JPH05133341A - Compressor - Google Patents

Abstract

PURPOSE:To provide a compressor which can attain high accuracy for changeover timing of pressure switchgear type operation and unloader type operation and can perform compression operation by surely suppressing a coil temperature of an electric motor to a predetermined value or less. CONSTITUTION:A temperature sensor 21 for detecting a coil temperature of an electric motor 2 is provided in the electric motor 2, and a mode select circuit 22, which compares a detection temperature of the temperature sensor 21 with a preset reference temperature to select/set an unloader type operation mode and a pressure switchgear type operation mode based on a result of the comparison, is provided in a control means 7. Since pressure switchgear type operation and unloader type operation are selected and set to perform compression operation by using the coil temperature of the electric motor 2 directly detected by the temperature sensor 21, changeover timing of the pressure switchgear type operation and the unloader type operation can be high accurately set in accordance with the coil temperature. Consequently, compression operation can be performed in a condition that the coil temperature is surely and high accurately suppressed to the predetermined value or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor for compressing a gas such as air.

[0002]

2. Description of the Related Art An example of a conventional compressor uses an electric motor as a drive source. Such a compressor is generally an unloader type in which the electric motor is continuously operated and a pressure in which the electric motor is intermittently operated. It is roughly classified into a switch type and an automatic switching type for obtaining compressed gas by appropriately switching between intermittent operation and continuous operation.

FIG. 5 shows a pressure switch type air compressor among those roughly classified as described above. In the figure, a compressor body 1 is configured to be driven by an electric motor 2 to perform air compression. An air tank 3 is provided so as to be connected to the discharge side of the compressor body 1 so as to store compressed air. This air tank 3 has a pressure switch 4
Is connected, and when the internal pressure of the air tank 3 reaches or exceeds a predetermined pressure value, a control signal is output accordingly. In addition,
Reference numeral 5 is a pressure gauge for measuring the internal pressure of the air tank 3.

An electromagnetic switch 6 is interposed between the electric motor 2 and a power source (not shown) so that the electric motor 2 can be operated / stopped by opening and closing. A control means 7 is provided so as to be connected to the electromagnetic switch 6 and the pressure switch 4, and the electromagnetic switch 6 is normally closed so that the electric motor 2
While the compressor body 1 is operated to obtain compressed air, the control signal is input from the pressure switch 4 to open the electromagnetic switch 6 to interrupt the operation, and the pressure of the air tank 3 becomes a predetermined value or less. Thus, the electromagnetic switch 6 is closed to restart the compression operation, and thus the compression operation can be intermittently performed (the pressure switch type operation is performed).

FIG. 6 shows an unloader type air compressor. In this air compressor, an unload mechanism 10 is provided so as to be interposed between the air tank 3 and the compressor body 1, and a push button switch 11 is provided between the electric motor 2 and a power source (not shown). 5 is different from that shown in FIG. 5 in that the installation of the pressure switch 4 shown in FIG. 5 is omitted, and other parts and members are the same as those shown in FIG.

The unload mechanism 10 is provided at the suction port of the compressor body 1, and is an intake valve 12 that is also a part of the compressor body 1, and an unloader that drives the intake valve 12 according to the compressed air that is added. The unloader 13 and the air tank 3 are connected to each other, and an unload pipe 14 and a pressure adjusting valve 15 interposed in the unload pipe 14 are provided. When the internal pressure of the air tank 3 is equal to or lower than the lower limit reference pressure value, the pressure adjusting valve 15 determines that the unloader 13 is in a state in which the internal pressure of the air tank 3 is not applied, that is, the state in which the intake valve 12 is not operated. While the opening / closing operation is performed, when the internal pressure of the air tank 3 is equal to or higher than the upper reference pressure value, the internal pressure of the air tank 3 is applied to the unloader 13 to forcefully open the intake valve 12.

In this air compressor, a push button switch
When 11 is pushed to perform the compression operation and the internal pressure of the air tank 3 becomes equal to or higher than the upper limit side reference pressure value, the internal pressure of the air tank 3 is applied to the unloader 13 to forcibly open the intake valve 12 and the electric motor 2 While the engine is operating, the generation of compressed air by the compressor body 1 and the supply of compressed air to the air tank 3 are stopped (the unloader operation is performed).

As an example of the automatic switching type air compressor, although not shown, it has a pressure switch 4, an electromagnetic switch 6 and an unload mechanism 10 shown in FIG. Instead of the pressure control valve 15, there is a discharge port that is provided in the middle of the unload pipe 14 and communicates with the atmosphere side. The connection of the port is switched according to the input signal and the intake valve is energized.
A three-way solenoid valve that can forcibly open 12 is installed, and Fig. 5
In the control means 7 shown in FIG. 2, the pressure rise time until the internal pressure of the air tank 3 changes from the lower limit side reference pressure value to the upper limit side reference pressure value, and the internal pressure of the air tank 3 changes from the upper limit side reference pressure value to the lower limit side reference pressure value. Based on the pressure drop time until it becomes, the used air amount ratio (ratio of the used air amount to the air amount discharged at the maximum pressure) is obtained, and this used air amount ratio is equal to or greater than the preset reference value. If there is, the three-way solenoid valve is operated to set the unloader type operation mode, and if the used air amount ratio is less than the reference value, the pressure switch 4 with the three-way solenoid valve de-energized. There is a configuration having a mode switching circuit for controlling the electromagnetic switch 6 via the switch to set the pressure switch type operation mode.

In this air compressor, the control means 7 having a mode switching circuit is based on the result of comparison between the ratio of the amount of used air obtained from the pressure rise time and the pressure fall time and the reference value.
While controlling the unloading mechanism 10 to perform unloader type operation (hereinafter referred to as U type operation), while controlling the electromagnetic switch 6 via the pressure switch 4 to perform pressure switch type operation (hereinafter, P-type operation).

[0010]

By the way, one of the major factors for switching between the U-type operation and the P-type operation is to suppress the coil temperature of the electric motor 2 to a predetermined value. In the air compressor, since there is a constant relationship between the used air amount ratio and the coil temperature of the electric motor 2,
The used air amount ratio is obtained from the change in the internal pressure of the air tank 3, and the U type operation and the P type operation are switched based on the comparison result of the used air amount ratio and the reference value. By setting the reference value based on the constant correlation existing with the temperature, the compression operation can be performed while the coil temperature is maintained within the predetermined value.

However, in this case, since the in-use coil temperature is detected by obtaining the used air amount ratio from the pressure change and then comparing the used air amount ratio with the reference value to obtain the coil temperature. When switching between the U-type operation and the P-type operation for suppressing the coil temperature to a predetermined value, there is a problem that highly accurate control cannot be performed.

The present invention has been made in view of the above circumstances, and is a state in which the switching temperature of the pressure switch type operation and the unloader type operation can be accurately performed and the coil temperature of the electric motor is reliably suppressed to a predetermined value or less. An object of the present invention is to provide a compressor that can be operated in compression.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a compressor main body by operating an unload mechanism provided in a compressor main body driven by an electric motor while the electric motor is operating. The unloader type operation mode in which the generation of compressed gas can be stopped and the pressure switch type operation mode in which the electric motor is operated intermittently by opening / closing the opening / closing means provided on the power supply side of the electric motor in response to a signal from the pressure detection means. In a compressor having a control means for selectively switching between and, the electric motor is provided with a temperature detection means for detecting a coil temperature of the electric motor, and the control means has a detection temperature of the temperature detection means and a preset reference temperature. And a mode selection circuit for selecting and setting the unloader type operation mode and the pressure switch type operation mode based on the comparison result. Characterized in that was.

[0014]

With this structure, the temperature sensor directly detects the coil temperature of the electric motor, and the mode selection circuit selects the pressure switch type operation or the unloader type operation using the temperature data detected by the temperature sensor. Since the compression operation is performed based on the operation method selected from the above, the switching timing between the pressure switch operation and the unloader operation can be set with high accuracy according to the coil temperature.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A compressor according to an embodiment of the present invention will be described below with reference to FIGS. The same members as those shown in FIGS. 5 and 6 are designated by the same reference numerals as those in FIGS. 5 and 6, and the description of the same members is omitted. In the figure, in place of the pressure control valve 15 of FIG. 6, a discharge port is provided in the middle of the unload pipe 14 and communicates with the atmosphere side, and the connection of the port is switched according to whether the power is supplied or not. A three-way solenoid valve 20 capable of forcibly opening the intake valve 12 is provided.

A temperature sensor 21 for detecting the coil temperature of the electric motor 2 is provided on the outer cover of the electric motor 2. In this case, the temperature sensor 21 may be embedded in the coil as shown by the dotted line in FIG. This temperature sensor 21 is connected to the control means 7. The control means 7 includes a mode selection circuit.
22 is provided, the detected temperature of the temperature sensor 21 is compared with a preset reference temperature, and if the detected temperature exceeds the reference temperature, the three-way solenoid valve 20 is operated to select the unloader type operation mode.・ While setting, if the detected temperature is lower than the reference temperature, the electromagnetic switch 6 is controlled via the pressure switch 4 with the three-way solenoid valve 20 de-energized to select the pressure switch operation mode. -It is designed to be set.

The operation of the air compressor configured as described above will be described with reference to FIGS. 3 and 4.

First, when the electromagnetic switch 6 is turned on and the power is turned on (step S1), the electric motor 2 and the compressor body 1 are operated to obtain compressed air, and the compressed air is supplied to the air tank 3. The internal pressure rises (step S2).
Internal pressure upper limit reference pressure value of the air tank 3 (in this case, 9.5k _g f / cm ²⁾ is reached the pressure switch 4 is turned off (step S3), and subsequently the detected temperature and the reference temperature of the temperature sensor 21 Is compared and determined (step S4).

If it is determined in step S4 that the detected temperature is equal to or lower than the reference temperature, the mode selection circuit 22 selects and sets the pressure switch type operation mode, and at this stage the electromagnetic switch 6 is turned off and the motor is driven. 2 and eventually the operation of the compressor body 1 is stopped (step S5). The internal pressure of the air tank 3 decreases as the operation of the compressor body 1 is stopped (step S6),
The value is lower reference pressure value (in this case, 8.0k _g f / cm ²⁾ when the following is reached the pressure switch 4 and the electromagnetic switch 6 is turned on (step S7), and compression operation (pressure switch machine type operation) is The process is started (step S8), and thereafter, the process returns to step S2 and the processes of steps S3 and S4 described above are performed.

When it is judged in the judgment processing of step S4 that the detected temperature exceeds the reference temperature, the mode selection circuit 22 operates the three-way solenoid valve 20 to select and set the unloader type operation mode, The U-type operation is carried out (step S9), and the internal pressure of the air tank 3 is lowered by the execution of the U-type operation (step S10). Pressure switch 4 at this stage
It is determined whether or not is turned on (step
S11).

In this step S11, for example, the air tank 3
The internal pressure of the pressure switch is less than or equal to the lower limit reference pressure value.
When is turned on, it is determined to be YES and the routine proceeds to step S8, and the operation of step S2 and the following steps is executed in the U-type operation. If the internal pressure of the air tank 3 is not lower than the lower limit reference pressure value in step S11, NO is determined.
Then, it is determined whether one minute has elapsed from the time when the U-type operation was set (step S12). Here, when it is determined that one minute has not elapsed, the processing is performed in the above step.
On the other hand, if YES is determined while returning to S11, the process is performed by returning to step S8 after performing the compression operation, and thereafter, the processes of steps S2 to S4 are performed as described above.

As described above, the temperature sensor 21 directly detects the coil temperature of the electric motor 2, and the mode selection circuit 22 selects the U type operation or the P type operation using the temperature data detected by the temperature sensor 21. Since the compression operation is performed based on the selected operation method, the switching timing between the U-type operation and the P-type operation can be set with high accuracy according to the coil temperature. Therefore, the compression operation can be performed in a state in which the coil temperature is reliably and accurately suppressed to a predetermined value or less.

In the above-mentioned automatic switching type air compressor, since the switching operation control is performed after determining the used air amount ratio based on the detection data of the pressure sensor, the control means 7 obtains the used air amount ratio and the calculating means. However, in the compressor of the present embodiment, such arithmetic means can be omitted, and the control means 7 can be simple and inexpensive accordingly. Even when the control means 7 is composed of a microcomputer,
This is also true.

Further, since the temperature sensor 21 is only required to be able to detect the coil temperature, it is not necessary to use the temperature sensor 21 having a special specification, and a commercially available product can be used. By using a commercially available product as described above, it is possible to reduce the cost of the entire apparatus in combination with the use of an inexpensive control means 7.

[0025]

Since the present invention is the compressor configured as described above, selection / setting of the pressure switch type operation and the unloader type operation is performed by using the coil temperature of the electric motor directly detected by the temperature sensor. Since the compression operation is performed on-the-fly, the switching timing of the pressure switch type operation and the unloader type operation can be set with high accuracy according to the coil temperature, and accordingly, the coil temperature must be reliably and accurately suppressed to a predetermined value or less. It becomes possible to perform the compression operation.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a compressor according to an embodiment of the present invention.

FIG. 2 is a front view showing the compressor.

FIG. 3 is a flowchart showing an operation of the compressor.

FIG. 4 is a waveform diagram showing an operation of the compressor.

FIG. 5 is a front view showing a pressure switch type air compressor as an example of a conventional compressor.

FIG. 6 is a front view showing an unload type air compressor as an example of a conventional compressor.

[Explanation of symbols]

 1 Compressor body 2 Electric motor 7 Control means 10 Unload mechanism 21 Temperature sensor 22 Mode selection circuit

Claims (1)

[Claims] 1. An unloader type operation mode in which generation of compressed gas by the compressor body can be stopped by operating an unload mechanism provided in the compressor body driven by the electric motor while the motor is operating, and A compressor having control means for selectively switching between a pressure switch type operation mode in which an electric motor is intermittently operated by opening / closing an opening / closing means provided on a power source side in response to a signal from a pressure detecting means, Is provided with temperature detecting means for detecting the coil temperature of the electric motor, and the control means compares the detected temperature of the temperature detecting means with a preset reference temperature, and based on the comparison result, the unloader type operation mode. And a mode selection circuit for selecting and setting a pressure switch type operation mode.