JPH0329590Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is an oil supply device for a screw compressor, in particular, the oil separated by an oil separator connected to the discharge port of the screw compressor is fed into the compressor through an oil supply pipe to the discharge pressure. The present invention relates to a lubrication device that is designed to lubricate with oil.

Oil supply devices configured in this manner have conventionally had the problem that oil accumulates in the compressor when the compressor is stopped, resulting in oil compression when the compressor is restarted, and a compression stroke in which oil is injected during startup. It has been pointed out that there is a problem in which the lubrication function is significantly degraded because sufficient discharge pressure cannot be used in the middle of the process.

For example, as described in Japanese Utility Model Application No. 56-77686 and schematically shown in FIG. 6, an oil separator 51 is connected to the discharge port of the screw compressor 50, and the oil separated by the oil separator 51 is The oil separator 51 is connected to the compressor 50 through the oil supply pipe 52 using the discharge pressure.
0, and the oil separator 51
and the compressor 50 are connected by an oil return pipe 54 interposed with a check valve 53 that allows flow only toward the oil separator 51. In this way, when the compressor 50 is stopped, the high and low pressure balance is maintained. Later, the oil in the compressor 50 is
Due to its own weight, the oil can be returned to the oil separator 51 via the oil return pipe 54, and the oil can be returned to the compressor 50.
A method has already been proposed to solve the problem of oil compression during restart.

Further, as described in Japanese Utility Model Application Publication No. 55-170491 and shown in FIG. A solenoid valve 56 is interposed between the compressor 50 and the suction side of the compressor 50 to separate the oil from the suction side of the compressor 50. An oil pipe 57 is separately provided that communicates with the oil area of the compressor 51, and the solenoid valve 56 is opened by a timer or differential pressure switch for a predetermined time when the compressor 50 is started, and the compression is carried out through the oil pipe 57. By lubricating the machine, it prevents the deterioration of the lubricating function due to insufficient pressure difference between the pressure during the compression stroke and the discharge pressure at startup, and cuts off the oil supply during steady operation to prevent oil compression. Some proposals have been made to prevent this.

By the way, although the system shown in Fig. 6 can solve the problem of oil compression at the time of restart, it cannot solve the problem of deterioration of the oil supply function at the time of startup.
On the other hand, what is shown in the figure solves the problem of the deterioration of the oil supply function at startup, but cannot solve the problem of oil compression at the time of restart, so it solves both of the above-mentioned problems. In order to do this, in addition to the oil supply pipe 52 of the oil supply mechanism, a check valve 5 shown in FIG.
3 with an oil return pipe 54 and a solenoid valve 56 shown in FIG.
As a result, the piping system becomes complicated, and the one shown in FIG. 7 requires a timer or differential pressure switch to control the opening and closing of the solenoid valve. There was also the problem of complicated electrical circuits.

The present invention was devised in view of the above problems, and the purpose is to improve the configuration of the check valve, and to create a simple piping system by simply adding one pipe to insert the check valve. Problems with oil compression when restarting, problems with deterioration of the oil supply function due to insufficient pressure difference between the discharge pressure and the discharge pressure during the compression stroke during which oil is injected during startup, and during steady operation. The problem of oil compression and oil compression can be solved at the same time.

Therefore, the configuration of the present invention separates the oil by the oil separator connected to the discharge port of the screw compressor.
The oil supply system is such that oil is supplied by discharge pressure through an oil supply pipe 4 during the compression stroke of the compressor 1, and the oil separator 3 is disposed below the compressor 1, and the oil separator 3 is disposed below the compressor 1. An oil pipe 6 equipped with a check valve 7 is connected between the side and the oil separator 3,
The check valve 7 opens and closes a first passage 8 communicating with the suction side of the compressor 1, a second passage 9 communicating with the oil separator 3, and the first passage 8 and the second passage 9. Formed from valve bodies 14, 23 and biasing body 16,
The force exerted by the biasing body 16 on the valve bodies 14, 23 overcomes the low differential pressure when starting and stopping the compressor 1, causing the valve bodies 14, 23 to open. It is set to a size that allows the compressor 1 to close at a high differential pressure during steady operation.

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

In Fig. 1, 1 is a screw compressor having a pair of rotors (not shown), a discharge pipe 2 is connected to the discharge port, and an oil separator is connected to the discharge pipe 2 to separate oil contained in the discharged gas. 3 is interposed, and this oil separator 3 is located below the compressor 1.

The bottom of the oil separator 3 and the compressor 1
An oil supply pipe 4 is used to connect the compressor 1 to the middle of the compression process, and an oil pipe 6 with a check valve 7 interposed between the suction side of the compressor 1 and the bottom of the oil separator 3 is connected as shown in FIG. In the illustrated example, since both the oil supply pipe 4 and the oil pipe 6 are connected to the bottom of the oil separator 3, the same pipe 46 is used to connect the oil supply pipe 4 and the oil pipe 6 to each other at the header 5. The suction side of the compressor 1 and the bottom of the oil separator 3 are communicated by branching.

Furthermore, the check valve 7 interposed in the oil pipe 6 has a second
It is formed as shown in the figure.

That is, in the case shown in FIG. 2, the first and second passages 8 and 9 made of cylindrical bodies are butted and joined, and
A closing plate 10 is provided at this joint portion to partition the insides of the passages 8 and 9. A valve seat surface 12 is formed in the center of this closing plate 10, which has a hollow truncated conical shape that expands toward the second passage 9, has a valve hole 11 in the center, and seats a valve body 14 whose inner surface will be described later. This is to fix the valve receiver 13.

Furthermore, while disposing the valve body 14 made of a steel ball in the second passage 9 and fixing the support rod 15 in the first passage 8, penetrating the valve hole 11,
One end is fixed to the valve body 14 and the other end is fixed to the fixed rod 15, and a biasing body 16 (hereinafter referred to as a spring) having a spring force, which will be described in detail later, is provided to start the compressor 1. The valve body 14 is opened by overcoming the low differential pressure at the time of starting and at the time of stopping.

Thus, the check valve 7 configured in this manner is interposed in the oil pipe 6 such that the first passage 8 communicates with the suction side of the compressor 1 and the second passage 9 communicates with the oil separator 3. It is.

Further, the spring force of the spring 16 is the same as that of the compressor 1.
When the differential pressure between the suction side of the oil separator 3 and the oil separator 3 side (discharge side of the compressor 1) is 0 or low, such as when the compressor 1 is started and stopped, the valve The valve body 14 is set to a value that allows the valve body 14 to be isolated from the valve seat surface 12 against the pressing force of oil applied to the body 14.

Further, when the differential pressure between the suction side and the discharge side of the compressor 1 becomes high during steady operation of the compressor 1, the pressure of the oil applied to the valve body 14 due to the high differential pressure causes the spring to The spring force is set to a value that allows the valve body 14 to be seated on the valve seat surface 12 against the force exerted by the check valve 16 and to close the check valve 7.

In FIG. 1, 17 is an oil cooler, 18 is a motor that drives the compressor 1, and 19 is the compressor 1.
It is the inlet of the

The operation of the oil supply device constructed in this way will be explained.

When the compressor 1 is started, the discharge pressure of the compressor 1 is low, so that almost no oil can be supplied to the compressor 1 from the oil supply pipe 4 connected during the compression process of the compressor 1. However, during this startup, the differential pressure between the suction side and the discharge side of the compressor 1 is small, and the spring 16 overcomes the low differential pressure and opens the valve body 14, causing the suction side of the compressor 1 to open. and the separator 3 are the oil pipes 6
Due to the small pressure difference between the suction side and the discharge side of the compressor 1, oil can be smoothly supplied from the oil separator 3 to the suction side of the compressor 1 through the oil pipe 6. can. Note that the direction of flow and pressure in the oil pipe 6 is the forward direction of oil supply to the compressor 1.

Further, during steady operation of the compressor 1, the discharge pressure is high, and while this discharge pressure can be used to smoothly supply oil from the oil supply pipe 4, the pressure difference between the suction side and the discharge side is also high. Therefore, the valve body 14 seats on the valve seat surface 12, closes the valve hole 11, and the check valve 7 is closed. Note that the direction of the pressure in the oil pipe 6 is the forward direction of oil supply to the compressor 1. As a result, during steady operation of the compressor 1, a large amount of oil will not flow into the suction side of the compressor 1 through the oil pipe 6, causing capacity loss or oil compression. It does not occur at all.

Moreover, when the compressor 1 is stopped, the differential pressure between the suction side and the discharge side of the compressor 1 becomes low again and becomes zero due to pressure equalization, so that the spring 16 Opening the valve hole 11 by urging the body 14 in the separating direction with respect to the valve seat surface 12;
The check valve 7 is opened. As a result, the oil in the compressor 1 can be returned to the oil separator 3 via the oil pipe 6 due to its own weight. Therefore, oil does not accumulate in the compressor 1, and oil compression at the time of restart can be reliably prevented. The direction of the flow and pressure in the oil pipe 6 during this stop is the direction of the compressor 1.
This is the opposite direction of refueling.

The structure of the check valve 7 is not limited to that shown in FIG. 2, but may be as shown in FIGS. 3 to 5.

That is, the valve body 20 shown in FIG. The operation of the valve body 23 allows communication/
First and second passages 8 and 9 are formed to be blocked.
The opening/closing passage 22 is closed by the inner surface of the valve hole 21 to block the first and second passages 8 and 9 when the valve body 23 is positioned on the left side in FIG. 3, and is opened when the valve element 23 is positioned on the right side. The first and second passages 8 and 9 are formed so as to communicate with each other.

Further, the left end of the valve hole 21 in FIG. Said first and second pressure chambers 26, 27
are communicated with the first and second passages 8 and 9 via pilot passages 28 and 29, respectively. Also,
A spring 16 is disposed in the first pressure chamber 26 . The spring force of this spring 16 is as shown in FIG. Due to this differential pressure, the valve body 23 is slightly pressed and moved to the right or left in FIG. 3 against the pressing force acting on the valve body 23 toward the left or right in FIG. When the pressure difference is large,
In other words, when there is a high differential pressure, the valve body 23 is set so that it contracts against the pressing force acting on the valve body 23 in the left direction in FIG. There is.

Furthermore, in the valve body 20 shown in FIG.
The left and right chambers are designated as first and second pressure chambers 26 and 27, a pipe having a first passage 8 is connected to the first pressure chamber 26, and the end surface is a valve seat surface on which the valve body 23 is seated. A pipe having two passages 9 is inserted, and this second passage 9 and the second pressure chamber 27
and are communicated via a pilot passage 31.

Furthermore, the first pressure chamber 26 is provided with a spring 16 that operates in substantially the same manner as in the embodiment described above.

By doing the above, the pressure on the discharge side of the compressor 1 increases when the compressor 1 is started or during steady operation, and the pressure difference between the suction side and the discharge side becomes a high differential pressure after passing through a low differential pressure. When the pressure on the discharge side is
It acts on the pressure chamber 26 and the second pressure chamber 27 via the pilot passage 31, and a first passage 8 communicating with the suction side of the compressor 1 is connected to the first pressure chamber 26. However, the pressure in the first pressure chamber 26 is lower than that in the second pressure chamber 27, and at startup, this pressure difference is a low pressure difference, and the valve body 23 moves only slightly. , oil flows from the second passage 9 to the first passage 8, that is, to the suction side of the compressor 1. During the subsequent steady operation, this pressure difference becomes a high pressure difference, and this pressure difference causes the valve body 23 to It moves to the left in Figure 4 and seats on the end face of the second passage 9 which serves as the seating surface, and oil does not flow from the second passage 9 to the first passage 8, that is, to the suction side of the compressor 1. . Also, when stopping, the first
The passage 8 communicates with the suction side of the compressor 1, and the second passage 9 communicates with the oil separator 3 disposed below the compressor 1, so that the oil in the compressor 1 is transferred to the separator 3.
The oil is returned to the

Further, the valve shown in FIG. 5 is provided with a valve chamber 32 in which a valve body 23 is loosely fitted inside the valve body 20, and first and second passages 8 and 9 opening into the valve chamber 32. A valve seat surface 33 on which the seat surface 23a of the valve body 23 is seated is formed at the end of the first passage 8 facing the valve chamber 32, and the spring 16 is disposed on the first passage 8 side, A guide cylinder 36 is integrally formed on the back surface of the valve body 23, and a passage 37 is further formed in the valve body 23 to communicate the second passage 9 and the valve chamber 32.

During the compression stroke in the compressor 1, the oil supply pipe 4
The oil supply device is configured to supply oil by discharge pressure through An oil pipe 6 equipped with a stop valve 7 is connected, and the check valve 7 connects a first passage 8 communicating with the suction side of the compressor 1, a second passage 9 communicating with the oil separator 3, and a second passage 9 communicating with the oil separator 3. It is formed of valve bodies 14 and 23 that open and close the first passage 8 and the second passage 9, and a biasing body 16, and the biasing body 16 applies the force acting on the valve bodies 14 and 23 to the compressor. This is because the valve bodies 14 and 23 are set to open operation to overcome the low differential pressure at the time of starting and stopping of the compressor 1, and close at a high differential pressure during steady operation of the compressor 1. , a specially designed check valve 7 that does not require a complicated electrical circuit.
Although it is a simple piping system that only adds one oil pipe 6 with Oil can be supplied from the oil separator 3 to the side via the oil pipe 6, preventing a decline in the lubrication function during startup. The oil can be returned to the oil separator 3 via the oil separator 3 through the oil separator 3, which solves the problem of oil compression during restart. Due to the differential pressure, the check valve 7 is now closed, and the oil supply to the suction side of the compressor 1 is cut off, resulting in the remarkable effect that no oil compression occurs.

[Brief explanation of drawings]

Fig. 1 is a piping system diagram of an embodiment of the present invention, Fig. 2 is a sectional view showing a check valve of the same embodiment, and Figs. 3 to 5 are sectional views showing check valves of different embodiments. 6 and 7 are piping system diagrams showing conventional examples. 1...screw compressor, 3...oil separator, 4
... Oil supply pipe, 6 ... Oil pipe, 7 ... Check valve, 8 ...
First passage, 9...Second passage, 14...Valve body, 16
...Biasing body, 23... Valve body.

Claims (1)

[Scope of utility model registration request] An oil supply device in which oil separated by an oil separator 3 connected to a discharge port of a screw compressor 1 is supplied by discharge pressure through an oil supply pipe 4 during the compression stroke of the compressor 1, The oil separator 3 is disposed below the compressor 1, and an oil pipe 6 interposed in a check valve 7 is connected between the suction side of the compressor 1 and the oil separator 3. The valve 7 includes a first passage 8 that communicates with the suction side of the compressor 1, a second passage 9 that communicates with the oil separator 3, and a valve body 14 that opens and closes the first passage 8 and the second passage 9. ,23 and
a biasing body 16, and the biasing body 16 applies the force acting on the valve bodies 14 and 23 to the valve body by overcoming the low differential pressure when starting and stopping the compressor 1. 14 and 23 are set to a size such that they open and close at a high differential pressure during steady operation of the compressor 1.