JP2008267222A - Liquid-cooled type screw compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid-cooled type screw compressor reducing power loss after injection of coolant to a rotor chamber housing a screw rotor. <P>SOLUTION: The liquid-cooled type screw compressor has a pair of mutually meshed male and female screw rotors 2a, 2b. In the liquid-cooled type screw compressor, a liquid injection hole 15 is formed to a screw suction end surface 16 of the rotor chamber 4 housing the screw rotors 2a, 2b, and the coolant can be injected from the liquid injection hole 15 to a screw discharge direction. The liquid injection hole 15 is formed to the screw suction end surface of the rotor chamber 4 adjacent to suction side end surfaces of the screw rotors 2a, 2b, or is formed to a screw suction end surface 16 on a female rotor 2b side of the rotor chamber 4, so that the coolant can be injected from the liquid injection hole 15 to the screw discharge direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement in a mechanism for injecting a coolant into a rotor chamber that houses a screw rotor in a liquid-cooled screw compressor having a pair of male and female screw rotors that mesh with each other.

  The temperature of the screw rotor (hereinafter also referred to as the rotor) of the screw compressor increases as the fluid is compressed. Therefore, a cooling mechanism for cooling the screw rotor is essential. As such a cooling mechanism, supply of cooling air or cooling liquid by an external cooling device has been conventionally used.

  First, a general cooling mechanism of an oil-cooled screw compressor according to a conventional example using cooling oil as the cooling liquid will be described below with reference to FIG. FIG. 7 is a sectional view of an oil-cooled screw compressor according to a conventional example.

  The oil-cooled screw compressor 21 includes a pair of male and female screw rotors 22 that mesh with each other in the rotor casing 20. The screw rotor 22 is rotatably supported by a suction-side bearing portion 23 and a discharge-side bearing portion 24, and shaft sealing portions 25, 26 are interposed between the bearing portions 23, 24 and the screw rotor 22. Are provided respectively. Also, lubrication holes 28, 29, and 30 are provided for lubricating the bearing portions 23, 24, the shaft seal portions 25, 26, and the lubrication locations such as the rotor chamber 27 that is a gas compression space in the screw compressor 21. Yes. Furthermore, drain oil return passages 33 and 34 for discharging the injected oil and returning it to the suction port 32 are provided.

  The gas sucked into the screw compressor 21 from the suction passage 35 is compressed while receiving oil injection from the oil injection hole 30 and is discharged from the discharge port 36 as compressed gas together with the oil. Here, the oil injected into the rotor chamber 27 functions as cooling of the gas compression portion, sealing between the screw rotors 22 and between the screw rotor 22 and the inner wall portion of the rotor casing 20, and lubrication. Yes.

  The oil injected into the bearing portions 23 and 24 and the shaft seal portions 25 and 26 is returned to the suction port 32 by the drain oil return passages 33 and 34, sucked together with the gas, and discharged from the discharge port 36. . The discharged compressed gas and oil are separated from each other in an oil separation / recovery unit (not shown), and the compressed gas is sent out to the discharge passage 37.

  A screw compressor according to another conventional example will be described below with reference to FIGS. FIG. 8 is a front sectional view showing a rotor casing of a screw compressor according to a conventional example in a state where the screw rotor is omitted. FIG. 8 is a sectional view taken along line JJ in FIG. 9, and FIG. It is sectional drawing which shows KK.

  The screw compressor according to this conventional example is a liquid for cooling into the rotor chamber 39 at the edge of the suction port 40 forming the suction side opening of the rotor chamber 39 of the casing 41 housing a pair of male and female screw rotors that mesh with each other. A liquid injection opening 42, a cooling portion 43 extending along the surface layer of the wall portion 46 of the suction port 40, and reaching the liquid injection opening 42. A cooling liquid injection hole 45 comprising an introduction part 44 for guiding the working liquid is provided.

  With this configuration, the wall portion 46 of the suction port 40 is cooled by the coolant, the gas of the suction port portion 40 is cooled, and the screw rotor is cooled by the coolant injected from the liquid injection opening 42. The gas sucked in is cooled (see Patent Document 1).

  However, as shown in FIGS. 7 and 9, the coolant injection mechanism of the screw compressor according to the conventional example is provided on the rotor chamber side wall of the rotor casing that houses the screw rotor and the edge of the suction port. A liquid injection hole is provided in a direction perpendicular to the axis, and the cooling liquid is injected from the liquid injection hole. Problems with such a coolant injection mechanism will be described below with reference to FIGS. 10 is a front cross-sectional view showing a rotor chamber of a liquid-cooled screw compressor according to a conventional example, a cross-sectional view showing an arrow U-U in FIG. 11, and FIG. 11 is a cross-section showing an arrow V-V in FIG. FIG.

  Now, in the rotor chamber 51 provided in the rotor casing 50, if the pair of male and female rotors 52a and 52b rotate in the direction of the arrow R in the figure, the shafts of the rotors 52a and 52b from the liquid injection hole 53, respectively. The coolant injected in the direction perpendicular to the center (in the direction of arrow A) collides with the teeth of the female rotor 52b and changes its direction in the direction of rotation of the rotor 52b, that is, in the direction of arrow B. As a reaction, a reaction force in the direction of arrow D acts on the teeth of the female rotor 52b. Next, the direction of movement changes in the direction of arrow C at the meshing portion of the rotors 52a and 52b.

Since the coolant injected from the liquid injection hole in the direction perpendicular to the axial center of the rotors 52a and 52b, that is, in the direction of the arrow A does not have the momentum in the directions of the arrows B and C, the reaction force accompanying the direction change Acts on the female rotor 52b and is added as loss power to a drive motor (not shown) that drives the compressor. Although this loss amount is about 2 to 3% of the motor shaft power, there is no conventional example relating to the improvement of the coolant injection mechanism for the purpose of reducing such power loss.
Japanese Utility Model Publication No. 6-34189

  Accordingly, an object of the present invention is to provide a liquid-cooled screw compressor that can reduce power loss after injecting coolant into a rotor chamber that houses a screw rotor.

  In order to achieve the above object, the liquid-cooled screw compressor according to claim 1 of the present invention employs a screw compressor having a pair of male and female screw rotors that mesh with each other, and a rotor chamber that houses the screw rotor. A liquid injection hole is provided in the screw suction end face, and a coolant can be injected from the liquid injection hole toward the screw discharge direction.

  The means employed by the liquid-cooled screw compressor according to claim 2 of the present invention is the liquid-cooled screw compressor according to claim 1, wherein the liquid injection hole is close to the suction side end surface of the screw rotor. It is provided on the screw suction end face of the rotor chamber.

  The means employed by the liquid-cooled screw compressor according to claim 3 of the present invention is the liquid-cooled screw compressor according to claim 1 or 2, wherein the liquid injection hole is formed on the female rotor side of the rotor chamber. It is provided on the screw suction end face.

  According to the liquid-cooled screw compressor according to claim 1 of the present invention, a liquid injection hole is provided in the screw suction end face of the rotor chamber housing the screw rotor, and the coolant is supplied from the liquid injection hole toward the screw discharge direction. Therefore, the coolant has a momentum from the time of injection toward the screw discharge direction, and power loss due to the change of the motion direction after the coolant injection is eliminated.

  In the liquid-cooled screw compressor according to claim 2 of the present invention, the liquid injection hole is provided on a wall surface where the screw suction end surface of the rotor chamber is in contact with the suction side end surface of the screw rotor. Since the cooling liquid is injected from the direction toward the screw discharge direction, the screw rotor is in a state where the tooth groove of the screw rotor is closed, and there is no possibility that the cooling liquid flows backward.

  Furthermore, according to the liquid-cooled screw compressor according to claim 3 of the present invention, the liquid injection hole is provided in the screw suction end surface on the female rotor side where the tooth thickness of the rotor chamber is thin. The time required to close the opening of the liquid injection hole is shortened, and the liquid injection can be sufficiently performed with the small diameter liquid injection hole.

  First, a liquid-cooled screw compressor according to Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic explanatory view showing a cooling system of a liquid-cooled screw compressor according to Embodiment 1 of the present invention. 2 is a cross-sectional view taken along the line XX of the screw compressor of FIG. 1, and is a cross-sectional view taken along the line ZZ of FIG. 3 is a cross-sectional view taken along the line YY of FIG.

  The liquid-cooled screw compressor according to the first embodiment of the present invention is a compression in which a pair of male and female screw rotors 2a and 2b mesh with each other and are rotatably accommodated in a rotor chamber 4 formed inside the rotor casing 3. A machine body 1 is provided. A suction flow path 5 is connected to the suction port 1a of the compressor body 1, and one end side of the discharge flow path 6 is connected to the discharge port 1b. Only one male rotor 2 a of the pair of male and female screw rotors 2 a and 2 b constituting the compressor body 1 is connected to the drive shaft 7 of the drive motor M.

  By rotating the screw rotors 2a and 2b in the direction indicated by the arrow R in FIG. 2 by the drive motor M, the gas supplied from the suction passage 5 is sucked into the screw rotors 2a and 2b of the compressor body 1. The air is sucked in from the side (the left side of the rotor in FIG. 2), compressed, and discharged from the discharge side (the right side of the rotor in FIG. 2) of the screw rotors 2a and 2b as a high-pressure fluid into the discharge channel 6.

  The drive motor M is housed in a motor housing inside the motor casing 8, and the motor casing 8 is integrally coupled to the rotor casing 3. The drive motor M includes a stator (not shown) fixed to the inner surface of the motor casing 8 and a rotor (not shown) that rotates about the drive shaft 7 and is controlled to rotate by a controller. The drive motor M transmits the rotational force of the drive shaft 7 supported by the suction side bearing 9a and the discharge side bearing 9b to the screw rotors 2a and 2b of the compressor body 1.

  On the other hand, the suction flow path 5 is provided with a suction adjustment valve 5a for adjusting the flow rate of the gas passing through the suction flow path 5, and the valve opening degree is controlled by a controller. An oil separation / recovery device 10 is interposed in the discharge flow path 6, and an oil separation element 10 a is provided inside the oil separation / recovery device 10. Since the oil is slightly mixed in the high-pressure gas flowing into the oil separation / recovery device 10, the oil is captured by the oil separation element 10 a provided in the oil separation / recovery device 10. The oil trapped by the oil separation element 10a is dropped by its own weight, and an oil reservoir 10b is formed below the oil separation / recovery device 10 inside.

  The oil recovered in the oil reservoir 10b in this manner is circulated by an oil pump (not shown) through an oil circulation passage 11 communicating from the oil separator / collector 10 to the compressor body 1. An oil cooler 12 is interposed in the oil circulation passage 11, and the passing oil is cooled by controlling the temperature by a controller (not shown). And the oil cooled by the oil cooler 12 is supplied to the site | part which needs supply of oil through the oil supply flow path provided in the rotor casing 3. FIG. Such an oil supply passage includes an oil supply passage 13 to the suction side bearing (and shaft seal portion) 9a, an oil supply passage 14 to the discharge side bearing (and shaft seal portion) 9b, the screw rotors 2a and 2b, and the rotor casing. 3 is composed of an oil injection flow path 15 to the compression space formed by 3.

  And, as shown in FIGS. 2 and 3, an oil flow path 15 to the compression space formed by the screw rotors 2a and 2b and the rotor casing 3 is provided on the rotor casing 3 that houses the screw rotors 2a and 2b. And an oil introduction hole 15b (oil supply hole) drilled toward the discharge side until reaching the screw suction end face 16 of the rotor chamber 4 in communication with the oil introduction hole 15a. including. That is, the oil supply hole 15b is formed in substantially the same direction as the rotor shaft center. Cooling oil can be injected in the injection direction indicated by the arrow Q toward the discharge direction by the oil supply passage 15, particularly the oil supply hole 15 b in the oil supply passage 15.

  3 indicates a wall surface 16a corresponding to the screw suction end surface 16 of the rotor chamber 4 adjacent to the suction side end surfaces of the screw rotors 2a and 2b. Moreover, the part which is not hatched other than the part of two circles has shown the suction part channel | path 16b of the rotor chamber 4. FIG. As described above, the cooling oil injection mechanism according to the present invention has the cooling oil injection hole 15b provided on the wall surface 16a corresponding to the screw suction end face 16 of the rotor chamber 4 adjacent to the suction side end faces of the screw rotors 2a and 2b. Thus, it is preferable to inject cooling oil from the oil injection hole 15b toward the discharge direction.

  Note that the wall surface 16a and the suction side end surfaces of the screw rotors 2a and 2b are close to each other as described above, and a minute gap of, for example, about 0.2 mm is formed between them. By injecting the cooling oil in this manner, the oil is poured in a state where the tooth grooves of the screw rotors 2a and 2b are closed, so that the cooling oil does not flow backward.

  Further, it is preferable that the oil supply hole 15 b is provided in the screw suction end face 16 on the female rotor 2 b side of the rotor chamber 4. The tooth thickness of the female rotor 2b is thinner than the tooth thickness of the male rotor 2a. For this reason, providing the oil supply hole 15b in the screw suction end face 16 on the female rotor 2b side and opening the oil supply hole 15b is more effective than providing the oil supply hole 15b in the screw intake end face 16 on the male rotor 2a side. This is because the probability that the hole is blocked by the teeth of the rotor is low.

  When the injection speed of the cooling oil injected from the oil injection hole 15b is higher than the peripheral speed of the rotors 2a and 2b × tan (lead angle), the teeth collide with the teeth of the female rotor 2b at point P in FIG. Due to this collision, the female rotor 2b receives a force having a rotational direction component, and thus acts in the direction in which the shaft power of the drive motor M is reduced, contrary to the arrow D in FIG.

  Since the cooling oil injected into the rotor chamber 4 in this manner has the momentum indicated by the arrow Q in FIG. 2 from the time of injection, the cooling oil injected into the rotor chamber 4 which has been generated in the prior art is obtained. Power loss due to direction change is reduced. Even when the injection speed of the cooling oil injected from the oil injection hole 15b is equal to or less than the peripheral speed of the rotors 2a and 2b × tan (lead angle), the effect is reduced, but the cooling oil injection speed is reduced. Is larger than the peripheral speed x tan (lead angle) of the rotors 2a and 2b, the power loss is reduced.

  Next, a liquid-cooled screw compressor according to Embodiment 2 of the present invention will be described below with reference to FIG. FIG. 4 is a cross-sectional view in the same direction as FIG. 3 according to the second embodiment of the present invention. The difference between the second embodiment of the present invention and the first embodiment is that the arrangement of the oil injection holes 15b and the oil introduction holes 15a is different, and the others are completely the same. The explanation about is to be stopped.

  In the first embodiment of the present invention, the lubrication hole 15b is a wall surface 16a (hatching portion) corresponding to the screw suction end surface 16 of the rotor chamber 4 adjacent to the suction side end surfaces of the screw rotors 2a and 2b, as shown in FIG. The cooling oil is injected from the oil injection hole 15 toward the discharge direction. On the other hand, in the second embodiment of the present invention, the oil supply hole 15b is provided in the suction passage 16b (non-hatched part) of the rotor chamber 4 as shown in FIG. The cooling oil was injected toward the end. By adopting such a configuration, the power loss due to the change in direction of the cooling oil injected into the rotor chamber 4 after the injection into the rotor chamber 4 is reduced as compared with the prior art, and the same effect as in the first embodiment can be obtained. Is possible.

  Note that the liquid-cooled screw compressor according to the present invention may be either the first embodiment or the second embodiment. However, in the second embodiment, the oil is injected into the suction portion passage 16b where the tooth groove of the female screw rotor 2b is not closed, so that the cooling oil may flow backward, and the first embodiment is preferable.

  As described above, the liquid-cooled screw compressor according to the present invention is provided with the liquid injection hole in the screw suction end surface forming the rotor chamber of the rotor casing that houses the screw rotor, and the liquid injection hole is directed from the liquid injection hole toward the screw discharge direction. Thus, the cooling liquid can be injected, so that the cooling liquid has a momentum in the screw discharge direction from the time of injection, and the power loss due to the change of the movement direction after the cooling liquid is injected is eliminated. In addition, since the liquid injection hole is provided on the screw suction end surface on the female rotor side where the tooth thickness is thin, the time during which the hole of the liquid injection hole is blocked by the teeth of the screw is shortened, and cooling is performed with the small diameter liquid injection hole. It becomes possible to do.

  In the embodiment of the present invention, the example of the oil-cooled screw compressor using the cooling oil as the coolant has been described. However, the coolant used in the coolant injection mechanism of the liquid-cooled screw compressor according to the present invention is not limited to coolant oil. The present invention is also applicable to a screw compressor using a refrigerant (in the case of a heat pump or a refrigerator) or cooling water.

  In the first and second embodiments of the present invention described above, the oil supply hole 15b is formed in the substantially same direction as the rotor shaft center, but the present invention is not limited to this. For example, FIGS. 5 and 6 relate to Embodiment 3 of the present invention, FIG. 5 is a sectional view in the same direction as FIG. 2, and FIG. 6 is a sectional view in the same direction as FIGS. As shown in FIGS. 5 and 6, the lubrication hole 15b may be configured to be inclined so as to approach a line segment S located between the axis of the male rotor 2a and the axis of the female rotor 2b as it extends to the discharge side. good.

  The present invention can also be applied to, for example, a heat pump and a refrigerator.

It is typical explanatory drawing which shows the cooling system of the liquid cooling type screw compressor which concerns on Embodiment 1 of this invention. It is sectional drawing which shows arrow XX of the screw compressor of FIG. 1, and is sectional drawing which shows arrow ZZ of FIG. It is sectional drawing which concerns on Embodiment 1 of this invention and shows the arrow YY of FIG. FIG. 4 is a cross-sectional view in the same direction as FIG. 3 according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view in the same direction as FIG. 2 according to the third embodiment of the present invention. FIG. 4 is a cross-sectional view in the same direction as FIGS. 3 and 4 according to the third embodiment of the present invention. It is sectional drawing of the liquid cooling type screw compressor which concerns on a prior art example. It is sectional drawing which showed the rotor casing of the screw compressor which concerns on a prior art example in the state which abbreviate | omitted the screw rotor, and is sectional drawing which shows JJ of FIG. It is sectional drawing which shows the arrow KK of FIG. FIG. 12 is a cross-sectional plan view showing a rotor chamber of a liquid-cooled screw compressor according to a conventional example, and is a cross-sectional view showing UU in FIG. 11. It is sectional drawing which shows arrow VV of FIG.

Explanation of symbols

M: drive motor, P: point where the injected coolant collides with the teeth of the female rotor,
Q: Lubrication direction, R: Rotor rotation direction,
1: compressor body, 1a: suction port, 1b: discharge port,
2a: male rotor, 2b: female rotor,
3: rotor housing, 4: rotor chamber, 5: suction flow path, 6: discharge flow path,
7: Drive shaft, 8: Motor casing,
9a: suction side bearing, 9b: discharge side bearing,
10: Oil separation and recovery device, 10a: Oil separation element, 10b: Oil reservoir,
11: Oil circulation channel, 12: Oil cooler,
13: Lubrication channel to the suction side bearing (and shaft seal),
14: Lubrication flow path to the discharge side bearing (and shaft seal),
15: Lubrication channel to the compression space formed by the screw rotor and the rotor casing,
15a: oil introduction hole, 15b: oil injection hole,
16: Screw suction end face of the rotor chamber,
16a: a wall surface where the screw suction end surface of the rotor chamber contacts the suction side end surface of the screw rotor;
16b: suction part passage

Claims (3)

  In a liquid-cooled screw compressor having a pair of male and female screw rotors that mesh with each other, a liquid injection hole is provided in a screw suction end surface of a rotor chamber that houses the screw rotor, and cooling liquid is supplied from the liquid injection hole toward the screw discharge direction. A liquid-cooled screw compressor characterized in that it can be injected.   The liquid-cooled screw compressor according to claim 1, wherein the liquid injection hole is provided in a screw suction end surface of the rotor chamber adjacent to a suction side end surface of the screw rotor. 3. The liquid-cooled screw compressor according to claim 1, wherein the liquid injection hole is provided in a screw suction end face on a female rotor side of the rotor chamber.

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