JPH05106572A - Single shaft type screw compressor - Google Patents

Abstract

PURPOSE:To decrease generation of beating sound raising a sense of uncomfort by reducing vibration of a drive shaft. CONSTITUTION:A screw rotor 11 mounted on the drive shaft 10 of a motor 9 borne rotatably by bearings 12a, 12b is pressed by a differential pressure of fluid to one side in radial direction of the rotor 11, which is achieved for example by changing the moving direction length of slide valves 18a, 18b for changing the capacity ratio of a compression chamber, and thereby the drive shaft 10 is pressed to one side in radial direction of the bearings 12a, 12b to lessen vibration caused by unbalanced rotating of the drive shaft 10, compared with the case without such pressing. Thus generation of the beating sound raising a sense of uncomfort is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-screw type screw compressor, and more specifically, a motor having a motor and a screw rotor attached to the drive shaft of the motor, which is mounted in a casing through a bearing provided in front of and behind the screw rotor. The present invention relates to a uniaxial screw compressor rotatably supported.

[0002]

2. Description of the Related Art Conventionally, a uniaxial screw compressor in which a screw rotor is mounted on a drive shaft of a motor and the motor drives the screw rotor is disclosed in, for example, Japanese Patent Laid-Open No. 3-26879.

As shown in FIG. 7, this single-screw type screw compressor has a casing D provided with a fluid suction portion B at one end and an oil separator C at the other end, and a stator E and A motor G including a rotor F and a screw rotor I mounted on a drive shaft H of the motor G are internally provided, and a bearing J provided with the drive shaft H between the screw rotor I and the motor G. , Rotatably supported via a bearing K provided on the oil separator C side of the screw rotor I from the suction portion B to the screw rotor I.
The low-pressure fluid sucked into a pair of compression chambers (not shown) formed at symmetrical positions in the radial direction is compressed and discharged to the oil separator C.

[0004]

However, an effective gap δ exists between the drive shaft H and the roller M of the bearing J as shown in an enlarged view in FIG. Since the chambers are arranged at symmetrical positions in the radial direction with respect to the drive shaft H, for example, the drive shaft H rotates with respect to the bearing J while rotating as shown by the arrow in FIG. Causes whirling as indicated by the dotted line, and the whirling causes the drive shaft H to vibrate. Therefore, due to the vibration of the drive shaft H, the gap between the stator E and the rotor F forming the motor G is also reduced to the drive shaft H.
Of the stator E
The magnetic flux density between the rotor F and the rotor F becomes unbalanced, and due to this magnetic flux density imbalance, a beat noise is generated at a beat cycle indicated by 2sf (s is a slip ratio, f is a power supply frequency), which causes discomfort. There was a problem.

An object of the present invention is to provide a uniaxial screw compressor which can reduce the vibration of the drive shaft to reduce the generation of whining noise which causes discomfort.

[0006]

The present invention is a casing 1
A uniaxial screw compression in which a motor 9 and a screw rotor 11 attached to a drive shaft 10 of the motor 9 are internally mounted, and the drive shaft 10 is rotatably supported via bearings 12a and 12b provided in front of and behind the screw rotor 11. In the machine, a differential pressure pressing means 24 for pressing the screw rotor 11 on one side in the radial direction of the rotor 11 with a differential pressure of fluid is provided.

Further, a pair of slide valves 18a, 18b for variably controlling the capacity are provided in the casing 1 symmetrically outward in the radial direction of the screw rotor 11 and movable in the axial direction of the screw rotor 11. Therefore, it is preferable to make the lengths of the slide valves 18a and 18b in the moving direction different so as to change the volume ratio of the pair of compression chambers 16a and 16b defined in the casing 1.

Further, a pair of liquid injection passages 33a, 3 are provided at radially symmetrical positions of the screw rotor 11 at an intermediate portion of the compression process in the pair of compression chambers 16a, 16b.
3b is opened to allow these liquid injection passages 33
a and 33b, the other liquid injection passage 33b or 33a corresponding to the injection amount from one liquid injection passage 33a or 33b
It is preferable to provide an injection amount changing means 34 for changing the injection amount from.

Further, in the above structure, a pair of oil supply passages 44a, 44b are used instead of the pair of liquid injection passages 33a, 33b.
b to at least one of the oil supply passages 44a or 44
The other oil supply passage 44b or 44 for the amount of oil supplied from b
It is preferable to provide oil supply amount changing means 45 for changing the amount of oil supply from a.

Further, a pair of liquid injection passages 33
a, 33b and a pair of oil supply passages 44a, 44b are replaced by a pair of economizer passages 55a, 55b, and the amount of refrigerant injected from one economizer passage 55a or 55b to at least one of these economizer passages 55a, 55b. The other economizer passage 55b or 5 to
Refrigerant injection amount changing means 5 for changing the refrigerant injection amount from 5a
6 may be provided.

[0011]

The pressure difference pressing means 2 for pressing the screw rotor 11 to one side in the radial direction of the rotor 11 by the pressure difference of the fluid.
4, the drive shaft 10 can be pressed together with the screw rotor 11 in the radial direction one side of the rotor 11, and the drive shaft 10 can be driven by pressing the drive shaft 10 in the radial direction one side of the bearings 12a, 12b. Vibration caused by whirling of the shaft 10 can be reduced as compared with the case where no pressure is applied. Therefore, the vibration of the drive shaft 10 can be reduced and the growling noise that causes discomfort can be reduced.

Further, a pair of slide valves 18a, 18b for variably controlling the capacity are provided in the casing 1 symmetrically outward in the radial direction of the screw rotor 11 and movable in the axial direction of the screw rotor 11. When the lengths of the slide valves 18a and 18b in the moving direction are made different and the volume ratio of the pair of compression chambers 16a and 16b defined in the casing 1 is changed, the timing of discharging from one compression chamber 16a or 16b To the other compression chamber 16b or 16a
Can be shifted with respect to the discharge timing from 1
1 due to the pressure difference between the internal pressures of the pair of compression chambers 16a and 16b
From the pair of compression chambers 16a, 16b to the screw rotor 1
1, the pressure balance of the fluid acting in the radial direction is disturbed, and the screw rotor 11 together with the drive shaft 10 can be pressed to one side in the radial direction of the screw rotor 11.

Therefore, a pair of slide valves 18a, 18b
Since the screw rotor 11 can be pressed to one side in the radial direction together with the drive shaft 10 by making the lengths of the drive shaft 10 different in the moving direction, vibration due to whirling of the drive shaft 10 is not affected by operating conditions. In addition, it is possible to reduce the amount, and it is not necessary to change the amount of liquid injection when performing liquid injection in the intermediate portion of the compression process of the pair of compression chambers or the amount of oil for injecting lubricating oil in order to improve the operating state. Further, even when the intercooling refrigerant in a liquid-gas mixed state is injected using the economizer pipe to improve the operating state, the amount of the intercooling refrigerant injected is not changed and vibration due to whirling of the drive shaft 10 is reduced. , Can reduce the growling noise. Therefore, the beat noise can be reduced without changing the liquid injection amount or the injection amount of the intermediate cooling refrigerant in the system for improving the operating state, or the oil injection amount can be reduced, and the versatility can be broadened. ..

Further, a pair of liquid injection passages 33a, 3 are provided at radially symmetrical positions of the screw rotor 11 at an intermediate portion of the compression process in the pair of compression chambers 16a, 16b.
3b is opened to allow these liquid injection passages 33
a and 33b, the other liquid injection passage 33b or 33a corresponding to the injection amount from one liquid injection passage 33a or 33b
When the injection amount changing means 34 for changing the injection amount from the above is provided, the injection amount changing means 34 causes the pressure drop of the compression chamber 16a or 16b having the larger liquid injection amount to the compression chamber 16b having the smaller liquid injection amount. Alternatively, since the pressure can be increased as compared with the pressure drop of 16a, a differential pressure is generated between the internal pressures of the pair of compression chambers 16a and 16b, and this differential pressure causes the screw rotor 11 to move in the radial direction of the screw rotor 11 together with the drive shaft 10. The screw rotor 11 can be pressed to one side, and while the efficient operation can be performed without changing the internal volume ratio of the pair of compression chambers 16a and 16b, the screw rotor 11 can be operated by using the injection amount changing means 34. Is pressed to one side in the radial direction together with the drive shaft 10, so this can be It can be easily reduced vibration caused by whirling of the drive shaft 10 it is possible to adjust the pressure.

Further, in the above construction, a pair of oil supply passages 44a, 44b are used instead of the pair of liquid injection passages 33a, 33b.
4b to at least one oil supply passage 44a or 4
The other oil supply passage 44b or 4 for the amount of oil supplied from 4b
When the oil supply amount changing means 45 for changing the oil supply amount from 4a is provided, the pair of compression chambers 16 is operated by the oil supply amount changing means 45.
a, 16b are made different in the amount of oil to be supplied to generate a pressure difference between the internal pressures of the pair of compression chambers 16a, 16b, and the screw rotor 11 is pressed together with the drive shaft 10 to one side in the radial direction of the screw rotor 11. be able to. Therefore, also in this case, while performing efficient operation without changing the internal volume ratio of the pair of compression chambers 16a and 16b,
Vibration due to whirling of the drive shaft 10 can be easily reduced by an external operation, and the vibration due to whirling of the drive shaft 10 can be reduced without being affected by operating conditions.

Also, a pair of liquid injection passages 33
a, 33b or a pair of oil supply passages 44a, 44b,
Using a pair of economizer passages 55a and 55b, at least one of these economizer passages 55a and 55b,
The amount of refrigerant injected from one economizer passage 55a or 55b to the other economizer passage 55b or 55a
In the case where the refrigerant injection amount changing means 56 for changing the refrigerant injection amount is provided, the refrigerant injection amount changing means 56 causes the pressure drop of the compression chamber 55a or 55b having the larger injection amount to the compression chamber having the smaller injection amount. Since it can be made larger than the pressure drop of 55b or 55a, a differential pressure is generated between the internal pressures of the pair of compression chambers 16a, 16b, and this differential pressure causes the screw rotor 11 to move together with the drive shaft 10 and the screw rotor 1
It can be pressed to one side in the radial direction of No. 1.

Therefore, the pair of liquid injection passages 3
3a, 33b and a pair of oil supply passages 44a, 44b are provided, it is possible to perform an efficient operation without changing the internal volume ratio of the pair of compression chambers 16a, 16b, and easily by an external operation. Vibration caused by whirling of the drive shaft 10 can be reduced.

[0018]

EXAMPLE As shown in FIG. 4, the single-screw compressor shown in FIGS. 1 and 2 is provided with an oil separator 2 on the discharge side of a casing 1, and is connected to the discharge side of this oil separator 2. It is used for a refrigeration system in which a condenser 3, an expansion valve 4 and an evaporator 5 are sequentially connected between the casing 1 and the suction side by a refrigerant pipe 6, and the casing 1 includes a stator 7 and a rotor. And a drive shaft 10 for the motor 9.
And a screw rotor 11 mounted inside the motor, and the drive shaft 10 is provided between the screw rotor 11 and the motor 9.
Is rotatably supported via a bearing 12b provided on the oil separator 2 side.

Further, on both sides in the radial direction of the screw rotor 11, as shown in FIG. 2, a pair of gate rotors 14a, 1 which engage with the groove 13 of the screw rotor 11 are formed.
4b to provide the groove 13 and the gate rotor 14
a, 14b and the inner peripheral wall 15 of the casing 1 that surrounds the outer peripheral portion of the screw rotor 11 in an airtight manner,
A pair of compression chambers 16a and 16b having the same volume are formed at radially symmetrical positions with respect to the central axis of the screw rotor 11, and the pair of compression chambers are driven by the rotation of the motor 9 to drive the screw rotor 11. The low pressure refrigerant sucked into 16a, 16b is compressed, and the compressed refrigerant is returned to the suction side of the casing 1 from the oil separator 2 through the condenser 3, the expansion valve 4 and the evaporator 5 in sequence. I try to circulate it.

Further, the drive shaft 1 is provided on the inner peripheral wall 15.
A pair of sliding grooves 17 extending in the same direction as 0 extends.
a and 17b are provided so that one pair of sliding grooves 17a and 17b
A pair of slide valves 18a and 18b are slidably arranged, and a connecting rod 21 that interlocks with the movement of a piston 20 installed in a piston chamber 19 is provided on the oil separator 2 side of the screw rotor 11. A rod 22 in which both ends of this connecting rod 21 are connected to a pair of slide valves 18a, 18b
a, 22b, and the movement of the piston 20 causes 1
The pair of slide valves 18a and 18b are simultaneously slid to slide the pair of slide valves 18a and 18b and the rods 22a and 2b.
Rod supporting members 23a, 23 slidably supporting 2b
The capacity of the uniaxial screw compressor can be controlled by changing the width of the gap with b.

Therefore, in the above construction, the differential pressure pushing means 24 for pushing the screw rotor 11 to the radial direction one side of the rotor 11 by the differential pressure of the fluid is provided.

That is, the differential pressure pressing means 24 of the embodiment shown in FIG. 1 is constructed by using a pair of slide valves 18a, 18b slidably arranged in the two slide grooves 17a, 17b. Therefore, of the pair of slide valves 18a and 18b, for example, the slide valve 1 shown on the lower side in FIG.
The moving direction length L of the slide valve 18b is made shorter than that of the slide valve 18a shown on the upper side in FIG. 1, regardless of the moving positions of the pair of slide valves 18a and 18b.
The gap between the rod support member 23b and the slide valve 18a is set to be slightly wider than the gap between the slide valve 18a and the rod support member 23a, and the timing at which the fluid consisting of the refrigerant gas is discharged from the compression chamber 16b is set to be greater than the timing at which the fluid is discharged from the compression chamber 16a. A little earlier, the screw rotor 11 is moved to the rotor 11 by the differential pressure of the refrigerant in the pair of compression chambers 16a and 16b.
It is configured so that it can be pressed to one side in the radial direction.

Next, the operation of the single-screw screw compressor constructed as described above will be described.

That is, the pair of slide valves 18a and 18b simultaneously slide along the axial direction of the screw rotor 11 in accordance with the movement of the piston 20, and the length of the slide valve 18b is Since the slide valve 18a is slightly shorter than the length of the slide valve 18a, the refrigerant is compressed in the compression chamber 16a.
The timing of discharging from b is slightly earlier than the timing of discharging from the compression chamber 16a. That is, the volume of the compression chamber 16b is slightly smaller than that of the compression chamber 16a. Therefore, the compression chamber 16
The refrigerant compressed in the compression chamber 16b is discharged from the compression chamber 16b shortly before the refrigerant compressed in a is discharged from the compression chamber 16a.
Since the pressure of the refrigerant radially acting on the screw rotor 11 from 16b can be made asymmetric, the screw rotor 11 together with the drive shaft 10 is moved from the compression chamber 16a side to the compression chamber 16b side, that is, in the radial direction one side. Can be pressed,
The drive shaft 10 can be pressed to one side in the radial direction of each bearing 12a, 12b.

Therefore, the drive shaft 10 is connected to the bearing 12
Since the vibration of the casing 1 due to the whirling of the drive shaft 10 can be brought into the state shown in FIG. 3 by pressing the a and 12b to one side in the radial direction, the screw rotor 11 shown in FIG. The vibration can be reduced as compared with the vibration when the pressure is not applied to one side in the direction.
The vibration of 0 can be reduced and the growling noise that causes discomfort can be reduced as much as possible.

Further, in the first embodiment described above, the pair of slide valves 18a, 18b symmetrically provided on the outer side in the radial direction of the screw rotor 11 have different lengths in the moving direction so that the screw rotor 11 is not moved. Since it is pressed to one side in the radial direction together with the drive shaft 10, vibration can be reduced without being affected by operating conditions, and as will be described later, in order to improve the operating state, a pair of compression chambers There is no need to change the amount of liquid injection when performing liquid injection to the intermediate part of the compression process, or the amount of oil to inject lubricating oil, and to inject the intermediate cooling refrigerant in the liquid gas mixed state using the economizer pipe. Even when the operating state is improved, the vibration due to whirling of the drive shaft 10 is reduced without changing the injection amount of the intermediate cooling refrigerant, and the beat noise is reduced. Door can be. Therefore, the beat noise can be reduced without changing the liquid injection amount or the injection amount of the intermediate cooling refrigerant in the system for improving the operating state, or the oil injection amount can be reduced, and the versatility can be broadened. ..

The second embodiment shown in FIG. 4 is a system in which liquid injection is carried out at an intermediate portion of the compression process of a pair of compression chambers in order to improve the operating condition, and the screw rotor and the drive shaft are arranged on one side in the radial direction. A liquid injection pipe 31 that branches from the downstream side of the condenser 3 in the refrigerant pipe 6 is provided, and an expansion valve 32 is interposed in the pipe 31 and the tip end portion of the pipe 31 is provided. In addition, a pair of liquid injection passages 33a, 33a opened at radially symmetrical positions of the screw rotor 11 at an intermediate portion of the compression process in the pair of compression chambers 16a, 16b.
b, and the pressure of the liquid refrigerant decompressed by the expansion valve 32 via the liquid injection passages 33a, 33b in the pair of compression chambers 16a, 16b during the compression process and the pressure of the condenser 3. Allow injection by pressure.

Further, one liquid injection pipe 33a
Is provided with an injection amount changing means 34 composed of a variable throttle so as to make a difference between the injection amounts injected into the pair of compression chambers 16a and 16b. For example, the compression chamber 16b having a large liquid injection amount and the liquid injection amount. The drive shaft 10 can be pressed together with the screw rotor 11 to the compression chamber 16b side, that is, to the one side in the radial direction by the differential pressure with the compression chamber 16a.

In the second embodiment shown in FIG. 4, the injection amount changing means 34 consisting of a variable throttle is used, and only one liquid injection passage 33a is interposed. However, instead of the variable throttle, the throttle amount is changed. A constant diaphragm may be used, or a variable diaphragm or a diaphragm having a constant diaphragm amount may be provided in each of the passages 33a and 33b to make the diaphragm amounts different.

In the case of the second embodiment, the pressure decreases as the temperature of the pair of compression chambers 16a and 16b decreases due to the liquid injection. However, the compression chamber 16b having a large amount of liquid injection is operated by the external operation of the variable throttle. Since the pressure drop of the refrigerant can be made larger than the pressure drop of the compression chamber 16a, the pressure of the refrigerant radially acting on the screw rotor 11 from the pair of compression chambers 16a, 16b is made asymmetrical to thereby make the screw rotor 11 asymmetric. It is possible to press 11 together with the drive shaft 10 from the compression chamber 16a side to the compression chamber 16b side, that is, one side in the radial direction of the screw rotor 11.

Therefore, according to the second embodiment, while the efficient operation can be performed without changing the internal volume ratio of the pair of compression chambers 16a, 16b, the screw is changed by using the injection amount changing means 34. Since the rotor 11 is pressed to the one side in the radial direction together with the drive shaft 10, the pressing force can be adjusted by an external operation, and vibration due to whirling of the drive shaft 10 can be easily reduced.

When the pressure difference between the pressure in the compression process in the pair of compression chambers 16a and 16b and the pressure in the condenser 3 becomes large, the humming noise also becomes large. The force pressing the drive shaft 10 is also increased, so that the vibration of the drive shaft 10 can be reduced and the whining noise can be reduced.

Further, the lubricating oil is normally injected into the intermediate portion of the compression process in the pair of compression chambers. By utilizing this injection of the lubricating oil, as in the third embodiment shown in FIG. In this case, an oil supply pipe 41 is connected to the oil separator 2, and an oil cooler 42 is inserted in the middle of the oil supply pipe 41 to pass through the cooler 42. The lubricating oil to be cooled can be cooled by the water flowing through the cooling water pipe 43, and a pair of compression chambers 16 are provided at the tip of the oil supply pipe 41 extending from the oil cooler 42 to the casing 1 side.
A pair of oil supply passages 44a and 44b opening at symmetrical positions in the radial direction of the screw rotor 11 are connected at an intermediate portion of the compression process in a and 16b, and are cooled by the oil cooler 42 via both oil supply passages 44a and 44b. To be able to replenish the lubricated oil.

Further, one of the oil supply passages 44a is provided with an oil supply amount changing means 45 composed of a flow rate adjusting valve, and the pair of compression chambers 1
The screw rotors 6a and 16b are provided with a difference in the amount of lubricating oil to be supplied to an intermediate portion of the compression process. With 11, the drive shaft 10 is pressed toward the compression chamber 16b.

In this case, by supplying the lubricating oil cooled by the oil cooler 42 to the pair of compression chambers 16a, 16b, the temperature of the pair of compression chambers 16a, 16b is lowered and the pressure is also lowered. By externally operating the flow rate adjusting valve, the pressure drop in the compression chamber 16b having a large amount of oil supply can be made larger than the pressure drop in the compression chamber 16a having a small amount of oil supply. Therefore, as in the first and second embodiments, A pair of compression chambers 16
The screw rotor 11 can be pressed together with the drive shaft 10 from the compression chamber 16a side to the compression chamber 16b side, that is, to the radial direction one side of the screw rotor 11 by the differential pressure of the refrigerant in a and 16b.

Therefore, according to the third embodiment, the amount of oil supplied to the pair of compression chambers 16a, 16b is made different by the oil supply amount changing means 45 composed of the flow rate adjusting valve, so that the screw rotor 11 and Since the drive shaft 10 can be pressed to one side in the radial direction, the drive shaft can be easily operated by an external operation while operating efficiently without changing the internal volume ratio of the pair of compression chambers 16a and 16b. 10 can be pressed to one side in the radial direction of the screw rotor 11, and since lubricating oil is used, it is less affected by operating conditions and the drive shaft 1
Vibration due to whirling of 0 can be reduced.

In the third embodiment shown in FIG. 5, the oil supply amount changing means 45 composed of the flow rate adjusting valve is used, but a throttle having a constant opening may be used instead of the flow rate adjusting valve. Although the flow rate adjusting valve is provided only in one of the oil supply passages 44a, the flow rate adjusting valves may be provided in both of the passages 44a and 44b so that the opening degrees of the two flow rate adjusting valves are different.

Further, FIG. 6 shows a method of injecting the intercooling refrigerant in a liquid-gas mixed state into the intermediate portion of the compression process in the pair of compression chambers by using the economizer pipe connected to the intercooler. As in the fourth embodiment, the intermediate cooling refrigerant may be used to press the drive shaft 10 together with the screw rotor 11 to one side in the radial direction of the screw rotor 11. That is, in the structure shown in FIG. 6, the intercooler 51 is interposed between the condenser 3 and the evaporator 5, and the intermediary expansion valve 52 and the intercooler are provided on the outlet side of the condenser 3. An economizer pipe 53 extending in the direction of the screw rotor 11 through the container 51 is provided, and one end of the economizer pipe 53 is provided with 1
Connect a pair of economizer passages 55a, 55b communicating with a pair of intermediate suction ports 54a, 54b opening at radially symmetrical positions of the screw rotor 11 at an intermediate portion of the compression process in the pair of compression chambers 16a, 16b, A part of the liquid refrigerant passing through the condenser 3 is decompressed by the intermediate expansion valve 52 and then introduced into the intermediate cooler 51 as indicated by a dotted arrow, and passes through the intermediate cooler 51 to The liquid refrigerant supplied to the evaporator 5 is heat-exchanged, and the liquid refrigerant is supercooled. On the other hand, the intermediate cooling refrigerant that has become a liquid-gas mixed state due to the heat exchange in the intermediate cooler 51 is paired with a pair of economizer ports. It is possible to improve the capacity of the single screw compressor by injecting it into the intermediate portion of the compression process in the pair of compression chambers 16a and 16b via 54a and 54b. In the respective intermediate suction port 54
Refrigerant injection amount changing means 56 for changing the diameters of a and 54b so as to change the refrigerant injection amount from the other economizer passage 55b with respect to the refrigerant injection amount from the one economizer passage 55a. The injection amount of the intermediate cooling refrigerant in a mixed state of the liquid gas to be injected into 16b is made different, and for example, from the intermediate suction port 54a having a small diameter to the compression chamber 16a,
The intermediate cooling refrigerant in a liquid gas mixed state can be injected into the compression chamber 16b from the intermediate suction port 54b having a large diameter, and the screw rotor 11 and the screw rotor 11 are driven by the differential pressure of the refrigerant in the pair of compression chambers 16a and 16b. The shaft 10 can be pressed toward the compression chamber 16b, that is, in the radial direction.

Most of the liquid refrigerant that has passed through the condenser 3 circulates from the intercooler 51 through the expansion valve 4 and the evaporator 5 to the suction side of the casing 1 as indicated by the solid arrow. To do.

In the case of the fourth embodiment shown in FIG. 6, the intercooling refrigerant, which has passed through the intercooler 51 and is in the liquid-gas mixed state, is injected into the pair of compression chambers 16a, 16b, thereby
The pressure of the pair of compression chambers 16a and 16b decreases as the temperature of the compression chambers 16a and 16b decreases, but the refrigerant injection amount changing means 56 reduces the pressure of the compression chamber 16b having a large injection amount.
Since it can be made larger than the pressure drop of No. 1, the screw rotor 11 is driven by the differential pressure of the refrigerant in the pair of compression chambers 16a and 16b as in the first to third embodiments.
With 0, the pressure can be pressed from the compression chamber 16a side to the compression chamber 16b side, that is, to one side in the radial direction of the screw rotor 11.

Therefore, according to the fourth embodiment, a pair of compression chambers 16a, 16 is provided from both economizer passages 55a, 55b.
By varying the injection amount of the intermediate cooling refrigerant in the mixed state of liquid gas to be injected into b, it is possible to press the drive shaft 10 together with the screw rotor 11 in the radial direction. Similarly, the drive shaft 10 can be pressed in the radial direction while performing efficient operation without changing the internal volume ratio of the pair of compression chambers 16a and 16b.

In the fourth embodiment described above, the refrigerant injection amount changing means 56 is constructed by making the diameters of the intermediate suction ports 54a, 54b different, but the lubricating oil is used as a pair of compression chambers 16a. , 16b, the injection amount of the intercooling refrigerant may be changed. Also,
The refrigerant injection amount changing means 56 is configured by making the diameters of the intermediate suction ports 54a and 54b different from each other.
Both the intermediate suction ports 54a and 54b have the same diameter,
A throttle or a flow rate adjusting valve may be provided in one of the economizer passages 55a or 55b, or both economizer passages 55a and 55b may be provided.
A flow rate adjusting valve may be provided in each of a and 55b, and the opening degrees of both flow rate adjusting valves may be different. In these cases, since the drive shaft 10 can be pressed to one side in the radial direction of the screw rotor 11 by using a throttle or a flow rate adjusting valve, the pressing force can be adjusted by an external operation, and the drive can be performed. Vibration caused by whirling of the shaft 10 can be easily reduced.

[0043]

As described above, according to the present invention, the casing 9 is internally provided with the motor 9 and the screw rotor 11 attached to the drive shaft 10 of the motor 9, and the drive shaft 10 is provided in front of and behind the screw rotor 11. , 12b in a uniaxial screw compressor rotatably supported by the differential pressure pressing means 24 for pressing the screw rotor 11 to one side in the radial direction of the rotor 11 by the differential pressure of the fluid. The pressure pressing means 24 can press the drive shaft 10 together with the screw rotor 11 in the radial direction one side of the screw rotor 11 by the pressure difference of the fluid, and the drive shaft 10 can be pressed in one radial direction of the bearings 12a and 12b. By pushing to the side, the vibration due to whirling of the drive shaft 10 can be reduced as compared with the case where it is not pushed.

Therefore, it is possible to reduce the vibration of the drive shaft 10 and to reduce the growling noise that causes discomfort as much as possible.

A pair of slide valves 18a, 18b for variably controlling the capacity are provided on the casing 1 symmetrically outward in the radial direction of the screw rotor 11 and movable in the axial direction of the screw rotor 11. When the lengths of the slide valves 18a and 18b in the moving direction are made different and the volume ratio of the pair of compression chambers 16a and 16b defined in the casing 1 is changed, the timing of discharging from one compression chamber 16a or 16b To the other compression chamber 16b or 16a
Can be shifted with respect to the discharge timing from 1
1 due to the pressure difference between the internal pressures of the pair of compression chambers 16a and 16b
From the pair of compression chambers 16a, 16b to the screw rotor 1
The pressure balance of the fluid acting in the radial direction with respect to 1 is lost, so that the screw rotor 11 can be pressed together with the drive shaft 10 to one side in the radial direction of the screw rotor 11.

Therefore, the pair of slide valves 18a, 18b
Since the screw rotor 11 and the drive shaft 10 can be pressed to one side in the radial direction by making the lengths of the drive shaft 10 different in the moving direction, vibration due to whirling of the drive shaft 10 is not affected by operating conditions. In addition, it is possible to reduce the amount, and it is not necessary to change the amount of liquid injection when performing liquid injection in the intermediate portion of the compression process of the pair of compression chambers or the amount of oil for injecting lubricating oil in order to improve the operating state. Further, even when the intercooling refrigerant in a liquid-gas mixed state is injected using the economizer pipe to improve the operating state, the amount of the intercooling refrigerant injected is not changed and vibration due to whirling of the drive shaft 10 is reduced. , Can reduce the growling noise. As a result, the beating noise can be reduced without changing the liquid injection amount or the injection amount of the intercooling refrigerant in the system for improving the operating state, or the oil injection amount can be reduced, and the versatility can be widened. is there.

Further, a pair of liquid injection passages 33a, 3a are formed at a radially symmetrical position of the screw rotor 11 at an intermediate portion of the compression process in the pair of compression chambers 16a, 16b.
3b is opened to allow these liquid injection passages 33
a and 33b, the other liquid injection passage 33b or 33a corresponding to the injection amount from one liquid injection passage 33a or 33b
When the injection amount changing means 34 for changing the injection amount from the above is provided, the injection amount changing means 34 causes the pressure drop of the compression chamber 16a or 16b having the larger liquid injection amount to the compression chamber 16b having the smaller liquid injection amount. Alternatively, since the pressure can be increased as compared with the pressure drop of 16a, a differential pressure is generated between the internal pressures of the pair of compression chambers 16a and 16b, and this differential pressure causes the screw rotor 11 to move in the radial direction of the screw rotor 11 together with the drive shaft 10. It can be pressed to one side.

Therefore, in this case, the pair of compression chambers 16
The injection amount changing means 3 while performing efficient operation without changing the internal volume ratio of a and 16b.
4, the screw rotor 11 is pressed to one side in the radial direction together with the drive shaft 10, so that the pressing force can be adjusted by an external operation, and vibration due to whirling of the drive shaft 10 can be easily reduced. The growl noise can be reduced.

Further, a pair of liquid injection passages 33
A pair of oil supply passages 44a, 44b is used instead of a, 33b, and at least one of the oil supply passages 44a or 44b is supplied with oil from the other oil supply passage 44b or 44a with respect to the amount of oil supplied from one oil supply passage 44a or 44b. When the oil supply amount changing means 45 for changing the amount is provided, the oil supply amount changing means 45 changes the oil supply amount to be supplied to the pair of compression chambers 16a and 16b so that the internal pressure of the pair of compression chambers 16a and 16b becomes a differential pressure. And the screw rotor 11 can be pressed together with the drive shaft 10 to one side in the radial direction of the screw rotor 11.

Therefore, also in this case, a pair of compression chambers 16a,
While efficiently operating without changing the internal volume ratio of 16b, the vibration due to whirling of the drive shaft 10 can be easily reduced by an external operation, and the drive shaft is less affected by the operating conditions. Vibration caused by whirling of 10 can be reduced.

Further, a pair of liquid injection passages 33
a, 33b or a pair of oil supply passages 44a, 44b,
Using a pair of economizer passages 55a and 55b, at least one of these economizer passages 55a and 55b,
The amount of refrigerant injected from one economizer passage 55a or 55b to the other economizer passage 55b or 55a
In the case where the refrigerant injection amount changing means 56 for changing the refrigerant injection amount is provided, the refrigerant injection amount changing means 56 causes the pressure drop of the compression chamber 55a or 55b having the larger injection amount to the compression chamber having the smaller injection amount. Since it can be made larger than the pressure drop of 55b or 55a, a differential pressure is generated between the internal pressures of the pair of compression chambers 16a, 16b, and this differential pressure causes the screw rotor 11 to move together with the drive shaft 10 and the screw rotor 1
It can be pressed to one side in the radial direction of No. 1.

Therefore, the pair of liquid injection passages 3
3a, 33b and a pair of oil supply passages 44a, 44b are provided, it is possible to perform an efficient operation without changing the internal volume ratio of the pair of compression chambers 16a, 16b, and easily by an external operation. Vibration caused by whirling of the drive shaft 10 can be reduced.

[Brief description of drawings]

FIG. 1 is a partial schematic cross-sectional view of a main part showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a graph showing vibration of a casing.

FIG. 4 is a piping system diagram showing a second embodiment.

FIG. 5 is a piping system diagram showing a third embodiment.

FIG. 6 is a piping system diagram showing a fourth embodiment.

FIG. 7 is a sectional view of a conventional example.

8 is a partial cross-sectional view taken along the line RR of FIG.

FIG. 9 is a graph showing vibration of a casing in a conventional example.

[Explanation of symbols]

 1 Casing 9 Motor 10 Drive Shaft 11 Screw Rotor 12a, 12b Bearing 16a, 16b Compression Chamber 18a, 18b Slide Valve 24 Differential Pressure Pressing Means 34 Injection Amount Changing Means 45 Oil Supply Amount Changing Means 56 Refrigerant Injection Amount Changing Means

Claims (5)

[Claims] 1. A casing 1 is internally provided with a motor 9 and a screw rotor 11 attached to a drive shaft 10 of the motor 9, and the drive shaft 10 is rotatable via bearings 12a, 12b provided in front of and behind the screw rotor 11. In the uniaxial screw compressor, the uniaxial screw compressor is provided with a differential pressure pressing unit 24 that presses the screw rotor 11 on one radial direction side of the rotor 11 with a differential pressure of fluid. Machine. 2. A pair of slide valves 18a, 18b for variably controlling the capacity are mounted on a casing 1 of the screw rotor 1
1 is provided symmetrically on the outer side in the radial direction and is movable in the axial direction of the screw rotor 11, and the lengths of the slide valves 18a and 18b in the moving direction are made different from each other to define a pair of casings 1. The uniaxial screw compressor according to claim 1, wherein the volume ratio of the compression chambers 16a, 16b is changed. 3. A pair of liquid injection passages 33a, 33b are formed at radially symmetrical positions of the screw rotor 11 at an intermediate portion of the compression process in the pair of compression chambers 16a, 16b.
To open these liquid injection passages 33a,
The uniaxial type according to claim 1, wherein at least one of the liquid injection passages 33b and 33b is provided with an injection amount changing means 34 for changing the injection amount from the other liquid injection passage 33b or 33a with respect to the injection amount from one liquid injection passage 33a or 33b. Screw compressor. 4. A pair of oil supply passages 44a, 44b are opened at radially symmetrical positions of the screw rotor 11 at an intermediate portion of the compression process in the pair of compression chambers 16a, 16b,
The oil supply amount changing means 45 for changing the oil supply amount from the other oil supply passage 44b or 44a with respect to the oil supply amount from one oil supply passage 44a or 44b is provided in at least one of the oil supply passages 44a and 44b. Single screw compressor. 5. A pair of economizer passages 55a, 55b are formed by opening a pair of economizer passages 55a, 55b at radially symmetrical positions of the screw rotor 11 at an intermediate portion of the compression process in the pair of compression chambers 16a, 16b. At least one of the economizer passages 55a or 55
The other economizer passage 5 with respect to the refrigerant injection amount from b
The uniaxial screw compressor according to claim 1, further comprising a refrigerant injection amount changing means 56 for changing an amount of refrigerant injected from 5b or 55a.