Patent Grant
7091832
Certain machinery components emit sounds when operating under normal conditions. These sounds can be considered to be annoying, but can be reassuring as a sign that the machinery component is operating normally. For example, personal computers are equipped with fans that keep the CPU cool during operation. Although computer fans have become more quiet, the blowing sound made by the fan, or the hum emitted by the fan motor, is usually discernible. The absence of this sound, or a change in its usual qualities, can be interpreted as a potential problem in the functioning of the computer.
Other types of machinery perform continuously over certain periods of time, and emit characteristic sounds the entire time of performance. If the machinery component normally emits a distinct sound at regular intervals, the sudden absence of this sound could be a sign that the machinery component is experiencing degradation in performance, or even failure. A person monitoring the function of the machinery component could recognize the absence of the sound and investigate the cause of the interruption. However, the person might be distracted and wouldn't necessarily notice the absence of the sound. Further, a change in pitch or frequency, indicating degradation, might not be easily recognized. Also, some machinery operates unattended for at least some periods of time, and therefore the absence of the sound would not be noticed.
For example, one type of magnet, used in NMR imaging systems and for other applications, is ouffitted with superconducting magnet coils. These coils must be kept below a particular temperature in order to function properly. For example, the magnet coils can be maintained within a selected operating temperature range by using liquid helium, which is kept cool by cryocoolers, typically one for each magnet coil. The compressor for the cryocoolers can be air cooled or water cooled. If the compressor is water cooled, and if access to the cooling water is accidentally cut off, such as if water access is turned off in the building or if water pressure drops due to an emergency, the cryocoolers can go into thermal shutdown. Even after the water is turned back on, the cryocoolers typically need to be manually restarted and do not turn themselves back on. Without the cryocoolers running, the magnet will not work properly.
A cryocooler makes a regular chirping sound under normal operating conditions. Under conditions that cause performance of the cryocooler to degrade or fail, this chirp can become less regular in its rate and pitch, can occur at less frequent intervals, or can even stop, depending on the particular malfunction. It would be advantageous to provide a process by which a change or absence of this chirp would be recognized, and an indication, such as an alarm, provided as notification of the change. It would also be advantageous to provide an apparatus that can perform such a process.
The present invention makes use of a natural effect of some machinery components to serve as the basis for detecting whether the component has broken down, is on the verge of failure, or is otherwise malfunctioning. As used herein, the term “malfunction” will refer to any aberration in the normal operation of a machine component, covering the range from harmless irregularity to complete failure. The present invention includes a process for monitoring the sound made by machinery components to determine when a malfunction might have occurred. The present invention also includes an apparatus that produces an indication based on a change in the sound made by the machinery component under normal operating conditions.
According to a particular aspect of the present invention, a sound variation indication apparatus includes a comparison element, an interval checker, and an indication generator. The comparison element receives an audio signal, compares the audio signal to a check value, and provides a status signal based on an outcome of the comparison. The status signal indicates a presence and absence of the sound input as corresponding to the check value, respectively indicating a presence value and an absence value. The interval checker receives the status signal and determines a value of the status signal at predetermined intervals, to provide an interval output. The interval output is a presence representation if a presence value is determined during an interval and an absence representation if no presence value is determined during an interval. The indication generator receives the interval output and generates an indication if the interval output is an absence representation.
The sound variation indication apparatus can also include a sound transducer that provides the audio signal to the comparison element, based on a received sound input. The sound transducer can include a microphone that receives the sound input and provides the audio signal. As an alternative example, the sound transducer can include a microphone that receives the sound input and provides a corresponding electrical signal, and a conditioning element that receives the electrical signal and provides the audio signal. For example, the conditioning element can be an amplifier that amplifies the electrical signal to provide the audio signal, or a buffer that buffers the electrical signal to provide the audio signal. Other conditioning elements, such as filters, can be used, either alone or in combination with the exemplary conditioning elements or other conditioning elements.
The comparison element can be a comparator circuit, in which case the check value is a voltage level corresponding to a level of the audio signal for an expected received sound input. The status signal can be a binary signal indicating the presence and absence of the expected received sound input. The interval checker can in this case provide an interval output that is an absence representation if the status signal does not indicate the presence of the expected received sound input during the predetermined interval. The interval checker can be an electronic circuit that can be fabricated on an integrated circuit chip, such as a retriggerable monostable multivibrator. The voltage level of the check value can correspond to an amplitude of the expected received sound input, the status signal can be a pulse corresponding to occurrence of the received sound input, and the predetermined interval can be based on a rate of recurrence of the expected received sound input. For example, if the status signal is a periodic pulse corresponding to the expected received sound input, which is expected to be a periodic sound input, the predetermined interval can be based on a frequency of the expected periodic sound input.
The indication generated by the indication generator can be a state change, such as a hardware state change or a software state change. The sound variation indication apparatus can also include an alarm device that is actuated by the state change. Alternatively, the indication generator can be the alarm itself. The alarm device can be a sensory device, such as a buzzer, bell, strobe, LED, or vibrating mechanism; a non-sensory hardware device, such as a switch, a latch, or a local network pager transmitter; or a software device, such as a telephone dialing program, a network prompter for sending an automated e-mail message, or a program for making a log entry.
In an exemplary application, the sound transducer can be disposed near enough to a machine component such that when the machine component makes a repeated sound at regular intervals when functioning normally, the sound transducer receives the repeated sound as the received sound input. In such an exemplary application, the machine component can be, for example, a cryocooler.
Alternatively, the apparatus of the present invention can also include a machine component disposed near enough to the sound transducer such that when the machine component makes a repeated sound at regular intervals when functioning normally, the sound transducer receives the repeated sound as the received sound input. As in the example above, the machine component can be a cryocooler.
In order to improve the sound detection aspects of the present invention, the sound variation indication apparatus can also include acoustic insulation material disposed to at least partially isolate the sound transducer from ambient sound inputs to distinguish the received sound input. Alternatively, or in addition, the sound variation indication apparatus can also include an acoustic insulation structure, such as an isolation chamber, disposed to at least partially isolate the sound transducer from ambient sound inputs in order to distinguish the received sound input.
According to another aspect of the present invention, a sound variation indication apparatus can have an indication generator that shares a number of parallel monitoring circuits, each of which monitors the sounds made by different machinery components. Such an apparatus includes a plurality of comparison elements, a corresponding plurality of interval checkers, a summary status checker, and an indication generator. The plurality of comparison elements each receives an audio signal from a respective one of the plurality of sound transducers. Each of the plurality of comparison elements compares the received audio signal to a corresponding check value, and provides a respective status signal based on an outcome of the comparison. Each of the status signals indicates a presence and absence of the respective sound input as corresponding to the check value, respectively indicating a presence value and an absence value. The plurality of interval checkers each receive the respective status signal and determine a value of the status signal at predetermined intervals, to provide a respective interval output that is a presence representation if a presence value is determined during an interval and an absence representation if no presence value is determined during an interval. The summary status checker receives the interval outputs and provides a summary status that has a first value if a number of interval outputs that are presence representations is at least a predetermined number, and that has a second value if the number of interval outputs that are presence representations is less than the predetermined number. The indication generator receives the summary status and generates an indication if the summary status is the second value. The sound variation indication apparatus can also include a plurality of sound transducers that provide the respective plurality of audio signals based on respective received sound inputs.
Thus, a certain number of malfunctions detected by the plurality of monitor circuits will cause an indication to be generated. For example, the predetermined number can be the same as the total number of interval outputs, that is, even one detected malfunction will cause the indication to be generated. In this case, the summary status checker can be a logic circuit that performs an AND operation on the interval outputs. Alternatively, to allow the indication to be reset, the summary status checker can include a logic circuit that performs an AND operation on the interval outputs to provide a summary representation, and a re-settable register that receives the summary representation and provides the corresponding summary status. The re-settable register can be, for example, a flip-flop circuit. The summary status checker can also include a relay that actuates the indication generator if the summary status is the second value.
Alternatively stated, the summary status checker can include a logic circuit that performs an AND operation on the interval outputs to provide a summary representation, and a flip-flop circuit that receives the summary representation and processes the summary representation to provide the summary status. The flip-flop circuit can be re-settable. As in the previous case, the summary status checker can also include a relay that actuates the indication generator if the summary status is the second value.
According to another aspect of the present invention, a process of generating an indication on absence of a sound input includes providing an audio signal based on a received sound input and comparing the audio signal to a check value. A status signal is provided based on an outcome of the comparison. The status signal indicates a presence and absence of the sound input as corresponding to the check value, respectively indicating a presence value and an absence value. A value of the status signal is determined at predetermined intervals, to provide an interval output that is a presence representation if a presence value is determined during an interval and an absence representation if no presence value is determined during an interval. An indication is generated if the interval output is an absence representation.
The sound input can be received by and the audio signal can be provided by a microphone, which can be at least partially isolated from ambient sound inputs to distinguish the received sound input. For example, acoustic insulation material or an acoustic insulation structure can be disposed around at least a portion of the microphone. The process can also include disposing the microphone proximate to a machine component to receive the sound input. The machine component makes a repeated sound at regular intervals when functioning normally, and the microphone receives the repeated sound as the received sound input. The machine component can be, for example, a cryocooler.
Providing an audio signal based on a received sound input can include receiving the sound input, providing a corresponding electrical signal, and conditioning the electrical signal to provide the audio signal. Conditioning the electrical signal can include, for example, amplifying the electrical signal to provide the audio signal, buffering the electrical signal to provide the audio signal, filtering the electrical signal to provide the audio signal, or any combination of these or other conditioning actions.
Comparing the audio signal to a check value can include providing the audio signal to a comparator circuit, which compares the audio signal to a voltage level corresponding to a level of the audio signal for an expected received sound input. The status signal can be a binary signal indicating the presence and absence of the expected received sound input. In this case, determining a value of the status signal at predetermined intervals can include providing an interval output that is an absence representation if the status signal does not indicate the presence of the expected received sound input during the predetermined interval. Determining a value of the status signal at predetermined intervals can be performed, for example, by a retriggerable monostable multivibrator. The voltage level can correspond to an amplitude of the expected received sound input. The status signal can be a pulse corresponding to occurrence of the received sound input, and the predetermined interval is based on a rate of recurrence of the expected received sound input. For example if the status signal is a periodic pulse corresponding to the expected received sound input, which is an expected periodic sound input, the voltage level can correspond to an amplitude of the expected received sound input, and the predetermined interval can be based on a frequency of the expected periodic sound input.
Thus, a process is provided by which a change or absence of an expected sound is recognized, and an indication provided as notification of the change. An apparatus is also provided that can perform such a process. In application, for example, a chirp detector or a low sound level indicator can be added to a magnet system as an early detector of a malfunction in a cryocooler. These detectors can be disposed, for example, on the cryocooler's compressor cooling lines, and can be surrounded by foam as necessary.
The indication generated by the process of the present invention can be a state change, such as a hardware state change or a software state change. The state change can in turn actuate an alarm. Alternatively, the generated indication can be the alarm itself. The alarm can be a sensory alarm, such as a sound, light, or vibration; a non-sensory alarm, such as movement of a switch, a latch, or a local network pager transmitter; or a software alarm, such as a telephone dialing action, a network prompt for sending an automated e-mail message, or actuation of a program for making a log entry. Thus, the indication can be a change of state, which in turn can provide a local alarm by way of a sensory warning or a remote alarm by pager or telephone. Once the indication has been generated, log entries can be made, e-mail can be sent, and, if appropriate, devices such as switches and latches can be set, to activate emergency back-up systems or to turn off the main system if continued operation under malfunction conditions could lead to failure.
It will be apparent to those of skill in the art that the apparatus of the invention can be embodied in a number of different ways, including analog circuitry, digital logic circuitry, software systems, and firmware, or any combination of these. Likewise, it is contemplated that the process of the invention as described herein and recited in the claims can be performed by hardware, firmware, or software, or any combination of these or any other apparatus.
With reference to
An interval checker 16 receives the status signal 14 and determines a value of the status signal 14 at predetermined intervals. As a result of this determination, the interval checker 16 provides an interval output 18 that is a presence representation if a presence value is determined during an interval and an absence representation if no presence value is determined during an interval. That is, the interval checker 16 begins checking the status signal 14 at the beginning of each predetermined interval. If the status signal 14 indicates a presence value during that interval, the interval checker 16 provides an interval output 18 that is a presence representation. On the other hand, if the interval lapses and the status signal 14 did not indicate a presence value during that interval, the interval checker 16 provides an interval output 18 that is an absence representation.
An indication generator 20 receives the interval output 18 from the interval checker 16. As long as the interval output 18 is a presence representation, the indication generator 20 does not issue an indication 22 of a variation of the sound input. However, the indication generator 20 does generate an indication 22 if the interval output 18 is an absence representation. The indication 22 that is generated can be, for example, a state change, such as a hardware state change or a software state change, which can in turn be used to actuate an alarm 23 or other additional device or action based on the sound input variation indication. Alternatively, the indication 22 can be the alarm itself. As previously described, an alarm device according to the present invention can be a sensory device, such as a buzzer, bell, strobe, LED, or vibrating mechanism; a non-sensory hardware device, such as a switch, a latch, or a local network pager transmitter; or a software device, such as a telephone dialing program, a network prompter for sending an automated e-mail message, or a program for making a log entry. Thus, the indication generator initiates a change of state, which in turn can provide a local alarm by way of a sensory warning or a remote alarm by pager or telephone. Once the indication has been generated, log entries can be made, e-mail can be sent, and, if appropriate, devices such as switches and latches can be set, to activate emergency back-up systems or to turn off the main system if continued operation under malfunction conditions could lead to failure.
According to particular embodiments of the present invention, the sound transducer 4 can include a microphone that receives the sound input 8 and provides the audio signal 6. As shown in
As shown in
The comparison element 10 can be embodied as a typical comparator circuit, such as that provided on a comparator IC. The check value 12 provided to the comparison element 10 is a voltage level to which the audio signal 6 is compared, corresponding to a level of the audio signal 6 for an expected received sound input 8. Thus, the expected sound input 8 provides a particular audio signal 6 according to the design of the sound transducer 4. The voltage level that serves as the check value 12 is set to the expected audio signal 6 level, so that a favorable comparison results in a status signal 14 that is a presence representation each time an expected sound input 8 is received. Thus, if digital circuitry is used, the status signal 14 can be a binary signal indicating the presence or absence of the expected received sound input.
Because the received sound input 8 is expected to be intermittently repeated according to a noted interval, the status signal 14 will likewise alternately indicate the presence and absence of the sound input 8. Because the indication should not be generated during times between issuance of the intermittent sound input 8, the interval checker 16 ensures that the indication stays off as long as the sound input 8 is received once during each interval. Thus, the interval checker 16 checks the status signal 14 over the course of each interval, and provides an interval output 18 that is an absence representation only if the status signal 14 does not indicate the presence of the expected received sound input 8 during the predetermined interval. If the status signal indicates the presence of the expected received sound input 8 at all during the predetermined interval, the interval output 18 will be a presence representation. As will be shown later, a retriggerable monostable multivibrator or similar circuit can be used as the interval checker 16.
Thus, as shown in
If it is expected that the sound input 8 is substantially periodic, and not just occurring at uncertain times within a time interval, the voltage level of the check value 12 corresponds to the amplitude of the expected received sound input 8, the status signal 14 is a periodic pulse corresponding to the expected received sound input 8, and the predetermined interval is based on a frequency of the expected periodic sound input 8. The interval checker 16 in this case can be made to check the status signal 14 more precisely, that is, to determine the state of the status signal 14 at periodic instances rather than at any time during a prescribed interval. This is important if a change in the periodic nature of the expected sound input 8 is considered a sign of malfunction.
As shown in
The exemplary embodiments described above can be modified to monitor more than one machine component simultaneously. According to another exemplary embodiment, a number of sound transducers 4 can provide a respective number of audio signals 6 based on respective received sound inputs, as shown in
As shown, a summary status checker 52 receives the interval outputs 18 and provides a summary status 54. The summary status 54 has a first value if a number of interval outputs that are presence representations is at least a predetermined number, and has a second value if the number of interval outputs that are presence representations is less than the predetermined number. The indication generator 20 receives the summary status 54 and generates an indication if the summary status 54 is the second value. Thus, if a predetermined number of sound inputs are absent during any interval, the indication will be generated. It is apparent to those of skill in the art that a combination of simple logic gates can be designed to provide predetermined summary status outputs according to any combination of inputs, giving all inputs equal weight or establishing priority for certain inputs over others. If an indication is to be generated if even one sound input is missing for an interval, the predetermined number is the same as the total number of interval outputs 18, that is, all the interval outputs 18 must be presence representations to avoid indicating a malfunction. In this case, the summary status checker 52 can be a logic circuit that performs an AND operation on the interval outputs, as shown in
With reference to
As shown, an audio signal, provided by an external microphone coupled across connectors J2/1 and J2/6, is amplified by an operational amplifier U1. The offset and gain of the operational amplifier U1 can be adjusted through the use of, for example, the potentiometers R2 and R4. The output signal U1/1 from the operational amplifier U1 is provided to the non-inverted input U2/5 of the comparator U2. When this signal exceeds a pre-set voltage level, the comparator U2 generates a positive TTL-level pulse at U2/2. This pre-set voltage level can be adjusted using the potentiometer R5 connected to the U2/4 input of the comparator U2.
The output U2/2 of the comparator U2 is provided to the “B” input U3/2 of a retriggerable monostable multivibrator U3. If this multivibrator input U3/2 is not pulsed after a certain period of time, for example, 30 seconds, the multivibrator “Q” output U3/13, which is otherwise a TTL-level high output, will switch to a TTL-level low output. The multivibrator output U3/13 is provided to the input U4/1 of an AND gate U4. The input signal to the other AND gate input U4/2 is provided by a circuit that is identical to that described above, as shown. Thus, if either (or both) AND gate input receives a TLL-level low, the AND gate output U4/3 will also be set to a TTL-level low; the output U4/3 is set at a TTL-level high as long as both inputs are also set at TTL-level highs.
The output U4/3 of the AND gate U4 is provided to the “set” input U5/4 of a D-type flip-flop circuit U5. When the “set” input is a TTL-level low, the inverted “Q” output U5/6 of the flip-flop circuit U5 will change state. That is, if the flip-flop output U5/6 is set to a high level under normal operating conditions, a low level at the “set” input U5/4 will cause the flip-flop output U5/6 to go low. The presence of a low signal at the flip-flop output U5/6 can be used to actuate an alarm, for example, through a relay K1. The relay K1 is just one example of a circuit component that can undergo a state change on actuation by the flip-flop circuit U5, serving as an initial indication of a variation in the sound input. The alarm can be any type of alarm device coupled across connectors J3/1 and J3/3, for example, a sensory alarm such as a buzzer or blinking LED, a telephone dialer, a paging transmitter, or a network prompter, and serves as a further indication of the sound input variation. The alarm can be protected by a fuse F1. The relay K1 and alarm can be reset by providing a low level signal at the “reset” input U5/1 of the flip-flop circuit U5, for example, by connecting it to ground momentarily through the use of a momentary switch SW1.
Thus, the exemplary circuit design monitors intermittent sound at two machine components, for example, periodic chirping at two cryocoolers. If either or both of the cryocoolers fail, the indication will be generated. Microphones can be placed in advantageous locations at the cryocoolers to detect the chirping and convert the sound to audio signals that can be processed by the circuit. It should be noted that, although the circuit has been provided to monitor two audio signals simultaneously, two audio inputs are not necessary. If only a single input is to be monitored, one input of the AND gate can be fixed at a high level through the use of, for example, a pull-up arrangement. Likewise, more than two audio inputs can be monitored by using multiple operational amplifier/comparator/multivibrator circuits, and multiple logic gates in place of the disclosed single AND gate, as will be apparent to those of ordinary skill in the art.
As shown in
This is related to U.S. Provisional Patent Application Ser. No. 60/388,805, which was filed on Jun. 14, 2002 now abandoned.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5164840 | Kawamura et al. | Nov 1992 | A |
| 5550925 | Hori et al. | Aug 1996 | A |
| 6718217 | Shinohara et al. | Apr 2004 | B1 |
| 6940986 | Belenger et al. | Sep 2005 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 60388805 | Jun 2002 | US |
