JP2004092508A - Air compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detection accuracy in irregularity occurrence of an air compressor. <P>SOLUTION: A signal processing substrate 50 of the air compressor includes an amplifier 74 amplifying detected signal detected by an irregularity detection sensor 38, a detector 76 shaping signal output from the amplifier 74 in waveform, a control circuit 78 determining existence of irregularity occurrence based on detected signal output from the detector 76, a memory 80 storing threshold of irregularity determining processing, an alarm 82 issuing an alarm when it is determined as irregularity occurrence. The control circuit 78 samples the detected signal output from the detector 76 under regular operation and computes a threshold (upper limit value) by multiplying average value Y of sampled values by arbitrary coefficients α when a threshold setting switch 48 is turned on. A computed value Y<SB>α</SB>is stored in the memory 80 as the threshold. Accordingly, the threshold (upper limit value) according to environment of installation location (such as hardness of floor) can be established. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an air compressor, and more particularly to an air compressor configured to determine the presence or absence of an abnormality in an activated air compressor.
[0002]
[Prior art]
For example, in an air compressor that transmits the rotational driving force of an electric motor to a crankshaft and reciprocates a piston to generate compressed air, an intake valve and a discharge valve are provided in a cylinder head, and the piston is operated in the operating direction of the piston. The intake valve or the discharge valve is configured to perform a valve opening operation or a valve closing operation accordingly.
[0003]
In this type of air compressor, operation noise and vibration such as reciprocation of a piston, opening and closing operations of an intake valve and a discharge valve are generated. Then, when an abnormality such as breakage occurs in each of the operation parts as described above, abnormal vibration and abnormal noise different from normal operation vibration and operation noise occur, and it can be seen that some failure has occurred.
[0004]
In such an air compressor, for example, as disclosed in JP-A-2-205728, elastic energy generated when a metal is broken is detected by an AE (acoustic emission) sensor and automatically detected. There is a configuration having a failure diagnosis function for stopping operation. Then, the computer having the failure diagnosis function compares the threshold value stored in the memory in advance with the detection value detected by the sensor to determine whether there is an abnormality.
[0005]
In addition to the above-described AE sensor, some have a failure diagnosis function of determining whether there is an abnormality in the air compressor using a sensor such as an acceleration sensor or a piezoelectric element.
[0006]
[Problems to be solved by the invention]
However, in the conventional air compressor as described above, since the threshold is operated so as to be stored in the memory at the stage of assembling at the factory, for example, a rubber mat is laid on a place to be installed after being delivered to the user. In some cases, the vibration characteristics change as compared with the case where the device is installed on a concrete surface, and it may not be possible to accurately determine the occurrence of an abnormality.
[0007]
Therefore, for example, if the threshold value is set based on the case where the air compressor is installed on a concrete surface, it is necessary to change the threshold value when the air compressor is installed on a place other than the concrete surface. Since it takes time, it is difficult to change the threshold value.
[0008]
Therefore, an object of the present invention is to provide an air compressor that solves the above problems.
[0009]
[Means for Solving the Problems]
The present invention has the following features to solve the above problems.
The present invention provides an air compression unit that compresses air, a sensor that detects vibration of the compression unit, a storage unit that stores a threshold value for an output value of the sensor in advance, a detection signal detected by the sensor, and a storage unit that stores the detection signal. Determining means for determining the presence or absence of an abnormality in accordance with a comparison result with the threshold value, and a threshold calculating means for activating the air compressor by a threshold setting operation after installation and calculating the threshold value in the air compressor. And a storage unit for storing the threshold value calculated by the threshold value calculation unit in the storage unit, so that it is possible to set a threshold value according to the environment of the installation location, and to accurately determine whether there is an abnormality. I can do it.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing an embodiment of the air compressor according to the present invention.
As shown in FIG. 1, the air compressor 10 includes an air compressor 12, an electric motor 16, and an operation unit 18 provided above an air tank 12. Further, wheels 20 are provided below the air tank 12.
[0011]
The air compressor 14 has first to third cylinders 22, 24, and 26, and is a multistage type that gradually increases the pressure of compressed air. The cylinders 22, 24, 26 are communicated via air lines 30, 32, 34, and the air compressed by the first cylinder 22 is introduced into the second cylinder 24 via the air line 30, The medium-pressure air compressed by the second cylinder 24 is introduced into the third cylinder 26 via the air line 32, and the high-pressure air compressed by the third cylinder 26 is introduced into the air tank 12 via the air line 34. Is done.
[0012]
The first to third cylinders 22, 24, 26 are provided on a crankcase 36 attached to the upper part of the air tank 12. An abnormality detection sensor 38 for detecting abnormal vibration is attached to a wall surface of the crankcase 36. The abnormality detection sensor 38 is a vibration detection sensor including a piezoelectric element or the like, and outputs a signal corresponding to the vibration of the crankcase 36.
[0013]
The rotational driving force of the electric motor 16 is transmitted to a pulley 44 provided on the back side of the crankcase 36 via a pulley 40 and a V-belt 42 connected to a motor rotation shaft (not shown).
[0014]
The operation unit 18 includes a power switch 46, a threshold setting switch 48, and a signal processing board 50. The power switch 46 is provided to be exposed on the front surface of the operation unit 18 and can be turned on or off at any time.
[0015]
The threshold setting switch 48 is covered by a cover 52, and is operated by opening the cover 52 immediately after the air compressor 10 is installed. Therefore, the threshold setting switch 48 does not usually need to be operated, and is hidden by the cover 52, and is provided so as not to be operated by mistake. The signal processing board 50 will be described later.
[0016]
FIG. 2 is a longitudinal sectional view taken along line AA in FIG.
As shown in FIG. 2, a crankshaft 54 is rotatably supported by bearings 56 and 58 inside the crankcase 36, and a pulley 44 is connected to one end 54 a of the crankshaft 54. A lower end of a connecting rod 60 is connected to the eccentric shaft 54b of the crankshaft 54, and a piston 62 is connected to an upper end of the connecting rod 60 via a piston pin (not shown).
[0017]
Therefore, when the rotational driving force of the electric motor 16 is transmitted to the pulley 44 via the V-belt 42, the crankshaft 54 is rotationally driven, and the connecting rod 60 swings to reciprocate the piston 62. A cylinder head 64 provided above each of the cylinders 22, 24, 26 has an intake valve 68 that opens and closes an intake passage 66 that sucks air, and a discharge valve 72 that opens and closes a discharge passage 70 that discharges compressed air. Having. As the piston 62 descends, the intake valve 68 opens and the discharge valve 72 closes. In addition, the intake valve 68 closes and the discharge valve 72 opens while the piston 62 rises.
[0018]
FIG. 3 is a block diagram showing the configuration of the signal processing board 50.
As shown in FIG. 3, the signal processing board 50 includes an amplifier (amplifier) 74 for amplifying the detection signal detected by the abnormality detection sensor 38, and a detector 76 for shaping the waveform of the signal output from the amplifier 74. A control circuit 78 for determining the presence or absence of an abnormality from the detection signal input from the detector 76, a memory 80 for storing a threshold value for the abnormality determination processing, and an alarm 82 for issuing an alarm when it is determined that an abnormality has occurred. Have. Further, the signal processing board 50 is provided with a power supply circuit 84 for supplying power to the motor 16 and a motor switch 86 for turning on or off the power output from the power supply circuit 84.
[0019]
The motor switch 86 is turned on or off based on a control signal from the control circuit 78. The motor switch 86 is turned on / off in conjunction with the on / off of the power switch 46, and the control circuit 78 determines that an abnormality has occurred. When it is turned off, the motor 16 is stopped and the motor 16 is stopped.
[0020]
4A and 4B are waveform diagrams of a signal detected in a normal state, FIG. 4A is a waveform diagram of an amplifier output, and FIG. 4B is a waveform diagram of a detector output.
As shown in FIGS. 4A and 4B, when the air compressor 10 is operating normally, the signal detected by the abnormality detection sensor 38 has a relatively small waveform.
[0021]
5A and 5B are waveform diagrams of a signal detected at the time of abnormality, FIG. 5A is a waveform diagram of an amplifier output, and FIG. 5B is a waveform diagram of a detector output.
When the air compressor 10 is operating abnormally (for example, the connecting rod 60 is broken or the bearings 56 and 58 are worn), abnormal vibration occurs in the crankcase 36. In this case, the signal detected by the abnormality detection sensor 38 has a relatively large waveform as shown in FIGS. 5A and 5B. Therefore, the control circuit 78 compares the signal output from the detector 76 with a preset threshold value, and when the signal output from the detector 76 changes to a value exceeding the preset threshold value, It is determined that an abnormality has occurred.
[0022]
Here, a control process executed by the control circuit 78 after the air compressor 10 assembled at the factory is delivered to a user and installed at an arbitrary place will be described.
[0023]
FIG. 6 is a flowchart for explaining the threshold setting process executed by the control circuit 78.
As shown in FIG. 6, when the threshold setting switch 48 is turned on in step S11 (hereinafter, “step” is omitted), the control circuit 78 proceeds to S12 and turns on the motor switch 86 to turn on the motor 16. Is started to reciprocate the pistons 62 of the first to third cylinders 22, 24, 26 to supply compressed air to the air tank 12.
[0024]
In the next step S13, the detection signal output from the detector 76 during normal operation is sampled at a constant cycle, and the sampled detection value is stored in the memory 80. Subsequently, the process proceeds to S14, and the current sampling number A (= A + 1) is stored in the counter K.
[0025]
In the next S15, it is checked whether or not the current number of samplings A has reached a preset value N (for example, N = 1000). In S15, the sampling processing of S13 and S14 is repeated until the number of times of sampling A reaches a preset value N. Then, in S15, when the number of samplings A reaches the preset value N, the process proceeds to S16, and the average value Y of the sampling values in the normal operation is calculated by dividing the total value of the sampling values by the number of samplings.
[0026]
In the next step S17, a threshold value (upper limit value) is calculated by multiplying the average value Y of the normal operation sampling value by an arbitrary coefficient α (corresponding to the threshold value calculating means described in claim 1). It should be noted that the coefficient α desirably satisfies α ≧ 2 in the case of a sine wave so as to exceed the maximum value in a normal state. The reason is that in the case of a sine wave, the fluctuation of the sampling value during normal operation (the amplitude between the maximum value and the minimum value) is approximately twice the average value Y. In the present embodiment, by giving a margin to the coefficient α and setting α = 5, it is possible to prevent a detection signal during normal operation from being erroneously determined to be abnormal.
[0027]
In the next step S18, the value (Y · α) calculated in the above step S17 is stored in the memory 80 as a threshold value (corresponding to the storage means described in claim 1). Thereafter, in S19, the motor switch 86 is turned off, and the power supply to the motor 16 is stopped.
[0028]
As described above, in the air compressor 10, when the threshold setting switch 48 is turned on, the vibration state in the case of normal operation at the installation location is detected, and the environment of the installation location (for example, the hardness of the floor surface) is detected. , Etc.) can be set. Therefore, the threshold value for performing the abnormality determination processing is a threshold value that actually corresponds to the environment (for example, the hardness of the floor) of the installation location of the air compressor 10, and the abnormality detection accuracy is improved.
[0029]
The air compressor 10 starts the normal operation mode (compressed air generation operation) when the power switch 46 is turned on after completing the threshold value (upper limit value) setting processing as described above.
[0030]
FIG. 7 is a flowchart for explaining a motor control process after the air compressor 10 is installed.
As shown in FIG. 7, when the power switch 46 is turned on in S21, the control circuit 78 proceeds to S22, turns on the motor switch 86, starts the motor 16, and starts the first to third cylinders. The compressed air is supplied to the air tank 12 by reciprocating the pistons 62 of 22, 22, and 26.
[0031]
In the next S23, it is confirmed that the timer is on. If the timer is not turned on in S23, the process proceeds to S24, and the timer is set on. If the timer is ON in S23, the process of S24 is omitted and the process proceeds to S25.
[0032]
In S25, it is checked whether or not a predetermined time set by the timer has elapsed. In S25, when the predetermined time set by the timer has elapsed, the process proceeds to S26, and the counters E1 and E2 and the timer are reset.
[0033]
If it is determined in S25 that the predetermined time set by the timer has not elapsed, the process of S26 is omitted and the process proceeds to S27.
[0034]
In the next S27, it is checked whether or not the output value of the signal output from the detector 76 is equal to or less than the lower limit. This lower limit value is set to a value slightly larger than zero so that a small sensor output when the abnormality detection sensor 38 is separated from the crankcase 36 can be detected.
[0035]
Therefore, in S27, when the output value of the signal output from the detector 76 is equal to or smaller than the lower limit, the process proceeds to S28, and 1 is added to the counter E1. In the next S29, it is checked whether or not the count value of the counter E1 is equal to or more than a predetermined number (for example, about 100 times).
[0036]
In S29, when the count value of the counter E1 is equal to or smaller than the predetermined number, the process returns to S22, and the processes from S22 onward are repeated. However, if the count value of the counter E1 is equal to or more than the predetermined number in S29, it is determined that the abnormality detection sensor 38 has been peeled off from the crankcase 36, and the process proceeds to S30, in which a warning is issued from the alarm 82 to notify the user. . Thereafter, in S31, the motor switch 86 is turned off to stop energizing the motor 16.
[0037]
Accordingly, it is understood that the abnormality is not an abnormality of the air compressor 10 but an abnormality due to a failure of the abnormality detection sensor 38, and it is understood that the air compressor 10 itself has no abnormality.
[0038]
If the output value of the signal output from the detector 76 is not equal to or smaller than the lower limit value in S27, the process proceeds to S32, and the output value of the signal output from the detector 76 is set to the threshold value (upper limit) set in the memory 80. Value). If the output value of the signal output from the detector 76 is not equal to or greater than the threshold value (upper limit value) set in the memory 80 in S32, the air compressor 10 is operating normally, and the process returns to S22. The processing after S22 is repeated.
[0039]
However, if the output value of the signal output from the detector 76 is equal to or more than the threshold value (upper limit value) set in the memory 80 in S32, it is because some abnormality has occurred in the air compressor 10, and the process proceeds to S33. Then, 1 is added to the counter E2. In the next S34, it is checked whether or not the count value of the counter E1 is equal to or more than a predetermined number (for example, about 10,000 times).
[0040]
If the count value of the counter E2 is not equal to or more than the predetermined number in S34, the process returns to S22, and the processes in and after S22 are repeated. However, in S34, when the count value of the counter E2 is equal to or more than the predetermined number, it is determined that some abnormality (for example, breakage of the connecting rod 60 or wear of the bearings 56 and 58) has occurred in the air compressor 10. , S35, and an alarm is issued from the alarm 82 to notify the user. Thereafter, in S36, the motor switch 86 is turned off to stop energizing the motor 16.
[0041]
As described above, when the count value of the counter E2 is equal to or more than the predetermined number in S34 within the predetermined time by the timer, it is determined that some abnormality has occurred in the air compressor 10, and when the predetermined time has elapsed, the counter is reset. Therefore, for example, when a tool is dropped on the crankcase 36 and an impact is detected by the abnormality detection sensor 38, it is not determined that an abnormality has occurred, and the abnormality occurrence detection accuracy can be increased.
[0042]
In the above-described embodiment, reciprocating compressed air is described as an example. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to an air compressor that generates compressed air by another method.
[0043]
Further, in the above embodiment, when the threshold setting switch 48 is turned on, the vibration state in the case of normal operation at the installation location is detected, and the environment (for example, the hardness of the floor) of the installation location is detected. Is set as an example, but the present invention is not limited to this. For example, when a plug of a power cable of the air compressor 10 is inserted into an outlet, the above-described threshold setting process is performed. May be executed.
[0044]
【The invention's effect】
As described above, according to the present invention, an air compression unit that compresses air, a sensor that detects vibration of the compression unit, a storage unit that stores a threshold value for an output value of the sensor in advance, and a detection unit that detects a sensor Determining means for judging the presence or absence of an abnormality according to the comparison result between the signal and the threshold value stored in the storage unit. And a storage unit for storing the threshold value calculated by the threshold value calculation unit in the storage unit, so that a threshold value can be set according to the environment of the installation location, and the determination of the presence or absence of an abnormality can be performed. Can be performed accurately. Therefore, the reliability of the abnormality determination can be improved.
[Brief description of the drawings]
FIG. 1 is a front view showing an embodiment of an air compressor according to the present invention.
FIG. 2 is a longitudinal sectional view taken along line AA in FIG.
FIG. 3 is a block diagram illustrating a configuration of a signal processing board 50.
4A and 4B are waveform diagrams of signals detected in a normal state, FIG. 4A is a waveform diagram of an amplifier output, and FIG. 4B is a waveform diagram of a detector output.
5A and 5B are waveform diagrams of a signal detected at the time of abnormality, FIG. 5A is a waveform diagram of an amplifier output, and FIG. 5B is a waveform diagram of a detector output.
FIG. 6 is a flowchart illustrating a threshold setting process executed by a control circuit 78;
FIG. 7 is a flowchart illustrating a motor control process after the air compressor 10 is installed.
[Explanation of symbols]
10 Air Compressor 12 Air Tank 14 Air Compressor 16 Electric Motor 18 Operation Unit 22 First Cylinder 24 Second Cylinder 26 Third Cylinder 30, 32, 34 Air Line 36 Crankcase 38 Abnormality Detection Sensor 46 Power Switch 48 Threshold Setting Switch 50 Signal processing board 52 Cover 54 Crankshaft 56, 58 Bearing 60 Connecting rod 62 Piston 68 Intake valve 72 Discharge valve 74 Amplifier 76 Detector 78 Control circuit 80 Memory 82 Alarm 84 Power supply circuit 86 Motor switch

Claims (1)

An air compressor for compressing air;
A sensor for detecting vibration of the compression unit,
A storage unit in which a threshold value for the output value of the sensor is stored in advance,
Determining means for determining the presence or absence of an abnormality according to a comparison result between a detection signal detected by the sensor and a threshold value stored in the storage unit;
In the air compressor provided with
Threshold calculation means for activating the air compression unit by a threshold setting operation after installation and calculating the threshold;
Storage means for storing the threshold value calculated by the threshold value calculation means in a storage unit,
An air compressor comprising:

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