponding to the change in force, can be measured by a connector 35. As explained below with reference to Figure 4, the measurements of the vibration amplitude can be improved based on the value of the contact force between the vibrating structure and the vibration sensor.
Figure 4 is a graph of frequency response of the vibration sensor 10. The horizontal axis of the graph shows a frequency range on a logarithmic scale. The vertical axis on the left shows a sensitivity of the vibration sensor in dB. The sensitivity of a vibration sensor can be interpreted, for example, as a relationship between the amplitude indicated at the output of the vibration sensor 10 and the vibration amplitude of the vibrating structure itself. The sensitivity, which is close to zero on the logarithmic scale of the hosgraph 300, corresponds to a sensitivity value of about one on the linear scale. Conversely, a positive value on the vertical axis indicates a high sensitivity and a negative value on the vertical axis indicates a bearing sensitivity. In general, the sensitivity of a vibration sensor is a function of the vibration frequency. If the sensitivity of the vibration sensor is known in addition to a suitable coefficient or other adjustment, predetermination of the relevant vibration amplitude of the vibration structure is used at a particular vibration frequency.
The vertical axis to the right shows the vibration amplitude. The sensitivity of the vibration sensor as a function of frequency can normally be obtained from the manufacturer of the vibration sensor or it can be determined experimentally. The vibration amplitude can therefore be calculated retroactively for a particular vibration frequency. If the sensitivity of the vibration sensor is also a function of the contact force between the sensor and the vibrating structure, then a measurement of the vibration amplitude, which does not take into account the contact force, reduces the accuracy of the measurement. For example, the curves F1, F2, F3 in Figure 4 may correspond to the vibration amplitude measurements over a frequency range, but using a different contact force. One skilled in the art would recognize that a vibration amplitude for a given vibration frequency can be calculated by integrating the acceleration signal twice and by adjusting the result based on the known sensitivity of the vibration sensor.
In the illustrated example, with a vibration frequency of about 1.4 kHz, the vibration sensor would indicate vibration amplitudes A1, A2 or A3 carried the respective sensitivity curves F1, F2, F3, depending on the magnitude of the contact force between the vibration sensor and the vibrating structure. To obtain more accurate vibration amplitude measurements, one can measure and use the contact force to select a suitable sensitivity curve, e.g. F1, F2or F3. The amplitude of the vibrating structure can then be determined from the appropriate sensitivity curve. For example, the force sensor 30 (described with reference to Figures 3A-3B) can measure contact force, which mania in turn can use to select the correct vibration sensitivity curve from the sensitivity curves F1, F2 and F3. In at least some embodiments, the sensitivity curves may be available in tabular form for simpler calculations per relevant vibration frequencies. The sensitivity curves in tabular form can be accessed by suitable electronics based on the force sensor reading, and can then be further processed to calculate the vibration amplitude, for example by using signal integration algorithms. In some embodiments, the sensitivity curves may be linearized using linearization circuits. For example, the sensitivity curves F1, F2, F3 may be linearized to produce linearized sensitivity curves L1, L2 and L3, respectively. In at least some embodiments, the linearized sensitivity curves make the vibration amplitude calculation easier and / or faster.
Figure 5 is a schematic diagram of a linearization circuit 500 in accordance with embodiments of the technology described herein. A non-linear input 110 (for example, the sensitivity curves F1, F2, F3 shown in Figure 4) can be fed to a function generator 120 which outputs a function which can be attenuated with an attenuator 130. Then the non-linear input 110 and the output from the attenuator 130 can be summed in a summing amplifier 140. providing a linearized output 150 (for example, delinearized the sensitivity curves L1, L2, L3 shown in Figure 4). The linearized output 150 can be used to more easily determine the vibration amplitudes. Many function generators and linearization circuits are commercially available, such as function generators AD640, AD639, AD538 and linearization circuits AD7569 by Analog Devices, Norvvood, Massachusetts.
From the foregoing, it will be appreciated that specific embodiments of the technology have been described herein for illustrative purposes, but that various modifications may be made without departing from the description. For example, in some embodiments a function analyzer may be used in conjunction with the technology described to determine dominant frequencies. In other embodiments, the output from the vibration sensor may be provided by an analog-to-digital conversion circuit for a subsequent data processing that may be performed outside the vibration detector. The vibration detector may further include analog or digital frequency filters to eliminate the unwanted harmonics or undertones of the vibration structure. In addition, while various advantages and features belonging to certain embodiments have been described above in the context of these embodiments, other embodiments may also exhibit such advantages and / or features, and all embodiments need not necessarily exhibit such advantages and / or disadvantages in order to fail within the scope of the technology. . Accordingly, the description may include other embodiments not expressly shown or described herein. The following examples provide further embodiments of the present technology.

权利要求:
Claims (1)
[1]
REQUIREMENTS Handheld vibration meter elï), comprising, a housing (E) a vibration sensor (ﬂ) _ arranged to be in contact with a single structure (§) _ and to convert vibrations of the structure (§) _to electrical signals, the vibration sensor (ﬂ) _ being at least partially housed inside huset_ (ﬂ); a vibration isolator (16, 20) made of a rubber-like material and in contact with the vibration sensor (Q), the vibration isolator (16, 20) being arranged to filter one or more vibration frequencies; and a force sensor (@) _ which is responsive to a contact force applied to a vibration sensor (ﬂ) _, characterized in that the vibration meter (Q) comprises a plurality of sensitivity curves (F1, F2, F3) the pre-vibration sensor_ (ﬂ), the vibration meter being arranged to select by sensitivity curves (F1, F2, F3) based on a power sensor (@) - measured contact force and to use that selection sensitivity curve when determining a vibration measurement. The vibration meter (200) of claim 1, wherein the force sensor (ä) comprises a pressure sensitive electrical resistor. A vibration meter (according to claim 1), wherein the force sensor (Qmar) is a first side facing substantially the vibration sensor (Q) and a second side facing away from the first side, the vibration meter relay) further comprising: a piston (Quid force sensor (@) _ second side, wherein the piston (ﬂ) _ is arranged to transmit the contact force to the force sensor _ (@), and a pad_ (4_5) at the top side of the force sensor (Q ﬁ). Vibration meter (200) according to claim 1, wherein the vibration isolator is a first vibration isolator (16) at a front of the vibration sensor ), the vibration meter (200) further comprising: 10. a second vibration isolator (20) at a rear of the vibration sensor (10), the vibration meter (200) of claim 1, the vibration isolator (20) comprising rubber, the vibration meter (200) of claim 1, further comprising means for predetermining an adjusted vibration sensor response from a combination of a vibration sensor response and a force sensor response.The vibration meter (200) of claim 6, wherein the means A determination of the adjusted vibration sensor response includes a look-up table, a processor, and a combination thereof. The vibration meter (200) of claim 6, wherein the at least one vibration sensor response and the adjusted vibration sensor response are linearized. A method for measuring vibrations of a vibrating equipment (å) using a vibration meter reli), comprising: sensing vibrations of the vibrating equipment_ (§) with a vibration sensor_ (ﬂ) having contact with the vibrating equipment_ (§), to provide a vibration sensor response with the vibration sensor_ (ﬂ), to measure a contact force between the vibration sensor (ﬂ) _ and the vibrating equipment_ (§), and to adjust the vibration sensor response based on the contact force to generate an adjusted vibration sensor response, the action adjusting comprising selecting one from a plurality of sensitivities; , F3) of the vibration sensor (QL based on the measured contact force and using the selected sensitivity curve in adjusting the sensor response. The method of claim 9, further comprising: 11. 12. 13. 14. 15. 11 The method of claim 10, further comprising: being asked tame an amplitude of the vibrations based on the adjusted vibration sensor response. The method of claim 9, further comprising: determining a frequency of the vibrations based on the adjusted vibration sensor response. The method of claim 9, further comprising: filtering one or more vibration frequencies using a vibration isolator (16, 20) made of a rubber-like material and in contact with the vibration sensor (ﬂ). A method according to claim 449, wherein the vibration isolator comprises: a first insulator (16) at a front side of the vibration sensor (Q), and a second insulator (20) at a rear side of the vibration sensor (E) - A method according to claim 9, wherein the measurement of a contact force the intermediate vibration sensor (10) and the vibrating equipment (§) are provided with a force sensor (30).

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法律状态:

优先权:

申请号 | 申请日 | 专利标题

US13/800,705|US9188479B2|2013-03-13|2013-03-13|Vibration sensor in a portable vibration meter|

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