Compressor and method for controlling the compressor

Abstract

This compressor previously obtains a bearing temperature rise of a bearing and stores the bearing temperature rise as a first bearing temperature rise pattern, compares an actual second bearing temperature rise pattern of the bearing detected by a temperature sensor with the prestored first bearing temperature rise pattern, and, when it is determined that the bearing temperature rise is a temperature rise due to grease filling, performs control so that an alarm is not activated.

Description

Technical Field

[0001] The present invention relates to a compressor and a method for controlling the compressor.

Background Art

[0002] An electric motor used in an air compressor generally uses a rolling bearing. Grease is used for lubrication of the bearing, and it is necessary to fill the grease at regular intervals after operation. At that time, the temperature of the bearing filled with grease temporarily rises due to agitation heat (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an air compressor, it is a common method to monitor the temperature of the motor bearing for the purpose of protecting the compressor. However, when filling the grease regularly, the bearing temperature rises due to agitation heat.

[0005] Therefore, especially in an electric motor with a long operation period, it is impossible to distinguish whether the temperature rise is due to bearing abnormalities such as motor deterioration and damage or the bearing temperature rise during grease filling, which leads to an alarm or trip and stops the compressor. For this reason, the monitoring accuracy of the motor bearing temperature of the compressor decreases.

[0006] An object of the present invention is to improve the monitoring accuracy of the motor bearing temperature of a compressor.

Means for Solving the Problems

[0007] A compressor according to one aspect of the present invention includes an electric motor having a grease lubricated bearing, a control unit for controlling the electric motor, a temperature sensor for detecting the temperature of the bearing, and a notification unit for issuing an alarm. The control unit grasps in advance the increase in the bearing temperature of the bearing and stores it as a first bearing temperature increase pattern, and compares the second bearing temperature increase pattern of the actual bearing detected by the temperature sensor with the first bearing temperature increase pattern stored in advance. As a result of the comparison, when it is determined that the increase in the bearing temperature is due to the temperature increase caused by grease filling, the control unit controls the notification unit not to issue the alarm.

Effect of the Invention

[0008] According to one aspect of the present invention, the monitoring accuracy of the electric motor bearing temperature of the compressor can be improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0010] Hereinafter, examples will be described with reference to the drawings.

Example

[0011] First, referring to FIG. 11, the overall configuration of the compressor will be described. As shown in FIG. 11, the compressor 100 has a grease (lubricant) - fed bearing 101, an electric motor (motor) 103 having a motor shaft 102, and a compressor main body provided with a gear case 104. A temperature sensor T for detecting the temperature of the bearing 101 and an inverter panel are connected to the electric motor 103. The compressor 100 has a control unit 105 that controls the electric motor 103 via the inverter panel based on the temperature detected by the temperature sensor T. The control unit 105 is connected to a notification unit via a bearing temperature monitoring unit disposed outside the compressor 100.

[0012] A filter 106 and a valve 107 are connected to the compressor main body, and the air sucked from the air suction port is sent to the compressor main body via the filter 106 and the valve 107.

[0013] A cooler 108 and a silencer 109 are connected to the compressor main body, and cooling water is supplied to the cooler 108 from the cooling water inlet. Then, air is sent from the cooler 108 to the air discharge port. Also, cooling water is supplied from the cooler 108 to the cooling water outlet. Further, air is sent from the cooler 108 via the silencer 109 to the air release port (used during unloading).

[0014] In the present invention, the control unit 105 grasps in advance the temperature rise of the bearing 101 of the bearing and stores it as the first bearing temperature rise pattern, and compares the second bearing temperature rise pattern of the actual bearing 101 detected by the temperature sensor T with the first bearing temperature rise pattern stored in advance. Then, as a result of the comparison, when it is determined that the rise in the bearing temperature is due to the temperature rise caused by grease filling, the control unit 105 controls so as not to issue an alarm from the notification unit.

[0015] Next, abnormal value monitoring using the pattern of the motor bearing temperature rise will be described with reference to FIGS. 1 to 3.

[0016] FIG. 1 shows an example of the variation in the motor bearing temperature during grease filling. When several minutes to several tens of minutes have elapsed since the grease was filled, the temperature of the bearing 101 rises due to agitation heat, and although the bearing is not abnormal, the bearing temperature exceeds the alarm value and an alarm is issued. Therefore, it is not possible to determine whether the bearing is actually abnormal and has exceeded the alarm value, or whether it is due to grease filling, and the motor is operated while suspecting its soundness, and it is necessary to monitor the bearing temperature even after filling.

[0017] FIG. 2 shows an example of the variation in the motor bearing temperature due to aging deterioration. When the motor 103 is operated for a long time, the load increases due to aging deterioration, and the bearing temperature tends to gradually rise over a long period of time.

[0018] When the bearing temperature has risen to a certain level, although it is a temperature at which an alarm is not issued during normal operation, the temperature of the bearing 101 easily exceeds the alarm value due to the temperature rise during grease filling. Therefore, as in FIG. 1, the motor is operated while suspecting its soundness, and it is necessary to periodically check the bearing temperature.

[0019] FIG. 3 shows an example of the variation in the motor bearing temperature due to a bearing abnormality. When bearing abnormalities occur, more load is applied to bearing 101, causing the bearing temperature to rise. This is unstable compared to the temperature changes during grease filling or over time as shown in Figures 1 and 2. Also, when bearing 101 breaks at a certain point, an excessive load occurs and the temperature rises rapidly. Therefore, the time from when bearing 101 breaks to when the temperature rises is short and it fluctuates rapidly.

[0020] Figure 4 shows the variation pattern of the bearing temperature in Example 1 of the present invention. After grease filling, the temperature of bearing 101 rises and reaches the alarm reporting temperature. However, it is determined from the temperature increase amount per unit time and the pattern of temperature stability that grease filling is the cause of the temperature rise, and the alarm is avoided from being reported by automatically raising the alarm value. Then, when the temperature drops and becomes below the initial alarm reporting temperature, the alarm reporting temperature is lowered to the initial value.

[0021] Specifically, first, a temperature rise is detected. Next, the temperature change from the start of the temperature rise to the arrival of the alarm reporting temperature is recorded for pattern discrimination. In the case of grease filling, the bearing temperature rises rapidly in a short time (about several minutes). On the other hand, in the case of bearing abnormalities, the bearing temperature rises gradually over a long period (about several months to several years).

[0022] Next, pattern discrimination is performed to determine whether it is grease filling or a bearing abnormality. In the case of grease filling, the alarm reporting temperature is raised to the alarm reporting temperature (2).

[0023] Next, when the bearing temperature becomes lower than the alarm reporting temperature (1), the alarm reporting temperature is lowered to the alarm reporting temperature (1).

[0024] Referring to the flowchart in Figure 5, the pattern determination process of Example 1 will be described in detail. First, a bearing temperature rise is detected (step 500). While the motor is operating, the temperature sensor detects a temperature rise within a predetermined time Δt (see Figure 4).

[0025] Next, it is determined whether the alarm reporting temperature has been exceeded (step 501).

[0026] If the alarm reporting temperature is exceeded (Yes in step 501), proceed to step 502. On the other hand, if the alarm reporting temperature is not exceeded (No in step 501), proceed to step 506 and continue the operation.

[0027] In step 502, pattern discrimination is performed and compared with the recorded pattern. The pattern of temperature rise within a predetermined time Δt is discriminated. The pattern of temperature rise is pre-recorded in the control unit 105 as a grease filling pattern for a temperature rise in a short time, and as a bearing abnormality pattern for a gentle temperature rise over a long period or a sudden, rapid, and unstable temperature rise. Then, it is collated and discriminated whether it is a grease filling or a bearing abnormality.

[0028] If the result of the pattern discrimination determines that it is a grease filling, raise the alarm reporting temperature, which is the threshold value, to prevent alarm reporting and continue the operation (step 503). In this way, in step 503, in order to prevent alarm reporting due to the temperature rise caused by grease filling, the threshold value of the alarm reporting temperature is raised (to be below the trip temperature) and the operation is continued.

[0029] If the result of the pattern discrimination determines that it is a bearing abnormality, issue a bearing abnormality alarm and stop the operation (step 507).

[0030] Next, it is determined whether the bearing temperature has dropped below the initial alarm reporting temperature (step 504).

[0031] If the result of the determination determines that it is below the initial alarm reporting temperature, return the alarm reporting temperature to the initial value (step 505) and continue the operation (step 509). In this way, by returning the alarm reporting temperature to the initial value, it is assumed that the grease filling is completed and the operation is continued. However, if the trip temperature (95 °C) is exceeded, the operation of the compressor 100 shall be stopped in any state.

[0032] If, as a result of the determination, it is determined that the initial alarm reporting temperature has been exceeded, the operation continues and returns to step 504 (step 508).

[0033] In this way, when the bearing temperature reaches the alarm reporting temperature (85 °C), pattern discrimination is performed to determine whether it is a bearing abnormality or a temperature rise due to grease filling.

[0034] The patterns are stored in advance, and those with similar temperature rise slopes, initial temperatures, and waveform stabilities are automatically selected. If it is a bearing abnormality, an alarm is reported and the operation is stopped. If it is determined that the temperature rise is due to grease filling, the alarm value is increased to prevent alarm reporting and the operation continues.

[0035] Here, during grease filling, the amount of temperature rise varies depending on the operating state of the compressor and the type of motor.

[0036] Fig. 6 shows the difference in temperature rise when grease is filled during loading and unloading. The upper curve is for loading, and the lower curve is for unloading.

[0037] During loading, the stirring heat is greater and the current value of the motor is also larger compared to unloading, so the amount of bearing temperature rise is greater. Also, during loading, the base temperature of the bearing is higher than during unloading, so when grease is filled during loading, it is easier to exceed the alarm reporting temperature.

[0038] In this way, during grease filling, the amount of temperature rise is greater during loading. Also, the base temperature is higher during loading than during unloading.

[0039] Fig. 7 shows the difference in temperature rise between a 2-pole motor and a 4-pole motor. The upper curve is for the 2-pole motor, and the lower curve is for the 4-pole motor.

[0040] Since the 2-pole motor has a higher rotational speed, the stirring heat during grease filling becomes larger, and the temperature rise is greater than that of the 4-pole motor. The base temperature of the bearing 101 of the 2-pole motor is higher than that of the 4-pole motor, so it is more likely to exceed the alarm reporting temperature.

[0041] Thus, the 2P motor with a higher rotational speed has greater stirring heat and a larger temperature rise than the 4P motor. Also, the base temperature is higher at 2P than at 4P.

[0042] Fig. 8 shows the difference in temperature rise according to the grease filling amount. The upper curve is for one-shot filling, the middle curve is for filling in small amounts, and the lower curve is for filling only once in a small amount. When filling grease, if the grease is filled in one shot, the amount of temperature rise becomes large. Also, it takes time for the temperature to drop.

[0043] For example, when filling 50 g of grease, the way the temperature rises is different between filling 1 g at a time and filling 50 g in one shot.

[0044] When filling in small amounts, the bearing temperature increases gradually step by step and does not exceed the alarm value. However, when filling in one shot, the temperature rises rapidly and exceeds the alarm value. Also, when filling the grease in one shot, it takes time for the temperature to drop.

[0045] In the above Example 1, by using the pattern of bearing temperature rise, it is possible to distinguish the temperature rise due to grease filling from the temperature rise due to bearing abnormalities such as motor deterioration and damage, and improve the monitoring accuracy.

[0046] In the above Example 1, the changes in the bearing temperature before grease filling, the amount of bearing temperature change for each grease filling amount and filling speed, and the amount of bearing temperature rise and fall due to the passage of time are patterned, and the cause of the bearing temperature rise is predicted from that pattern. Then, the bearing temperature rise pattern is grasped in advance and the threshold value of the alarm reporting value is automatically increased.

[0047] In the above-described Example 1, it is possible to detect overfilling, insufficient filling, and appropriate filling of grease to the motor, grasp the phenomena actually occurring when the bearing temperature rises, and take appropriate measures. As a result, it is possible to abolish the operation of stopping the compressor for inspection when the bearing temperature rises even though the motor is not abnormal conventionally, and there is an effect of suppressing unnecessary inspection costs. Further, when filling the grease, it is possible to prevent false alarms from being issued by raising the threshold value for detecting abnormalities in the bearing temperature rise.

Example

[0048] Example 2 will be described with reference to FIGS. 9 and 10.

[0049] FIG. 9 shows the content of avoiding alarm reporting during grease filling. After the grease is filled, the bearing temperature rises and reaches the alarm reporting temperature. However, as in FIG. 4 of Example 1, it is determined whether it is due to grease filling or bearing abnormality by comparing with the previously recorded temperature rise pattern.

[0050] When it is determined that it is grease filling, the alarm reporting temperature is invalidated and no alarm is issued. Thereafter, when the temperature drops and becomes lower than the initial alarm reporting temperature, the alarm reporting temperature is reactivated and the normal operation is resumed.

[0051] Specifically, first, the temperature rise is detected. Next, the temperature change from the start of the temperature rise to the arrival of the alarm reporting temperature is recorded for pattern discrimination. In the case of grease filling, the bearing temperature rises rapidly in a short time (about several minutes). On the other hand, in the case of bearing abnormality, the bearing temperature rises gently over a long period (about several months to several years).

[0052] Next, pattern discrimination is performed to determine whether it is grease filling or bearing abnormality. In the case of grease filling, the alarm reporting temperature is invalidated. Next, when the bearing temperature becomes lower than the alarm reporting temperature, the alarm reporting temperature is activated and the normal operation is performed.

[0053] Referring to the flowchart of FIG. 10, the pattern determination process of Example 2 will be described in detail.

[0054] First, a bearing temperature rise is detected (step 500). While the motor 103 is operating, the temperature sensor T detects a temperature rise within a predetermined time Δt.

[0055] Next, it is determined whether the alarm reporting temperature has been exceeded (step 501).

[0056] If the alarm reporting temperature has been exceeded (Yes in step 501), the process proceeds to step 502. On the other hand, if the alarm reporting temperature has not been exceeded (No in step 501), the process proceeds to step 506 and the operation continues.

[0057] In step 502, pattern discrimination is performed and compared with the recorded pattern. The pattern of the temperature rise within the predetermined time Δt is discriminated. If the pattern of the temperature rise is a temperature rise in a short time, it is the pattern of grease filling. A temperature rise due to a long-term gentle temperature rise or a sudden, rapid, and unstable temperature rise is recorded in the control unit 105 in advance as the pattern of bearing abnormality, and it is collated and discriminated whether it is grease filling or bearing abnormality.

[0058] If it is determined that it is grease filling as a result of the pattern discrimination, the alarm reporting temperature is invalidated so as not to issue an alarm (step 510). In this way, in step 510, in order to prevent an alarm from being issued due to the temperature rise caused by grease filling, the alarm reporting temperature is invalidated and the operation continues.

[0059] If it is determined that there is a bearing abnormality as a result of the pattern discrimination, a bearing abnormality alarm is issued and the operation is stopped (step 507).

[0060] Next, it is determined whether the bearing temperature has dropped and whether the bearing temperature has become lower than the alarm reporting temperature (step 511).

[0061] As a result of the determination, if the bearing temperature drops and the bearing temperature becomes lower than the alarm reporting temperature (Yes in step 511), the alarm reporting temperature is validated (step 512), and the operation continues (step 509). It is assumed that the grease filling is completed by returning the alarm reporting temperature to the initial value and the operation continues. However, if the trip temperature (95 °C) is exceeded, the operation of the compressor 100 shall be stopped under any circumstances.

[0062] As a result of the determination, if the bearing temperature drops and the bearing temperature does not become lower than the alarm reporting temperature (No in step 511), the operation continues and returns to step 511 (step 508).

[0063] In this way, when the bearing temperature reaches the alarm reporting temperature (85 °C), pattern discrimination is performed to determine whether it is a bearing abnormality or a temperature increase due to grease filling.

[0064] The patterns are stored in advance, and those with similar temperature increase slopes, initial temperatures, and waveform stabilities are automatically selected. If it is a bearing abnormality, alarm reporting and operation stop are performed. If it is determined that the temperature increase is due to grease filling, the alarm reporting temperature is invalidated to prevent alarm reporting and the operation continues.

[0065] In the above Embodiment 2, the changes in the bearing temperature before grease filling, the grease filling amount, the change amount of the bearing temperature for each filling speed, and the change amount of the bearing temperature increase and decrease over time are patterned, and the cause of the bearing temperature increase is predicted from the pattern. The bearing temperature increase pattern is grasped in advance, and the alarm is invalidated when the alarm reporting temperature is reached.

[0066] According to the above Embodiment 2, it is possible to detect overfilling, insufficient filling amount, and appropriate filling amount of grease to the motor, grasp the actual phenomenon occurring when the bearing temperature rises, and take appropriate measures. As a result, it is possible to abolish the operation of stopping and inspecting the compressor when the bearing temperature rises even though the motor is not abnormal conventionally, and there is an effect of suppressing extra inspection costs. Also, when filling grease, it is possible to prevent false alarm reporting by invalidating the alarm reporting temperature.

[0067] Thus, in the above-described embodiment, by using the pattern of the bearing temperature rise, it is possible to distinguish the temperature rise due to grease filling from the temperature rise due to bearing abnormalities such as motor deterioration and damage, and improve the monitoring accuracy.

Explanation of Signs

[0068] 100 Compressor 101 Bearing 102 Motor Shaft 103 Electric Motor 104 Gear Case 105 Control Unit 106 Filter 107 Valve 108 Cooler 109 Silencer

Claims

1. An electric motor having a grease lubricated bearing, A control unit for controlling the electric motor, A temperature sensor for detecting the temperature of the bearing, A compressor having a notification unit that issues an alarm when the temperature of the bearing detected by the temperature sensor exceeds an alarm reporting temperature, The control unit, Stores in advance the bearing temperature rise of the bearing as a first bearing temperature rise pattern, Based on the first bearing temperature rise pattern and the second bearing temperature rise pattern of the bearing detected by the temperature sensor, determines whether the rise in the bearing temperature is due to a temperature rise caused by grease filling or a temperature rise due to an abnormality of the bearing, When it is determined that the rise in the bearing temperature is due to a temperature rise caused by grease filling, controls so as not to issue the alarm from the notification unit. A compressor characterized by this.

2. The notification unit, Issues an alarm when the temperature of the bearing detected by the temperature sensor exceeds a first alarm reporting temperature that is an initial value, The control unit, When it is determined that the rise in the bearing temperature is due to a temperature rise caused by grease filling, controls so as not to issue the alarm from the notification unit by raising the first alarm reporting temperature to a second alarm reporting temperature higher than the first alarm reporting temperature. The compressor according to claim 1, characterized by this.

3. The control unit, When the bearing temperature becomes equal to or lower than the first alarm reporting temperature, controls to return the alarm reporting temperature to the first alarm reporting temperature. The compressor according to claim 2, characterized by this.

4. The control unit, When it is determined that the rise in the bearing temperature is due to a temperature rise caused by grease filling, controls so as not to issue the alarm from the notification unit by invalidating the alarm reporting temperature. The compressor according to claim 1, characterized by this.

5. The control unit, When the bearing temperature becomes lower than the alarm reporting temperature, validates the alarm reporting temperature. The compressor according to claim 4, characterized by this.

6. The control unit, As the first bearing temperature rise pattern, Stores a pattern in which the bearing temperature of the electric motor fluctuates during grease filling, a pattern in which the bearing temperature of the electric motor fluctuates due to aging deterioration, and a pattern in which the bearing temperature of the electric motor fluctuates due to a bearing abnormality. The compressor according to claim 1, characterized by this.

7. The control unit, As the first bearing temperature rise pattern, The compressor according to claim 1, characterized in that it stores a pattern corresponding to the operating state of the compressor during the grease filling, a pattern corresponding to the type of motor of the electric motor, or a pattern corresponding to the amount of grease filling.

8. The control unit The compressor according to claim 1, characterized in that, during the comparison, it selects the first bearing temperature rise pattern whose temperature rise slope, initial temperature, or waveform stability is approximated to the actual second bearing temperature rise pattern of the bearing.

9. A control method for a compressor equipped with an electric motor having a grease lubricated bearing, comprising: A temperature detection step of detecting the temperature of the bearing; An alarm reporting step of reporting an alarm when the temperature of the bearing detected in the temperature detection step exceeds the alarm reporting temperature; A storage step of previously storing the bearing temperature rise of the bearing as a first bearing temperature rise pattern; A determination step of determining whether the rise in the bearing temperature is due to temperature rise caused by grease filling or due to an abnormality of the bearing based on the first bearing temperature rise pattern stored in the storage step and the second bearing temperature rise pattern of the bearing detected in the temperature detection step; A control method for a compressor, characterized by comprising a control step of controlling not to report an alarm when it is determined in the determination step that the rise in the bearing temperature is due to temperature rise caused by grease filling.

10. The alarm reporting step is Reporting an alarm when the temperature of the bearing detected in the temperature detection step exceeds the first alarm reporting temperature which is the initial value; The control step is The control method for a compressor according to claim 9, characterized in that, when it is determined that the rise in the bearing temperature is due to temperature rise caused by grease filling, the control is performed so as not to report an alarm by raising the first alarm reporting temperature to a second alarm reporting temperature higher than the first alarm reporting temperature.

11. The control step is The control method for a compressor according to claim 9, characterized in that, when it is determined that the rise in the bearing temperature is due to temperature rise caused by grease filling, the control is performed so as not to report an alarm by invalidating the alarm reporting temperature.

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