JPH0413436Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention is a single screw compressor for compressing refrigerant, and more specifically, the present invention includes a single screw compressor for compressing refrigerant, and more specifically, a rotor having an internal space and a screw crest in the internal space, and In addition to incorporating a pair of gate rotors that mesh with the
The present invention relates to a single screw compressor for compressing refrigerant, which injects a liquid containing oil and liquid refrigerant into the internal space.

(Prior art) Conventional screw compressors contain oil and liquid refrigerant for the purpose of cooling the compressed gas, lubricating the rotor, and improving the sealing performance between the rotor grooves facing each other across the screw ridge in the rotor. Liquid is injected into the interior space of the casing.

Incidentally, the injection structure for injecting the liquid into the internal space of the casing includes forming an injection hole opening into the internal space in the casing or a capacity control slide valve movably attached to the casing; A liquid supply path is provided in the casing or slide valve, and this supply path is connected to a pump or an oil separator provided on the discharge side via piping.

However, in the injection structure configured as above,
When the rotor is driven to inject liquid into the internal space, when the screw crest of the rotor crosses the injection hole, the injection hole is closed or almost closed, so that a liquid hammer phenomenon occurs. and pressure pulsations occur in the liquid supply path and piping,
There was a problem with high vibration noise.

In order to solve this problem, for example,
As shown in Japanese Patent No. 104110, an injection structure including a plurality of injection holes has been proposed.

As schematically shown in FIG. 7, this injection structure includes one liquid supply path A provided in the casing C housing the rotor R, and
, a plurality of injection holes N ₁ , N ₂ , N ₃ are provided which communicate with the liquid supply path A and open into the space S between the inner wall of the casing C and the rotor R.

According to this injection structure, all the injection holes (N ₁ to _{N 3} ) are not closed at the same time by the screw crest of the rotor R, and the liquid supply path A is closed to any of the injection holes (N ₁ to N 3 ). Since the flow is generated by communicating with the internal space S via N ₃ ), there is no sudden drop in flow velocity, and pressure pulsations are alleviated accordingly.

(Problems to be solved by the invention) The conventional injection structure mentioned above is a structure in which one injection hole is simply divided into multiple parts.
Although pressure pulsations can be alleviated compared to a single injection hole, a significant reduction in pressure fluctuations cannot be expected.

Therefore, in order to reduce the pressure fluctuation sufficiently, it is possible to provide a larger number of injection holes (N ₁ to _{N 3} ), but forming a large number of injection holes requires a lot of work and is expensive. In addition, when a large number of the injection holes are provided over a wide area, the large number of injection holes that communicate with one liquid supply path sandwich the screw crest of the rotor and communicate with the high-pressure side groove and the low-pressure side groove. As a result, there is a risk that bypass flow will occur and the compression efficiency will decrease.
This is not a sufficient solution to the above-mentioned problem.

The purpose of this invention is to make it possible to significantly reduce pressure pulsations with a simple structure and to reliably reduce vibration noise even with a single injection hole without increasing the number of injection holes. .

(Means for solving the problem) The present invention includes a liquid refrigerant in the liquid injected into the internal space of the casing, and this liquid refrigerant can be gasified by pressure loss, and the liquid refrigerant is gasified,
By making the liquid to be injected a two-phase flow of gas and oil, in other words, by including a gas flow,
This invention was devised by focusing on the fact that almost no liquid hammer phenomenon occurs even if the injection holes are closed by the screw ridges of the rotor, and as shown in FIG. , the rotor 3
A pair of gate rotors meshing with each other are housed in a casing 1 having a suction chamber 4 and a discharge chamber 5, and a space 9 between the inner wall 2 of the casing 1 and the rotor 3 and the pair of gate rotors.
Injection holes 4 for injecting liquid containing oil and liquid refrigerant to
In a single screw compressor for refrigerant compression having an injection structure with 0, the injection hole 40 has an opening on the opening side to the space 9 that is closed by the screw crest 3a, and the screw ridge 3
a, the volume occupied by the injected liquid supplied to the injection hole 40 during this closing time is the volume in which the liquid refrigerant in the injected liquid is gasified (Vν>d ₂ νt, where d is the Injection hole 40
, ν is the flow rate of the liquid, and t is the maximum time for the screw crest 3a to close the injection hole 40. ) is characterized in that a gasification chamber 41 is provided.

(Function) The injection hole 40 has an opening closed by the screw crest 3a on the opening side to the space 9,
A gasification chamber 41 having a volume larger than the volume occupied by the injection liquid supplied to the injection hole 40 during this closing time when closed by the screw ridge portion 3a, and having a volume in which the liquid refrigerant of the injection liquid is gasified.
, a part of the injected liquid is necessarily gasified in this gasification chamber 41 and injected into the space 9 in a two-phase flow with oil.

Therefore, even when the screw crest 3a crosses the opening of the gasification chamber 41 and closes it due to the drive of the rotor 3, the pressure fluctuation in the gasification chamber 41 is small, and the liquid hammer phenomenon is prevented. This allows the pressure pulsation to be significantly alleviated.

(Embodiment) The single screw compressor shown in FIG. 1 is used in a refrigeration system to compress refrigerant. A rotor 3 is installed inside the rotor 3, and a pair of gate rotors (not shown) are meshed with the rotor 3, and low pressure gas refrigerant is sucked from the suction chamber 4 by the rotation of these rotors, and the rotor 3 is connected to the cylindrical inner wall 2 and the rotor. 3 and the gate rotor, and then discharged from the discharge chamber 5 through a discharge port (not shown).

In addition, the compressor shown in FIG. 1 has a structure in which the fluid on the high pressure side is bypassed to the low pressure side at an intermediate portion of the casing 1 between the high pressure side communicating with the discharge chamber 5 and the low pressure side communicating with the suction chamber 4. The slide valve 7 is provided with a capacity control passage 6 for controlling the capacity, a slide valve 7 for adjusting the opening degree of the passage 6, and an operation mechanism 8 for operating the slide valve 7. An injection hole 40 for injecting a liquid containing oil and liquid refrigerant is provided in a space 9 between the inner wall 2 of the rotor 3 and the gate rotor.

The slide valve 7 is slidably supported in a valve hole 21 provided in the casing 1, and an operating mechanism 8 for operating the slide valve 7 controls the volume of the valve hole on the back side of the slide valve 7. This capacity control chamber 22 is used as the chamber 22, for example, through the valve hole 21.
Restriction passage 26 such as the gap between and slide valve 7
This communicates with the discharge chamber 5, and through this communication, high pressure gas pressure is applied to the back side end face of the slide valve 7, and low pressure side pressure acts on the front end face of the slide valve 7 facing the suction chamber 5. The slide valve 7 is pressed to the left side in FIG. 1 due to the pressure difference between the slide valve 7 and the control passage 6, and the control passage 6 is completely closed. A spring holder 23 is fixed, and the slide valve 7 is biased in the opening direction between the spring holder 24 attached to the tip of the spring holder 23 and the cover plate 12, so that the closing force due to the pressure difference is small. A spring 25 is provided to open the slide valve 7 when the temperature is low, and a solenoid valve 33 is connected to the capacity control chamber 22 on the low pressure side.
Balance passages 35 and 36 having 34 holes are connected through balance holes 31 and 32.

However, in the above configuration, the solenoid valve 3
3 and 34 and make the capacity control chamber 22 high pressure, the slide valve 7 is fully closed to perform full capacity operation, and by opening one or both of the solenoid valves 33 and 34, the Capacity control room 2
2 is opened to the low pressure side, the slide valve 7 is moved by the force of the spring 25, and the capacity control passage 6 is opened to perform capacity control operation.

The amount of movement when the electromagnetic valves 33 and 34 are opened is set by the formation positions of the balance holes 31 and 32, and the movement of the slide valve 7 is determined when the balance holes 31 and 32 are closed. If it breaks, it will be stopped.

In FIG. 1, 13 is an inner seal ring that is fixed to the casing 1 and faces the end surface of the rotor 3, 14 and 15 are bearings that support the drive shaft 10 of the rotor 3, and 16 is the inner seal ring that is fixed to the casing 1 and faces the end surface of the rotor 3. It is an outer ring fixed to the outside of the casing 1 and holds the outer races of the bearings 14 and 15.

Reference numeral 17 denotes a first liquid supply passage connected to an oil pump (not shown) or an oil separator provided on the discharge side of the compressor via an external pipe (not shown); and is formed continuously on the casing 1. Reference numeral 18 denotes a second liquid supply passage provided in the slide valve 7, which communicates with the first liquid supply passage 17, and the oil supplied from the first and second liquid supply passages 17, 18. A liquid containing liquid refrigerant is injected into the space 9 from the injection hole 40 provided in the slide valve 7.

Therefore, the present invention improves the liquid injection structure having the injection holes 40 in the single screw compressor for refrigerant compression configured as described above.
As shown in FIG. 2, the injection hole 40 has an opening on the opening side to the space 9, which is closed by the screw crest 3a, and when the injection hole 40 is closed by the screw ridge 3a, the injection A gasification chamber 41 is provided which is larger than the volume occupied by the injection liquid supplied to the hole 40 and has a volume in which the liquid refrigerant of the injection liquid is gasified.

That is, the volume Vν of the gasification chamber 41 is defined by the diameter of the injection hole 40 being d, the flow rate of the liquid being ν,
The screw crest 3a of the rotor 3 is connected to the injection hole 40.
The setting is made so that Vν>π/4d ² νt, where t is the maximum value of the time to block the area. Furthermore, the above volume
Vν is calculated as follows: Vν=π/4(D ^{2 −} d ² ) l. However, D is the diameter of the gasification chamber 41,
l is the length of the gasification chamber 41.

Further, the volume Vν may be made larger than the volume obtained by π/4d ² νt, but in reality, it is 1.5 to 2
It is preferable to double the amount.

As is clear from the above, when the rotor 3 is driven to compress the gas refrigerant taken in from the suction chamber 4 and to discharge it to the discharge chamber 5, the injection hole 40 has the first and second liquid supply passages 17. , 18, and is injected into the space 9 from the injection hole 40. The opening side of the injection hole 40 to the space 9 is closed by the screw crest 3a. A gasification chamber 41 is provided, which has a volume Vν which is larger than the volume occupied by the injection liquid supplied to the injection hole 40 during the closing time when the screw peak 3a closes the gasification chamber 41. Therefore, the liquid refrigerant is gasified in the gasification chamber 41 and injected into the space 9 in a two-phase flow of oil and gas refrigerant.

For this reason, the screw crest 3a of the rotor 3
Even if the liquid crosses the opening of the gasification chamber 41 and closes it, the liquid hammer phenomenon does not occur.

Therefore, pressure fluctuations can be significantly reduced, and
Since the pressure of the first and second liquid supply passages 17 and 18 can be set to the same level as the discharge pressure or a pressure higher than the discharge pressure, even if a plurality of the injection holes 40 are provided, these injection holes 40 acts as a bypass passage, and a bypass flow is generated from the high pressure side to the low pressure side across the screw crest 3a, which solves the problem of reduced compression efficiency.

Moreover, since the gasification chamber 41 is provided on the opening side of the injection hole 40 to the space 9, replacing it with
Since it is not provided in the first and second liquid supply passages 17 and 18, pressure loss is hardly a problem,
Furthermore, the injection flow rate can be easily controlled.

Moreover, the number of the injection holes 40 may be one,
Since it is not essential to provide a plurality of injection holes, the number of holes to be machined can be reduced compared to the case where a large number of injection holes are provided to significantly alleviate pressure pulsations, and workability can be improved accordingly.

Incidentally, using the structure shown in FIG.
When the pressure fluctuation at the piping connection section where the external piping is connected to the liquid supply passage 17 was actually measured, the results shown in FIG. 3 were obtained. From this result, it can be seen that the pressure fluctuation is significantly reduced compared to the pressure fluctuation actually measured in the conventional injection structure shown in FIG. 4, that is, a structure in which no gasification chamber is formed.
That is, as is clear from the actual measurement results of pressure fluctuations shown in FIGS. 3 and 4, in the injection structure according to the present invention, the pressure amplitude is reduced to less than half that of the conventional example.

Further, as a result of performing frequency analysis under substantially the same conditions as those used for the measurement of pressure fluctuations, the results shown in FIG. 5 were obtained.

Based on this result, the sixth section shows the frequency analysis of the conventional example.
As is clear from the comparison with the results in the figure, not only is the overall sound pressure level decreasing, but the sound pressure level in the high frequency band near 5KHz has almost disappeared, and the noise is increasing based on the high frequency components. I see that it has been resolved.

In the embodiment described above, only one injection hole 40 is formed, but a plurality of injection holes may be formed.

Although the present invention is applied to a single-screw compressor for compressing refrigerant having a capacity control mechanism, the capacity control mechanism may be omitted, and in a case having a capacity control mechanism, the injection hole 40 is formed in the slide valve 7. However, other shapes may be formed in the casing 1.

(Effect of the invention) The injection hole 40 for injecting liquid containing oil and liquid refrigerant into the space 9 between the inner wall 2 of the casing 1 and the rotor 3 and the pair of gate rotors is provided with the injection hole 40 on the opening side to the space 9. It has an opening that is closed by the screw peak 3a, and when the opening is closed by the screw peak 3a, the volume is larger than the volume occupied by the injection liquid supplied to the injection hole 40 during this closing time,
Since the gasification chamber 41 having a volume in which the liquid refrigerant of the injected liquid is gasified is provided, the liquid refrigerant contained in the injected liquid is gasified in the gasification chamber 41, and a two-phase mixture of oil and gas refrigerant is formed. Since the gas is injected into the space 9 as a flow, even if the injection hole 40 is closed by the screw crest 3a of the rotor 3, the gasification chamber 41
The pressure fluctuations are small, and the liquid hammer phenomenon hardly occurs in the liquid supply system that supplies liquid to the injection holes 40, making it possible to significantly reduce pressure fluctuations.

Therefore, the vibration of the supply system that supplies the liquid to the injection hole 40 can be reduced, and the supply piping can be made with a lower strength.Since the vibration can be reduced, the operating noise of the compressor, especially high frequency components, can be reduced. Based on this, noise can also be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted sectional view showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view of main parts, Fig. 3 is a pressure waveform diagram according to an embodiment of the present invention, and Fig. 4 shows a gasification chamber. FIG. 5 is a frequency-sound pressure level characteristic diagram according to the embodiment of the present invention, FIG. 6 is a frequency-sound pressure level characteristic diagram according to the conventional example, and FIG. 7 is an injection diagram. FIG. 2 is a schematic explanatory diagram showing a conventional example in which a plurality of holes are provided. DESCRIPTION OF SYMBOLS 1... Casing, 2... Inner wall, 3... Rotor, 3a... Screw mountain part, 4... Suction chamber, 5... Discharge chamber, 9... Space, 40
...Injection hole, 41...Gasification chamber.

Claims (1)

[Scope of utility model registration request] one rotor 3 having a screw crest 3a;
A pair of gate rotors that mesh with the rotor 3 are housed in a casing 1 having a suction chamber 4 and a discharge chamber 5, and a space between the inner wall 2 of the casing 1 and the rotor 3 and the pair of gate rotors. 9, in a single screw compressor for refrigerant compression equipped with an injection structure having an injection hole 40 for injecting liquid including oil and liquid refrigerant, the injection hole 4
0 has an opening closed by the screw crest 3a on the opening side to the space 9, and when the screw crest 3a closes the opening, the injection is supplied to the injection hole 40 during this closing time. The volume that is larger than the volume occupied by the liquid and in which the liquid refrigerant of the injected liquid is gasified (Vν>d ² νt, where d is the diameter of the injection hole 40, ν is the flow velocity of the liquid, and t is the volume at which the screw ridge portion 3a is 1. A single-screw compressor for compressing refrigerant, characterized in that a gasification chamber 41 is provided with a gasification chamber 41 having a maximum time for closing an injection hole 40.