KR20210029261A - Liquid-cooled screw compressor - Google Patents

Abstract

The liquid-cooled screw compressor 1 includes a liquid supply port 11A provided in the casing 2 in order to supply the liquid supplied from the liquid supply line 15 to the rotor chamber 2b. The liquid supply port 11A is divided into an inlet portion 21 in fluid communication with the liquid supply line 15, an injection portion 22 in fluid communication with the rotor chamber 2b, and the inlet portion 21. An intermediate portion 23 having a constant flow path cross-sectional area Am, which fluidly connects the thread portion 22 is provided. The passage cross-sectional area Ai of the opening 22a of the injection portion 22 with respect to the rotor chamber 2b is larger than the passage cross-sectional area Am of the intermediate portion 23.

Description

Liquid-cooled screw compressor

The present invention relates to a liquid-cooled screw compressor.

In a liquid-cooled screw compressor such as an oil-cooled screw compressor, a liquid (e.g., oil) is supplied into the rotor chamber for lubrication and cooling of compressed air, and the hermetic rotor is engaged and rotated. The liquid is being mixed. The oil supply port into the rotor chamber provided in the oil-cooled screw compressor disclosed in Patent Document 1 is a so-called drill hole, and has a straight pipe shape having a constant diameter between both ends.

Japanese Patent Publication No. 2014-214740

In a liquid-cooled screw compressor, power loss other than the power for compressing air, such as power loss due to agitation of the liquid or power loss due to the viscosity of the liquid in a narrow gap between the rotor chamber and the teeth of the screw rotor, is reduced. have. Due to these power losses, by liquid cooling, the efficiency may be lowered on the contrary.

In addition, as in the oil supply port of Patent Document 1, if the shape of the liquid supply port is a straight tube shape, when the screw rotor passes directly above the liquid supply port during operation, the flow of the liquid supplied from the liquid supply port to the rotor chamber is inhibited, and the speed is reduced. It is lowered. Due to this decrease in speed, the dispersibility of the liquid in the toothed groove decreases, and the cooling efficiency of the compressed air may decrease.

From the above reasons, the conventional liquid-cooled screw compressor has room for improvement in terms of reducing power required for compressing air to a required pressure and improving cooling efficiency.

In the liquid-cooled screw compressor, an object of the present invention is to reduce power required for compressing air to a required pressure and to improve cooling efficiency.

One aspect of the present invention is provided in a casing, a rotor chamber in which a pair of screw rotors are accommodated, and a liquid supply port provided in the casing to supply the liquid supplied from the liquid supply line to the rotor chamber, and the liquid supply port , An inlet portion in fluid communication with the liquid supply line, an injection portion in fluid communication with the rotor chamber, and an intermediate portion having a constant flow path cross-sectional area fluidly connecting the inlet portion and the injection portion, and the There is provided a liquid-cooled screw compressor in which the passage cross-sectional area of the opening portion of the injection portion to the rotor chamber is larger than the passage cross-sectional area of the intermediate portion.

The opening of the injection portion of the liquid supply port to the rotor chamber has a passage cross-sectional area larger than the passage cross-sectional area of the intermediate portion of the liquid supply port. With this configuration, compared to the case where the liquid supply port has a straight pipe shape (so-called drill hole) with a constant flow path cross-sectional area between both ends, at the moment when the toothed portion of the screw rotor passes directly above the liquid supply port during operation, the intermediate rotor The distance between the actual measurement end and the tooth end becomes longer. In other words, when the liquid injected from the liquid supply port passes through the gap between the teeth (tooth ends) of the screw rotor and the casing, the cross-sectional area through which the liquid can pass is enlarged. Accordingly, the pressure loss during liquid injection into the rotor chamber is reduced. By this pressure loss reduction, it is possible to increase the flow velocity of the liquid injected into the rotor chamber while keeping the volume flow rate of the liquid supplied to the liquid supply port the same as that in the case where the liquid supply port is a drill hole. In other words, without increasing the volume flow rate, the flow rate of the liquid injected into the rotor chamber can be increased compared to the case where the liquid supply port is a drill hole. The increase in flow velocity promotes atomization when the liquid column collides with the toothed surface of the toothed portion of the screw rotor, thereby increasing the heat transfer area of the droplets and improving the cooling efficiency for compressed air. Therefore, it is possible to reduce the power required to compress air to the required pressure.

For example, in order to increase the flow velocity of the liquid sprayed into the rotor chamber, if the volume flow rate of the liquid supplied to the liquid supply port is increased, the power loss due to the stirring of the liquid by the teeth of the screw rotor or the teeth of the screw rotor It increases the power loss due to the viscosity of the liquid in the narrow gap between) and the casing. However, as described above, according to an aspect of the present invention, the volume flow rate of the liquid supplied to the liquid supply port remains the same, and since the flow velocity of the liquid injected into the rotor chamber can be increased, no increase in power loss occurs. Does not.

Preferably, the diameter in the opening of the injection portion is larger than the width of the tooth end at a right angle to the axis of the tooth portion of the screw rotor.

In the present specification, the "axis-perpendicular tooth end width" of the toothed portion of the screw rotor refers to the width of the smooth surface of the toothed end in a cross section orthogonal to the rotor axis of the toothed portion. By setting the diameter of the opening to be larger than the width of the tooth tip at the right angle of the axis, the smooth surface does not block the injection part of the liquid supply port when the tooth part of the screw rotor passes directly above the liquid supply port. Loss can be reduced.

The diameter of the middle portion may be 0.7 mm or more and 18 mm or less, and the diameter of the opening portion of the injection portion may be 4.0 times or less than the diameter of the middle portion.

In particular, the diameter in the opening of the injection part may be 1.5 times or more and 3.0 times or less of the diameter of the intermediate part.

The injection portion may have an inverted tapered shape in which the passage cross-sectional area gradually increases from a portion connected to the intermediate portion toward the opening.

The injection portion may have a constant cross-sectional area of the flow path from a portion connected to the intermediate portion to the opening portion, and a step in which the cross-sectional area of the flow passage discontinuously increases in a portion connected to the intermediate portion of the injection portion.

The liquid supply port includes a pipe member having both ends of the pipe member inserted into an installation hole penetrating from the liquid supply line provided in the casing to the rotor chamber, wherein the intermediate portion is defined by the pipe member, and the rotor of the pipe member The end surface facing the seal may be located in the installation hole, and the injection portion may be defined by the end surface of the pipe member and a wall around the hole of the installation hole.

With this configuration, dimensional control during processing of providing the liquid supply port in the casing is performed by directly processing the casing itself, such as by excavation, so that the intermediate portion and the flow passage cross-sectional area larger than the flow passage cross-sectional area of the intermediate portion are opened to the rotor chamber. Compared with the case of forming the injection portion provided in the device, it becomes easier. Since dimensional control during processing becomes easy, a higher level of quality stability can be secured. In addition, by using another pipe member, the diameter of the intermediate portion of the liquid supply port can be easily changed according to the product specifications. In addition, the processing performed on the casing to provide the injection port does not require processing of steps in which the cross-sectional area of the flow path increases discontinuously or processing of a tapered shape in which the cross-sectional area of the flow path is continuously enlarged, and installation holes (through holes) are not required. Since only formation of) is required, the number of steps can be reduced.

The inlet portion may have a tapered shape in which a passage cross-section gradually decreases from a portion connected to the liquid supply line toward the intermediate portion.

The inlet portion, from a portion connected to the liquid supply line to a portion connected to the intermediate portion, has a constant flow passage cross-sectional area larger than the flow passage cross-sectional area of the intermediate portion, and at a portion connected to the intermediate portion of the inlet portion, the flow passage cross-sectional area This discontinuously decreasing step may be formed.

With these configurations, the abrupt reduction in the cross-sectional area of the flow path when the liquid flows into the inlet of the liquid supply port from the liquid supply line is alleviated, and the pressure loss is reduced. As a result, it is possible to more effectively increase the flow velocity of the liquid injected into the rotor chamber without increasing the volume flow rate of the liquid supplied to the liquid supply port.

According to the liquid-cooled screw compressor according to the present invention, the cooling efficiency of compressed air is improved, and the power required to compress the air to the required pressure can be reduced, that is, the efficiency can be improved.

1 is a schematic plan view of an oil-cooled screw compressor according to a first embodiment of the present invention.
Fig. 2 is a cross-sectional view taken along the line II-II in Fig. 1;
Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1;
4 is a schematic diagram of a compressor system including an oil-cooled screw compressor according to a first embodiment of the present invention.
5 is an enlarged view of a portion V in FIG. 3.
Fig. 6 is a cross-sectional view taken along another section of a portion V of Fig. 3;
Fig. 7 is a view of an oil supply port as viewed from a female rotor chamber.
Fig. 8 is a cross-sectional view similar to that of Fig. 5 of a conventional oil-cooled compressor.
9 is a cross-sectional view similar to that of FIG. 6 of a modified example of the first embodiment.
Fig. 10 is a cross-sectional view similar to that of Fig. 6 of another modified example of the first embodiment.
Fig. 11 is a cross-sectional view similar to that of Fig. 3 of an oil-cooled screw compressor according to a second embodiment of the present invention.
12 is a cross-sectional view similar to that of FIG. 6 of the second embodiment.
13 is a cross-sectional view similar to that of FIG. 6 of a modified example of the second embodiment.
14 is a cross-sectional view similar to that of FIG. 6 of another modified example of the second embodiment.
Fig. 15 is a cross-sectional view similar to that of Fig. 3 of an oil-cooled screw compressor according to a third embodiment of the present invention.
Fig. 16 is a cross-sectional view similar to that of Fig. 6 of the third embodiment.
17 is a perspective view of an orifice tube.
18 is a graph showing the relationship between flow rate and cross-sectional efficiency.

(First embodiment)

1 to 3, the oil-cooled screw compressor (liquid-cooled screw compressor) 1 according to the first embodiment of the present invention includes a male rotor chamber 2a and a female rotor chamber 2b that are spatially communicated with each other. ) Is provided with a casing (2) is formed. The male rotor 3 is accommodated in the male rotor chamber 2a, and the female rotor 4 is accommodated in the female rotor chamber 2b. In addition, the casing 2 is provided with a suction port 2c and a discharge port 2d spatially communicating with the rotor chambers 2a and 2b.

The male rotor chamber 2a is defined by a cylindrical surface 2e and a pair of end surfaces 2g and 2h. In addition, the female rotor chamber 2b is defined by a cylindrical surface 2f and a pair of end surfaces 2g and 2h in common with the male rotor chamber 2a.

The male rotor (screw rotor) 3 includes a rotor shaft 3a and a plurality of helical teeth 3b provided on the outer periphery of the rotor shaft 3a. Similarly, the female rotor 4 includes a rotor shaft 4a and a plurality of helical teeth 4b provided on the outer periphery of the rotor shaft 4a. Between the pair of toothed portions 4b adjacent to each other, a spiral toothed groove 4c is defined, respectively. The rotor shaft 3a of the male rotor 3 is rotatably supported around its own axis line Lm by bearings 5A and 5B. The rotor shaft 4a of the female rotor 4 is also rotatably supported around its own axis Lf by bearings 6A and 6B.

A drive mechanism 7 including a motor is mechanically connected to the rotor shaft 3a on the inlet 2c side of the male rotor 3. When the male rotor 3 is rotated by the drive mechanism 7, the teeth 3b of the male rotor 3 are engaged in a state in which they enter the toothed groove 4c of the female rotor 4, and thereby the male rotor (3) and the female rotor (4) rotate synchronously. Instead of the male rotor 3, the female rotor 4 may be rotationally driven by a drive mechanism.

The gas (air in this embodiment) sucked from the inlet 2c is trapped in a confined space defined by the toothed portion 3b of the male rotor 3 and the toothed groove 4c of the female rotor 4, It is compressed while moving in the direction of the axis Lm and Lf along the rotation of the rotors 3 and 4, and is discharged from the discharge port 2d.

The casing 2 is provided with three oil supply ports (liquid supply ports) 11A, 11B and 11C to supply oil (liquid) for cooling, lubrication, and the like to the female rotor chamber 2b. These lubrication ports 11A to 11C are open at the bottom of the female rotor chamber 2b, and are on a straight line along the axis Lf of the female rotor 4 (which is also the axis of the female rotor chamber 2b). It is placed. The number of lubrication ports may be one or two, or four or more. In addition, instead of or in addition to the oil supply port for the female rotor chamber 2b, an oil supply port for the male rotor chamber 2a may be provided. The oil supply ports 11A to C will be described in detail later.

Since oil is supplied to the female rotor chamber 2b from the oil supply ports 11A to 11C, the air discharged from the discharge port 2d contains oil. Referring also to FIG. 4, air discharged from the discharge port 2d is introduced into the separator 13 through the air pipe 12A. In the separator 13, air and oil are separated. The air from which the oil has been separated is sent from the air piping 12B to equipment or facilities that require compressed air. The oil separated from the air by the separator 13 passes through the oil supply piping 14, and the oil supply line (liquid supply line) 15 provided in the casing 2 (in this embodiment, a long formed by piercing through the casing 2). Is sent to the hole). Oil is supplied from the oil supply line 15 to the female rotor chamber 2b through the oil supply ports 11A to 11C. In this way, oil circulates between the oil-cooled screw compressor 1 and the separator 13. In this embodiment, an oil pump 16 for feeding oil from the separator 13 to the oil-cooled screw compressor 1 is provided in the oil supply pipe 14.

Next, the oil supply ports 11A to 11C will be described in detail. In the following description, when there is no need to distinguish in particular with respect to the three oil supply ports 11A to 11C, reference numeral 11 is used for one oil supply port.

5 to 7, the oil supply line 15 and the female rotor chamber 2b are in fluid communication with the oil supply port 11. The oil supply port 11 as a whole extends straight in a direction orthogonal to the axis Lm of the female rotor 4 (which is also the axis of the female rotor chamber 2b).

The oil supply port 11 includes an inlet portion 21 in fluid communication with the oil supply line 15, an injection portion 22 in fluid communication with the female rotor chamber 2b, and an inlet portion 21 and an injection portion. It has an intermediate part 23 which fluidly connects 22.

In this embodiment, the shape of the cross section of the inlet part 21 and the intermediate part 23 orthogonal to the axis line Li of the oil supply port 11 is circular. This cross-sectional shape may be other than circular. Further, the inlet portion 21 has a constant diameter De, the intermediate portion 23 also has a constant diameter Dm, and their diameters De and Dm are the same. In other words, the flow path cross-sectional areas Ae and Am are constant over the entire range from the inlet portion 21 to the intermediate portion 23.

The injection section 22 has an opening 22a that opens in the cylindrical surface 2f of the casing 2 defining the female rotor chamber 2b, more specifically, the female rotor chamber 2b. In this embodiment, the shape of the cross section of the injection part 22 orthogonal to the axis line Li of the oil supply port 11 is circular. This cross-sectional shape may be other than circular. In this embodiment, the injection portion 22 has a diameter Di that gradually increases from the portion 22b connected to the intermediate portion 23 toward the opening 22a. In other words, the injection portion 22 has an inverted tapered shape in which the passage cross-sectional area Ai gradually increases from the portion 22b where the injection portion 22 connects with the intermediate portion 23 toward the opening 22a. Due to this inverted tapered shape, the flow passage cross-sectional area Ai in the opening 22a of the injection portion 22 is larger than the flow passage cross-sectional area Am of the intermediate portion 23.

The diameter Di at the opening 22a of the injection part 22 is larger than the width Wt of the right-axis tooth tip of the tooth part 4b of the female rotor 4. The "axis right angle tooth tip width" refers to the width of the smooth surface 4d of the tip of the tooth portion 4b in a cross section perpendicular to the axis line Lf of the loch shaft 4a of the tooth portion 4b.

The diameter Dm of the intermediate portion 23 may be set to be 0.7 mm or more and 18 mm or less. The diameter Di in the opening 22a of the injection part 22 can be set to 4 times or less the diameter Dm of the intermediate part 23. In particular, the diameter Di in the opening 22a of the injection part 22 can be set to be 1.5 times or more and 3.0 times or less of the diameter Dm of the intermediate part 23.

The oil supplied by the oil supply line 15 enters the oil supply port 11 through the inlet part 21, flows into the intermediate part 23, and the end of the intermediate part 23 on the female rotor chamber 2b side. It is sprayed from (23a). The injected oil is supplied to the female rotor chamber 2b through the injection part 22.

The diameter Di at the opening 22a of the injection part 22 of the oil supply port 11 to the female rotor chamber 2b, thus the flow path cross section Ai is the diameter Dm of the intermediate part 23 of the oil supply port 11 Therefore, it is larger than the passage cross-sectional area Am. Therefore, compared to the case where the oil supply port 11 has a straight pipe shape (so-called drill hole) with a constant flow path cross-sectional area between both ends, as shown in Fig. 8, the toothed portion 4b of the female rotor 4 during operation. At the moment when the gas passes just above the oil supply port 11, the distance between the end 23a of the intermediate portion 23 on the female rotor chamber 2b side and the toothed end of the toothed portion 4b increases. In other words, when the oil injected from the oil supply port 11 passes through the gap between the toothed end of the toothed portion 4b of the female rotor 4 and the cylindrical surface 2f of the casing 2, the oil can pass through. The cross-sectional area is enlarged. Accordingly, the pressure loss during oil injection into the female rotor chamber 2b is reduced. Due to this pressure loss reduction, the volume flow rate of oil supplied to the oil supply port 11 is the same as that in the case where the oil supply port 11 is a drill hole as shown in FIG. 8, and is sprayed into the female rotor chamber 2b. You can increase the oil flow rate. In other words, it is possible to increase the flow rate of oil injected into the female rotor chamber 2b than in the case where the oil supply port 11 is a drill hole without increasing the volume flow rate. This increase in flow velocity promotes atomization when the liquid column collides with the toothed surface of the toothed portion 4b of the female rotor 4, increases the heat transfer area of the oil droplets, and improves the cooling efficiency for compressed air. . Therefore, it is possible to reduce the power required to compress air to the required pressure.

For example, in order to increase the flow velocity of oil injected into the female rotor chamber 2b, if the volume flow rate of the liquid supplied to the oil supply port 11 is increased, the agitation of the oil by the teeth 4b of the female rotor 4 The power loss due to the viscosity of the oil in the narrow gap between the toothed portion 4b (toothed end) of the female rotor 4 and the cylindrical surface 2f of the casing 2 is increased. However, in this embodiment, the volume flow rate of the oil supplied to the oil supply port 11 can be increased while the flow rate of the oil injected into the female rotor chamber 2b can be increased, so that no increase in power loss occurs. .

As described above, the diameter Di at the opening 22a of the injection portion 22 is larger than the width Wt of the right-axis tooth tip of the tooth portion 4b of the female rotor 4. Therefore, when the toothed portion 4b of the female rotor 4 passes directly above the oil supply port 11, the smooth surface 4d of the tip of the toothed portion 4b causes the oil supply port 11 to be The pressure loss at the time of oil injection to the female rotor chamber 2b can be more effectively reduced without clogging the injection portion 22.

9 and 10 show a modified example of the first embodiment.

In the modification of Fig. 9, the inlet portion 21 of the oil supply port 11 has a diameter De from the portion 21a connecting with the oil supply line 15 toward the portion 21b connecting with the intermediate portion 23, thus It has a tapered shape in which the flow path cross-sectional area Ae decreases gradually.

In the modified example of Fig. 10, the inlet portion 21 of the oil supply port 11 is from the portion 21a connected to the oil supply line 15 to the portion 21b connected to the intermediate portion 23, and the intermediate portion ( 23) has a constant diameter De larger than the diameter Dm. In other words, the inlet portion 21 is a constant flow path larger than the cross-sectional area Am of the intermediate portion 23 from the portion 21a connected to the oil supply line 15 to the portion 21b connected to the intermediate portion 23. It has a cross-sectional area Ae. Therefore, a step 25 is formed in a portion where the inlet portion 21 is connected to the intermediate portion 23 and the flow path cross-sectional area is rapidly or discontinuously decreased.

With the configuration shown in Figs. 9 and 10, the abrupt reduction of the cross-sectional area of the flow path when oil flows from the oil supply line 15 to the inlet 21 of the oil supply port 11 is alleviated, and the pressure loss is reduced. . As a result, more effectively, it is possible to increase the flow rate of the oil injected into the female rotor chamber 2b without increasing the volume flow rate of the oil supplied to the oil supply port 11.

In the following 2nd and 3rd embodiment, the difference from 1st Embodiment is demonstrated. Structures, functions, etc. not specifically mentioned for these embodiments are the same as those of the first embodiment. In addition, in the drawings according to these embodiments, the same reference numerals are attached to elements that are the same as or similar to those of the first embodiment. In addition, the overall configuration of the oil-cooled compressor according to the first embodiment shown in Figs. 1, 2, and 4 is the same for these embodiments as well.

(2nd embodiment)

In the oil-cooled screw compressor 1 according to the second embodiment of the present invention shown in FIGS. 11 and 12, the injection portion 22 of the oil supply port 11 is a portion 22b connected to the intermediate portion 23. ) To the opening 22a, the intermediate portion 23 has a constant diameter Di larger than the diameter Dm. In other words, the injection portion 22 has a constant flow passage cross-sectional area Ae larger than the flow passage cross-sectional area Am of the intermediate portion 23 from the portion 22b connected to the intermediate portion 23 to the opening 22a. Therefore, a step 26 is formed in a portion of the injection portion 22 connected to the intermediate portion 23, in which the flow passage cross-sectional area increases abruptly or discontinuously.

Since the opening 22a of the injection part 22 to the female rotor chamber 2b has a passage cross-sectional area Ae larger than the passage cross-sectional area Am of the intermediate part 23, the female rotor chamber 2b does not increase the volume flow rate. ), it can increase the flow rate of the oil sprayed. By this speed increase, the cooling efficiency for compressed air is improved, and the power required to compress the air to the required pressure can be reduced. Further, since the flow velocity of the liquid injected into the female rotor chamber can be increased while the volume flow rate of the oil supplied to the oil supply port 11 remains the same, no increase in power loss occurs. In addition, since the diameter Di at the opening 22a of the injection part 22 is larger than the width Wt of the toothed end at a right angle to the axis of the toothed part 4b of the female rotor 4, the tip surface of the toothed part 4b is The provided smooth surface 4d does not block the injection part 22, and the pressure loss at the time of oil injection to the female rotor chamber 2b can be more effectively reduced.

13 and 14 show a modified example of the second embodiment.

In the modified example of Fig. 13, the inlet portion 21 of the oil supply port 11 is from the portion 21a connected to the oil supply line 15 to the portion 21b connected to the intermediate portion 23, and the intermediate portion ( 23) has a constant flow path cross-sectional area Ae larger than the flow path cross-sectional area Am. Therefore, a step 25 is formed in a portion of the inlet portion 21 connected to the intermediate portion 23, in which the flow path cross-sectional area is discontinuously decreased. The thickness THm of the intermediate portion 23 is larger than the sum of the thickness THe of the inlet portion 21 and the thickness THi of the injection portion 22.

In the modified example of Fig. 14, the inlet portion 21 of the oil supply port 11 has a diameter De from the portion 21a connecting with the oil supply line 15 toward the portion 21b connecting with the intermediate portion 23, thus It has a tapered shape in which the flow path cross-sectional area Ae decreases gradually. 13 and 14, when oil flows into the inlet portion 21 of the oil supply port 11 from the oil supply line 15, the abrupt reduction in the cross-sectional area of the flow path is alleviated, and the pressure loss is reduced. As a result, more effectively, it is possible to increase the flow rate of the oil injected into the female rotor chamber 2b without increasing the volume flow rate of the oil supplied to the oil supply port 11.

(3rd embodiment)

In the oil-cooled screw compressor 1 according to the third embodiment of the present invention shown in FIGS. 15 and 16, the oil supply port 11 is provided by providing a separate member to the casing 2.

The casing 2 is provided with an installation hole 31 penetrating from the oil supply line 15 to the female rotor chamber 2b. In this embodiment, the mounting hole 31 is a circular shape having a constant diameter Da. An orifice tube (pipe member) 32 having both end openings, that is, a shaft hole 32a in the center, shown in FIG. 17 is inserted or fitted into the mounting hole 31 and is fixed to the casing 2 .

The end surface 32b of the orifice tube 32 on the female rotor chamber 2b side is located in the mounting hole 31 and is concave with respect to the cylindrical surface 2f defining the female rotor chamber 2b. Further, the end surface 32c of the orifice tube 32 on the side of the oil supply line 15 is also located in the installation hole 31. The inlet part 21 of the oil supply port 11 is defined by the end surface 32c of the orifice tube 32 and the hole circumferential wall 31a of the mounting hole 31. Further, the shaft hole 32a of the orifice tube 32 constitutes the intermediate portion 23 of the oil supply port 11. Moreover, the injection part 22 of the oil supply port 11 is defined by the end surface 32b of the orifice tube 32 and the hole circumferential wall 31a of the installation hole 31.

The injection part 22 in this embodiment has the same shape as that of the 2nd embodiment. Particularly, in the intermediate portion 23, that is, at the portion where the shaft hole 32a of the orifice tube 32 and the injection portion 22 are connected, a step 26 in which the cross-sectional area of the flow path increases discontinuously is formed.

The inlet part 21 in this embodiment has a shape similar to that shown in FIG. Particularly, in a portion where the inlet portion 21 connects with the intermediate portion 23, that is, the shaft hole 32a of the orifice tube 32, a step 25 is formed in which the channel cross-sectional area is discontinuously decreased.

In addition to the effects similar to those of the first and second embodiments and their modified examples, the present embodiment has the following effects. First, dimensional control during processing of providing the oil supply port 11 in the casing 2 is performed by directly processing the casing 2 itself, such as by excavation, and the intermediate portion 23 and the intermediate portion 23 Compared to the case of forming the injection part 22 provided in the opening of the rotor chamber with a flow passage cross-sectional area larger than the passage cross-sectional area of, it becomes easier. By facilitating dimensional control during processing, higher quality stability can be secured. In addition, by using another orifice tube 32, the diameter Dm of the intermediate portion 23 of the oil supply port 11 can be easily changed according to the use of the product. In addition, the processing performed on the casing 2 to provide the oil supply port 11 does not require processing of steps in which the cross-sectional area of the flow path increases discontinuously or processing of a tapered shape in which the cross-sectional area of the flow path is continuously expanded. , Since only the formation of the mounting holes 31 is required, the number of steps can be reduced.

(exam)

A test was conducted to confirm the effect of the present invention. In this test, the oil-cooled screw compressor 1 of the third embodiment (the oil supply port 11 is constituted by the orifice tube 32 as shown in FIG. 15), as shown in FIG. 8 as a comparative example. An oil-cooled screw compressor 1 (a drill hole in which the lubrication port 11 has a constant diameter) was used. For each oil-cooled screw compressor 1 (75 KW), it was actually operated at two types of circulation flow rates, and the adiabatic efficiency (the ratio of the theoretical power consumption to the actual power consumption) was obtained. The discharge pressure of each oil-cooled screw compressor 1 was set to 0.7 MPa. The ambient temperature was 20°C.

In both the third embodiment and the comparative example, the diameter Dm of the intermediate portion 23 of the three oil supply ports 11A to 11C is equal to the width Wt of the right-angled tooth end of the tooth portion 4b of the female rotor 4 It was 4.4 times (Dm=4.4×Wt).

In the third embodiment, the circulating flow rate calculated the heat insulation efficiency when operating at a _{predetermined flow rate Q 0} (L/min) and about 1.4×Q _{0 (L/min).} When the circulation flow rate is Q ₀ (L/min), the diameter Di of the injection part 22 of the oil supply ports 11A, 11B, 11C is 2.2Dm (Di=2.2×Dm), 2.9Dm (Di=2.9), respectively. ×Dm) and 2.9Dm (Di=2.9×Dm). On the other hand, the diameter Di of the injection part 22 of the lubrication ports 11A, 11B and 11C when the lubricating oil amount is 1.4 × Q _{0 (L/min) is 1.7Dm (Di = 1.7 ×Dm) and 2.2Dm (} Di=2.2xDm) and 2.2Dm (Di=2.2xDm).

Fig. 18 shows the test results. As shown in Fig. 18, it was confirmed that the oil-cooled screw compressor 1 of the third embodiment improved the heat insulation efficiency by about 1% compared to the comparative example.

1: Oil-cooled screw compressor (liquid-cooled screw compressor)
2: casing
2a: male rotor chamber
2b: female rotor chamber
2c: inlet
2d: discharge port
2e, 2f: cylindrical surface
2g, 2h: end face
3: male rotor
3a: rotor shaft
3b: teeth
4: female rotor
4a: rotor shaft
4b: teeth
4c: toothed groove
4d: smooth surface
5A, 5B, 6A, 6B: bearing
7: drive mechanism
11A, 11B, 11C: oil supply port (water supply port)
12A, 12B: air piping
13: separator
14: oil supply piping
15: Lubrication line (liquid supply line)
16: oil pump
21: inlet
21a, 21b: part
22: injection part
22a: opening
22b: part
23: middle part
23a: end
25, 26: step difference
31: mounting hole
31a: wall around the hole
32: orifice tube
32a: shaft hole
32b, 32c: end faces

Claims (9)

A rotor chamber provided in the casing and accommodating a pair of screw rotors,
In order to supply the liquid supplied from the liquid supply line to the rotor chamber, a liquid supply port provided in the casing is
Equipped,
The liquid supply port,
An inlet in fluid communication with the liquid supply line,
An injection part in fluid communication with the rotor chamber,
And an intermediate portion having a constant flow passage cross-sectional area fluidly connecting the inlet portion and the injection portion,
A liquid-cooled screw compressor in which a flow passage cross-sectional area of the opening portion of the injection portion with respect to the rotor chamber is larger than the passage cross-sectional area of the intermediate portion. The liquid-cooled screw compressor according to claim 1, wherein a diameter in the opening portion of the injection portion is larger than a width of a tooth end at a right angle to the axis of the tooth portion of the screw rotor. The method according to claim 1 or 2, wherein the diameter of the middle portion is 0.7 mm or more and 18 mm or less,
A liquid-cooled screw compressor, wherein a diameter in the opening portion of the injection portion is 4.0 times or less a diameter of the intermediate portion. The liquid-cooled screw compressor according to claim 3, wherein a diameter in the opening of the injection part is 1.5 times or more and 3.0 times or less of a diameter of the intermediate part. The liquid-cooled screw compressor according to claim 1 or 2, wherein the injection portion has an inverted taper shape in which the passage cross-sectional area gradually increases from a portion connected to the intermediate portion toward the opening. The passage according to claim 1 or 2, wherein the injection part has a constant cross-sectional area of the flow path from a portion connected to the intermediate part to the opening,
A liquid-cooled screw compressor, wherein a step of discontinuously increasing the flow path cross-sectional area is formed at a portion connected to the intermediate portion of the injection unit. The liquid supply port according to claim 6, wherein the liquid supply port is provided with a tube member having both ends of openings inserted into an installation hole penetrating from the liquid supply line provided in the casing to the rotor chamber,
The intermediate portion is defined by the tubular member,
The end surface of the pipe member facing the rotor chamber is located in the installation hole,
A liquid-cooled screw compressor, wherein the injection portion is defined by the end surface of the pipe member and a wall around the hole of the installation hole. The liquid-cooled screw compressor according to claim 1 or 2, wherein the inlet portion has a tapered shape in which a flow path cross-section gradually decreases from a portion connected to the liquid supply line toward the intermediate portion. The passage according to claim 1 or 2, wherein the inlet portion has a constant flow passage cross-sectional area larger than the passage cross-sectional area of the intermediate portion from a portion connected to the liquid supply line to a portion connected to the intermediate portion,
A liquid-cooled screw compressor, wherein a step in which the passage cross-sectional area is discontinuously decreased is formed at a portion connected to the intermediate portion of the inlet portion.

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