CN105156313A - Air compressor - Google Patents

Abstract

The air compressor includes: a compressor body compressing air; a tank storing air compressed in the compressor body; and a control part controlling the drive of the compressor body. The control part controls the compressor body so that an operation cycle time in which the compressor stops, starts and stops again is not shorter than a predetermined time.

Description

Air compressor

(This application is a divisional application of the invention patent application with the same name whose application date is July 23, 2012 and whose application number is 201210256108.8)

technical field

This invention relates to air compressors.

Background technique

Patent Document 1 describes an air compressor that detects the pressure change rate in a tank, selects an intermittent operation control mode that stops the motor when the pressure in the tank reaches an upper limit, and does not stop the motor but Continuous operation control mode that puts the compressor in a no-load state.

Patent Document 2 describes another air compressor that measures the driving time of the compressor, and discharges compressed air to the outside when the upper limit pressure is detected before the driving time reaches a predetermined time.

Patent Document 1: Japanese Patent Application Laid-Open No. 1-104990

Patent Document 2: Japanese Patent Laid-Open No. 2003-139067

Contents of the invention

In the air compressor of Patent Document 1, since the upper limit value of the tank pressure used as a reference for stopping the compressor is fixed, even if the interval between operation and stop is sufficiently large, it is necessary to increase the pressure in the container to If it is more than necessary, the power consumption cannot be sufficiently reduced.

On the other hand, the air compressor in Patent Document 2 measures only the driving time of the compression part, and does not measure the stop time of the compression part. Therefore, for example, when the consumption of compressed air is small and the drive time of the compressor is short, the stop time of the compressor is long, and the number of switching between operation and stop of the compressor is not many as a whole. In Patent Document 2, in such a case, since the driving time of the compression unit is short, the operation of the compression unit is continued until the driving time reaches a predetermined time, so power consumption cannot be sufficiently reduced. In addition, even when the consumption of compressed air is small, if the total time of the drive time and stop time of the compressor is short, the number of operation/stop switching of the compressor may be large overall. In Patent Document 2, even in such a case, it is judged that the driving time of the compression unit has reached a predetermined time and the compression unit is stopped. Therefore, the number of times of operation/stop switching per unit time is large, and the life of the motor and electronic components cannot be ensured. .

In view of the above problems, the present invention aims to provide an air compressor capable of ensuring the life of a motor and electronic components while reducing power consumption.

In order to solve the above-mentioned problems, the present invention provides an air compressor, which is characterized in that it includes: a compressor body that compresses air; an air tank that stores air compressed by the compressor body; and a drive for the compressor body A control unit that performs control, wherein the control unit controls the compressor main body so that an operation cycle time from when the compressor is stopped to when it is started and then stopped again is equal to or longer than a predetermined time.

According to the present invention, it is possible to provide an air compressor capable of ensuring the life of a motor and electronic components while reducing power consumption.

Description of drawings

Fig. 1 is an overall view of an air compressor according to Embodiment 1 of the present invention.

Fig. 2 is an explanatory view showing an unloading state of Embodiment 1 of the present invention.

Fig. 3 is a wiring diagram of Embodiment 1 of the present invention.

Fig. 4-1 is an explanatory diagram of the operation of Embodiment 1 of the present invention.

Fig. 4-2 is an explanatory diagram of the operation of Embodiment 1 of the present invention.

4-3 are diagrams for explaining the operation of Embodiment 1 of the present invention.

Fig. 5 is an explanatory diagram of the operation of the intermittent operation control method.

Fig. 6 is an explanatory diagram of the operation of the continuous operation control method.

Fig. 7 is a graph showing the relationship between pressure and power in an air compressor.

Explanation of reference signs

1 air tank

2 compressor body

3 three-way solenoid valve

4 Unloading piping

5 Magnetic contactor

6 control substrate

7 monitors

8 operation switch

9 motors

10 contacts

11 pressure sensor

12 suction valve

13 unloading piston

14 shut-off valve

15 cylinder heads

Detailed ways

As an operation control method of an air compressor, an intermittent operation control method and a continuous operation control method are known. Using FIGS. 5 and 6, two methods will be described. The intermittent operation control method shown in Figure 5 is such a control method, that is, when the pressure of the air tank reaches the upper limit pressure, the pressure switch is closed to stop the motor, and when the pressure reaches the lower limit pressure, the pressure switch is closed and the motor start. On the other hand, the continuous operation control method shown in FIG. 6 is such a control method that, when the pressure of the air tank reaches the upper limit pressure, for example, the suction valve is opened (opened) to perform no-load (unloading) operation to reduce the load on the motor. Close the suction valve at the lower limit pressure to return to normal load operation. The characteristics and problems of the two approaches are as follows.

(a) Intermittent operation control mode

As shown in FIG. 5, since the electric motor is stopped when the pressure in the air tank reaches the upper limit pressure, unnecessary electric power is not consumed. However, since the motor is restarted at the lower limit pressure, if the motor is repeatedly operated and stopped frequently, there is a problem that the motor is likely to overheat and the life of electronic components is shortened.

(b) Continuous operation control mode

As shown in FIG. 6 , when the pressure in the air tank reaches the upper limit pressure, the motor is not stopped, but the load is reduced by opening the air valve or the like. In this case, unloading power that does not eject air, that is, excess electric power is consumed. Since the motor performs unloaded operation, the load on the motor and electronic components is light. On the other hand, since power is also consumed during unloaded operation, there is a problem of consuming excess power that does not contribute to air compression.

As mentioned above, each control method has its own characteristics. However, it is very difficult to correctly judge the operating conditions of the air compressor and choose a certain control method.

In the air compressor, in order to suppress power consumption, as the above-mentioned intermittent operation control method, it is more effective to stop full operation and lower the upper limit of the control pressure. This is because, as shown in FIG. 7 , the power increases as the operating pressure of the compressor increases.

On the other hand, in the intermittent operation control mode, when the upper limit pressure is too low relative to the minimum required lower limit pressure in the equipment, depending on the amount of air used, the operating cycle of the compressor may be too short. , The compressor starts and stops excessively, and the motor overheats and deteriorates.

Therefore, it is necessary to appropriately select the upper limit pressure and the operation control method according to the amount of air used in order to improve the life of the motor and electronic components while reducing power consumption.

[Example 1]

Embodiment 1 of the present invention in view of the above technical problem will be described using FIG. 1 , FIG. 2 , FIG. 3 , FIG. 4-1 , FIG. 4-2 , and FIG. 4-3 .

FIG. 1 shows the overall structure of a reciprocating compressor as an example of an air compressor. The air compressed in the compressor main body 2 that takes in air and compresses it is stored in the air tank 1 . A cylinder head 15 is installed on the compressor body 2 , and a suction valve 12 and an unloading piston 13 shown in FIG. 2 are installed in the cylinder head 15 . An unloading pipe 4 having a three-way solenoid valve 3 is provided between the air tank 1 and the compressor main body 2 .

The loaded state and the unloaded state will be described using FIG. 2 . By energizing the three-way solenoid valve 3, the pressure in the air tank 1 is applied to the unloading piston 13 operating the suction valve 12 of the compressor body 2 to forcibly form the unloading (suction valve open) state shown on the right side of FIG. 2 . Therefore, even if the compressor main body 2 is activated, the suction valve 12 is opened, so the air compressed in the compressor main body 2 is not stored in the air tank 1, but released to the atmosphere. On the other hand, by turning off the energization of the three-way solenoid valve 3, a state (loaded state) with no pressure applied to the unloading piston 13 shown on the left side of FIG. 2 is established, and the suction valve 12 is normally opened and closed. Thus, compressed air is stored in the air tank 1 when the compressor body 2 is activated under load.

FIG. 3 shows a wiring diagram in this embodiment. The electromagnetic contactor 5 and the three-way solenoid valve 3 are connected to a control board 6 as a control unit, and are controlled by the control board 6 together with the three-way solenoid valve 3 . The control board 6 uses the pressure sensor 11 to detect the pressure of the air tank 1 and circulates a signal to make the electromagnetic contactor 5 work in the electronic circuit according to the pressure to control the operation and stop of the motor 9. In addition, the three-way solenoid valve 3 The unloading piston 13 is operated to control the unloaded state and the loaded state by passing a signal. A display 7 for displaying a set pressure and the like is mounted on the control board 6 .

Referring to FIG. 3 and FIG. 4-1, FIG. 4-2, and FIG. 4-3, the content of the control of the compressor by the control board 6 as a control part in this embodiment is demonstrated.

In the state where the operation switch 8 is not operated, since the power supply of the motor 9 is cut off, the compressor is in a stopped state. The air tank 1 is atmospheric pressure or the pressure of the air remaining in the air tank 1. In the state where the three-way solenoid valve 3 is not energized, the unloading pipe 4 is in the atmospheric pressure state and is out of the unloading state, so the suction valve 2 is in a loaded state (can be state of compression operation).

When the operation switch 8 is pressed, according to the signal from the control board 6, the electromagnetic contactor 5 operates, the contact 10 is closed, and the motor 9 is started. When the motor 9 is activated, the compressor main body 2 operates, and the pressure in the air tank 1 rises. When the pressure reaches the predetermined stop pressure Poff0 (arbitrary setting) and is detected by the pressure sensor 11, the detection signal is input to the control board 6, and the power supply of the electromagnetic contactor 5 is cut off according to the signal from the control board 6, The motor 9 stops, and the compressor body 2 also stops.

After the compressor main body 2 is stopped, the air is consumed due to the operation of the customer's equipment connected to the stop valve 14, and the pressure in the air tank 1 decreases. When the pressure of the air tank 1 is lower than the specified reference pressure (recovery pressure Pon) and is detected by the pressure sensor 11, according to the signal from the control board 6, the electromagnetic contactor 5 is energized to close the contact, and the motor 9 starts again. Start, the compressor body 2 starts running again.

The intermittent operation control method controls the operation/stop of the compressor main body 2 through such control. Here, in this embodiment, in addition to the above-mentioned intermittent operation control, continuous operation control for controlling the loaded state/unloaded state is also performed. Switching between intermittent operation control and continuous operation control will be described.

In the intermittent operation control mode, the operating cycle time T of the compressor body 2 (the time of one cycle from the stop of the compressor body 2 to the stop again after starting), the ratio of the used air volume (the used air volume to the compressor The ratio of the amount of air generated by the main body 2) is 50% (the time of running and stopping is the same) in most cases. This is because, when the amount of air used is large, the pressure of the air tank 1 is difficult to rise, and the operation time of the compressor body 2 becomes long; The time during which the main body 2 stops becomes longer.

Therefore, in this embodiment, switching is performed between the intermittent operation control and the continuous operation control, so that the operation cycle time T of the compressor body 2 is equal to or greater than the predetermined reference operation cycle time _T0 , so as to realize the life of the motor 9 and the electronic components. improvement.

The control of switching between the intermittent operation control and the continuous operation control so that the operation cycle time T of the compressor main body 2 becomes equal to or greater than a predetermined reference operation cycle time _T0 in this embodiment will be described using FIG. 4-1. First, when the compressor main body 2 starts to operate, the pressure in the air tank 1 rises. When the pressure reaches a predetermined stop pressure Poff0, the motor 9 is stopped, and a timer (not shown) in the control board 6 starts measuring the operation cycle time T. After the compressor body 2 stops, the air is consumed due to the work of the customer's machine connected to the shut-off valve 14, and when the pressure in the air tank 1 is lower than the recovery pressure Pon and is detected by the pressure sensor 11, the motor 9 starts again , the compressor body 2 starts running again.

After restarting the operation of the compressor body, when the timer reaches the reference operation cycle time T ₀ (the operation cycle time predetermined as the time to ensure the life of the motor, electronic components, etc.: not shown), even if it has not reached the stop The pressure Poff0 also stops the motor 9 and stops the operation of the compressor body 2 . Here, the measurement of the timer is reset, the measurement of the operation cycle time T is restarted, and the same control is repeated. Thereby, the excess operation time of the compressor main body 2 can be reduced and power consumption can be reduced.

After the compressor body restarts, if the pressure in the air tank 1 reaches the upper limit of the stop pressure (maximum upper limit pressure Pmax) before the timer reaches the reference operation cycle time _T0 , if the operation of the compressor body is stopped , the switching interval of the motor 9 and the control board 6 is shortened, and the life of the motor 9 and other electronic components cannot be improved. Therefore, in this embodiment, a signal is transmitted from the control board 6 to the three-way solenoid valve 3 to form an unloaded state and switch to a continuous operation control mode. Thereby, overheating of the electric motor and electronic components can be prevented, and the lifetime improvement of the electric motor 9 and other electronic components can be aimed at. On the other hand, when the timer reaches the reference operation cycle time _T0 , the compressor main body 2 is stopped, and the power supply to the three-way solenoid valve 3 is cut off, thereby changing from the unloaded state to the loaded state. That is, the continuous operation control method is switched to the intermittent operation control method. Here, the measurement of the timer is reset, the measurement of the operation cycle time T is restarted, and the same control is repeated. Thereby, the excess operation time of the compressor main body 2 can be reduced and power consumption can be reduced.

However, in the case of performing the above-mentioned control, for example, when the amount of air used is small, after the compressor main body 2 is stopped and before the compressor main body 2 is restarted, or when the compressor main body 2 is restarted, the pressure in the air tank 1 is sufficient. Before rising, the reference cycle time T ₀ will elapse. In this case, if the above-mentioned control is used, the compressor main body 2 will be restarted and immediately stopped, and then the compressor main body 2 will be restarted immediately, and the switching interval between the motor 9 and the control board 6 will temporarily become too short. Then, at least before reaching the predetermined reference pressure P0 between the upper limit value of the stop pressure (maximum upper limit pressure Pmax) and the return pressure Pon, the compressor main body 2 is operated, and the switching interval between the motor 9 and the control board 6 can be prevented from being temporarily closed. become too short.

That is, in this embodiment, the compressor main body 2 is stopped when the elapsed time from the stop of the compressor main body 2 to the restart is equal to or greater than the reference operation cycle time _T0 and the pressure is equal to or greater than a predetermined reference pressure P0.

In the above, the control of switching between the intermittent operation control and the continuous operation control and making the operation cycle time T equal to or longer than the predetermined time by the timer has been described. In this embodiment, instead of the control of measuring the reference operation cycle time _T0 using a timer, the control of calculating the stop pressure Poff for stopping the compressor main body 2 may be performed. The control for calculating the stop pressure Poff for stopping the compressor main body 2 will be described using FIG. 4-2 . As shown in Fig. 4-2, when the compressor main body 2 stops and the pressure in the air tank 1 drops to the reference pressure P1, the timer starts measurement. When the pressure in the air tank 1 reaches the return pressure Pon, the compressor main body 1 is restarted, and when the pressure in the air tank 1 reaches the reference pressure P1 again, the measurement by the timer is terminated. Here, let the time from P1 to P1 be T, and compare and calculate with the reference operation cycle time _T0 . In this way, the time from Poff to Poff is the reference operation cycle time T ₀ , so the stop pressure Poff for operation at the reference operation cycle time T ₀ can be obtained.

In addition, when the stop pressure _Poff obtained by calculation is larger than the upper limit value of the stop pressure (maximum upper limit pressure Pmax), as shown in FIG. Similarly, the control board 6 sends a signal to the three-way solenoid valve 3 to form an unloaded state and switch to a continuous operation control mode. In this case as well, during _T3 shown in FIG. The compressor main body 2 is stopped, the power supply to the three-way solenoid valve 3 is cut off, and the unloaded state becomes the loaded state.

The control to calculate the stop pressure Poff for stopping the compressor main body 2 can stabilize the stop pressure Poff when there is little variation in the amount of air used. In addition, by setting the operation cycle time T to be longer than the reference operation cycle time _T0 with respect to the stop pressure Poff, it is possible to prevent the operation cycle time T from being shorter than the reference operation cycle time _T0 even if the amount of air used changes rapidly. .

Here, the control of switching between the intermittent operation control and the continuous operation control based on the timer so that the operation cycle time T becomes a predetermined time or more may be combined with the control of calculating the stop pressure Poff for stopping the compressor main body 2. . For example, it is possible to calculate the stop pressure Poff to stop the compressor main body 2 when the amount of air used changes little. Then, control is performed to switch between the intermittent operation control and the continuous operation control based on the timer so that the operation cycle time T becomes equal to or longer than a predetermined time. In this case, two timers are used for each control.

In addition, a flow sensor (not shown) may be provided between the stop valve 14 and the air tank 1, and the corresponding stop pressure Poff may be determined from a database storing the relationship between the value of the flow sensor and the stop pressure Poff.

According to the present embodiment, by making the operation cycle time T longer than the reference operation cycle time T ₀ , the lifetime of the motor and electronic components can be ensured. In addition, it is possible to reduce unnecessary operation time of the compressor main body 2 and reduce power consumption.

[Example 2]

Embodiment 2 of the present invention will be described. Here, description of the same configuration as that of the first embodiment is omitted.

In this embodiment, a temperature sensor is installed on the casing or internal parts of the motor 9 to detect the signal of the temperature sensor. When the detected temperature exceeds a predetermined value due to insufficient cooling or the like, the reference operation cycle time T ₀ is extended.

Thereby, even when the temperature detected by the temperature sensor is high, the lifetime can be ensured even when the temperatures of the motor 9 and the electronic components rise. On the other hand, when the detected temperature is lower, the load on the motor 9 and the electronic components is reduced. Even if the reference operation cycle time _T0 is shorter, it will not affect the life of the motor 9 and the electronic components. By keeping the reference operation cycle time T ₀ short, power consumption can be suppressed.

Here, in this embodiment, as in the first embodiment, even if the reference operation cycle time T ₀ is reached, the compressor body 2 is operated at least until the pressure reaches a predetermined reference pressure between the stop pressure Poff0 and the return pressure Pon. , and in addition to the reference operating cycle time T ₀ , the reference pressure can also be changed according to the temperature detected by the temperature sensor.

Thus, when the temperature detected by the temperature sensor is high, by increasing the reference pressure for stopping the operation of the compressor main body 2, it is possible to sufficiently ensure the time until the compressor main body 2 is stopped and restarted. The lifetime can be ensured even when the temperature of the electronic component rises. On the other hand, when the detected temperature is low, since the load on the motor 9 and electronic components becomes lower, the reference pressure for stopping the operation of the compressor main body 2 is lowered. The time of this time is short temporarily, also can not affect the life-span of electric motor 9, electronic parts. In this case, since the compressor main body 2 can be stopped at a low pressure, power consumption can be suppressed.

[Example 3]

Embodiment 3 of the present invention will be described. Here, descriptions of the same configurations as in Embodiments 1 and 2 are omitted.

In this embodiment, when it is not necessary to increase the pressure of the compressed air used, and the value of the recovery pressure Pon to restart the compressor body 2 is set lower than the specified value, the value of the recovery pressure Pon is the specified value. In the above case, the value of the reference operation cycle time T ₀ is set to be shorter.

Thus, when the value of the recovery pressure to restart the compressor body 2 is low, since the load on the electric motor 9 and electronic components is small, even if the reference operation cycle time _T0 is shortened, the electric motor 9 will not be affected. , The life of the electronic components, as a whole, because the pressure of the operation of the compressor body 2 is reduced, power consumption can be suppressed.

Here, in this embodiment, as in the first embodiment, even if the reference operation cycle time T ₀ is reached, the compressor body 2 is operated at least until the pressure reaches a predetermined reference pressure between the stop pressure Poff0 and the recovery pressure Pon. , and in addition to the reference operation cycle time T ₀ , the reference pressure for stopping the operation of the compressor body 2 can also be changed according to the recovery pressure Pon.

When the value of the recovery pressure Pon for restarting the compressor body 2 is low, the load on the motor 9 and electronic components becomes lower, so even if the reference pressure for stopping the operation of the compressor body 2 is lowered, the compressor body 2 The time from stopping to restarting is temporarily short, and it will not affect the lifespan of the motor 9 and electronic parts. In this case, since the compressor body 2 can be stopped at a relatively low pressure, power consumption can be suppressed.

[Example 4]

Embodiment 4 of the present invention will be described. Here, descriptions of the same structures as those in Embodiments 1-3 are omitted.

In the case where the stop pressure Poff for stopping the compressor body 2 and the recovery pressure Pon for restarting are fixed, the number of starts of the compressor body 2 depends on the ratio of the used air volume (the ratio of the used air volume to the generated volume of compressed air) ) is 50% (the time of running and stopping is the same) the most cases. Less than 50% of the time the stop time was longer than the running time, and more than 50% of the cases the running time was longer than the stop time.

Here, the smaller the used air volume ratio than 50%, the smaller the number of starts and the smaller the load on electronic components compared to when the used air volume ratio is 50%. In addition, the lower the air volume ratio used, the more time it takes for the pressure in the air tank 1 to decrease, the longer the time for the compressor main body 2 to stop, and the load on the motor 9 decreases.

In this embodiment, the reference operation cycle time T ₀ is shortened when the used air volume is less than a predetermined value below 50% than when it is above the predetermined value in consideration of the above.

Thus, when the air volume ratio used is below the predetermined value of 50%, since the load on the motor 9 and electronic components is reduced, even if the value of the reference operation cycle time _T0 is shortened, it will not affect The lifetime of the electric motor 9 and the electronic components can be reduced as a whole by reducing the upper limit pressure value Poff, so power consumption can be suppressed.

Here, in this embodiment, as in the first embodiment, even if the reference operation cycle time T ₀ is reached, the compressor body 2 is operated at least until the pressure reaches a predetermined reference pressure between the stop pressure Poff0 and the return pressure Pon. , and in addition to the reference operating cycle time T ₀ , the reference pressure for stopping the operation of the compressor body 2 can also be changed according to the air volume ratio used.

When the used air volume ratio is lower than the specified value of 50%, the load on the motor 9 and electronic components becomes lower, so even if the reference pressure for stopping the operation of the compressor body 2 is lowered, the compressor body 2 will stop after the compressor body 2 stops. The time to restart is temporarily short, and it will not affect the life of the motor 9 and electronic components. In this case, since the compressor main body 2 can be stopped at a low pressure, power consumption can be suppressed.

The embodiment described above is only an example for implementing the present invention, and does not limit the technical scope of the present invention. That is, the present invention can be implemented in various forms as long as it does not deviate from its technical idea or its main characteristics. Moreover, this invention can also be implemented by combining Examples 1-4.

Claims (8)

1. An air compressor, characterized in that, possesses: The body of the compressor that compresses the air; an air tank storing air compressed by the compressor body; a control section that controls driving of the compressor body; and a measuring unit for measuring the operation cycle time of the compressor main body, The control part controls the compressor body so that the compressor body is stopped when the pressure of the air tank reaches a stop pressure, and the compressor body is started when the pressure of the air tank reaches a recovery pressure, The stop pressure is set so that the operation cycle time of the compressor main body becomes equal to or greater than a reference operation cycle time based on a measurement result of the measurement unit. 2. The air compressor according to claim 1, characterized in that: The measuring unit performs a measurement from when the pressure of the air tank reaches the reference pressure after the compressor main body is stopped, until the pressure of the air tank drops to the recovery pressure, and after the compressor main body starts, the pressure of the air tank reaches the reference pressure. The time until the pressure reaches the reference pressure again is measured, and the control unit calculates the stop pressure by comparing the time measured by the measurement unit with the reference operation cycle time. 3. The air compressor according to claim 2, characterized in that: The control unit performs an unloading operation in which the air compressed by the compressor body is released to the atmosphere when the calculated stop pressure exceeds the maximum upper limit pressure of the air tank. 4. The air compressor according to claim 3, characterized in that: The control unit may stop the compressor main body when the reference operation cycle time or more has elapsed based on the measurement of the measurement unit when the unloading operation is performed. 5. The air compressor according to claim 1, characterized in that: The motor driving the compressor body is provided with a temperature sensor, The control unit increases the reference operation cycle time when the temperature of the temperature sensor is equal to or higher than a predetermined value. 6. The air compressor according to claim 1, characterized in that: The control unit changes the reference operation cycle time according to the set value of the recovery pressure. 7. The air compressor according to claim 1, characterized in that: The control unit changes the reference operation cycle time according to the used air volume ratio, Wherein the used air volume ratio is the ratio of the used air volume to the air volume generated by the compressor body. 8. The air compressor of claim 1, wherein: The control unit may stop the compressor main body when the reference operation cycle time or more has elapsed based on the measurement by the measurement unit while performing unloading operation when a change in the amount of air used increases.