JPH025919B2 - - Google Patents

Description

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

Conventionally, in this type of screw compressor, liquid is injected into the rotor working space to remove compression heat and to lubricate and seal the rotor. It supplied oil to the space. 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 injection 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. Furthermore, 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 evaporates, 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. It is possible to prevent a decrease in efficiency due to heating of the suction side fluid, 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 when used in a refrigerator. The purpose of this invention is to provide a screw compressor with highly reliable performance.

The present invention is supported rotatably about the respective bore axes in 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 of the cylindrical bores. 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 a 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 the slide valve is provided with a suction side end of the slide valve. In a screw compressor equipped with an injection port for injecting oil into the working space of the rotor after trapping the suction gas of the rotor, a part of the wall of the casing is provided with a hole within 2 pitches from the suction port closing edge to the suction port closing edge. An injection hole for injecting oil into the rotor working space is provided, and an oil passage leading to the injection hole communicates with an oil groove on the contact surface of the rotor casing with the slide valve. An oil groove leading to the oil supply inlet of the compressor is provided on the discharge side of the oil groove, and the slide valve has an oil injection hole into the rotor working space at a position beyond one pitch of the rotor from the low pressure control edge. The oil injection hole of the valve communicates with an oil groove leading to the oil filler inlet 42 of the compressor via an oil passage provided inside the slide valve, and the oil passage provided inside the slide valve communicates with the oil passage inside and extends in the axial direction. Two openings are provided separately on the surface of the slide valve 32, and when the slide valve 32 is located at the maximum load side, the opening near the low pressure control edge of the two openings of the slide valve passes through the oil injection hole provided in the casing. The opening that overlaps the oil groove and is far from the low-pressure control edge overlaps the oil groove leading to the oil filler inlet of the compressor, and by moving the slide valve 32 toward the partial load side, the opening on the side of the slide valve closer to the low-pressure control edge overlaps the oil groove leading to the oil filler inlet of the compressor. The opening is a screw compressor arranged so that it does not overlap with an oil groove leading to an oil injection hole provided in the casing.

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 move even though they have the same lead.The male rotor 4 and female rotor 5, which engage with each other by providing thread grooves and threads with large leads on their outer peripheries, The 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 between them and the stepped portion by nuts 14 and 15 screwed into the respective shaft portions. .

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 rpm, as an example.

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, and is sent to each bearing through an oil path.
The separated oil is cooled, pressurized, and sent to the inlet 41 again.

Next, the main parts of the present invention will be described.

FIG. 4 is an enlarged sectional view taken along line CC in FIG. In the figure, the male rotor 4 and the female rotor 5 are shown unfolded, and the center of the land is indicated by a two-dot chain line.

An oil supply inlet 42 that communicates with the same hydraulic power source as the oil supply inlet 41 of the compressor is opened in the rotor casing 1, and the oil supply passage passes through the rotor casing 1 and connects to the sliding surface of the slide valve 32 of the rotor casing 1. It opens into a long groove 43 carved in the axial direction at a position on the discharge side. A long groove 44 is provided in a line with the long groove 43 at a position close to the suction side. The long grooves 43 and 44 are provided as oil grooves. Oil passages 45 and 46 are perpendicular to the axial direction of the slide valve 32 and open in the long grooves 43 and 44, respectively, and communicated internally through an axial oil passage 47.
is provided in the slide valve 32. Since the oil passages 45 and 46 having openings 45a and 46a on both sides of the slide valve 32 need only maintain their relative positions in the axial direction (described later), they may be oriented in a direction crossing the axis. An oil injection hole 49 is provided in the slide valve 32 at a position one pitch beyond the discharge side of the male rotor 4 and female rotor 5 from the low pressure control edge 48 of the slide valve 32, and in order to guide oil to this injection hole, An oil passage 51 is provided that branches from the communicating oil passage 46.

The suction chamber that continues from the long groove 44 to the suction port 23 is completely blocked by the meshing of the male rotor 4 and female rotor 5. From the suction port closing position, the mountain ends of the male rotor 4 and female rotor 5 coincide with the end of the suction port 23. An oil injection hole 53 is provided that opens into the rotor working space within two pitches from the suction port closing edge 52.

The spacing between the oil passages 45 and 46 is such that the distance between their centers is equal to the length of the long groove 43, and when the slide valve 32 reaches the left travel limit position in FIG. The oil passage 45 is aligned with or near the opening, and the oil passage 45 opens near the left end of the long groove 43. Oil passage 46 and long groove 44
The distance from the right end is such that when the slide valve 32 is moved to the right, the oil injected from the oil injection hole 53 at the right end of the oil passage 46 and the long groove 44 does not communicate with the intake chamber enlarged by the movement of the slide valve 32.

The long grooves 43 and 44 are oil grooves whose positions need only be defined in the axial direction, and there is no problem even if they are wide grooves, and they may be located at different positions in the circumferential direction.

The oil passages 45 and 46 have different cross-sectional dimensions, and the oil passages 45 and 46 are designed to change the amount of oil that enters through the inlet 42 and the long groove 43.
The cross-sectional area of the oil passage 46 is larger than that of the oil passage 46.

Two openings 45 provided in the slide valve 32
The openings 46a near the low pressure control edge 48 of a, 46a are made smaller than the other openings 45a, and the two openings 45a, 46a are connected to the oil groove 43 which communicates with the oil filler inlet of the compressor by the movement of the slide valve 32.
The oil grooves 43 are selectively arranged at positions overlapping with the oil grooves 43 so that the area of overlap with the oil grooves 43 gradually changes.

When the screw compressor is started and operated under full load, the slide valve 32 is at the left travel limit position as shown in FIG. 43
from the oil passage 45, through the oil passage 47, through the oil passage 46, through the long groove 44, through the oil passage 50 of the rotor casing 1, through the oil injection hole 53, from the suction opening closing position of the rotor to the suction opening closing edge 52. Inject into the rotor action space within 2 pitches.

Oil passing through the branched oil passage 51 in the slide valve 32 is injected from the oil injection hole 49 into the rotor working space. Since this position follows the movement of the slide valve 32, oil is injected into the rotor working space in the same compression working state.

FIG. 5 shows the opening 46a of the oil passage 46 when the slide valve 32 is moved to the right to shift from full load to partial load.
is removed from the end of the long groove 44, and no oil goes into the long groove 44, and no oil comes out from the oil injection hole 53.
leads to the intake chamber. Therefore, oil does not mix into the suction side refrigerant, and the temperature of the refrigerant does not increase due to oil. Regardless of the position of the slide valve 32, oil is injected into the rotor working space from the oil injection hole 49 as described above.

FIG. 6 shows a case where the slide valve 32 moves further to the right and is further subjected to a partial load, and oil does not come out from the oil injection hole 53 and oil is injected into the rotor working space only from the oil injection hole 49. . Oil passage 46 and long groove 4
The opening 45a of the oil passage 45 is off to the right end of the long groove 43 by the radius difference between the circular oil passages 45 and 46 so that the oil passage 45 is closed.

FIG. 7 is a diagram showing a position where the slide valve 32 has moved to the right from the state shown in FIG. Oil enters the passage 51 and is injected from the oil injection hole 49 into the rotor working space.
Since the oil passage 46 has a smaller cross-sectional area than the oil passage 45 to reduce the amount of oil passing through it, the amount of oil supplied to the rotor working space is the smallest.

Until the slide valve 32 moves to the right and the opening 46a of the oil passage 46 is removed from the long groove 43, oil continues to be jetted out from the oil injection hole 49 in the same state.

When the slide valve 32 moves to the right to the unload position, the opening 46a of the oil passage 46 and the long groove 43 are separated from each other, and no oil comes out from the oil injection hole 49.

As described above, at full load as shown in FIG. Oil is injected from the oil injection hole 49 into the rotor working space. As the partial load progresses, the rotor suction opening closing edge 52 first moves from the rotor suction opening closing position.
Then, the oil supply to within two pitches of the rotor is cut off, and then oil is supplied to the rotor working space only from the oil injection hole 49, and as the partial load progresses further, the oil passage 45 and the oil passage 46 are cut off. By switching, the amount of oil supplied from the oil injection hole 49 to the rotor working space is reduced. The rotor action space includes the rotor 4,
5 moves toward the discharge side, the groove volume (rotor action space) decreases, the pressure and temperature of the refrigerant gas rises, and the appropriate amount of oil to be injected differs from the low pressure section to the high pressure section.

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 colder oil is injected into the low-pressure part of the long groove of the male and female rotors 4 and 5, which is up to 2 pitches from the suction opening closing edge, and the oil is stirred. suppress.

From the injection port 49 of the slide valve 32 (the high-pressure area after the second pitch), additional oil is injected to increase the oil amount in order to prevent tooth profile leakage and because the increase in volumetric ratio is greater than the increase in stirring power. Prevent a decrease in volumetric efficiency.

The screw compressor of the present invention has 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 of the cylindrical bores. comprising a male rotor and a female rotor that are rotatably supported and mesh with each other, the casing having 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 are provided with an end wall suction port and an end wall discharge port, respectively, and bearings for supporting male and female rotors on the suction side and the discharge side, respectively, and a capacity control slide valve 32 is provided in the casing. In the screw compressor, the slide valve 32 is provided with an injection port for injecting oil into the rotor working space after trapping the rotor suction gas from the suction side end of the slide valve 32. From the suction opening closing position to the suction opening closing edge 2
An injection hole is provided to inject oil into the rotor action space within the pitch, and an oil passage leading to the injection hole leads to an oil groove on the contact surface with the slide valve of the rotor casing, and furthermore, the oil passage leading to the injection hole communicates with the oil groove on the contact surface with the slide valve of the rotor casing. An oil groove leading to the oil supply inlet of the compressor is provided on the discharge side of the oil groove on the surface, and the slide valve has an oil injection hole into the rotor working space at a position beyond one pitch of the rotor from the low pressure control edge. , the oil injection hole of the slide valve communicates with an oil groove leading to the oil filler inlet of the compressor via an oil passage provided inside the slide valve, and the oil passage provided inside the slide valve communicates internally with the shaft. Two openings are provided on the surface of the slide valve 32, separated in the direction, and when the slide valve is located on the maximum load side, the opening near the low pressure control edge of the two openings of the slide valve is connected to the oil injection hole provided in the casing. The opening farthest from the low-pressure control edge overlaps the oil groove leading to the oil filler inlet of the compressor, and the movement of the slide valve toward the part-load side causes the opening on the side of the slide valve closer to the low-pressure control edge to Since the screw compressor is arranged so that the opening does not overlap with the oil groove leading to the oil injection hole provided in the casing, the following remarkable effects are achieved.

(1) Prevents the oil injected from each oil injection hole of the rotor casing and slide valve over the entire capacity range from directly leaking and flowing into the space communicating with the suction port in the rotor chamber, and prevents the oil from flowing into the suction side fluid. It is possible to prevent a decrease in efficiency due to heating 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.

(2) Two openings 45 provided in the slide valve 32
Opening 46a near low pressure control edge 48 of a, 46a
is made smaller than the other opening 45a, and the two openings 45a and 46a are made smaller than the other opening 45a.
In the case where the slide valve is selectively arranged at a position overlapping with the oil groove 43 so that the area of overlap with the oil groove 43 leading to the oil filler inlet of the compressor gradually changes by the movement of the slide valve 2. By gradually reducing the amount of oil injected from the rotor, the power for stirring oil in the rotor during partial load can be extremely efficiently reduced, and the partial load characteristics can be improved.

(3) If the oil groove provided in the casing is made into a long groove and is provided on the rotor side from the center of the slide valve, the slide valve will be pushed toward the opposite side of the rotor by hydraulic pressure, and there will be no risk of contact between the slide valve and the rotor, and the rotor Decrease in efficiency due to damage can be prevented.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention; FIG. 1 is a longitudinal sectional view, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is a sectional view taken along line B-B in FIG. 1. 4 to 7 are enlarged sectional views taken along line CC in FIG. 1, showing the effects of the present invention. 1... Rotor casing, 2... Suction casing, 3... Discharge casing, 4... Male rotor, 5
... Female rotor, 23 ... Suction port, 32 ... Slide valve, 42 ... Inlet, 43, 44 ... Oil groove,
45, 46... Oil passage, 45a, 46a... Opening, 47... Oil passage, 48... Low pressure control edge, 49
... Oil injection hole, 50, 51 ... Oil passage, 52 ...
Suction port closing edge, 53...Oil injection hole.

Claims (1)

[Scope of Claims] 1. 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 of the bore, A male rotor and a female rotor are rotatably 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 The end wall on the discharge side is provided with an end wall suction port and an end wall discharge port, respectively, and bearings for supporting the male and female rotors on the suction side and the discharge side, and a capacity control slide valve 32 is provided in the casing, In a screw compressor in which the valve 32 is equipped with an injection port for injecting oil from the suction side end wall of the slide valve 32 into the rotor working space after suction gas of the rotor is trapped, the suction port is located in a part of the wall of the casing. An injection hole 53 is provided for injecting oil into the rotor working space within two pitches from the suction port closing edge 52, and an oil passage 50 communicating with the injection hole 53 is connected to the oil groove 44 on the sliding surface of the rotor casing with the slide valve. and further the slide valve 32 of the rotor casing.
An oil groove 43 communicating with the oil supply inlet of the compressor is provided on the sliding surface of the oil groove 44 on the discharge side, and the slide valve is connected to the rotor working space at a position beyond one pitch of the rotor from the low pressure control edge 48. The oil injection hole 49 of the slide valve communicates with an oil groove 43 leading to the oil filler inlet 42 of the compressor via an oil passage provided inside the slide valve, The provided oil passage has two openings 45a and 46a on the surface of the slide valve 32, which communicate with each other internally and are spaced apart in the axial direction,
When the slide valve 32 is located on the maximum load side,
The two openings 45a, 4 of the slide valve 32
The opening 46a near the low pressure control edge 48 of 6a is an oil groove 44 communicating with an oil injection hole 53 provided in the casing.
The opening 4 that overlaps with and is far from the low pressure control edge 48
5a overlaps the oil groove 43 leading to the oil filler inlet 42 of the compressor, and due to the movement of the slide valve 32 to the partial load side, an opening 46a on the side closer to the low pressure control edge 48 of the slide valve 32 is provided in the casing. The screw compressor is arranged so that the oil groove 44 leading to the oil injection hole 53 does not overlap with the oil groove 44. 2 Two openings 45 provided in the slide valve 32
The openings 46a near the low pressure control edge 48 of a, 46a are made smaller than the other openings 45a, and the two openings 45a, 46a are connected to the oil groove 43 which communicates with the oil filler inlet of the compressor by the movement of the slide valve 32.
The screw compressor according to claim 1, wherein the screw compressor is selectively arranged at a position overlapping the oil groove 43 so that the area of overlap with the oil groove 43 gradually changes. 3. The screw compressor according to claim 1 or 2, wherein the oil groove provided on the inner wall surface of the casing is a long groove and is provided closer to the rotor than the center of the slide valve.