JPH0463986A - Screw compressor - Google Patents

Abstract

PURPOSE:To improve durability of the seal part of a piston in a driving cylinder by providing outflow and inflow ports for pressure oil on both ends of a cylinder for driving an internal volume ratio adjusting valve. CONSTITUTION:In a compressor main body S, the interior of a cylinder 12 fixed on a casing 3 is divided with a partition wall 7 into a first chamber 8 and a second chamber 9, and pistons 14,15 are slidably provided in the respective chambers. In the first chamber 8 outflow and inflow ports 10X, 10Y for pressure oil are provided. Through holes 21-23 can be selectively communicated through a groove 20 formed on an internal volume ratio adjusting valve 5. Hereby, the through holes 21-23 are selectively communicated to communicate the outflow and inflow ports 10X, 10Y to a low pressure flow passage or a high pressure flow passage, and three stages of internal volume ratio can be adjusted. In this way, the outflow and inflow ports 10X, 10Y are provided on both end parts of the cylinder 12, hence an 0-ring 19 for seal is not injured at operation of the piston 14, and durability of the seal part can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a screw compressor equipped with an internal volume ratio control valve that adjusts the internal volume ratio in three stages: low, medium, and high.

(Prior Art) Conventionally, a screw compressor is known which is equipped with an internal volume ratio control valve that adjusts the volume ratio in three stages: low, medium, and high.

FIG. 5 shows the internal volume ratio control valve 31 of this screw compressor.
A piston 33 is slidably provided in a cylinder 32, and an internal volume ratio adjusting valve 31 is provided so as to be movable forward and backward via a piston rod 34. The cylinder 32 is provided with a first outflow port 35X, a second outflow port 35Y at both ends, and a third outflow port 35Z in the center for pressure oil, and an O-ring 36 for sealing is fitted around the piston 33. be.

By the way, in a screw compressor, the internal volume ratio is V
i (-V l/V o , V + ; theoretical maximum volume after confinement, vo : theoretical minimum volume just before discharge), specific heat ratio as Pd/Ps (Pd; discharge pressure, P
s: suction pressure), the adiabatic efficiency is maximized when ViK=Pd/Ps.

Therefore, in order to achieve this maximum efficiency, when the internal volume ratio of the compressor is reduced to a low internal volume ratio, the first inlet 35X is communicated with the high pressure channel, and the second inlet 35Y is communicated with the low pressure channel. At the same time, the third inlet/outlet 35Z is closed, resulting in the state shown by the solid line in FIG. On the other hand, when the internal volume ratio is medium, the first outflow port 35X and the second outflow port 35Y are communicated with the high-pressure flow path, the third outflow port 35Z is communicated with the low-pressure flow path, and the two-dot chain line in FIG. In the state shown in , when the internal volume ratio is high, the first inlet/outlet 35X
is connected to the low-pressure flow path, the second outflow port 35Y is connected to the high-pressure flow path, and the third outflow port 35Z is closed to create the state shown by the broken line in FIG.

(Problems to be Solved by the Invention) In the conventional compressor described above, the cylinder 32 for driving the internal volume ratio control valve is provided with a third inlet 35Z in the center of the cylinder 32 in addition to both ends, that is, in the piston loaf. be. For this reason, each time the piston 33 passes through the third outflow port 35Z, the O-ring 36 is rubbed and damaged, resulting in a problem that it is easily cut and lacks durability.

The present invention has been made to address the above-mentioned conventional problems, and provides a screw that makes it possible to improve the durability of the seal portion of the piston in the driving cylinder of an internal volume ratio control valve that adjusts the internal volume ratio in three stages. The aim is to provide a compressor.

(Means for Solving the Problems) In order to solve the above problems, the present invention rotatably accommodates a pair of male and female screw rotors that mesh with each other in a casing, and provides internal space between the screw rotors and the casing. In a screw compressor equipped with an internal volume ratio adjustment valve that can be moved forward and backward by a volume ratio adjustment valve drive cylinder,
A first groove is formed in the internal volume ratio adjusting valve, and a first groove is formed in the casing, the center axis of which is located on the same plane perpendicular to the advancing and retracting direction of the internal volume ratio adjusting valve, and in a position where it can communicate with the groove. ．． Second. a third through hole, a first flow ratio inlet for pressure fluid at the rotor side end of the piston working space of the drive cylinder, and a second flow ratio inlet for pressure fluid at the side opposite to the rotor;
When the internal volume ratio is low, the first inlet is communicated with the high-pressure flow path, the second inlet is communicated with the low-pressure flow path, and the first inlet is communicated with the low-pressure flow path.
．． The third through hole is brought into communication through the groove and with the low pressure flow path through a separate restricting means, and when the internal volume ratio is high, the first inlet is connected to the low pressure flow path and the second outflow inlet is connected to the low pressure flow path. is communicated with the high pressure flow path, and the above-mentioned 1. The third through hole is brought into communication via the groove and with the low-pressure flow path through a separate restricting means, while when the internal volume ratio is medium, the first inlet and third through hole are connected to the third through hole. The second inlet/outlet and the first through hole are in communication, the second through hole is in communication with the high pressure flow path, and the first through hole is in communication with the high pressure flow path. Second. The third through holes are in a non-communicating state with each other or in a communicating state with each other via the groove, and the third through holes are in a non-communicating state with each other or in a communicating state with each other via the groove. The second inlet/outlet is placed in communication with the low-pressure flow path via a separate throttle means, and when the internal volume ratio control valve is located closer to the low internal volume ratio position than the middle internal volume ratio position, the second inlet/outlet is placed in communication with the low pressure flow path through a separate throttle means. When the second through holes are in communication via the groove and the internal volume ratio control valve is located closer to the high internal volume ratio position than the middle internal volume ratio position, the second through hole is in communication with the second through hole. The third through holes were formed so as to communicate with each other through the groove.

(Function) By forming as described above, it is possible to adjust the internal volume ratio in three stages by simply providing the pressure oil outlet inlet at two locations on both ends of the cylinder for driving the internal volume ratio adjustment valve. This prevents damage to the seal portion of the piston of the cylinder.

(Example) Next, one embodiment of the present invention will be described with reference to the drawings.

1 to 3 show a screw compressor according to the present invention,
In the figure, S indicates the compressor main body. As shown in detail in FIGS. 2 and 3, this compressor main body S rotatably houses a pair of male and female screw rotors 4 that mesh with each other in a casing 3 that has a suction port I on one side and a discharge port 2 on the other side. At the same time, an internal volume ratio adjustment valve 5 and a volume IM adjustment slide valve 6 are provided between the casing 3 and the rotor 4 so as to be movable forward and backward.

Further, the inside of the casing 3 is divided by a partition wall 7 into a first chamber 8 on the rotor side and a second chamber 9 on the anti-rotor side.
Room 8. A cylinder I2 provided with a first outflow port 10X, a second outflow port 10Y, and outflow ports 11X and IIY for pressurized oil is fixed in the second chamber 9, and the partition wall 7 is secured by C-shaped retaining rings I3 on both sides. It is fixed.

A first piston 14 is slidably disposed within the first chamber 8 on the rotor side.
A second piston 15 is slidably provided in the second chamber 9 on the side opposite to the rotor, and the first piston I4 connects the internal volume ratio control valve 5 to the rotor 4 and the casing 3 via the first piston rod I6. The second piston 15 moves the slide valve 6 back and forth between the rotor 4 and the inner wall of the casing 3 via the second piston rod 17. Further, the retreat position of the internal volume ratio control valve 5 is restricted by a stopper 18 that is a part of the casing 3. Further, the second piston rod 17 passes through the first piston rod 16 so as to be relatively movable, and the slide valve 6 is connected to the internal volume ratio control valve 5.
The internal volume ratio control valve 5j is configured to operate within the operating space of the internal volume ratio control valve 5j or an extension space thereof, and to regulate the retreating position of the slide valve 6 through the internal volume ratio control valve 5j. Note that the first piston 14. An O-ring 19 for sealing is fitted around the second piston 15.

In addition, the internal volume ratio adjusting valve 5 is formed with a groove 20 in the form of two rectangular shapes whose corners overlap each other and whose positions are shifted in the forward and backward directions of the valve. The first, second, . Third through hole 21, 22.23
is perforated. When the internal volume ratio regulating valve 5 is in a low internal volume ratio state where the internal volume ratio regulating valve 5 is moved to the left, the second through holes 21 and 22 communicate with each other through the groove 20, and the internal volume ratio regulating valve 5 is in the middle state. position, when the middle white part volume ratio is in the state M, the first. Second. Third through hole 21, 2
2.23 is in communication, and when the internal volume ratio control valve 5 is in the state H of high internal volume ratio in which it has moved to the right, the second. The third through holes 22 and 23 are formed so as to communicate with each other. In addition, the second. Since the third through hole 22.23 appears overlapping with the first through hole 2I in FIGS. 1 and 2,
For convenience, the reference number is shown in parentheses next to the first through hole 21.

On the other hand, a suction passage 24 is connected to the suction side of the compressor main body S, and a discharge passage 25 is connected to the discharge side, and the oil in the discharge gas is separated and collected in the discharge passage 25 for circulation use. An oil separation and recovery device 26 is provided.

The oil reservoir section 27 at the lower part of the oil separation and recovery device 26 is connected to a first inlet 10X by a flow path A equipped with an on-off valve a, a second outflow inlet 10Y connected to a flow path B equipped with an on-off valve A, and a second outflow inlet 10Y connected to an on-off valve C. It is possible to communicate with each of the second through-holes 22 through a flow path C provided with a flow path C. In addition, the first through hole 21 is connected to the second inlet/outlet JOY and the third through hole 2 by a flow path equipped with an on-off valve d.
3 is a first inlet/outlet lOX through a flow path E equipped with an on-off valve e.
It is possible to communicate with. Furthermore, the first inlet/outlet 10X
is connected to the second inlet/outlet 10Y by a flow path F equipped with an on-off valve r.
are connected to the suction flow path 2 by a flow path G equipped with an on-off valve g.
4, the first through hole 21 is connected to a flow path V equipped with a restricting means V, and the second through hole 22 is connected to a restricting means W.
It is communicated with the suction flow path 24 by a flow path W provided with. In this embodiment, the flow path F and the flow path G, and the flow path V and the flow path W are each merged into one flow path on the suction flow path 24 side.

Then, as shown in Table 1 below, by opening and closing the on-off valves a''-g, the screw compressor is brought into a state with a low internal volume ratio of 11, a medium internal volume ratio ■, and a high internal volume ratio ■. In the table, the open state of the on-off valve and the closed state of O1 are represented by C.

(Leaving space below) Table 1 To explain this table in more detail, when the internal volume ratio I is low, on-off valve a is opened, on-off valves c, d, e, and f are closed. The left side of the piston 14 is set to low pressure and the right side is set to high pressure to move the internal volume ratio control valve 5 to the left. Also, when the internal volume ratio is high, the valve opens and closes.

f is opened, on-off valves a, c, d, e, and g are closed to make the left side of the first piston 14 a high pressure and the right side a low pressure, and move the internal volume ratio control valve 5 to the right.

On the other hand, when the volume ratio of the middle part is ■, the on-off valves c, d
, e are opened, and on-off valves a, b, f, and g are closed. and,
As shown in FIG. 3, when the internal volume ratio control valve 5 is in a low internal volume ratio state, the first. The second through hole 2122 communicates with the groove 20, and the left side of the first piston 14 also communicates with the high-pressure flow path C via the flow path. The flow path also communicates with the low-pressure suction flow path 24, but since the flow rate is restricted by the restricting means W, the left side of the first piston I4 is kept at high pressure, while the right side is connected to the suction flow. Since it communicates only with the passage 24 and is in a low pressure state, the first piston 14 moves to the right, that is, to the side of the state M of the medium volume ratio. In this case, the flow path V
Since the flow rate inside is restricted by the restricting means V, the first
The piston 14 does not move suddenly to the right, so that hunting does not occur. On the other hand, when the internal volume ratio control valve 5 is in the high internal volume ratio state H, the second and third through holes 22 and 23 communicate through the groove 20, and the second through hole 22 and the third through hole 22,23 communicate with each other through the channel E. The right side of the first piston 14 also communicates with the high pressure flow path C. As a result, the throttling means V is reduced in the same manner as in the case of the low internal volume ratio.

Due to the action of W, the right side of the first piston 14 is maintained at a high pressure, and the pressure oil gradually flows from the left side to the suction channel 24 side, and the first piston 14 is moved to the left side, that is, the middle part volume ratio state M
move to the side.

On the other hand, when the internal volume ratio control valve 5 is in the state M of the middle part volume ratio, the first. Second. Third through hole 21°22.23
are in communication via the groove 20, and both the left and right sides of the first piston 14 are also in communication with a high-pressure flow path C. Then, due to the action of the throttle means v and w, the first piston 14 has equally high pressure on its left and right sides, and maintains the state M of the volume ratio of the middle part.

That is, by opening and closing the on-off valves a to g shown in the column (■) of Table 1, the internal volume ratio control valve 5 is set to a low level.

Regardless of whether it is in the state of high internal volume ratio or H, it will move to state M of medium volume ratio and remain in this state.

In addition to the internal volume ratio adjustment described above, when operating at full load, the slide valve 6 is brought into contact with the internal volume ratio adjustment valve 5 by positioning the second piston 15 at the left end as shown in FIG. Then, with no gap between the two valves, open the suction port 1. While the gas sucked in is compressed in its entirety and discharged to the discharge port 2, in the case of partial load or no-load operation, only the slide valve 6 is operated by operating the second piston 15 to the right in FIG. Move it to the right to create a gap between this and the internal volume ratio control valve 5, and allow some or all of the gas sucked in from the suction port 1 to escape from the gap to the suction port 2 without being compressed. It looks like this.

FIG. 4 shows an internal volume ratio control valve 5, a first . Second. Third through hole 21.22
．． Only the portion 23 is shown, and the other portions are substantially the same as the first embodiment, and their explanation will be omitted.

In this second embodiment, two rectangular grooves 20a and 20b are formed at different positions in the valve advancing and retracting direction and in a direction perpendicular thereto, so that they do not overlap with each other, and the first and second rectangular grooves 20a and 20b are formed at different positions in the valve advancing and retracting direction and in a direction perpendicular thereto. Second
．． The third through holes 21, 22, and 23 are drilled in the same manner as in the first embodiment.

4 at the time of the volume ratio of the middle part.

The state of H is the same as in the first embodiment, but in the state of M, the first . Second. The third through holes 21, 22, 23 are in a non-communicating state with each other, and the first piston 14
The H position is maintained by creating a low pressure state on the left and right sides of.

(Effects of the Invention) As is clear from the above description, according to the present invention, by simply providing pressure oil inlets at both ends of the cylinder for driving the internal volume ratio control valve, three levels of low, medium, and high can be achieved. This makes it possible to adjust the internal volume ratio, and the sealing portion of the piston of this cylinder is not damaged when it is operated, resulting in an effect that the durability of the device can be improved.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a screw compressor according to a first embodiment of the present invention, Fig. 2 is a sectional view of the compressor main body in Fig. 1, and Fig. 3 is a cross-sectional view of the compressor main body shown in Fig. 2. 4 shows the same positional relationship as FIG. 3 in the second embodiment of the present invention. FIG. 5 shows the conventional screw FIG. 2 is a conceptual diagram showing an internal volume ratio control valve of the compressor and a driving section thereof. 3...Casing, 4...Screw rotor, 5...
Internal volume ratio control valve, IOX, Y... Outflow inlet, 12.
... Cylinder, 14... First piston, 21... First through hole, 22... Second through hole, 23... Third through hole, 24... Suction channel, 25...・Discharge channel, 26・
... Oil separation and recovery device, S ... Compressor body, P ... Vertical plane, v, w ... Throttle means. Figure 1

Claims (1)

[Claims] (1) A pair of male and female screw rotors that mesh with each other are rotatably housed in a casing, and an internal volume ratio adjustment valve is provided between the screw rotor and the casing so as to be movable forward and backward by an internal volume ratio adjustment valve drive cylinder. In the screw compressor, the internal volume ratio regulating valve has a groove, and the casing has a central axis located on the same plane perpendicular to the advancing and retreating direction of the internal volume ratio regulating valve, and at a position where it can communicate with the groove. first, second, and third through holes formed in;
A first inlet for pressure fluid is provided at the rotor side end of the piston operating space of the drive cylinder, and a second inlet for pressure fluid is provided on the side opposite to the rotor.
an inlet and an inlet, and when the internal volume ratio is low, the first inlet and the second inlet are connected to the high-pressure flow path and the second inlet and outflow to the low-pressure flow path, and the first and third through holes are connected to each other through the groove. and communicate with the low-pressure channel through a separate restricting means, and when the internal volume ratio is high, the first inlet is communicated with the low-pressure channel, the second inlet is communicated with the high-pressure channel, and the The first and third through holes are brought into communication via the groove and the low pressure flow path through a separate throttle means, while when the internal volume ratio is medium, the first inlet and the third through hole are in communication with each other through the groove.
The through hole, the second inlet and outlet, and the first through hole are in communication, the second through hole is in communication with the high pressure flow path, and the first, second, and third through holes are not in communication with each other. state or in communication with each other via the groove, and the first and second inlets are in communication with the low pressure flow path through separate throttling means, and the internal volume ratio control valve is set from the middle internal volume ratio position. When in the low internal volume ratio position, the first and second through holes are in communication via the groove, and the internal volume ratio control valve is in the high internal volume ratio position rather than the middle internal volume ratio position. The screw compressor is characterized in that the second and third through holes are formed so as to be in communication with each other via the groove.