JPH0429105Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a multistage compressor that includes a plurality of low-pressure side compression sections.

Some multi-stage compressors are pressure open/close types that stop operating when the pressure in the air tank that stores compressed air is within a predetermined range.
In such a multi-stage compressor, if the amount of air consumed in the air tank is small, the operation will be stopped for a long time, and the temperature of each part of the compressor will cool down to the same level as room temperature. When operation is started again with each part cooled down, the air compressed in the low-pressure compression part is cooled in the intermediate pipe as it moves to the high-pressure compression part through the intermediate pipe. , condensation of moisture contained in the compressed air occurs. If the drain generated by this condensation is directly sent to the high-pressure side compression section, various problems will occur. For example, if the multistage compressor is a reciprocating type, condensate that has entered the high-pressure side compression section (high-pressure side cylinder) from the intermediate pipe will flow into the crankcase through the gap between the cylinder and the piston, and the condensate will flow into the crankcase through the gap between the cylinder and piston. It mixes into the lubricating oil stored in the inner bottom of the crankcase, making the lubricating oil cloudy and reducing its lubrication function, and causing problems such as rust inside the crankcase.

Therefore, in the past, an intercooler (for example, a radiator) was installed in the middle of the intermediate pipe to actively condense the moisture in the compressed air flowing through the intermediate pipe, and the generated drain was installed at the end of the intercooler. Measures have been developed to direct the water to the outside via a drain separator, but such measures require a large installation space and are costly because the intercooler itself is high temperature and large in size. Problems such as high blood pressure occur.

This idea was made in view of the above circumstances, and in a multi-stage compressor equipped with multiple low-pressure side compression sections, the generation of drain in the intermediate pipe that leads compressed air from the low-pressure side compression section to the high-pressure side compression section was developed. The purpose is to prevent this with a compact and inexpensive mechanism, and its characteristics are as follows:
A plurality of low-pressure side compression sections that compress air to the same predetermined pressure, and a high-pressure side compression section that further compresses the compressed air sent from these low-pressure side compression sections via an intermediate pipe and sends it to an air tank. The multi-stage compressor is equipped with an unloader that opens a suction valve, an unloader operating mechanism that operates the unloader, and an unloader operating mechanism that is installed in a part of the plurality of low-pressure side compression sections. An operation control device is provided for operating the intermediate pipe for a predetermined period of time required to raise the temperature of the intermediate pipe from room temperature to a predetermined temperature when the compressor starts operating.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a schematic configuration of a multi-stage compressor according to an embodiment, and FIG. 2 shows details of the main parts of FIG. 1.

This multi-stage compressor is a reciprocating type compressor that compresses air using a piston mechanism that reciprocates within the cylinder.In the upper part of the crankcase 1, there are two low-pressure side compressors that compress air to the same predetermined pressure. (hereinafter referred to as low-pressure side cylinders) 2 and 3, and a high-pressure side compression section (hereinafter referred to as high-pressure side cylinders) that further compresses the air compressed by these low-pressure side cylinders 2 and 3.
4, and air compressed in the high-pressure side cylinder 4 is stored in an air tank 6 below the crankcase 1 via a rear pipe 5. In addition, this multi-stage compressor is equipped with an electric motor 7 (second
(see figure) is also a pressure opening/closing type.

A silencer 8 for air intake is provided at the top of each of the low-pressure cylinders 2 and 3, and the air compressed by these cylinders 2 and 3 is transferred to the high-pressure cylinder 4 via an intermediate pipe 9. sent to.

As shown in FIG. 2, the low-pressure side cylinders 2 and 3 include a cylinder 11 on which an air compression piston slides;
A cylinder head 12 having a suction port 12a and fixed to the upper part of the cylinder 11; a suction valve 13 attached to the cylinder side surface of the cylinder head 12 for opening and closing the suction port 12a;
The head cover 15 is attached to the upper part of the cylinder head 12 to provide a suction chamber 14 communicating with the suction port 12a, and to which the silencer 8 is attached. and,
Among these low pressure side cylinders 2 and 3, one cylinder 2
As shown in FIG. 2, a suction valve opening type unloader 16 that opens the suction valve 13 to put the cylinder 2 into no-load operation, and an unloader operating mechanism 17 for operating the unloader 16; An operation control device 1 that operates the unloader operating mechanism 17 for a predetermined time, that is, the time required for the intermediate pipe to rise in temperature from room temperature to a predetermined temperature, when the compressor starts operating, that is, when the electric motor 7 starts energizing.
8 is provided.

The unloader 16 has the suction port 12a.
a guide cylinder 16a provided on the head cover 15 correspondingly to the unloader piston, and an unloader piston that is slidably supported within the guide cylinder 16a and has an operating shaft 16b at its lower end for pushing open the suction valve 13. 16c, and a spring 16d that urges the piston 16c upward so that the operation shaft 16b does not push open the suction valve 13.
A cavity 16e serving as a pressure chamber is formed above the piston 16c by the upper wall of the piston 6a.

The unloader operating mechanism 17 includes an air tank 6
The unloader piston 16c is driven using the compressed air inside the tank, and the pipe 19 is connected to a pipe line 19 that communicates the air tank 6 with the cavity 16e.
It consists of a solenoid valve 20 disposed inside. This solenoid valve 20 is a 3-port, 2-position switching valve that is used as a normally closed valve, and its position is switched by the operation control device 18. Under normal conditions, the pipe line 19a on the unloader 16 side is open to the atmosphere. When the pipe line 19b on the air tank 6 side is closed and the position is switched by the control device 18, the pipe line 19 opens the air space 1 as shown in the figure.
6e and the inside of the air tank 6 are in communication, and the compressed air inside the air tank 6 is delivered to the unloader piston 1.
It will act on the upper part of 6c.

The biasing force of the spring 16d mentioned above is caused by the set pressure of the compressed air in the air tank 6 acting on the unloader piston 16c (when the pressure in the air tank 6 rises to a predetermined value, the compression operation of the compressor is interrupted and the unloading operation is switched off). However, it is set to a value slightly smaller than this predetermined pressure value), and if compressed air with a pressure higher than the set pressure in the air tank 6 acts on the unloader piston 16c, the unloader piston 16c is pushed down. The suction valve 13 is opened.

In this embodiment, as the operation control device 18, a timer is used which starts energization when the electric motor 7 starts operating. The energization time of this timer is set in consideration of the time required for the intermediate pipe 9 and the like of the compressor to rise in temperature from room temperature to a predetermined temperature after the start of operation.

In a compressor with such a configuration, when the pressure in the air tank 6 drops to a predetermined value, the compressor will restart operation, but in that case, when the electric motor 7 as the drive source is energized, At the same time, the operation control device 18
The solenoid valve 20 is energized by the solenoid valve 20, and the solenoid valve 20 is opened. As a result, the air in the air tank 6 is guided to the cavity 16e of the unloader 16 provided in the low-pressure cylinder 2, pushing down the unloader piston 16c and opening the suction valve 13 of the low-pressure cylinder 2.

Therefore, at the start of operation, one low-pressure side cylinder 2 is operated in an unloaded manner, and the other low-pressure side cylinder 3 is unloaded.
Compressed air will be sent to cylinder 4 on the higher pressure side,
The amount of air sent from the low-pressure cylinders 2 and 3 to the high-pressure cylinder 4 is reduced compared to during normal operation (when both low-pressure cylinders 2 and 3 perform compression normally), and the amount of air sent from the low-pressure cylinders 2 and 3 to the high-pressure cylinder 4 is reduced by that amount. The air pressure inside the intermediate pipe 9 decreases, and the temperature at which moisture contained in the air flowing through the intermediate pipe 9 condenses (dew point temperature) decreases.

Therefore, even if the temperature of the intermediate pipe 9 has fallen to about room temperature, moisture condensation within the intermediate pipe 9 is less likely to occur, and drainage within the intermediate pipe 9 is prevented from occurring. Therefore, the operation of the unloader 16 causes problems due to the generation of condensate, such as condensate entering the crankcase 1 from the high-pressure side cylinder 4, making the lubricating oil in the crankcase 1 cloudy, and reducing the lubrication function. This prevents inconveniences such as rust on parts inside the crankcase 1.

When a predetermined period of time has elapsed after the start of operation, the intermediate pipes 9 and 10 reach a predetermined temperature due to the air sent from the low-pressure cylinder 3 and the heat transfer from each cylinder 2, 3, and 4. Solenoid valve 20
The energization to is stopped, the conduit 19a on the unloader 16 side is opened to the atmosphere, and the conduit 19b on the air tank 6 side is closed. Then, the unloader piston 16c is pushed back upward by the biasing force of the spring 16d, the opening of the suction valve 13 is released, and the cylinder 2 also returns to normal operation. In this way, when both the low-pressure side cylinders 2 and 3 begin to perform compression, the amount of air sent to the high-pressure side cylinder 4 increases, and the pressure inside the intermediate pipe 9 increases to a predetermined value. Although the dew point temperature increases within 9,
At this time, since the temperature of the intermediate pipe 9 has already risen to a predetermined temperature or higher, no drainage occurs within the intermediate pipe 9.

In the above-described embodiment, the unloader piston 16c is operated by pneumatic pressure, but the unloader piston 16c may be moved back and forth directly by a solenoid, a hydraulic cylinder, or the like. Furthermore, a timer is used to set the operating time of the solenoid valve 20, but instead of using the timer, the temperature of the intermediate pipe 9 is detected by a temperature sensor,
The temperature sensor may energize the solenoid valve 20 when the temperature of the intermediate pipe 9 is below a predetermined value, and stop energizing the solenoid valve 20 when the temperature of the intermediate pipe 9 rises to a predetermined value. . In this way, even if the temperature around the compressor changes, it can be handled reliably.

In addition, in the above-mentioned embodiment, as a multi-stage compressor,
Although a reciprocating type compressor is shown, the present invention can be applied to other types of multi-stage compressors as long as they have two or more low-pressure compression sections. As a multi-stage compressor,
It can also be applied to unloader types other than pressure opening/closing types.

As explained above, according to the present invention, there are a plurality of low-pressure side compression sections that compress air to the same predetermined pressure, and the compressed air sent from these low-pressure side compression sections via an intermediate pipe is further compressed. A multi-stage compressor is equipped with a high-pressure compression section that compresses the air and sends it to an air tank, and a part of the plurality of low-pressure compression sections includes an unloader that opens a suction valve and an unloader that operates the unloader. and an operation control device that operates the unloader operating mechanism for a predetermined time required for the intermediate pipe to rise in temperature from room temperature to a predetermined temperature at the start of operation of the compressor. a At the start of operation, the operation control device can unload some of the low-pressure side compression sections for the predetermined time required for the intermediate pipe to rise from room temperature to a predetermined temperature, and the flow from the low-pressure side to the high-pressure side is enabled. By reducing the amount of compressed air flowing through the intermediate pipe, the pressure within the intermediate pipe is reduced, and the dew point temperature at which moisture contained in the air flowing within the intermediate pipe condenses can be lowered.
Even when the temperature of the intermediate pipe has fallen to about room temperature, it is possible to prevent moisture from condensing within the intermediate pipe, and b. In addition, the temperature can be raised by the air sent from the low-pressure side compression section to the high-pressure side compression section and the heat transfer from each low-pressure and high-pressure compression section, thereby increasing the temperature of the intermediate pipe during the unloading operation. This can be useful for preventing moisture from condensing in the intermediate pipe, and can also help prevent moisture from condensing in the intermediate pipe. It is possible to prevent drainage from occurring within the pipe, and the new parts added to prevent drainage are relatively small, such as some mechanical parts for the unloader, solenoid valves, and timers. Since it requires low-cost parts and only needs to be installed in some low-pressure side compression sections, the condensate prevention mechanism is more compact and cheaper to manufacture than when using a conventional intercooler. d Furthermore, according to the present invention, only a part of the low-pressure side compression section is brought into the unloading state by one driving source, and the remaining low-pressure side compression section compresses air and transfers this compressed air to the high-pressure side. Since the compressed air is sent to the compression section, the above effects can be achieved without causing any inconvenience by only slightly reducing the amount of compressed air sent to the air tank at the start of operation.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of one embodiment of the present invention;
The figure is a detailed view of the main part of FIG. 1. 1... Crank case, 2, 3... Low pressure side compression section (low pressure side cylinder), 4... High pressure side compression section (high pressure side cylinder), 5... Rear pipe, 6... Air tank,
7... Electric motor, 8... Silencer, 9... Intermediate pipe, 11... Cylinder, 12... Cylinder head, 12a... Suction port, 13... Suction valve,
14...Suction chamber, 15...Head cover, 16...
...Unloader, 16a...Guide tube, 16b...Operation shaft, 16c...Unloader piston, 16d...
... Spring, 16e ... Blank space, 17 ... Unloader operation mechanism, 18 ... Operation control device, 19, 19a,
19b...Pipe line, 20...Solenoid valve.

Claims (1)

[Scope of utility model registration request] A plurality of low-pressure side compression sections that compress air to the same predetermined pressure, and a high-pressure side compression section that further compresses the compressed air sent from these low-pressure side compression sections via an intermediate pipe and sends it to an air tank. The multi-stage compressor is equipped with an unloader that opens a suction valve, an unloader operating mechanism that operates the unloader, and an unloader operating mechanism that is installed in a part of the plurality of low-pressure side compression sections. A multi-stage compressor, characterized in that it is provided with an operation control device that operates for a predetermined time period required for the intermediate pipe to rise in temperature from room temperature to a predetermined temperature when the compressor starts operating.