JPS6321387A - Starting load reducing device for oil cooling type screw compressor - Google Patents

Abstract

PURPOSE:To speedily carry out the acceleration of a motor by installing an oil tank at the position lower than that of a compressor and higher than that of an oil separator into an oil supplying piping for connecting a cooler and the compressor and connecting the oil tank and the oil separator through a check valve. CONSTITUTION:An oil tank 11 for temporarily storing the oil supplied into a compressor 1 is arranged at the position lower than that of the compressor 1 and higher than that of an oil separator 2. A cooler 5 and the compressor 1 are allowed to communicate through oil feeding pipes 4 and 12 in the upper part of the oil feeding tank 11, and the oil separator 2 is allowed to communicate to the lower part of the oil tank 11 through an oil recovering pipe 10 equipped with a check valve 9. Since the oil which forms the trouble on start of a motor does not exist in the compressor 1, starting the compressor 1 is easily carried out, and supplying a large quantity of oil having a large viscosity at a low temperature into the compressor 1 in the acceleration time of the motor is prevented and acceleration for the motor can be carried out speedily.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a startup load reduction device for an oil-cooled screw compressor, and in particular, in addition to load reduction at startup, it also reduces load at the time of acceleration immediately after startup. The present invention relates to improvements to oil supply circuits that also take into account the above.

[Conventional technology]

In general, an oil-cooled screw compressor (hereinafter referred to as a compressor) houses a rotor IB supported on both sides by bearings IC and ID in a gauging IA, and a casing IA as shown in FIG. is equipped with an air suction part (not shown) equipped with a throttle valve, and the rotor IB is rotated by a motor (not shown), and the air sucked from the air suction part is transferred onto the O-tor IB. The air is compressed by guiding the air into the thread grooves and supplying oil there. Such an oil supply circuit for the compressor 1 introduces air compressed by the compressor 1 into the oil separator 2, separates oil from the compressed air in the oil separator 2, and supplies the separated oil to the oil in the oil separator 2. The oil in the oil chamber 2B is collected into the oil chamber 2B, and the oil in the oil chamber 2B is pushed out to the oil supply pipe 3 by the pressure of the compressed air in the space of the oil separator 2, and after being cooled by the cooler 5, it is sent to the compressor This is to supply oil to 1.

In the above-mentioned oil supply circuit, in order to reduce the load at the time of starting the compressor 1, conventionally, as shown in the figure, the two spaces of the oil separator 2 and the oil supply pipe 4 are separated by a solenoid valve 6 and a check valve 7.
A check valve 9 is provided in the oil supply pipe 4 close to the cooler 5, and a solenoid valve 6 is connected when the operation is stopped.
A known method is to open the oil separator 2 and introduce the compressed air within the space of the oil separator 2 into the oil supply pipe 4, and then cut off the oil flowing into the compressor 1 after the operation is stopped (for example, in Japanese Patent Laid-Open No. 59 -99297).

In addition, as shown in Fig. 3, the compressor 1 and oil separator 2
are communicated with each other by an oil recovery pipe 10 having a check valve 9, and the compressor 1 is arranged at a higher position than the oil separator 2,
After the operation is stopped, the compressed air in the space for two people in the oil separator 2 is released to the atmosphere, the differential pressure between the compressor 1 and the oil separator 2 is eliminated, and the residual oil remaining inside the compressor 1 is removed by the weight of the oil. A method of recovering the oil to the oil separator 2 was also known.

[Problems to be Solved by the Invention] However, both of the above conventional devices are methods for reducing the load only at the start of operation, and do not consider load reduction during a certain period of time from the start of operation, that is, when the motor accelerates. It wasn't. Especially when the oil viscosity is high at low temperatures, the pressure inside the oil separator increases immediately after starting operation, and a large amount of oil is supplied to the compressor, which increases the motor load torque and prevents the motor from accelerating quickly. There was a problem.

The present invention was made to solve the above problems, and
The purpose is to provide a starting load reduction device for an oil-cooled screw compressor that limits the amount of oil supplied to the compressor to the necessary minimum during a certain period of motor acceleration time from startup.

[Failure to solve the problem]

The start-up load reduction device for an oil-fed screw compressor of the present invention includes a compressor that compresses gas, an oil separator that separates oil from the compressed gas, and an oil separator that converts the separated oil in the oil separator into oil using the pressure of the compressed gas. In the start-up load reduction device for an oil-cooled screw compressor, which includes an oil supply circuit that pushes oil out of the separator and supplies oil to the compressor via a cooler, an oil tank is connected to an oil supply pipe that connects the cooler and the compressor. The oil tank and the separator are connected by an oil recovery pipe having a check valve, and the oil tank is located at a position lower than the compressor and higher than the oil separator.

[Effect]

According to the above configuration, when the operation is started, compressed gas is sent to the oil separator, the pressure in the oil separator increases, and the oil in the oil chamber is pushed out to the oil supply pipe. Since the oil tank is provided in the middle of the oil supply piping, oil will not flow into the compressor unless the oil tank is filled with oil, suppressing an increase in motor load torque due to the inflow of highly viscous oil at low temperatures.

Also, immediately after startup, the inside of the compressor becomes negative pressure.

The mist of oil in the oil tank is sucked in, and this mist of oil lubricates the compressor during the motor acceleration time.

Furthermore, when the motor acceleration is completed, the oil tank is filled with oil and oil supply to the compressor is started at this timing. Furthermore, during operation, the pressure of compressed gas within the oil separator also acts on the oil recovery pipe, but this is shut off by a check valve provided in the oil recovery pipe.

Next, when the operation is stopped, the compressed gas inside the oil separator is released to the atmosphere, and the differential pressure between the inside of the compressor and the inside of the oil separator disappears, so the residual oil inside the compressor is absorbed by its own weight and transferred to the oil separator. At the same time, the remaining oil in the oil tank is also collected in the oil separator, and the oil in the compressor and oil tank becomes empty.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

Note that the same parts as in the conventional device are denoted by the same reference numerals, and detailed explanations will be omitted.

The oil supply circuit of this embodiment is as shown in FIG.

Immediately after startup, an oil tank 11 that temporarily stores oil to be supplied to the compressor 1 is placed at a position lower than the compressor 1 and higher than the oil separator 2. The machine 1 is connected to the oil supply pipe 4 and the oil supply pipe 12, respectively.

The lower part of the oil tank communicates with the two spaces of the oil separator 2 through an oil recovery pipe 10 having a check valve 9, and also communicates the oil chamber 2B of the oil separator 2 with the cooler 5 through an oil supply pipe 3. be. Note that the oil supply pipe 12 is also used for recovering residual oil from the compressor 1.

Next, the operation of this embodiment will be explained.

At the time of startup, most of the oil is collected in the oil separator 20 oil chamber 2B, and there is a large amount of oil attached to the inner surface of the casing IA of the compressor 1, the rotor IB, and the bearing IC1ID. There's nothing to do. Therefore, the rotational load torque of the motor for driving the rotor IB is reduced, and the compressor 1 quickly starts rotating. When the compressor 1 starts rotating, the air compressed by the compressor 1 is sent to the oil separator 2, and the pressure of the two spaces in the oil separator 2 increases rapidly. Oil chamber 2 due to increased pressure
The oil in B is pushed out to the oil supply pipe 3, cooled by a cooler, and then flows into the oil tank 11 through the oil supply pipe 4. The oil tank 11 is empty before startup, and the oil tank 11 will not be filled with oil until a certain period of time has elapsed. Therefore, unless the oil tank ll is filled with oil, oil will not flow into the compressor 1, and the motor that drives the compressor 1 will not be able to accelerate quickly for a certain period of time until the motor that drives the compressor 1 completes acceleration. can.

In addition, when the compressor 1 is started, the throttle valve installed in the air suction part of the compressor 1 is closed, so when the compressor 1 is started, the inside of the compressor 1 becomes negative pressure, and the oil A part of the oil that has flowed into the tank 11 and is floating in the oil tank 11 in the form of mist is sucked into the compressor 1. For this reason, the oil supply is not completely cut off even during the motor acceleration time.
This mist of oil provides lubrication.

When the motor acceleration is completed, the oil tank 11 is filled with oil, and a large amount of oil is started to be supplied to the compressor 1.

Next, when the operation is stopped, the supply of compressed air to the oil separator 2 is stopped, the pressure inside the oil separator 2 decreases, and the flow of oil to the oil tank 11 is stopped. Furthermore, the two spaces in the oil separator 2 are opened to the atmosphere, and when the differential pressure inside the compressor 1, oil tank 11, and oil separator 2 disappears, the remaining oil inside the compressor l flows through the oil supply pipe 12. The oil flows backward due to its own weight and is collected into the oil tank 11, and further, the oil in the oil tank 11 is collected into the oil chamber 2B of the oil separator 2 through the oil recovery pipe 1o. In this way, the oil in the compressor 1 and the oil tank 11 becomes empty after a certain period of time has passed since the operation was stopped.

Note that the piping for collecting residual oil in the compressor 1 does not pass through the oil tank 1, but connects the compressor 1 and the oil separator 2.
It can also be provided separately between.

Further, the oil supply pipe 3 and the oil supply pipe 12 can be connected not only to the upper part of the oil tank 11 but also to any part of the oil tank.

It is possible to continue.

〔Effect of the invention〕

According to the present invention, since there is no oil inside the compressor that would impede motor starting at the time of start-up, the compressor can be started easily.Furthermore, since an oil tank is provided, A large amount of low-temperature, highly viscous oil is not supplied to the compressor within the fixed motor acceleration time, and the motor is accelerated quickly. Furthermore, since mist-like oil is being supplied even during this acceleration time, there is no risk of poor lubrication compared to a method in which the oil flow is completely cut off for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing one implementation of the present invention, and FIGS. 2 and 3 are system diagrams showing a conventional starting load reduction device for an oil-cooled screw compressor.

Claims (1)

[Claims] 1. A compressor that compresses gas, an oil separator that separates oil from the compressed gas, and a compressor that pushes the separated oil in the oil separator out of the oil separator by the pressure of the compressed gas and passes through a cooler to the compressor. In the starting load reduction device for an oil-fed screw compressor, the oil tank is provided in the oil supply pipe connecting the cooler and the compressor, and the oil tank and the separator are connected to each other by a check valve. 1. A start-up load reduction device for an oil-cooled screw compressor, characterized in that the oil tank is located at a position lower than the compressor and higher than the oil separator.