JP7335089B2 - Liquid-cooled screw compressor - Google Patents

Description

The present invention relates to liquid-cooled screw compressors.

A liquid-cooled screw compressor, such as an oil-cooled screw compressor, is constructed by supplying a liquid (e.g., oil) to the rotor chamber for lubrication and cooling of the compressed air, and rotating the male and female rotors in mesh with each other. The liquid is entrained in the compressed air that is in the process of being compressed. The oil supply port into the rotor chamber provided in the oil-cooled screw compressor disclosed in Patent Document 1 is a so-called drilled hole, and has a straight pipe shape with a constant diameter between both ends.

JP 2014-214740 A

In a liquid-cooled screw compressor, there are power losses other than the power for compressing the air, such as power loss due to liquid agitation and power loss due to the viscosity of the liquid in the narrow gap between the rotor chamber and the teeth of the screw rotor. There is power loss. Because of these power losses, liquid cooling can actually reduce efficiency.

Further, if the shape of the liquid supply port is straight like the oil supply port of Patent Document 1, when the screw rotor passes directly above the liquid supply port during operation, the liquid is supplied from the supply port to the rotor chamber. The flow of liquid is blocked and slowed down. This velocity reduction can reduce the dispersibility of the liquid in the tooth spaces and reduce the cooling efficiency of the compressed air.

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

An object of the present invention is to reduce the power required to compress air to a required pressure and to improve the cooling efficiency in a liquid-cooled screw compressor.

According to one aspect of the present invention, a rotor chamber provided in a casing and housing a pair of screw rotors, a liquid supply line provided in the casing, and a liquid supply line connected to the liquid supply line are supplied from the liquid supply line. a fluid inlet in the casing for supplying liquid to the rotor chamber, the fluid inlet having an inlet portion in fluid communication with the fluid supply line; and an intermediate portion having a constant flow cross-sectional area fluidly connecting the inlet portion and the injection portion, the opening of the injection portion to the rotor chamber being connected to the rotor chamber . When viewed from the rotor chamber side, the plane perpendicular to the axis of the fuel filler port is circular, the cross-sectional area of the flow path of the opening is larger than the cross-sectional area of the flow path of the intermediate portion, and the opening of the injection portion provides a liquid-cooled screw compressor , wherein the diameter at is greater than the tip width of a tooth portion perpendicular to the axis of the screw rotor .

The opening of the injection part of the liquid supply port to the rotor chamber has a channel cross-sectional area that is larger than the channel cross-sectional area of the intermediate part of the liquid supply port. With this configuration, the teeth of the screw rotor pass directly above the liquid supply port during operation, compared to the case where the liquid supply port has a straight pipe shape (so-called drilled hole) with a constant flow passage cross-sectional area between both ends. At an instant, the distance between the end of the intermediate portion on the rotor chamber side and the tip of the tooth increases. In other words, when the liquid injected from the liquid supply port passes through the gap between the tooth portion (tooth tip) of the screw rotor and the casing, the cross-sectional area through which the liquid can pass increases. Therefore, the pressure loss during liquid injection into the rotor chamber is reduced. This reduction in pressure loss makes it possible to increase the flow velocity of the liquid injected into the rotor chamber while maintaining the same volumetric flow rate of the liquid supplied to the liquid supply port as in the case where the liquid supply port is a drilled hole. In other words, the flow velocity of the liquid injected into the rotor chamber can be increased more than when the liquid supply port is a drilled hole without increasing the volumetric flow rate. This increase in flow velocity promotes atomization when the liquid column collides with the tooth surfaces of the screw rotor, increases the heat transfer area of the droplets, and improves the cooling efficiency of the compressed air. Therefore, the power required to compress the air to the required pressure can be reduced.

If the volumetric flow rate of the liquid supplied to the liquid supply port is increased in order to increase the flow velocity of the liquid injected into the rotor chamber, the power loss due to the stirring of the liquid by the teeth of the screw rotor and the teeth of the screw rotor (tooth It increases the power loss due to the viscosity of the liquid in the narrow gap between the tip and the casing. However, as described above, according to one aspect of the present invention, the flow velocity of the liquid injected into the rotor chamber can be increased while the volumetric flow rate of the liquid supplied to the liquid supply port remains the same, resulting in an increase in power loss. does not occur.

The liquid supply line may be provided along a rotor axial direction of the screw rotor, and a plurality of the liquid supply ports may be arranged on a straight line along the rotor axial direction.

In this specification, the "axis-perpendicular tip width" of the tooth portion of the screw rotor refers to the width of the smooth surface of the tip of the tooth portion in a cross section perpendicular to the rotor axis of the tooth portion. By setting the diameter of the opening to be larger than the tip width perpendicular to the axis, the smooth surface does not block the injection part of the liquid supply port when the teeth of the screw rotor pass directly above the liquid supply port. , the pressure loss can be more effectively reduced when the liquid is injected into the rotor chamber.

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

In particular, the diameter of 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 section may have a reverse tapered shape in which the cross-sectional area of the flow path gradually increases from a portion connected to the intermediate section toward the opening.

The injection section has a constant flow passage cross-sectional area from a portion connected to the intermediate portion to the opening, and a discontinuous flow passage cross-sectional area at a portion of the injection portion connected to the intermediate portion. may be formed.

The liquid supply port includes a tubular member having both ends opened and inserted into a mounting hole penetrating from the liquid supply line provided in the casing to the rotor chamber. An end face of the pipe member facing the rotor chamber may be positioned within the mounting hole, and the injection portion may be defined by the end face of the pipe member and the peripheral wall of the mounting hole.

With this configuration, the dimensional control at the time of processing to provide the liquid supply port in the casing can be achieved by directly processing the casing itself by excavation or the like to form an intermediate portion and a flow passage cross-sectional area larger than the flow passage cross-sectional area of the intermediate portion. This is easier than in the case of forming the injection part provided in the opening to the rotor chamber. By facilitating dimensional control during processing, a higher level of quality stability can be ensured. In addition, by using different pipe members, the diameter of the intermediate portion of the liquid supply port can be easily changed according to product specifications. Furthermore, as the processing applied to the casing to provide the injection port, it is not necessary to process a step that increases the cross-sectional area of the flow channel discontinuously or to process a tapered shape that continuously expands the cross-sectional area of the flow channel. Since only the formation of mounting holes (through holes) is required, the number of man-hours can be reduced.

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

The inlet portion has a constant flow channel cross-sectional area larger than the flow channel cross-sectional area of the intermediate portion from the portion connected to the liquid supply line to the portion connected to the intermediate portion. A step may be formed in a portion connecting with the intermediate portion so that the cross-sectional area of the flow passage decreases discontinuously.

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

ADVANTAGE OF THE INVENTION According to the liquid-cooled screw compressor of the present invention, the cooling efficiency of compressed air is improved, and the power required for compressing air to a 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. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1; 2 is a cross-sectional view taken along line III--III of FIG. 1; FIG. 1 is a schematic diagram of a compressor system including an oil-cooled screw compressor according to a first embodiment of the present invention; FIG. FIG. 4 is an enlarged view of portion V of FIG. 3; 4A and 4B are cross-sectional views at different cross-sections of portion V of FIG. 3; The figure which looked at the oil filler port from the female rotor chamber. Sectional drawing similar to FIG. 5 of the conventional oil-cooled compressor. Sectional drawing similar to FIG. 6 of the modification of 1st Embodiment. Sectional drawing similar to FIG. 6 of the other modification of 1st Embodiment. Sectional drawing similar to FIG. 3 of the oil-cooled screw compressor which concerns on 2nd Embodiment of this invention. Sectional drawing similar to FIG. 6 of 2nd Embodiment. Sectional drawing similar to FIG. 6 of the modification of 2nd Embodiment. Sectional drawing similar to FIG. 6 of the other modification of 2nd Embodiment. FIG. 3 is a cross-sectional view similar to FIG. 3 of an oil-cooled screw compressor according to a third embodiment of the present invention; Sectional drawing similar to FIG. 6 of 3rd Embodiment. A perspective view of an orifice tube. Graph showing the relationship between the amount of oil and cross-sectional efficiency.

(First embodiment)
1 to 3, an oil-cooled screw compressor (liquid-cooled screw compressor) 1 according to a 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. and a casing 2 formed with. A male rotor 3 is housed in the male rotor chamber 2a, and a female rotor 4 is housed in the female rotor chamber 2b. The casing 2 is also provided with a suction port 2c and a discharge port 2d that are spatially connected to 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. The female rotor chamber 2b is defined by a cylindrical surface 2f and a pair of end surfaces 2g and 2h common to the male rotor chamber 2a.

The male rotor (screw rotor) 3 includes a rotor shaft 3a and a plurality of spiral teeth 3b provided on the outer circumference of the rotor shaft 3a. Similarly, the female rotor 4 has a rotor shaft 4a and a plurality of spiral teeth 4b provided on the outer circumference of the rotor shaft 4a. A spiral tooth space 4c is defined between each pair of teeth 4b adjacent to each other. A rotor shaft 3a of the male rotor 3 is rotatably supported by bearings 5A and 5B about its own axis Lm. A 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 of the male rotor 3 on the suction port 2c side. When the male rotor 3 is rotated by the driving mechanism 7, the teeth 3b of the male rotor 3 engage with the tooth grooves 4c of the female rotor 4, whereby 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.

Gas (air in this embodiment) sucked from the suction port 2c is confined in a confinement space defined by the tooth portions 3b of the male rotor 3 and the tooth grooves 4c of the female rotor 4, causing the rotors 3 and 4 to rotate. As a result, it is compressed while moving in the directions of the axes Lm and Lf, 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 for supplying oil (liquid) for cooling, lubrication, etc., to the female rotor chamber 2b. These oil supply ports 11A to 11C open at the bottom of the female rotor chamber 2b and are arranged on a straight line along the axis Lf of the female rotor 4 (which is also the axis of the female rotor chamber 2b). The number of filler ports may be one, two, or four or more. Further, 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 fuel filler ports 11A to 11C will be detailed later.

Since the 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. Also referring to FIG. 4, the air discharged from the discharge port 2d is introduced into the separator 13 through the air pipe 12A. The separator 13 separates air and oil. The air from which the oil has been separated is sent from the air pipe 12B to equipment or facilities that require compressed air. The oil separated from the air by the separator 13 is sent through an oil supply pipe 14 to an oil supply line (liquid supply line) 15 provided in the casing 2 (a long hole drilled in the casing 2 in this embodiment). . Oil is supplied from an oil supply line 15 to the female rotor chamber 2b through the oil supply ports 11A to 11C. Thus, 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 fuel filler ports 11A-11C will be described in detail. In the following description, reference number 11 is used for one fuel filler port when there is no particular need to distinguish between the three fuel filler ports 11A to 11C.

Referring to FIGS. 5 to 7, the oil supply line 15 and the female rotor chamber 2b are fluidly communicated through the oil supply port 11. As shown in FIG. The oil filler 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 fuel supply port 11 has an inlet portion 21 fluidly communicating with the oil supply line 15, an injection portion 22 fluidly communicating with the female rotor chamber 2b, and an intermediate portion 23 fluidly connecting the inlet portion 21 and the injection portion 22. Prepare.

In the present embodiment, the shape of the cross section of the inlet portion 21 and the intermediate portion 23 perpendicular to the axis Li of the filler port 11 is circular. This cross-sectional shape may be other than circular. The inlet portion 21 has a constant diameter De and the intermediate portion 23 also has a constant diameter Dm, and these diameters De and Dm are the same. In other words, the channel cross-sectional areas Ae and Am are constant throughout from the inlet portion 21 to the intermediate portion 23 .

The injection part 22 comprises an opening 22a opening into the female rotor chamber 2b, more specifically into the cylindrical surface 2f of the casing 2 defining the female rotor chamber 2b. In this embodiment, the shape of the cross section of the injection part 22 perpendicular to the axis Li of the filler port 11 is circular. This cross-sectional shape may be other than circular. In this embodiment, the injection part 22 has a diameter Di that gradually increases from a portion 22b that connects to the intermediate part 23 toward the opening 22a. In other words, the injection portion 22 has an inverse tapered shape in which the flow 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 portion 22a. Due to this inverse tapered shape, the channel cross-sectional area Ai at the opening 22 a of the injection part 22 is larger than the channel cross-sectional area Am at the intermediate part 23 .

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

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

The oil supplied through the oil supply line 15 enters the oil supply port 11 at the inlet portion 21, flows into the intermediate portion 23, and is jetted from the end portion 23a of the intermediate portion 23 on the female rotor chamber 2b side. The injected oil passes through the injection portion 22 and is supplied to the female rotor chamber 2b.

The diameter Di at the opening 22a of the injection portion 22 of the fuel filler port 11 with respect to the female rotor chamber 2b, and therefore the flow passage cross-section Ai, is larger than the diameter Dm of the intermediate portion 23 of the fuel filler port 11, and therefore the flow passage cross-sectional area Am. Therefore, as compared with the case where the oil filler port 11 has a straight pipe shape (a so-called drilled hole) in which the flow passage cross-sectional area is constant between both ends as shown in FIG. 11, the distance between the end portion 23a of the intermediate portion 23 on the side of the female rotor chamber 2b and the tip of the tooth portion 4b increases. In other words, when the oil injected from the oil supply port 11 passes through the gap between the tip of the tooth portion 4b of the female rotor 4 and the cylindrical surface 2f of the casing 2, the cross-sectional area through which the oil can pass increases. Therefore, pressure loss during injection of oil into the female rotor chamber 2b is reduced. Due to this reduction in pressure loss, the volumetric flow rate of the oil supplied to the oil supply port 11 remains the same as in the case where the oil supply port 11 has a drilled hole as shown in FIG. Can increase flow velocity. In other words, the flow velocity of the oil injected into the female rotor chamber 2b can be increased more than when the oil supply port 11 is a drilled hole without increasing the volumetric flow rate. This increase in flow speed promotes atomization when the liquid column collides with the tooth surface of the tooth portion 4b of the female rotor 4, increases the heat transfer area of the oil droplets, and improves the cooling efficiency of the compressed air. Therefore, the power required to compress the air to the required pressure can be reduced.

If the volumetric flow rate of the liquid supplied to the oil filler port 11 is increased in order to increase the flow velocity of the oil injected into the female rotor chamber 2b, power loss due to the stirring of the oil by the teeth 4b of the female rotor 4 and The viscosity of the oil in the narrow gap between the tooth portion 4b (tooth tip) of the casing 2 and the cylindrical surface 2f of the casing 2 increases the power loss. However, in this embodiment, the flow velocity of the oil injected into the female rotor chamber 2b can be increased while the volumetric flow rate of the oil supplied to the oil filler port 11 remains the same, so an increase in power loss does not occur.

As described above, the diameter Di at the opening 22a of the injection portion 22 is larger than the axis-perpendicular tip width Wt of the tooth portion 4b of the female rotor 4. As shown in FIG. Therefore, when the toothed portion 4b of the female rotor 4 passes right above the oil filler opening 11, the injection portion 22 of the oil filler opening 11 is not blocked by the smooth surface 4d of the tip of the toothed portion 4b. Pressure loss during oil injection to the rotor chamber 2b can be reduced.

9 and 10 show a modification of the first embodiment.

In the modified example of FIG. 9, the inlet portion 21 of the fuel filler port 11 has a tapered shape in which the diameter De, and therefore the flow passage cross-sectional area Ae, gradually decreases from the portion 21a connected to the fuel supply line 15 toward the portion 21b connected to the intermediate portion 23. have.

10, the inlet portion 21 of the fuel filler port 11 has a constant diameter De larger than the diameter Dm of the intermediate portion 23 from the portion 21a connected to the fuel supply line 15 to the portion 21b connected to the intermediate portion 23. . In other words, inlet portion 21 has a constant flow passage cross-sectional area Ae larger than flow passage cross-sectional area Am of intermediate portion 23 from portion 21 a connected to oil supply line 15 to portion 21 b connected to intermediate portion 23 . Therefore, a step 25 is formed at a portion where the inlet portion 21 is connected to the intermediate portion 23 so that the cross-sectional area of the flow passage decreases abruptly or discontinuously.

The configuration shown in FIGS. 9 and 10 alleviates a rapid reduction in the cross-sectional area of the flow path when oil flows from the oil supply line 15 into the inlet 21 of the oil supply port 11, thereby reducing pressure loss. As a result, the flow velocity of the oil injected into the female rotor chamber 2b can be increased more effectively without increasing the volumetric flow rate of the oil supplied to the oil filler port 11. FIG.

In the following second and third embodiments, points different from the first embodiment will be described. Structures, functions, and the like that are not specifically mentioned in these embodiments are the same as those in the first embodiment. In addition, in the drawings relating to these embodiments, the same reference numerals are given to the same or similar elements as those of the first embodiment. Furthermore, 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.

(Second embodiment)
In the oil-cooled screw compressor 1 according to the second embodiment of the present invention shown in FIGS. It has a constant diameter Di greater than the diameter Dm of 23. 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 at a portion of the injection portion 22 that is connected to the intermediate portion 23 so that the cross-sectional area of the flow passage increases abruptly or discontinuously.

Since the opening 22a of the injection portion 22 for the female rotor chamber 2b has a flow passage cross-sectional area Ae larger than the flow passage cross-sectional area Am of the intermediate portion 23, the jet is injected into the female rotor chamber 2b without increasing the volumetric flow rate. Can increase oil flow rate. This increase in speed improves cooling efficiency for the compressed air and reduces the power required to compress the air to the required pressure. Further, since the flow velocity of the liquid injected into the female rotor chamber can be increased while the volumetric flow rate of the oil supplied to the oil supply port 11 remains the same, an increase in power loss does not occur. Furthermore, since the diameter Di at the opening 22a of the injection portion 22 is larger than the axis-perpendicular tip width Wt of the tooth portion 4b of the female rotor 4, the injection portion 22 is blocked by the smooth surface 4d of the tip surface of the tooth portion 4b. Therefore, it is possible to more effectively reduce pressure loss during injection of oil into the female rotor chamber 2b.

13 and 14 show a modification of the second embodiment.

In the modified example of FIG. 13 , the inlet portion 21 of the fuel filler port 11 has a constant flow larger than the flow passage cross-sectional area Am of the intermediate portion 23 from the portion 21 a connected to the fuel filler line 15 to the portion 21 b connected to the intermediate portion 23 . It has a cross-sectional area Ae. Therefore, a step 25 is formed in a portion of the inlet portion 21 connected to the intermediate portion 23 so that the cross-sectional area of the flow passage decreases discontinuously. The thickness THm of the intermediate portion 23 is greater 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 fuel filler port 11 has a tapered shape in which the diameter De, and therefore the flow passage cross-sectional area Ae, gradually decreases from the portion 21a connected to the fuel supply line 15 toward the portion 21b connected to the intermediate portion 23. have. The configuration of FIGS. 13 and 14 alleviates a rapid reduction in the cross-sectional area of the flow path when oil flows from the oil supply line 15 into the inlet 21 of the oil supply port 11, thereby reducing pressure loss. As a result, the flow velocity of the oil injected into the female rotor chamber 2b can be increased more effectively without increasing the volumetric flow rate of the oil supplied to the oil filler port 11. FIG.

(Third 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 attaching another member to the casing 2 .

The casing 2 is provided with a mounting hole 31 penetrating from the oil supply line 15 to the female rotor chamber 2b. In this embodiment, the mounting hole 31 is circular with a constant diameter Da. An orifice tube (pipe member) 32, shown in FIG.

An end face 32b of the orifice pipe 32 on the side of the female rotor chamber 2b is located in the mounting hole 31 and recessed from the cylindrical surface 2f defining the female rotor chamber 2b. An end face 32 c of the orifice pipe 32 on the oil supply line 15 side is also located inside the mounting hole 31 . The inlet portion 21 of the oil filler port 11 is defined by the end face 32c of the orifice pipe 32 and the hole peripheral wall 31a of the mounting hole 31 . Further, the shaft hole 32 a of the orifice pipe 32 constitutes the intermediate portion 23 of the filler port 11 . Further, the end face 32b of the orifice pipe 32 and the hole peripheral wall 31a of the mounting hole 31 define the injection portion 22 of the oil filler port 11. As shown in FIG.

The injection part 22 in this embodiment has the same shape as that of the second embodiment. In particular, the intermediate portion 23, that is, the portion where the shaft hole 32a of the orifice pipe 32 and the injection portion 22 are connected, is formed with a step 26 that discontinuously increases the flow passage cross-sectional area.

The inlet portion 21 in this embodiment has a shape similar to that shown in FIG. In particular, a step 25 that discontinuously decreases the cross-sectional area of the flow passage is formed at the portion where the inlet portion 21 connects with the intermediate portion 23 , that is, the shaft hole 32 a of the orifice pipe 32 .

In addition to the same effects as those of the first and second embodiments and their modifications, this embodiment has the following effects. First, the dimensional control at the time of processing to provide the fuel filler port 11 in the casing 2 is to directly process the casing 2 itself by excavation or the like, and to form an intermediate portion 23 and a flow passage section larger than the flow passage cross-sectional area of the intermediate portion 23 . This is easier than in the case of forming the injection part 22 having an area at the opening with respect to the rotor chamber. By facilitating dimensional control during processing, a higher level of quality stability can be ensured. Also, by using a different orifice pipe 32, the diameter Dm of the intermediate portion 23 of the filler port 11 can be easily changed according to product use. Furthermore, the machining of the casing 2 to provide the oil filler port 11 requires machining of a step that increases the cross-sectional area of the flow path discontinuously and machining of a tapered shape that continuously expands the cross-sectional area of the flow path. Since only the formation of the mounting holes 31 is required, the number of man-hours can be reduced.

(test)
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 orifice pipe 32 constitutes the oil supply port 11 as shown in FIG. 15) and the oil-cooled screw compressor shown in FIG. Machine 1 (a drilled hole with a constant diameter for the oil filler port 11) was used. Each oil-cooled screw compressor 1 (75 kW) was actually operated with two different amounts of circulating oil, and the adiabatic efficiency (ratio of theoretical power consumption to actual power consumption) was determined. The discharge pressure of each oil-cooled screw compressor 1 was set to 0.7 MPa. 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 filler ports 11A to 11C is 4.4 times the tip width Wt perpendicular to the axis of the tooth portion 4b of the female rotor 4. (Dm = 4.4 x Wt).

For the third embodiment, the adiabatic efficiency was obtained when the engine was operated with a predetermined oil amount Q ₀ (L/min) and approximately 1.4×Q ₀ (L/min) as the circulating oil amount. When the circulating oil amount is Q ₀ (L/min), the diameters Di of the injection portions 22 of the oil filler ports 11A, 11B, and 11C are 2.2 Dm (Di=2.2×Dm) and 2.9 Dm (Di= 2.9×Dm), and 2.9 Dm (Di=2.9×Dm). On the other hand, when the lubricating oil amount is 1.4×Q ₀ (L/min), the diameter Di of the injection portion 22 of each of the oil supply ports 11A, 11B, and 11C is 1.7Dm (Di=1.7×Dm), 2.2 Dm (Di = 2.2 x Dm), and 2.2 Dm (Di = 2.2 x Dm).

FIG. 18 shows the test results. As shown in FIG. 18, it has been confirmed that the oil-cooled screw compressor 1 of the third embodiment has improved adiabatic efficiency by about 1% as 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 suction port 2d discharge port 2e, 2f cylindrical surface 2g, 2h end surface 3 male rotor 3a rotor shaft 3b tooth portion 4 female rotor 4a rotor shaft 4b tooth portion 4c tooth groove 4d smooth surface 5A , 5B, 6A, 6B bearing 7 drive mechanism 11A, 11B, 11C oil supply port (liquid supply port)
12A, 12B air pipe 13 separator 14 oil supply pipe 15 oil supply line (liquid supply line)
16 oil pump 21 inlet 21a, 21b portion 22 injection portion 22a opening 22b portion 23 intermediate portion 23a end 25, 26 step 31 mounting hole 31a hole peripheral wall 32 orifice pipe 32a shaft hole 32b, 32c end face

Claims (9)

a rotor chamber provided in the casing and containing a pair of screw rotors;
a liquid supply line formed in the casing along the axial direction of the screw rotor ;
a liquid supply port provided in the casing along a direction intersecting with the liquid supply line for connecting to the liquid supply line and supplying the liquid supplied from the liquid supply line to the rotor chamber; ,
The liquid supply port is
an inlet in fluid communication with the liquid supply line;
an injector in fluid communication with the rotor chamber;
an intermediate portion having a constant flow passage cross-sectional area fluidly connecting the inlet portion and the injection portion;
The opening of the injection section with respect to the rotor chamber has a circular shape as viewed from the rotor chamber side as a plane perpendicular to the axis of the liquid supply port, and the opening of the injection section and the opening of the inlet section with respect to the liquid supply line. is larger than the flow passage cross-sectional area of the intermediate portion , and the diameter at the opening of the injection portion is larger than the tip width of the tooth portion perpendicular to the axis of the screw rotor. type screw compressor. 2. The liquid-cooled screw compressor according to claim 1, wherein a plurality of said liquid supply ports are arranged on a straight line along said rotor axial direction. The intermediate portion has a diameter of 0.7 mm or more and 18 mm or less,
3. The liquid-cooled screw compressor according to claim 1, wherein the diameter of the opening of the injection section is 4.0 times or less the diameter of the intermediate section. 4. The liquid-cooled screw compressor according to claim 3, wherein the diameter of the opening of the injection section is 1.5 times or more and 3.0 times or less of the diameter of the intermediate section. 5. The liquid according to any one of claims 1 to 4, wherein the injection part has a reverse tapered shape in which the cross-sectional area of the flow path gradually increases from a portion connected to the intermediate part toward the opening. Cold screw compressor. The injection part has a constant flow passage cross-sectional area from a portion connected to the intermediate part to the opening,
5. The liquid cooling type according to any one of claims 1 to 4, wherein a step is formed in a portion of the injection section that is connected to the intermediate portion so that the cross-sectional area of the flow passage increases discontinuously. screw compressor. The liquid supply port includes a tubular member with both ends open, which is inserted into a mounting hole penetrating from the liquid supply line provided in the casing to the rotor chamber,
the tubular member defines the intermediate portion;
an end surface of the tubular member facing the rotor chamber is located in the mounting hole,
7. The liquid-cooled screw compressor according to claim 6, wherein said injection portion is defined by said end face of said pipe member and a peripheral wall of said mounting hole. 7. The liquid-cooled screw compressor according to any one of claims 1 to 6, wherein the inlet section has a tapered shape in which the flow passage cross section gradually decreases from the portion connected to the liquid supply line toward the intermediate portion. machine. The inlet section has a constant flow channel cross-sectional area larger than the flow channel cross-sectional area of the intermediate portion from the portion connected to the liquid supply line to the portion connected to the intermediate portion,
8. The liquid cooling type according to any one of claims 1 to 7, wherein a step is formed in a portion of the inlet portion connected to the intermediate portion so that the cross-sectional area of the flow passage decreases discontinuously. screw compressor.

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