阅读说明：本技术 液冷式螺旋压缩机 (Liquid-cooled screw compressor ) 是由 田中孝二 野口透 坂口广宣 今城贵德 于 2019-08-09 设计创作，主要内容包括：液冷式螺旋压缩机(1)具备供液口(11A),所述供液口(11A)为了将被从供液线路(15)供给的液体向转子室(2b)供给而被设置于壳体(2)。供液口(11A)具备：入口部(21),与供液线路(15)流体地连通；喷射部(22),与转子室(2b)流体地连通；以及中间部(23),将入口部(21)与喷射部(22)流体地连接,具有一定的流路截面积(Am)。喷射部(22)的相对于转子室(2b)的开口部(22a)的流路截面积(Ai)比中间部(23)的流路截面积(Am)大。(The liquid-cooled screw compressor (1) is provided with a liquid supply port (11A), and the liquid supply port (11A) is provided in the housing (2) in order to supply liquid supplied from a liquid supply line (15) to the rotor chamber (2 b). The liquid supply port (11A) is provided with: an inlet (21) in fluid communication with the liquid supply line (15); an injection section (22) that is in fluid communication with the rotor chamber (2 b); and an intermediate portion (23) that fluidly connects the inlet portion (21) and the injection portion (22) and has a constant flow path cross-sectional area (Am). The cross-sectional area (Ai) of the injection section (22) relative to the opening (22 a) of the rotor chamber (2 b) is larger than the cross-sectional area (Am) of the intermediate section (23).)

1. A liquid-cooled screw compressor, characterized in that,

the disclosed device is provided with:

a rotor chamber provided in the housing and accommodating a pair of screw rotors; and

a liquid supply port provided in the housing to supply the liquid supplied from the liquid supply line to the rotor chamber;

the liquid supply port includes:

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 fluidly connecting the inlet portion and the injection portion and having a constant flow path cross-sectional area;

the cross-sectional area of the flow path of the injection part with respect to the opening of the rotor chamber is larger than the cross-sectional area of the flow path of the intermediate part.

2. The liquid-cooled screw compressor as claimed in claim 1,

the diameter of the opening of the injection part is larger than the width of the tooth top of the screw rotor at right angle to the shaft.

3. Liquid-cooled screw compressor according to claim 1 or 2,

the diameter of the intermediate portion is 0.7mm to 18 mm;

the diameter of the opening of the injection part is 4.0 times or less the diameter of the intermediate part.

4. The liquid-cooled screw compressor as claimed in claim 3,

the diameter of the opening of the injection part is 1.5 times to 3.0 times of the diameter of the intermediate part.

5. Liquid-cooled screw compressor according to claim 1 or 2,

the injection part has a reverse tapered shape in which the flow path cross-sectional area increases from a portion connected to the intermediate part toward the opening.

6. Liquid-cooled screw compressor according to claim 1 or 2,

the cross-sectional area of the flow path from the portion of the injection part connected to the intermediate part to the opening part is constant;

a step in which the cross-sectional area of the flow path is discontinuously increased is formed in a portion of the injection portion connected to the intermediate portion.

7. The liquid-cooled screw compressor as claimed in claim 6,

the liquid supply port includes a pipe member having both ends open, and the pipe member is inserted into a mounting hole provided in the housing and penetrating from the liquid supply line to the rotor chamber;

defining the intermediate portion by the tube member;

an end surface of the pipe member facing the rotor chamber is positioned in the mounting hole;

the ejection portion is defined by the end surface of the pipe member and a hole peripheral wall of the mounting hole.

8. Liquid-cooled screw compressor according to claim 1 or 2,

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

9. Liquid-cooled screw compressor according to claim 1 or 2,

the inlet portion has a constant flow path cross-sectional area larger than the flow path 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 step in which the cross-sectional area of the flow path is discontinuously reduced is formed in a portion of the inlet portion that is connected to the intermediate portion.

Technical Field

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

Background

In a liquid-cooled screw compressor such as an oil-cooled screw compressor, a liquid (for example, oil) is supplied into a rotor chamber for lubrication and cooling of compressed air, and the liquid is mixed into the compressed air in a compression process in which male and female rotors rotate while meshing with each other. The oil-cooled screw compressor disclosed in patent document 1 includes an oil supply port to the rotor chamber, which is a so-called bore and has a straight pipe shape with a constant diameter between both ends.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-214740.

Disclosure of Invention

Problems to be solved by the invention

In the liquid-cooled screw compressor, there are power losses other than power for compressing air, such as power loss due to stirring of liquid and power loss due to viscosity of liquid in a narrow gap between a rotor chamber and a tooth portion of a screw rotor. Because of these power losses, the efficiency may be reduced by making the liquid cooling type.

Further, if the liquid supply port is formed in a straight tube shape as in the oil supply port of patent document 1, 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 blocked, and the speed decreases. Due to this speed reduction, the dispersibility of the liquid in the tooth grooves may be reduced, and the cooling efficiency of the compressed air may be reduced.

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

The invention aims to reduce power required for compressing air to required pressure and improve cooling efficiency in a liquid-cooled screw compressor.

Means for solving the problems

One aspect of the present invention provides a liquid-cooled screw compressor including: a rotor chamber provided in the housing and accommodating a pair of screw rotors; and a liquid supply port provided in the housing to supply the liquid supplied from the liquid supply line to the rotor chamber; the liquid supply port includes: 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 fluidly connecting the inlet portion and the injection portion, the intermediate portion having a constant flow path cross-sectional area; the cross-sectional area of the flow path of the injection part with respect to the opening of the rotor chamber is larger than the cross-sectional area of the flow path of the intermediate part.

The injection portion of the liquid supply port has a flow path cross-sectional area larger than a flow path cross-sectional area of an intermediate portion of the liquid supply port with respect to an opening portion of the rotor chamber. With this configuration, the distance between the rotor chamber side end portion and the tooth tip of the intermediate portion becomes longer at the moment when the tooth portion of the screw rotor passes directly above the liquid supply port during operation, as compared with the case where the liquid supply port is in a straight pipe shape (so-called drilled hole) having a constant flow path cross-sectional area between both ends. In other words, when the liquid ejected from the liquid supply port passes through a gap between the tooth portion (tooth tip) of the screw rotor and the casing, the cross-sectional area through which the liquid can pass is enlarged. Therefore, the pressure loss when the liquid is ejected into the rotor chamber is reduced. Because of this reduction in pressure loss, the flow velocity of the liquid ejected into the rotor chamber can be increased while maintaining the same volume 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 ejected into the rotor chamber can be increased without increasing the volume flow rate as compared with the case where the liquid supply port is a drilled hole. This increase in the flow velocity promotes atomization when the liquid column collides with the tooth surface of the tooth of the helical rotor, increases the heat transfer area of the liquid droplets, and improves the cooling efficiency of the compressed air. Thus, the power required to compress the air to the required pressure can be reduced.

If the volume flow rate of the liquid supplied to the liquid supply port is increased in order to increase the flow velocity of the liquid ejected into the rotor chamber, the power loss due to the stirring of the liquid by the teeth of the screw rotor and the power loss due to the viscosity of the liquid in the narrow gap between the teeth (tooth tips) of the screw rotor and the casing are increased. However, as described above, according to one aspect of the present invention, the flow velocity of the liquid ejected into the rotor chamber can be increased while keeping the volume flow rate of the liquid supplied to the liquid supply port the same, and therefore, the increase in power loss does not occur.

Preferably, the diameter of the opening of the injection part is larger than the width of a shaft perpendicular tooth crest of the tooth part of the screw rotor.

In the present specification, the "axial right-angle tooth tip width" of a tooth portion of a helical rotor refers to a width of a smooth surface that a tip of the tooth portion has in a cross section orthogonal to a rotor axis of the tooth portion. By setting the diameter of the opening portion to be larger than the width of the shaft right-angled tooth crest, when the tooth portion of the screw rotor passes directly above the liquid supply port, the smooth surface does not block the ejection portion of the liquid supply port, so that the pressure loss at the time of ejecting the liquid into the rotor chamber can be more effectively reduced.

The diameter of the intermediate portion may be 0.7mm to 18 mm; the diameter of the opening of the injection part is 4.0 times or less the diameter of the intermediate part.

In particular, the diameter of the opening of the ejection portion may be 1.5 times or more and 3.0 times or less the diameter of the intermediate portion.

The ejection portion may have a reverse tapered shape in which the flow path cross-sectional area increases from a portion connected to the intermediate portion toward the opening portion.

The cross-sectional area of the flow path from the portion of the injection portion connected to the intermediate portion to the opening portion may be constant; a step in which the cross-sectional area of the flow path is discontinuously increased is formed in a portion of the injection portion connected to the intermediate portion.

The liquid supply port may include a pipe member having both ends open, and the pipe member may be inserted into a mounting hole provided in the housing and penetrating from the liquid supply line to the rotor chamber; defining the intermediate portion by the tube member; an end surface of the pipe member facing the rotor chamber is positioned in the mounting hole; the ejection portion is defined by the end surface of the pipe member and a hole peripheral wall of the mounting hole.

With this configuration, the dimension control at the time of providing the liquid supply port in the casing is facilitated as compared with a case where the casing itself is directly processed by excavation or the like to form the intermediate portion and the injection portion having a flow path cross-sectional area larger than the flow path cross-sectional area of the intermediate portion with respect to the opening portion of the rotor chamber. The dimension control during processing is facilitated, and higher quality stability can be ensured. Further, by using different pipe members, the diameter of the intermediate portion of the liquid supply port can be easily changed in accordance with the product specification. Further, as the processing performed on the housing to provide the liquid supply port, the processing of a step in which the flow path cross-sectional area is discontinuously increased or the processing of a tapered shape in which the flow path cross-sectional area is continuously enlarged is not necessary, and only the formation of the mounting hole (through hole) is required, so that man-hours can be reduced.

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

The inlet portion may have a flow passage cross-sectional area larger than the flow 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 step in which the cross-sectional area of the flow path is discontinuously reduced is formed in a portion of the inlet portion that is connected to the intermediate portion.

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

Effects of the invention

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

Drawings

Fig. 1 is a schematic plan view of an oil-cooled screw compressor according to embodiment 1 of the present invention.

Fig. 2 is a sectional view at line II-II of fig. 1.

Fig. 3 is a sectional view at the line III-III of fig. 1.

Fig. 4 is a schematic view of a compressor system including an oil-cooled screw compressor according to embodiment 1 of the present invention.

Fig. 5 is an enlarged view of a portion V of fig. 3.

Fig. 6 is a cross-sectional view at a different section of the portion V of fig. 3.

Fig. 7 is a view of the oil supply port as viewed from the female rotor chamber.

Fig. 8 is a cross-sectional view similar to fig. 5 of the conventional oil-cooled compressor.

Fig. 9 is a cross-sectional view similar to fig. 6 of a modification of embodiment 1.

Fig. 10 is a cross-sectional view similar to fig. 6 of another modification of embodiment 1.

Fig. 11 is a sectional view similar to fig. 3 of the oil-cooled screw compressor according to embodiment 2 of the present invention.

Fig. 12 is a sectional view similar to fig. 6 of embodiment 2.

Fig. 13 is a cross-sectional view similar to fig. 6 of a modification of embodiment 2.

Fig. 14 is a cross-sectional view similar to fig. 6 of another modification of embodiment 2.

Fig. 15 is a sectional view similar to fig. 3 of the oil-cooled screw compressor according to embodiment 3 of the present invention.

Fig. 16 is a sectional view similar to fig. 6 of embodiment 3.

Fig. 17 is a perspective view of a throttle tube.

Fig. 18 is a graph showing a relationship between oil amount and cross-sectional efficiency.

Detailed Description

(embodiment 1)

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

The male rotor chamber 2a is defined by a cylindrical surface 2e and a pair of end surfaces 2g, 2 h. 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 2 a.

The male rotor (helical rotor) 3 includes a rotor shaft 3a and a plurality of helical teeth 3b provided on the outer periphery of the rotor shaft 3 a. 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 4 a. Between the pair of teeth 4b adjacent to each other, a helical tooth groove 4c is defined. The rotor shaft 3a of the male rotor 3 is rotatably supported by bearings 5A and 5B about its own axis Lm. The rotor shaft 4a of the female rotor 4 is also supported by bearings 6A and 6B so as to be rotatable about its own axis Lf.

A drive mechanism 7 including a motor is mechanically connected to the rotor shaft 3a on the suction port 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 with each other while entering the slots 4c of the female rotor 4, and thereby the male rotor 3 and the female rotor 4 are rotated in synchronization with each other. Instead of the male rotor 3, the female rotor 4 may be rotationally driven by a drive mechanism.

The gas (air in the present embodiment) sucked in from the suction port 2c is confined in the confining space defined by the teeth 3b of the male rotor 3 and the teeth grooves 4c of the female rotor 4, compressed while moving in the direction of the axes Lm and Lf in accordance with the rotation of the rotors 3 and 4, and discharged from the discharge port 2 d.

The casing 2 is provided with 3 oil supply ports (liquid supply ports) 11A, 11B, and 11C for supplying oil (liquid) for cooling, lubrication, and the like to the female rotor chamber 2B. These oil supply ports 11A to 11C are 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 (also the axis of the female rotor chamber 2 b). The number of the fuel fill ports may be 1, 2, or 4 or more. Further, an oil supply port for the male rotor chamber 2a may be provided instead of or in addition to the oil supply port for the female rotor chamber 2 b. The fuel fill ports 11A to 11C are described in detail later.

Since the oil is supplied from the oil supply ports 11A to 11C to the female rotor chamber 2b, the air ejected from the ejection port 2d contains the oil. Referring to fig. 4, the 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 pipe 12B to the equipment or facility that requires compressed air. The oil separated from the air by the separator 13 is sent to an oil supply line (liquid supply line) 15 (in the present embodiment, a long hole bored in the casing 2) provided in the casing 2 via an oil supply pipe 14. 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 the present 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 fill ports 11A to 11C will be described in detail. In the following description, when it is not necessary to distinguish the 3 fuel fill ports 11A to 11C, reference numeral 11 is used for 1 fuel fill port.

Referring to fig. 5 to 7, the oil supply line 15 and the female rotor chamber 2b are fluidly communicated through 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 (also the axis of the female rotor chamber 2 b).

The oil feed port 11 includes an inlet portion 21 fluidly communicating with the oil feed 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.

In the present embodiment, the inlet portion 21 and the intermediate portion 23 have a circular shape in cross section perpendicular to the axis Li of the oil supply port 11. The 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 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 unit 22 includes an opening 22a that opens in the female rotor chamber 2b, more specifically, in the cylindrical surface 2f of the housing 2 defining the female rotor chamber 2 b. In the present embodiment, the cross-section of the injection portion 22 perpendicular to the axis Li of the fuel fill inlet 11 is circular. The cross-sectional shape may be other than circular. In the present embodiment, the ejection portion 22 has a diameter Di that increases from the portion 22b connected to the intermediate portion 23 toward the opening 22 a. In other words, the injection portion 22 has a reverse tapered shape in which the flow path cross-sectional area Ai increases from the portion 22b where the injection portion 22 and the intermediate portion 23 are connected to each other toward the opening portion 22 a. Due to the reverse tapered shape, the flow path sectional area Ai of the opening 22a of the injection portion 22 is larger than the flow path sectional area Am of the intermediate portion 23.

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

The diameter Dm of the intermediate portion 23 may be set to 0.7mm to 18 mm. The diameter Di of the opening 22a of the ejection portion 22 may be set to be 4 times or less the diameter Dm of the intermediate portion 23. In particular, the diameter Di of the opening 22a of the ejection portion 22 may 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 from the oil supply line 15 enters the oil supply port 11 at the inlet portion 21, flows into the intermediate portion 23, and is injected from the end portion 23a of the intermediate portion 23 on the female rotor chamber 2b side. The injected oil is supplied to the female rotor chamber 2b through the injection portion 22.

The diameter Di of the injection portion 22 of the fuel fill port 11 at the opening 22a to the female rotor chamber 2b, and thus the flow path cross-sectional area Ai, are larger than the diameter Dm of the intermediate portion 23 of the fuel fill port 11, and thus the flow path cross-sectional area Am. Therefore, as compared with the case where the fuel fill port 11 has a straight tubular shape (so-called drilled hole) with a constant cross-sectional flow area between both ends, the distance between the tip of the tooth portion 4b and the end portion 23a of the intermediate portion 23 on the female rotor chamber 2b side at the moment when the tooth portion 4b of the female rotor 4 passes directly above the fuel fill port 11 during operation becomes longer. In other words, when the oil injected from the oil supply port 11 passes through the gap between the tooth tips of the tooth portions 4b of the female rotor 4 and the cylindrical surface 2f of the housing 2, the cross-sectional area through which the oil can pass is enlarged. Therefore, the pressure loss when the oil is injected into the female rotor chamber 2b is reduced. Due to this reduction in pressure loss, the flow velocity of the oil injected into the female rotor chamber 2b can be increased while maintaining the same volume flow rate of the oil supplied to the oil fill port 11 as in the case where the oil fill port 11 is a drilled hole as shown in fig. 8. In other words, the flow velocity of the oil injected into the female rotor chamber 2b can be increased as compared with the case where the oil supply port 11 is a bore hole without increasing the volume flow rate. This increase in the flow velocity promotes atomization when the liquid column collides with the tooth surface of the tooth 4b of the female rotor 4, increases the heat transfer area of the oil droplets, and improves the cooling efficiency for the compressed air. Thus, the power required to compress the air to the required pressure can be reduced.

If the volume flow rate of the liquid supplied to the oil supply port 11 is increased in order to increase the flow velocity of the oil injected into the female rotor chamber 2b, the power loss due to the stirring of the oil by the tooth portions 4b of the female rotor 4 and the power loss due to the viscosity of the oil in the narrow gap between the tooth portions 4b (tooth tips) of the female rotor 4 and the cylindrical surface 2f of the housing 2 are increased. However, in the present embodiment, the flow velocity of the oil injected into the female rotor chamber 2b can be increased while keeping the volume flow rate of the oil supplied to the oil supply port 11 the same, and therefore, an increase in power loss does not occur.

As described above, the diameter Di of the opening 22a of the injection portion 22 is larger than the axial perpendicular crest width Wt of the tooth portion 4b of the female rotor 4. Therefore, when the tooth portions 4b of the female rotor 4 pass directly above the fuel fill port 11, the pressure loss at the time of injecting the oil into the female rotor chamber 2b can be more effectively reduced without blocking the injection portion 22 of the fuel fill port 11 by the smooth surface 4d provided at the tip ends of the tooth portions 4 b.

Fig. 9 and 10 show a modification of embodiment 1.

In the modification of fig. 9, the inlet portion 21 of the fuel fill port 11 has a tapered shape in which the diameter De gradually decreases from the portion 21a connected to the fuel supply line 15 to the portion 21b connected to the intermediate portion 23.

In the modification of fig. 10, the inlet portion 21 of the fuel fill inlet 11 has a constant diameter De greater 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, the inlet portion 21 has a constant flow path cross-sectional area Ae larger than the flow path cross-sectional area Am of the intermediate portion 23 from the portion 21a connected to the supply line 15 to the portion 21b connected to the intermediate portion 23. Therefore, a step 25 in which the flow path cross-sectional area sharply or discontinuously decreases is formed in a portion where the inlet portion 21 and the intermediate portion 23 are connected.

With the configuration shown in fig. 9 and 10, a sudden decrease in the flow passage cross-sectional area when oil flows from the oil supply line 15 into the inlet portion 21 of the oil supply port 11 is alleviated, and the pressure loss is reduced. As a result, the flow velocity of the oil injected into the female rotor chamber 2b can be increased more effectively without increasing the volume flow rate of the oil supplied to the oil supply port 11.

The following embodiments 2 and 3 are different from embodiment 1 in point. The structure, function, and the like of these embodiments that are not particularly described are the same as those of embodiment 1. In the drawings relating to these embodiments, the same or similar elements as those in embodiment 1 are given the same reference numerals. The overall configuration of the oil-cooled compressor according to embodiment 1 shown in fig. 1, 2, and 4 is the same for these embodiments.

(embodiment 2)

In the oil-cooled screw compressor 1 according to embodiment 2 of the present invention shown in fig. 11 and 12, the injection portion 22 of the oil supply port 11 has a constant diameter Di larger than the diameter Dm of the intermediate portion 23 from the portion 22b connected to the intermediate portion 23 to the opening portion 22 a. In other words, the injection part 22 has a constant flow path cross-sectional area Ae larger than the flow path cross-sectional area Am of the intermediate part 23 from the part 22b connected to the intermediate part 23 to the opening 22 a. Therefore, a step 26 in which the flow path cross-sectional area sharply or discontinuously increases is formed in a portion of the injection portion 22 that is connected to the intermediate portion 23.

Since the opening 22a of the injection part 22 with respect to the female rotor chamber 2b has a larger flow path cross-sectional area Ae than the flow path cross-sectional area Am of the intermediate part 23, the flow velocity of the oil injected into the female rotor chamber 2b can be increased without increasing the volume flow rate. By this speed increase, the cooling efficiency for the 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 keeping the volume flow rate of the oil supplied to the oil supply port 11 the same, an increase in power loss does not occur. Further, since the diameter Di of the opening 22a of the injection portion 22 is larger than the axial right-angle tooth crest width Wt of the tooth portion 4b of the female rotor 4, the smooth surface 4d provided on the tip surface of the tooth portion 4b does not block the injection portion 22, and the pressure loss at the time of injecting the oil into the female rotor chamber 2b can be more effectively reduced.

Fig. 13 and 14 show a modification of embodiment 2.

In the modification of fig. 13, the inlet portion 21 of the fuel fill inlet 11 has a constant flow path cross-sectional area Ae larger than the flow path cross-sectional area Am 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. Therefore, a step 25 in which the flow path cross-sectional area is discontinuously reduced is formed in a portion of the inlet portion 21 that is connected to the intermediate portion 23. 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 ejection portion 22.

In the modification of fig. 14, the inlet portion 21 of the fuel fill port 11 has a tapered shape in which the diameter De gradually decreases from the portion 21a connected to the fuel supply line 15 to the portion 21b connected to the intermediate portion 23. With the configuration of fig. 13 and 14, a sudden decrease in the flow passage cross-sectional area when oil flows from the oil supply line 15 into the inlet portion 21 of the oil supply port 11 is alleviated, and the pressure loss is reduced. As a result, the flow velocity of the oil injected into the female rotor chamber 2b can be increased more effectively without increasing the volume flow rate of the oil supplied to the oil supply port 11.

(embodiment 3)

In the oil-cooled screw compressor 1 according to embodiment 3 of the present invention shown in fig. 15 and 16, an oil supply port 11 is provided by attaching another member to the casing 2.

The housing 2 is provided with a mounting hole 31 penetrating from the oil supply line 15 to the female rotor chamber 2 b. In the present embodiment, the mounting hole 31 is a circular shape having a constant diameter Da. The throttle pipe (pipe member) 32 shown in fig. 17, which is open at both ends, i.e., has a shaft hole 32a at the center, is inserted or fitted into the mounting hole 31 and fixed to the housing 2.

An end surface 32b of the throttle pipe 32 on the female rotor chamber 2b side is positioned in the mounting hole 31 and is recessed from a cylindrical surface 2f defining the female rotor chamber 2 b. Further, an end surface 32c of the throttle pipe 32 on the side of the oil supply line 15 is also positioned in the mounting hole 31. The inlet portion 21 of the oil fill port 11 is defined by the end surface 32c of the throttle pipe 32 and the hole peripheral wall 31a of the attachment hole 31. Further, the shaft hole 32a of the throttle pipe 32 constitutes the intermediate portion 23 of the fuel fill inlet 11. Further, the end surface 32b of the throttle pipe 32 and the hole peripheral wall 31a of the mounting hole 31 define the injection portion 22 of the fuel fill port 11.

The ejection portion 22 of the present embodiment has the same shape as that of the portion of embodiment 2. In particular, a step 26 in which the flow path cross-sectional area is discontinuously increased is formed in the intermediate portion 23, i.e., a portion where the axial hole 32a of the throttle pipe 32 and the injection portion 22 are connected.

The inlet portion 21 of the present embodiment has the same shape as that of the portion shown in fig. 13. In particular, a step 25 in which the flow path cross-sectional area is discontinuously reduced is formed in a portion where the inlet portion 21 and the intermediate portion 23, that is, the axial hole 32a of the throttle pipe 32 are connected.

The present embodiment has the following effects, except for the same effects as those of embodiments 1 and 2 and their modifications. First, dimensional control at the time of providing the fuel fill port 11 in the casing 2 is easier than the case where the casing 2 itself is directly processed by excavation or the like to form the intermediate portion 23 and the injection portion 22 having a flow path cross-sectional area larger than the flow path cross-sectional area of the intermediate portion 23 is provided in the opening portion of the rotor chamber. The dimension control during processing is facilitated, and higher quality stability can be ensured. Further, by using different throttle pipes 32, the diameter Dm of the intermediate portion 23 of the fuel fill inlet 11 can be easily changed in accordance with the product use. Further, as the machining performed on the housing 2 to provide the fuel fill port 11, the machining of a step in which the flow path cross-sectional area is discontinuously increased or the machining of a tapered shape in which the flow path cross-sectional area is continuously enlarged is not necessary, and only the formation of the mounting hole 31 is required, so that man-hours can be reduced.

(test)

Tests for confirming the effects of the present invention were carried out. In this test, the oil-cooled screw compressor 1 according to embodiment 3 (the oil supply port 11 is formed by the throttle pipe 32 as shown in fig. 15) was used, and the oil-cooled screw compressor 1 shown in fig. 8 (the oil supply port 11 is a drilled hole having a constant diameter) was used as a comparative example. The oil-cooled screw compressors 1 (75 KW) were actually operated with two circulating oil amounts, and the adiabatic efficiency (the ratio of the theoretical power consumption to the actual power consumption) was determined. The discharge pressure of each oil-cooled screw compressor 1 was set to 0.7 MPa. The ambient temperature was 20 ℃.

In any of embodiment 3 and comparative example, the diameter Dm of the intermediate portion 23 of each of the 3 fuel-supply ports 11A to 11C is 4.4 times (Dm =4.4 × Wt) the shaft perpendicular crest width Wt of the tooth portion 4b of the female rotor 4.

In embodiment 3, the oil amount Q is determined with the circulating oil amount as a predetermined value₀(L/min) and about 1.4 XQ₀(L/min) insulation efficiency in operation. The circulating oil amount is Q₀The diameters Di of the injection portions 22 of the fuel supply ports 11A, 11B, and 11C at (L/min) are 2.2Dm (Di =2.2 × Dm), 2.9Dm (Di =2.9 × Dm), and 2.9Dm (Di =2.9 × Dm), respectively. On the other hand, the amount of the lubricating oil was 1.4 XQ₀The diameters Di of the injection portions 22 of the fuel supply ports 11A, 11B, and 11C at (L/min) are 1.7Dm (Di =1.7 × Dm), 2.2Dm (Di =2.2 × Dm), and 2.2Dm (Di =2.2 × Dm), respectively.

Fig. 18 shows the test results. As shown in fig. 18, it was confirmed that the oil-cooled screw compressor 1 according to embodiment 3 is improved in adiabatic efficiency by about 1% as compared with the comparative example.

Description of the reference numerals

1 oil-cooled screw compressor (liquid-cooled screw compressor)

2 casing

2a male rotor chamber

2b female rotor chamber

2c suction inlet

2d spout

2e, 2f cylindrical surface

2g, 2h end face

3 male rotor

3a rotor shaft

3b tooth part

4 female rotor

4a rotor shaft

4b tooth part

4c tooth groove

4d smooth surface

5A, 5B, 6A, 6B bearing

7 driving mechanism

11A, 11B, 11C oil supply port (liquid supply port)

12A, 12B air piping

13 separator

14 oil supply pipe

15 oil supply line (liquid supply line)

16 oil pump

21 inlet part

Sections 21a, 21b

22 jet part

22a opening part

Part 22b

23 intermediate part

23a end part

25. 26 step difference

31 mounting hole

Peripheral wall of hole 31a

32 throttle pipe

32a shaft hole

32b, 32c end faces.