JPS642796B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oil injection type screw compressor that compresses gas by rotating a pair of mutually meshing screw rotors in a rotor chamber.

Conventionally, in this type of screw compressor, in the type that injected liquid into the rotor working space for lubrication and sealing, oil was supplied to the rotor working space from an oil hole installed in the casing near the suction port closing position. . In this case, at maximum load, oil is supplied to the rotor working space after suction gas is trapped, so there is no reduction in the effective suction amount. However, when the slide valve moves during capacity control and the suction port closing position changes, the oil injected from the oil hole provided in the casing leaks to the suction side.

This leaked oil has a high temperature of approximately 45 to 65°C, heating the suction side working fluid and reducing volumetric efficiency. Furthermore, the volume of the leaked oil itself causes a decrease in the effective suction amount of the compressor. In addition, especially in refrigerators that use R12, R22, etc. as refrigerants, 15 to 40% by weight of the refrigerant is dissolved in the oil and the refrigerant in the oil vaporizes, increasing its volume by several tens of times or more, reducing the effectiveness of the compressor. Significantly reduces inhalation volume.

The present invention eliminates the above drawback by injecting oil from the oil hole provided in the casing only when the maximum load is near, and prevents oil from directly leaking and flowing into the space communicating with the suction port in the rotor chamber. This can prevent a decrease in efficiency due to heating of the fluid on the suction side, and a decrease in the effective suction amount on the suction side due to refrigerant vaporization, especially when using a refrigerant that easily dissolves in oil, such as in a refrigerator. The purpose of this invention is to provide a screw compressor with high performance and high reliability.

The present invention provides two cylindrical bores provided in a casing parallel to each other and overlapping each other such that the distance between the axes is smaller than the diameter thereof, each rotatable about the bore axis. A male rotor and a female rotor are supported and mesh with each other, and the casing includes a suction side end wall and a discharge side end wall perpendicular to the bore axis at both ends of the bore, the suction side end wall and the discharge side end wall. The end walls each have an end wall suction port and an end wall discharge port, and bearings for supporting the male and female rotors are provided on the suction side and the discharge side, respectively, and a slide valve for capacity control is provided in the casing, and a slide valve is provided in the slide valve. In a screw compressor equipped with an injection port that injects oil from the suction side end of the rotor into the working space of the rotor after the suction gas of the rotor is trapped, a part of the wall of the casing is provided with a suction port closing position or the rotor after the intake gas is trapped. An injection port for injecting oil into the working space of the rotor within 2 pitches is provided, and an oil supply passage to the injection port leads from the oil supply port inlet of the compressor to an oil groove on the outer circumference of the slide valve. The oil groove of the rotor casing that is in contact with the oil groove and the slide valve are arranged so that the overlap is broken by the movement of the slide valve, and the oil groove of the rotor casing communicates with the injection port into the rotor working space, and the slide valve moves during partial load. The screw compressor is characterized in that the oil groove of the casing and the oil groove of the slide valve are then cut off.

Embodiments of the present invention will be described below with reference to the drawings. The drawings all show screw compressors.
1 is a longitudinal sectional view, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a sectional view taken along line BB in FIG. 1.

Both sides of the rotor casing 1 form a suction side end wall and a discharge side end wall, which are sealed by a suction casing 2 and a discharge casing 3, and a male rotor 4 and a female rotor 5 having shapes as shown in FIG. 3 are engaged with each other. Both rotors are in contact with the bicircular arc-shaped outer periphery of the casing 1 on the discharge side. When both rotors rotate in the direction of the arrow shown in the figure, the positions where they engage each other gradually shift even though they have the same lead, and the male rotor 4 and female rotor 5 engage with each other by providing thread grooves and threads with large leads on their outer peripheries. is an integrated shaft portion 4a,
4b, 5a, 5b are supported in the radial direction by journal bearings 6, 7 fitted into the suction casing 2, respectively, and journal bearings 8, 9 fitted into the discharge casing 3, respectively, and thrust ball bearings 12, fitted into the discharge casing 3. The shaft portion 4a of the male rotor 4 and the shaft portion 5a of the female rotor 5 are fitted into the inner ring 13, and their axial movement is restrained by nuts 14 and 15 screwed into the respective shaft portions between them and the stepped portions. has been done.

An integral shaft portion 4a of the male rotor 4 projects outside the machine to form a shaft end portion 4c, and the male rotor 4 is driven by the shaft end portion 4c.

The shaft portion 4a is sealed by a shaft sealing device 18 such as a mechanical seal in a seal cover 17 fixed to a cover 16 fixed to the discharge casing 3. A liner ring 19 is also driven into the cover 16 at a portion through which the shaft portion 4a passes.

The two ends of the suction casing are covered by a cover 21.

A suction passage 22 is provided in the upper part of the suction casing 2, and a suction port 23 is opened at a position on the upper end surface between the male rotor 4 and the female rotor 5. A discharge port 24 is provided on the end surface of the discharge casing 3 opposite to the position below the suction port 23 where the male rotor 4 and the female rotor 5 meet, and a discharge passage 25 in the discharge casing 3 communicates with the outside of the machine. ing.

A cylinder 26 is fitted into the suction casing 2 and the cover 21 and is held down by a cover 27.

A piston 28 sealed by a sealing ring 29 is fitted into the cylinder 26, and the piston rod 31 changes the suction side volume extended into the rotor casing 1 through the sealing ring 33 fitted into a hole in the suction casing 2. It is fixed to a slide valve 32 that adjusts the suction amount by adjusting the suction amount.

The cylinder 26 is covered by a cover 27 fixed to the cover 21, and the piston rod 31 passes through a sealing ring 33' inserted into a hole in the cover 27 and comes out to the outside. The position is detected and the amount of suction is controlled. 34 and 35 are cylinder 2
6 is the pressure oil inlet/outlet.

When the shaft end 4c rotates the male rotor 4 as shown by the arrow in FIG. 3, the female rotor 5 that engages with the male rotor 4 rotates at the same speed in the opposite direction to the male rotor 4. These rotation speeds are rotated at high speed by an electric motor with a synchronous speed of about 3000 r.p.m.

When the male rotor 4 and female rotor 5 rotate, they pass through the suction passage 22 from piping (not shown) and from the suction port 23 to the rotor casing 1, male rotor 4, and female rotor 5.
Gas is sucked into the suction space formed by
The outer peripheries of the male rotor 4 and the female rotor 5 are in close contact with the inner periphery of the casing 1 from the part indicated by the reference numeral 36, and one pitch of the discharge side of these rotors becomes a working space, as shown in FIG. In FIG. 2, the gas is compressed as the volume between the male rotor 4, the female rotor 5, and the casing 1 gradually decreases, and is discharged from the discharge port 24 and sent from the discharge passage 25 to the discharge side piping.

A piston 37 for balancing the thrust of the male rotor 4 and female rotor 5 is locked at the end of the shaft portion 4a, and the piston 37 slides into a cylinder 38 fixed in the suction casing 2 and is inserted into the cylinder chamber. 3
9 is formed.

Next, let's talk about the cooling and lubricating oil supply channels.
Pressure oil sent from a pump (not shown) is piped to an inlet 41 provided in the discharge casing 3. Entrance 4
1 is the oil path 4 to the journal bearing 8 on the discharge side.
2, an oil path 43 to the journal bearing 6 and the cylinder chamber 39, and an oil path 44 to the shaft seal device 18.

The oil passage 42 passes through an oil passage 46 from a groove 45 on the outer periphery of the journal bearing 8 and is connected to a groove 47 on the outer periphery of the journal bearing 9 . In the journal bearings 8 and 9, holes radially penetrating from the grooves 45 and 47 on the outer periphery are connected to oil grooves 49 and 51 on the shaft side, respectively.

The ends of the oil grooves 49 and 51 are shown in Fig. 2 in the partially enlarged view.
As shown in FIG. It communicates with the space 54 inside the cover 16,
The space 54 is connected to the discharge passage 25 through a passage 55 formed in the discharge casing 3, as shown in FIG.

The oil passage 43 reaches the suction casing 2 through the rotor casing 1, and in the suction casing 2, the oil passage 43 is connected to the cylinder chamber 39 and the groove 5 on the outer periphery of the journal bearing 6.
6 and the groove 56 on the outer periphery of the journal bearing 7 through the oil passage 57 in the suction casing.
It is connected to 8. In the journal bearings 6 and 7, holes radially penetrating from the grooves 56 and 58 on the outer periphery are connected to oil grooves 59 and 61 on the shaft side, respectively.

The ends of the oil grooves 59 and 61 are shown in Fig. 2 in the partially enlarged view of Fig. 2.
As shown in Figure b, the oil groove 59 is connected to the orifice 62,
The oil groove 61 communicates with chambers 64 and 65 of the suction casing 2 through an orifice 63, respectively.
65 are communicated through a passage 66.

From the chamber 65, an oil passage 67 communicates from the suction casing 2 to the rotor casing 1.

The end of the oil passage 67 is provided with an oil passage 68 that opens into the rotor casing 1 at a position two pitches from the suction closing edge of the suction side end wall, or is provided near this.
The oil passage 67 further communicates with an oil passage 69 in the discharge casing 3, and the oil passage 69 is connected to the cover 16 and the seal cover 1.
7 to reach the shaft sealing device 18.

The oil passage 44 leads from the discharge casing 3 into the cover 16 and further into the seal cover 17,
The shaft sealing device 18 is lubricated and the oil from the oil passage 69 is combined with the space 5 between the liner ring 19 and the shaft portion 4a.
4.

As shown in FIGS. 3 and 1, the rotor casing 1 is provided with an oil inlet 71 connected to a pipe from the same lubricating oil source as the inlet 41, and a slide valve 3.
It opens into an oil groove 72 carved in the axial direction on the surface of 2,
As shown in FIG. 4 of the lubrication system diagram, the oil groove 72 overlaps and communicates with the oil groove 73 in the axial direction of the rotor casing 1, and as the slide valve 32 moves, the oil groove 72 no longer overlaps and is disconnected. There is. The oil groove 73 overlaps with a short oil groove 74 in the axial direction of the slide valve 32.

From the oil groove 72, it passes through the inside of the slide valve 32 and from the suction start position of the male rotor 4 and female rotor 5.
That is, the injection port 75 opens into the rotor action space on the discharge side of the rotor by one pitch from the end of the slide valve 32.
From the oil groove 73, an oil passage 76 is bored in the rotor casing 1 so that an oil supply port 76a is located one pitch from the suction edge 23a of the suction side end wall. That is, oil is supplied to the rotor working space after the suction port is closed.

The screw compressor described above was used for refrigerators, and the oil from which the refrigerant gas was separated and recovered in the oil separator was cooled to around 40 to 50 degrees Celsius in the oil cooler, and then pressurized by the pump, and the oil was sent to the inlet 41. , 71. From the inlet 41, the oil enters the groove 45 through the oil passage 42, and from the groove 45, it passes through the oil hole and enters the oil groove 49, where the sliding surface of the journal bearing 8 is cooled and lubricated.

On the other hand, the pressure oil that enters the groove 47 from the groove 45 through the oil passage 46 enters the oil groove 51 from the oil hole, and the sliding surface of the journal bearing 9 is cooled and lubricated.

Pressure oil in oil grooves 49, 51 is supplied to orifices 52, 53.
The oil amount is adjusted by the thrust ball bearings 12 and 12, respectively.
13 is cooled and lubricated, passes through a space 54 and a passage 55, and enters the discharge passage 25 with an increase in temperature and a decrease in viscosity.

The discharge end wall where the rotor casing 1 and the discharge casing 3 are in contact is at a temperature of 60 to 90 degrees Celsius due to the influence of compression heat, and the temperature of the oil rises above the heat generated by the bearings, reaching a temperature of around 65 to 75 degrees Celsius. It is becoming. These oils may not be returned to the discharge passage 25 from the passage 55, but may be returned to the discharge piping or the oil cooler through a connecting pipe.

The pressure oil branched into the oil path 43 is transferred to the suction casing 2
One side passes through the oil hole from the groove 56 and enters the oil groove 59 to cool and lubricate the journal bearing 6, while the other enters the cylinder chamber 39 and applies operating pressure to the piston 37 to prevent oil leaking from between the piston 37 and cylinder 38. enters room 64. Pressure oil entering the oil passage 57 from the groove 56 reaches the groove 58 and enters the oil groove 61 through the oil hole to cool and lubricate the journal bearing 7. Oil grooves 59, 61
The amount of pressurized oil supplied is adjusted by orifices 62 and 63 and enters chambers 64 and 65, respectively.Since chamber 64 and oil leaking from cylinder chamber 39 are in communication with each other, the oil is sent to oil passage 67.

The pressure oil sent to the oil passage 67 is sent to the journal bearing 6,
7 is the suction side, which has a relatively low temperature and viscosity, and maintains lubrication performance. These pressure oils enter the sliding surface between the female rotor 5 and the rotor casing 1 through the oil passage 68, where lubrication and sealing are performed, and the male rotor 4.
Sealing and lubrication between the female rotor 5 and the female rotor 5 are performed.

The end wall on the suction side where the rotor casing 1 and the suction casing 2 are in contact is in contact with the suction port 23, so the temperature on the suction side of the compressor is generally influenced by -40 to 10 degrees Celsius and is cold, so the oil passing through it is cold. In terms of the amount of heat generated by the journal bearings 6 and 7, the temperature rise is small and may be lower or not much different from the temperature before the bearings are lubricated.

Rotor casing 1 and female rotor 5 from oil passage 67
The oil is supplied between the oil passages 69 and 69, which lubricates the shaft sealing device 18, and is then discharged from the space 54 through the passage 55 to the discharge port 24.

When the oil supply method from the inlet 71 shown later is used, the oil passage 68 is provided when almost the full load is applied, that is, when the slide valve 32 moves only near the left end, but it is provided when the oil passage is provided in the right direction. If the slide valve 32 moves to the end movement limit, the lubricating oil will be released into the suction space, so it may not be provided.

The oil entering from the inlet 71 is sent to the injection port 7 from the oil groove 72.
5, from the injection port 75 to the male rotor and female rotor 5.
It ejects into the outer working space of. Since this jet port 75 moves when the slide valve 32 is moved to the right, it can take an appropriate position that does not communicate with the suction space when a partial load is applied. Oil grooves 72, 73, 74
Oil is supplied to the outer working spaces of the male rotor 4 and female rotor 5 at a position one pitch on the discharge side from the suction port closing edge 23a through the oil passage 76.

Slide valve 32 moves to the right and oil grooves 72, 73
If the space is far apart, no oil will flow to the oil groove 73 and no oil will be supplied from the oil passage 76. That is, in the case of a partial load below a certain level, oil is supplied to the outer periphery of the male rotor 4 and the female rotor 5 through the slide valve 32 and only through the injection port 75. Therefore, the lubricating oil does not overflow into the suction space from the oil passage 76 due to movement of the slide valve 32.

Cooled oil is supplied from the oil passage 68, the injection port 75, and the oil passage 76, and each has the characteristic that a small orifice is sufficient in cross section.

The rotor working space moves toward the discharge side due to the rotation of the rotors 4 and 5, the groove volume (rotor working space) decreases, the pressure and temperature of the refrigerant gas rises, and the proper injection oil is adjusted from the low pressure part to the high pressure part. Amounts vary.

Increasing the amount of oil improves the volumetric efficiency, but increases the power for stirring the oil. For this reason, in the present invention, a small amount of cold oil is injected from the central part of the grooves of the male and female rotors 4 and 5 to the low-pressure part with a long groove length up to the two pitches of the suction edge, thereby suppressing the oil stirring operation. . However, when the refrigerant in oil leaks to the suction side due to depressurization, the volume increases from 30 to
If it is 120 times larger and leaks, the loss will be large.

In order to prevent tooth profile leakage from the injection port 75 (high pressure area after 2nd pitch) of the slide valve 32, additional oil is injected to increase the oil volume and volume, since the improvement in volumetric efficiency is greater than the increase in stirring power. Prevent loss of efficiency.

As described above, according to the screw compressor of the present invention, oil is supplied to the rotor working space from the injection port provided at the suction port closing position of the rotor casing through the oil groove provided in the slide valve and the oil groove provided in the rotor casing. Since it can be intermittent by overlapping, oil is not supplied from the suction port closing position of the rotor casing or the injection port within 2 pitches of the rotor after the suction port is closed by moving the slide valve during capacity control, so the suction space that communicates with the injection port and the suction port Lubricating oil will not leak even if connected to. Further, since the injection port provided in the slide valve is always located in the rotor action space after closing, it does not communicate with the suction space.
Therefore, the high-temperature lubricating oil does not heat the suction-side working fluid and reduce the volumetric efficiency. In a large range of output without capacity control, the rotor working space is supplied with oil from the injection port of the rotor casing and the injection port of the slide valve, so that sufficient oil is supplied when the output is large.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention, and FIG. 1 is a longitudinal sectional view, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIGS. 2a and 2b are parts of FIG. 2. Enlarged view,
FIG. 3 is a sectional view taken along line BB in FIG. 1, and FIG. 4 is a lubrication system diagram. 1... Rotor casing, 2... Suction casing, 3... Discharge casing, 4... Male rotor, 4
a, 4b, 5a, 5b... shaft portion, 5... female rotor, 6, 7, 8, 9... journal bearing, 12,
13... Thrust ball bearing, 16... Cover, 17
... Seal cover, 18 ... Shaft sealing device, 19 ...
Liner ring, 21...cover, 22...suction passage, 23...suction port, 24...discharge port, 36...
Position, 41... Inlet, 42, 43, 44... Oil passage, 45, 47... Groove, 46... Oil passage, 49...
Oil groove, 51... Oil groove, 52, 53... Orifice, 54... Space, 55... Passage, 56... Groove,
57... Oil passage, 59, 61... Oil groove, 62, 63
... Orifice, 64, 65 ... Room, 66 ... Passage, 67, 68, 69 ... Oil passage, 71 ... Entrance,
72, 73, 74...Oil groove, 75...Injection port, 7
6...Oil road.

Claims (1)

[Claims] 1 Supported rotatably about the bore axis in two cylindrical bores provided in parallel in the casing and overlapping each other such that the distance between the axes is smaller than the diameter thereof. The casing includes a male rotor and a female rotor that mesh with each other, and the casing has a suction side end wall and a discharge side end wall perpendicular to the bore axis at both ends of the bore, and the suction side end wall and the discharge side end wall have each has an end wall suction port and an end wall discharge port, and bearings for supporting the male and female rotors on the suction side and the discharge side, and a slide valve for capacity control is provided in the casing, and the slide valve is provided with a slide valve on the suction side of the slide valve. In a screw compressor equipped with an injection port that injects oil from the end into the working space of the rotor after the suction gas of the rotor is trapped, the suction port is located in a part of the wall of the casing or within two pitches of the rotor after being trapped. An injection port for injecting oil into the working space of the rotor is provided, and an oil supply passage to the injection port leads from the oil supply port inlet of the compressor to an oil groove on the outer periphery of the slide valve, and the oil groove on the slide valve is in contact with the slide valve. The oil groove of the rotor casing and the slide valve are arranged so that their overlap is severed by the movement of the slide valve, and the oil groove of the rotor casing communicates with the injection port into the rotor working space. A screw compressor characterized in that the oil groove in the casing and the oil groove in the slide valve are isolated.