JPH11351168A - Screw type refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw type refrigerating device capable of uniformly cooling from the upper side to the lower side of a motor and enlarging a high- load operating range. SOLUTION: This screw type refrigerating device stores a screw rotor 25 in a rotor casing 26 integrally formed with a motor casing 27 for a motor 23 for driving a screw rotor 25, has a suction port 35 communicating with cavities 7, 34B in the motor casing 27, includes a closed cooling medium circulation flow passage 1 containing a semi-closed screw compressor 1 for sucking cooling medium gas to be compressed from the cavities 7, 34B as well as a condenser, an expansion valve and an evaporator, and a liquid injection flow passage 11 for guiding the cooling medium parted from an area between the condenser and the expansion valve from a liquid injection hole 6 formed in the end face 30 of the motor casing 27 into the motor casing 27. The suction port 35 is formed under the axial center of the rotor 29 in the motor 23 and the liquid injection hole 6 is formed above the axial center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw type refrigerating apparatus using a semi-hermetic screw compressor for guiding a circulating refrigerant into a screw rotor driving motor before sucking the refrigerant and cooling the motor.

[0002]

2. Description of the Related Art Conventionally, a screw type refrigerating apparatus using a semi-hermetic screw compressor shown in FIGS. 5 and 6 has been known.
The refrigerating apparatus includes, in addition to the screw compressor 21, a closed refrigerant circulation flow path including at least a condenser (not shown), an expansion valve, and an evaporator, and generates heat in the condenser as is well known. The evaporator generates cold heat. The screw compressor 21 has a motor casing 23 on one side of a compressor main body 22 and an oil separation / collection unit 24 on the other side, and a rotor casing containing a pair of male and female screw rotors 25 meshing with each other of the compressor main body 22. 26, a motor casing 27 of the motor 23 and a casing 28 of the oil separation and recovery unit 24 are integrally formed. One of the paired screw rotors 25 shares an axis with the rotor 29 of the motor 23.

[0003] An end face 30 on one side of the motor casing 27 is formed with an inlet 31 through which the refrigerant gas from the evaporator flows, and this refrigerant gas is filtered from the inlet 31 as indicated by a solid line arrow. 32, and flows into the motor casing 27, and a gap in the motor casing 27, that is, the motor casing 2
Through a gap 34A between the stator 7 and the stator 33 and a gap 34B between the stator 33 and the rotor 29, the air is guided to a suction port 35 communicating with the gaps 34A and 34B. A liquid injection hole 36 is formed on the side of the inflow port 31 of the end face 30 to guide the refrigerant liquid branched from the portion of the refrigerant circulation flow path between the condenser and the expansion valve into the motor 23. The refrigerant liquid is sprayed from the liquid injection hole 36 as shown by a two-dot chain line arrow and guided to the voids 34A and 34B.

The motor 23 uses a refrigerant gas from the liquid injection hole 36 together with the refrigerant gas from the inflow port 31 passing through the gaps 34A and 34B, thereby including a motor coil, especially a motor coil which is easily overheated. The stator 33 is cooled. The refrigerant liquid from the liquid injection hole 36 is supplied to the voids 34A,
The refrigerant gas becomes a refrigerant gas in the process of passing through 34B, and is sucked from the suction port 35 together with the refrigerant gas from the inflow port 31. Incidentally, a lower portion of the oil separation and recovery unit 24 is an oil sump 37, and an oil sump 37
Is guided to a lubrication point such as a bearing / shaft seal portion, a rotor chamber, etc. in the compressor main body 22.

[0005] In the compressor body 22, the refrigerant gas sucked from the suction port 35 is compressed while receiving oil injection, and is compressed.
8 is discharged with oil. The refrigerant gas accompanying the oil is gas-liquid separated by an oil separation element 39 in the oil separation and recovery unit 24, and the oil is temporarily stored in an oil storage unit 37,
It flows into the oil supply channel. On the other hand, the compressed refrigerant gas from which oil has been separated is sent out from the screw compressor 21 by a discharge pipe 40 extending from the oil separation element 39, guided to the condenser, and circulated through the refrigerant circulation flow path.

[0006]

In the case of the above-mentioned conventional screw type refrigerating apparatus, the suction port 35 is located below the axis of the rotor 29, the liquid injection hole 36 is near the inflow port 31, and It is located on its side. Therefore, most of the refrigerant liquid sprayed from the liquid injection hole 36 flows downward as indicated by the arrow. A gap 34A between the motor casing 27 and the stator 33 is disposed on the outer peripheral portion of the stator 33 so as to have an equal angular interval over the entire circumference and an equal cross-sectional area.

For this reason, the liquid injection hole 36
Most of the refrigerant liquid flowing from above does not flow to the gap 34A above the axis of the rotor 29, but flows to the gap 34A below. As a result, when the load on the motor 23 is large, the lower part of the motor 23 is cooled, but the degree of superheat at the upper part cannot be reduced. Normally, when the degree of superheat is increased, the motor protector is operated, and the screw compressor 21 is stopped in an emergency. Therefore, in the case of the above-described device, there is a problem that an operation range under a high load is limited. SUMMARY OF THE INVENTION The present invention has been made to eliminate such a conventional problem, and has provided a screw refrigeration apparatus capable of uniformly cooling from an upper part to a lower part of a motor and capable of expanding an operation range under a high load. It is something to offer.

[0008]

In order to solve the above-mentioned problems, a first invention is to accommodate the above-mentioned screw rotor in a rotor casing integrally formed with a motor casing of a motor for driving the screw rotor, wherein a suction port is provided. A closed refrigerant circulation flow path including at least a condenser, an expansion valve, and an evaporator, in addition to a semi-hermetic screw compressor that communicates with a gap in the motor casing and sucks and compresses a refrigerant gas from the gap. And a liquid injection hole formed on the end face of the motor casing opposite to the rotor casing, the refrigerant liquid branched from a portion between the condenser and the expansion valve in the refrigerant circulation flow path. A screw type refrigeration apparatus having a liquid injection flow path for guiding the liquid injection into the motor casing. Hall, to the side where the inlet is positioned with respect to the axis of the rotor in the motor and formed so as to be located on the opposite side.

According to a second aspect of the present invention, the screw rotor is housed in a rotor casing formed integrally with a motor casing of a motor for driving the screw rotor, and a suction port communicates with a gap in the motor casing. In addition to the semi-hermetic screw compressor that sucks and compresses the refrigerant gas from the gap, at least a condenser, economizer,
A closed refrigerant circulation flow path including a first expansion valve and an evaporator is provided, and the refrigerant circulation flow path branches from a portion between the economizer and the first expansion valve, and passes through a second expansion valve. An economizer flow path that passes through the economizer separately from the portion of the refrigerant circulation flow path in the economizer and that can exchange heat to reach a refrigerant gas compression space in the compressor body of the screw compressor; (2) a liquid injection passage for guiding the refrigerant liquid branched on the primary side or the secondary side of the expansion valve from the liquid injection hole formed in the end face of the motor casing on the opposite side to the rotor casing into the motor casing. In the screw-type refrigeration apparatus provided, the liquid injection hole is positioned such that the suction port is positioned with respect to the axis of the rotor of the motor. The side was formed so as to be located on the opposite side.

In a third aspect of the present invention, the cross section of the gap between the motor casing and the stator in the gap is formed such that the liquid injection hole is located at a position closer to the axis than the side where the suction port is located. It was formed so that the side where is located was larger.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 to 3 show a screw-type refrigeration apparatus according to a first embodiment of the present invention. Parts common to the screw-type refrigeration apparatuses shown in FIGS. . In FIG. 1, * and * indicate that they are continuous. This screw-type refrigeration apparatus includes a closed refrigerant circulation flow path I including a screw compressor 1, a condenser 2, a first expansion valve 3, and an evaporator 4, and a refrigerant between the condenser 2 and the first expansion valve 3. A liquid injection flow path II that branches off from the circulation flow path I and reaches the screw compressor 1 via an on-off valve 5, for example, an electromagnetic on-off valve.

The screw compressor 1 has a liquid injection hole 6 instead of the above-described liquid injection hole 36, and has a gap 7 instead of the above-described gap 34A. The liquid injection hole 6 is formed so as to be located on the opposite side of the axis of the rotor 29 from the side where the suction port 35 is located. Specifically, in the case of the illustrated apparatus, the liquid injection hole 6 is located above because the suction port 35 is located below. The liquid injection channel 6 is connected to the liquid injection hole 6.

The void 7 is provided with a liquid injection hole 6
The upper part is formed so that the cross section is larger at the upper part than at the lower part. The oil in the oil sump 37 is supplied from the screw compressor 1 via the oil cooler 8, the oil filter 9 and the oil pump 10 to the compressor main body 2.
An oil supply passage III extending to an oil supply point such as a bearing / shaft seal portion, a rotor chamber, or the like in 2, extends. This kind of oil supply channel III
Are well-known, and various configurations are known, and are not limited at all.

The compressor main body 22 includes a temperature sensor or a pressure sensor (not shown) provided in the compressor main body 22.
When the detected temperature or the detected pressure in the refrigerant flowing portion is equal to or higher than the set value, the on-off valve 5 is controlled to be in the open state, and the liquid injection passage II allows the refrigerant liquid to function as an orifice. From inside the motor casing 27. As described above, in the case of this screw compressor 1, the suction port 35 is located below, and the liquid injection hole 6
Is located above, the refrigerant liquid from the liquid injection hole 6 flows not only in the lower part of the motor casing 27 but also in the upper part.

Further, as shown in FIG. 3, in the screw compressor 1, the cross section of the cavity 7 is formed so that the upper part is larger than the lower part, and the upper part is larger than the lower part. The refrigerant flows more easily. Therefore, in the screw compressor 1, the gap 7 between the motor casing 27 and the stator 33 and the gap 34 </ b> B between the stator 33 and the rotor 29 are uniformly distributed from the upper portion to the lower portion. Flows in,
With the heat of vaporization, the motor 23, particularly the stator 33, is cooled as a whole and efficiently uniformly. As a result, the operating range of the screw-type refrigeration system under a high load is expanded.

FIG. 4 shows a screw type refrigerating apparatus according to a second embodiment of the present invention, and the same parts as those of the above-mentioned screw type refrigerating apparatuses are denoted by the same reference numerals and the description thereof will be omitted. As in the above description, also in FIG. 4, the “*” and “*” indicate that they are continuous. In this screw refrigerating apparatus, an economizer 11 is provided in a portion of a refrigerant circulation flow path I between a condenser 2 and a first expansion valve 3, and a condenser is provided instead of the liquid injection flow path II in the first embodiment. Branching from the portion of the refrigerant circulation flow path I between the second expansion valve 3 and the first expansion valve 3, the heat is exchanged separately from the portion of the refrigerant circulation flow path I in the economizer 11 through the second expansion valve 12 and heat exchange. An economizer flow path IV that passes through the economizer 11 and reaches the refrigerant gas compression space in the compressor main body 22 and a refrigerant liquid branched on the secondary side of the second expansion valve 12 via the on-off valve 5. And a liquid injection flow path V for spraying into the motor casing 27 from a liquid injection hole 36 functioning as an orifice.

The refrigerant liquid in the refrigerant circulation channel I is supercooled by the economizer 11 to improve the coefficient of performance of the screw type refrigeration system. In addition,
The economizer 11 itself is conventionally known. On the other hand, the on-off valve 5 is controlled in the same manner as described above, and the refrigerant liquid which has exited the second expansion valve 12 and has dropped in temperature and pressure is guided into the motor casing 27 from the liquid injection hole 36 in the same manner as described above. The liquid injection flow path V is not necessarily the second
It is not necessary to branch to the expansion valve 12 on the secondary side, and it may be branched to the second expansion valve 12 on the primary side as shown by an arrow X in FIG.

Also in the second embodiment, since the screw compressor 1 is common to the first embodiment, the cooling is efficiently and uniformly performed from the upper part to the lower part of the motor 23 as described above. The operating range of the screw-type refrigeration system under a high load is expanded. Although the screw compressor in each of the above-described embodiments has the suction port 35 below the axis of the rotor 29, the present invention is not limited to this. In this case, the liquid injection hole 6 is located below the axis.
The screw compressor 21 is not limited to a single-stage screw compressor, but may be a multi-stage screw compressor having two or more screw rotors.

[0019]

As is apparent from the above description, according to the first aspect, the screw rotor is housed in a rotor casing integrally formed with a motor casing of a motor for driving the screw rotor, and the suction port is provided with the above-described suction port. In addition to the semi-hermetic screw compressor, which communicates with the gap in the motor casing and sucks and compresses the refrigerant gas from this gap,
At least a condenser, an expansion valve, and a closed refrigerant circulation flow path including an evaporator are provided. The refrigerant liquid branched from a portion between the condenser and the expansion valve in the refrigerant circulation flow path is supplied to the rotor. In a screw-type refrigeration apparatus having a liquid injection flow path that leads into the motor casing from a liquid injection hole formed on an end surface of the motor casing on the opposite side of the casing, the liquid injection hole includes a shaft center of a rotor of the motor. Is formed on the side opposite to the side where the suction port is located.

According to the second invention, the screw rotor is housed in a rotor casing formed integrally with a motor casing of a motor for driving the screw rotor, and a suction port communicates with a gap in the motor casing. A closed refrigerant circulation flow path including at least a condenser, an economizer, a first expansion valve, and an evaporator, in addition to a semi-hermetic screw compressor for sucking and compressing the refrigerant gas from the gap, Branching from a portion of the circulation flow path between the economizer and the first expansion valve,
An economizer that passes through the economizer through the second expansion valve and separately and heat-exchangeably from the portion inside the economizer of the refrigerant circulation flow path to reach the refrigerant gas compression space in the compressor body of the screw compressor. The flow path and the refrigerant liquid branched on the primary side or the secondary side of the second expansion valve are introduced into the motor casing from a liquid injection hole formed on the end face of the motor casing on the side opposite to the rotor casing. In a screw type refrigerating apparatus having a liquid injection flow path, the liquid injection hole is formed so as to be located on a side opposite to a side where the suction port is located with respect to an axis of a rotor of the motor. . As a result, the refrigerant liquid sprayed into the motor casing spreads from the upper part to the lower part of the motor, and the motor can be cooled uniformly and efficiently efficiently, and the operating range under high load can be expanded. This has the effect of becoming

Further, according to the third aspect of the present invention, the cross section of the gap between the motor casing and the stator in the gap is formed so that the cross section of the liquid is larger than the side where the suction port is located with respect to the axis. It is formed so that the side where the injection hole is located is larger. For this reason, there is an effect that the effects of the first and second aspects of the invention are made more remarkable.

[Brief description of the drawings]

FIG. 1 is a view showing an entire configuration of a screw type refrigeration apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a semi-hermetic screw compressor in the apparatus shown in FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a view showing an entire configuration of a screw type refrigeration apparatus according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a semi-hermetic screw compressor in a conventional screw refrigeration apparatus.

6 is a sectional view taken along line VI-VI of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Screw compressor 6 Liquid injection hole 7 Void 23 Motor 25 Screw rotor 26 Rotor casing 27 Motor casing 29 Rotor 30 End face 34B Void 35 Suction port I Refrigerant circulation channel II Liquid injection channel

Claims (3)

[Claims] 1. The screw rotor is housed in a rotor casing integrally formed with a motor casing of a motor for driving the screw rotor, and a suction port communicates with a gap in the motor casing. In addition to a semi-hermetic screw compressor that sucks and compresses gas, it has a closed refrigerant circulation channel including at least a condenser, an expansion valve and an evaporator, and the condenser and the condenser in the refrigerant circulation channel. A screw-type refrigeration provided with a liquid injection flow path for guiding a refrigerant liquid branched from a portion between the expansion valve and a liquid injection hole formed in an end face of the motor casing opposite to the rotor casing into the motor casing. In the apparatus, the liquid injection hole is provided with respect to an axis of a rotor of the motor. A screw-type refrigerating device, wherein the refrigerating device is formed so as to be located on a side opposite to a side where a suction port is located. 2. The screw rotor is housed in a rotor casing integrally formed with a motor casing of a motor for driving the screw rotor, and a suction port communicates with a gap in the motor casing. In addition to a semi-hermetic screw compressor for sucking and compressing gas, at least a condenser, an economizer, a first expansion valve and a closed refrigerant circulation channel including an evaporator,
The refrigerant circulating flow path branches off from the portion between the economizer and the first expansion valve, passes through the second expansion valve, and is separated from the portion of the refrigerant circulating flow path inside the economizer and heat-exchanged. An economizer flow path that passes through the economizer and reaches a refrigerant gas compression space in the compressor body of the screw compressor, and a refrigerant liquid branched on the primary side or the secondary side of the second expansion valve. In a screw-type refrigeration system having a liquid injection passage formed in the motor casing from a liquid injection hole formed on an end face of the motor casing on the side opposite to the rotor casing, the liquid injection hole is provided with a rotor of the motor. A screw type formed so as to be located on a side opposite to a side where the suction port is located with respect to an axis. Freezing equipment. 3. A cross section of the gap between the motor casing and the stator in the gap, the cross section of the gap between the liquid injection hole and the side where the suction port is located with respect to the axis. The screw refrigeration device according to claim 1, wherein the screw refrigeration device is formed so as to be larger.