JPH02140489A - Compressor - Google Patents

Abstract

PURPOSE:To prevent liquid compression and make it near the isothermal compression so as to improve its efficiency, in compressing refrigerant gas under turning of a swirler, by providing the title device with an injection nozzle, its change-over valve and a swirler for injecting liquid refrigerant in a minite fog state at an optional timing. CONSTITUTION:In a rotary compressor for compressing refrigerant gas, a compression space 20, which is contracted between a roller 12 and a vane 19 by the turning motion of the roller 12, is formed in a cylinder 11. A liquid refrigerant injection device 17 is positioned in the vicinity of the refrigerant gas exit 101 so as to face to the compression chamber at approximately any position in a compression stroke. The liquid refrigerant injection device 17 is provided with a nozzle 23, a valve body, swirler, an electro-magnet and an armature. When pulse-formed voltage is applied to the electro-magnet, the armature is inhaled to open the valve, so that minite fog like liquid refrigerant decentered and swirled by the swirler is injected through the small hole of the nozzle 23. Accordingly, this liquid refrigerant is easily gasified so as to prevent liquid compression, and also is made near the isothermal compression so as to prevent the valve from being damaged and obtain the maximum energy efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a compressor used in an air conditioner or the like, and particularly relates to a compressor that injects liquid refrigerant into a compression chamber during a compression stroke.

[Prior Art] When a compressor for refrigerant compression is operated at high speed or the discharge pressure is set high, the temperature of the discharged refrigerant gas increases, which generally causes thermal decomposition of the refrigerant and a decrease in motor efficiency. Conventionally, the compressor is cooled to prevent This conventional cooling method includes (a) a method in which the discharged gas is cooled once outside the compressor and then returned to the compressor, a method in which the discharged gas is cooled using a heat vibrator, and (c) a method in which the discharged gas is cooled by using a heat vibrator. There are methods such as injecting it into the compression chamber of the compressor during the compression stroke.

The conventional device for carrying out the method (c) above is JP-A-53-4
0451, the flow rate of liquid refrigerant to be injected is measured with a flow meter, and the flow rate of liquid refrigerant to be injected is controlled by a flow rate control valve according to the refrigeration load, or as described in JP-A-54-40347, A liquid injection nozzle is provided so that the liquid refrigerant injected from two liquid injection holes collides with each other, and the liquid refrigerant interferes with each other to form a mist. Provide overload detection means that operates when the temperature of As described in 1986-59039, a solenoid valve that opens and closes based on a detection signal from a cylinder pressure detector is installed in the bypass passage, and when the cylinder pressure of the compressor exceeds a predetermined value, Liquid refrigerant was forcibly injected.

[Problems to be Solved by the Invention] Among the conventional techniques for performing the method (c) above, Japanese Unexamined Patent Application Publication No. 1986-
40451.61-159054. Jitsukai Showa 60-590
The prior art described in No. 39 provides a cooling means by liquid refrigerant injection as described above, but no consideration is given to the evaporation time of the liquid refrigerant in the cylinder. remains in the cylinder without being completely evaporated, resulting in liquid compression and insufficient heat exchange during the compression process, making it impossible to approach isothermal compression and requiring a significant amount of compression power. There was a problem in that it was not possible to reduce the

Furthermore, in the conventional description described in JP-A No. 54-40347, liquid injection nozzles are provided so that the liquid refrigerant injected from the liquid injection holes collide with each other to form a mist. Not only is this method necessary and there is a problem with the installation space, but also the method involves colliding the ejected liquid dε to create a liquid film and generating T agglomerations from the outer periphery of the liquid film. When injection is performed, atomization is not sufficiently promoted and the droplets tend to become large, and the diameter of the droplets is easily influenced by the speed of the jet flow, that is, the pressure level of the condenser, which is the source of the liquid refrigerant. There was a problem.

The present invention provides a compressor that performs the method (c), in which the injected liquid refrigerant is made into minute liquid droplets and all evaporated during the compression stroke to prevent liquid compression and bring the compression stroke closer to an isothermal change. It also aims to reduce IEN power and maximize cycle energy efficiency.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a compressor according to claims 1 to 5, respectively.

[Function] When high-pressure liquid refrigerant is introduced into the liquid refrigerant injection device and the valve is opened by a pulse electric signal to the valve operating means, the liquid refrigerant flows eccentrically with respect to the central axis of the injection nozzle due to the swirler. Since the injection is given a swirl and is injected into the compression chamber of the compressor while rotating at high speed from an injection nozzle with a small hole diameter, it becomes a fine spray in a very short time due to instability due to centrifugal force, cavitation effect, and surface tension of the liquid film. It splits into liquid droplets. The smaller the particle size of the liquid droplets, the smaller the volume, so the evaporation rate is faster. In addition, since high-pressure liquid refrigerant is injected, even if the injection time is very short, a sufficient flow rate can be injected to cool the compressor. Therefore, if these minute liquid droplets are injected during the compression stroke, high-speed operation However, since it receives heat from the gas and evaporates all of it by the time the compression stroke ends, it becomes possible to bring the compression stroke closer to isothermal compression, and liquid compression can be completely prevented.

Furthermore, since this injection timing can be arbitrarily changed depending on the time when a pulse electric signal command is sent to the valve operating means of the liquid refrigerant injection device, the optimum timing at which the compression power is minimized can be selected.

Since the injection time and, by extension, the injection amount can be changed arbitrarily by pulse electric signal commands, the injection time and injection timing are controlled to maximize the efficiency of the entire cycle, that is, the ratio of heating capacity or cooling capacity to electrical input. I can do it.

[Example] An example of the present invention will be explained with reference to FIGS. 1 to 11.
FIG. 1 shows a cycle configuration of a heat pump type room air conditioner with inverter idle rotation speed control as a representative example of the cycle. This cycle consists of a compressor 1, a four-way valve 2 for changing the flow direction of the refrigerant, an outdoor heat exchanger 3, an expansion valve 4, an indoor heat exchanger 5, and a microcomputer 7 for controlling the rotational speed of the compressor, etc. , an inverter motion device 8, a switching valve 6 for switching the liquid refrigerant flow path, a drive circuit 9 for the liquid refrigerant injection device, an in-room sensor built into the indoor heat exchanger 5 (not shown), and an outdoor heat exchanger. It consists of outdoor sensors etc. built into 3. In the case of cooling operation, the refrigerant and gas discharged from the compressor 1 are returned to the compressor 1 through an outdoor heat exchanger 3 as a condenser, an expansion valve 4, and an indoor heat exchanger 5 as an evaporator. , also in case of heating operation.

Refrigerant gas discharged from the compressor 1 flows back to the compressor 1 through an outdoor heat exchanger 5 as an evaporator, an expansion valve 4, and an indoor heat exchanger 3 as a condenser. In order to cool the compressor 1, liquid refrigerant is injected into the compressor during the compression stroke. In this case, the air is switched so that it is guided from the indoor heat exchanger 5 to the compressor 1.

FIG. 2 shows an example of a rolling screw type rotary compressor as the compressor 1, and the liquid refrigerant injection '! An example in which A-7 is installed is shown. The rotary compressor is composed of a casing 10, a cylinder 1, a roller 12, an upper bearing 13, a lower bearing 4, a shaft 15, a motor 16, and the like. A liquid refrigerant injection device 17 (the structure of which will be described in detail later) is attached to the cylinder 11 and is connected to a liquid refrigerant introduction pipe 18 . This liquid refrigerant injection device 17 is installed in a position such that its injection nozzle 23 is in the third position.
As shown in the figure, it is provided in a position where it faces into the compression chamber 20 formed by the roller 12, the vane 19, the upper and lower bearings 13, 14, and the cylinder 11 at almost any stage of the compression stroke.

In other words, the ejection nozzle 23 of the liquid refrigerant injection device 17 is located at a position where it faces the compression chamber 20 even when the compression chamber 20 is near the end of the compression stroke, that is, the refrigerant gas discharge port 1
It is located near 01. When the motor 16 rotates, the roller 12 eccentric to the axis of the shaft 15 moves within the cylinder 11, reducing the spatial volume of the compression chamber 20 and compressing the refrigerant gas in the compression chamber.
02 and is discharged to the cycle via a discharge valve (check valve) not shown. At the same time, the spatial volume of the suction chamber 21 increases, and refrigerant gas is sucked through the suction port 102. By repeating this operation, the refrigerant gas is continuously raised to high pressure and circulated throughout the cycle. That is, during cooling operation, high-temperature, high-pressure refrigerant gas discharged from the compressor 1 is cooled to liquid in the outdoor heat exchanger 3 serving as a condenser, is throttled to low pressure by the expansion valve 4, and is used as an evaporator. After receiving heat and evaporating it in the indoor heat exchanger 5, it returns to the compressor 1. During heating operation, the refrigerant circulates in the opposite direction, i! ! It is liquefied in the indoor heat exchanger as AI, vaporized in the outdoor heat exchanger 3 as a nuclear generator, and returned to the compressor 1.

By the way, as mentioned earlier, in the above-mentioned conventional technology in which the gas during the compression stroke in the compressor is cooled by injection of liquid refrigerant, the evaporation time is slow due to the large diameter of the liquid refrigerant, and therefore In particular, during high-speed operation, liquid compression cannot be prevented, and pressure changes during the compression stroke cannot be brought close to isothermal compression, making it impossible to reduce compression power. According to the present invention, this conventional drawback is overcome as described below.

FIG. 4 shows a liquid refrigerant injection device 17 in the embodiment of the present invention.
The structure of is shown in a cross-sectional view. This includes a valve body 22, a nozzle 23,
It is composed of a swirler 24, an electromagnet 25, an armature 26, a gap pressure regulating stopper 27, an outer body part 28, and the like.

A space 29 located upstream of the valve body 22 stores liquid refrigerant introduced through the groove of the armature 26 via the liquid refrigerant introduction pipe 18 . In this liquid refrigerant injection device 17,
When a pulse voltage is applied to the electromagnet 25, it attracts the armature 26 and opens the valve body 22, and the liquid refrigerant in the space 29 passes through the circumference of the stopper 27 and the swirler 24, and then enters the compressor from a small hole in the nozzle 23. It is injected into the compression chamber 20 inside the cylinder. At this time, the liquid refrigerant flows eccentrically with respect to the central axis of the nozzle 23 by the swirler 24, so that it is given a swirl and flows through the nozzle 23 as a swirling flow.

It is ejected forming a thin, approximately cone-shaped liquid film. Since the liquid refrigerant is ejected under high pressure, it swirls at high speed, and due to the effects of strong centrifugal force, cavitation, and the surface tension of the liquid film, it breaks up into very small diameter droplets in a very short time. The larger the diameter of the droplets, the smaller the volume per droplet, and therefore the faster the evaporation time. For example, as shown in FIG.
In the case of 2, when the diameter of the droplet is 10 μm, it evaporates in 5 ms. Therefore, if the radius of gyration and the diameter of the nozzle are designed so that the diameter of the liquid droplets is 10 μm or less, the rotational speed of the compressor can be reduced to 12 μm or less.
Up to 00Orρm, all the liquid refrigerant can be evaporated during the compression stroke. Therefore, heat is directly absorbed from the refrigerant gas during the compression stroke, so the pressure change in the compression stroke approaches isothermal compression, as shown in Figure 6 by the relationship between the size of the liquid droplets and the pressure change on the acupressure diagram. This allows liquid compression to be prevented even during high-speed operation.

As a result, compression power can be reduced and effective compressor cooling can be achieved.

The application of a pulse voltage to the electromagnet 25 of the liquid refrigerant injection device 17 is performed by the microcomputer 7 via the liquid refrigerant injection device drive circuit 9, as shown in FIG.

The opening time of the valve body 22 of the liquid refrigerant injection device 17 is determined as follows. The rotation speed of the compressor is Nc, the suction pressure is Ps, the discharge pressure is pd, the suction temperature is T3, the discharge temperature when not being cooled is Td, the discharge temperature to which you want to cool by liquid refrigerant injection is Tdc, the volume If the efficiency is 77, the specific volume of the suction gas is Vs, and the logical volume is Vth, then the refrigerant circulation 1k G r is Gr” ηv ・Vth e Nc
/ v s - (1) If the enthalpy at the compressor outlet when not being cooled is hd, and the enthalpy at the compressor outlet after cooling is hdc, the required cooling amount Qc is.

Qc= G r()i (3h d(z)
...(2) becomes. Cooling injection*a
i is the constant pressure specific heat of the liquid refrigerant, CPn, and the temperature of the liquid refrigerant is T.

, if the saturation temperature at discharge pressure is Tsat, and the latent heat of vaporization is L, then Gi”Qc/ (CPA (Tsat To)
+ L) ・i3) Injection - Injection volume of liquid refrigerant per injection (Ii is the specific volume of liquid refrigerant v (, as qi''Gi −vo/Nc −
(4) becomes. Therefore, the opening time tb of the injection valve 22 is
The membrane area of the nozzle part is Δ, the gravitational acceleration is g, and the flow coefficient is α
, the cylinder pressure at the time of injection is Pc, then b=qt/(α ・A 2g Pd-P(,)
・vo)・・・(5) Find it as follows. Therefore, as shown in FIG. 7, the compressor rotational speed Nc, discharge pressure Pd, required cooling ff1qc, or
As shown in FIG. 8, the compressor rotation speed Nc.

A three-dimensional map of the discharge pressure Pd and the opening time tb of the injection valve 22 can be created in advance. This map is stored in the microcomputer 7 as a database. In this way, the required cooling amount Qc can be calculated using the database shown in Fig. 7 from the discharge pressure that can be detected from the in-room sensor or outdoor sensor and the separately determined rotational speed of the compressor. The opening time tb of the injection valve 22 can be determined by interpolation using the database shown in FIG.

When the required cooling ff1Qo is determined from the database shown in FIG. 7, the cylinder internal pressure P3. Using poly1-rope index n, P c = P s (Vth/vc)
・++ Since it can be predicted as (6), the injection valve opening time tb can be finally found using equation (5) in the same way as when using the database shown in FIG.

In addition to the data map method described above, a method of calculating the opening time tb of the injection valve 22 in real time is also possible. That is, calculation formulas for 1-volume efficiency η9, enthalpy h, and specific volume V are memorized.

As shown in the flowchart in Figure 9, based on the compressor speed value, the detected values from the in-room sensor and the outdoor sensor, the suction temperature, discharge temperature, refrigerant circulation amount, enthalpy, cooling amount, injection volume, injection Valve opening time (1) to (5)
The injection valve opening time t4. can be found.

The microcomputer 7 applies a pulse voltage to the electromagnet 25 of the liquid refrigerant injection device 17 via the drive device 9 so as to realize the opening time tb of the injection valve 22 determined as described above.

Furthermore, the liquid refrigerant injection device 17 can be controlled to inject liquid droplets at arbitrary timing by electric signal commands. Therefore, it is possible to optimally control the injection timing of liquid droplets so that the compression power is minimized. A specific circuit for doing this is shown in FIG. This circuit consists of a circuit for detecting the compressor motor current value, a circuit for detecting the rotation angle of the shaft 15 from the top dead center position, a circuit for driving the liquid refrigerant injection device 17 according to an electric command signal, and a microcomputer. The operation will be explained with reference to the flowchart in FIG. Since the voltage is constant with respect to the drive current detection value of the compressor motor (A), the power required for compression can be calculated by integrating the current detection value during one rotation of the compressor using the microcomputer 7 (B). . When the rotational speed is the same and the pressure conditions are the same, the minimum value can be found by comparing the calculated power values for each rotation.

Compare the power value at the previously set liquid refrigerant injection timing (i.e. injection angle, i.e. the rotation angle of shirts 1 to 15 at the time of injection) with the power value at the injection timing changed this time, and inject towards the smaller value. By shifting the timing, the optimal injection timing can be selected (1). This optimal injection timing, that is, the set injection rotation angle and the detected rotation angle (o) of the shaft 15.
(force), and when they become the same, the compressor can be operated with the minimum power by sending an electrical signal command (ki) to the dynamic circuit of the liquid refrigerant injection device. Furthermore, when the evaporation time is sufficiently shorter than the time for one rotation of the compressor, it is more effective to inject the liquid refrigerant several times during one rotation. By storing the injection timing at which the compression power obtained in this manner is minimum as a database, the control speed can be increased when the engine is operated again.

Further, FIG. 11(a) shows the liquid refrigerant injection amount and the energy efficiency of the entire cycle. In the embodiment of the present invention.

It is also possible to control the opening time of the injection valve 22 of the liquid refrigerant injection device 17, that is, the amount of liquid refrigerant injection, by electrical signal commands so as to maximize the energy efficiency of the entire cycle. The specific method will be explained with reference to FIG. 11(b).

In order to maximize the energy efficiency of the cycle, for example, the ratio of heating capacity to electrical input or the ratio of cooling capacity to electrical input may be controlled to be maximized. Both the heating capacity and the cooling capacity are the capacity of the indoor side, that is, the capacity of the heat exchanger 5.

As shown in the Mollier diagram of FIG. 11(b), if the enthalpy difference Δh at the entrance and exit of the heat exchanger 5 and the refrigerant circulation amount Gr are determined, the heating capacity Q h can be determined. Cooling capacity Q cooQ,
, respectively.

Qhot=Δhh・ (G1・161)...
(7) Qcoog=Δh, -Gr -(
It can be calculated using U. Here, the suffix and C represent the heating time and the cooling time, respectively. Circulation M G r.

Since the liquid refrigerant injection amount G1 can be calculated using equations (1) and (3), the heating capacity can be determined by storing the enthalpy difference Δh together with the operating conditions in a database or by calculating it from the temperature measurement at the inlet and outlet of the heat exchanger. , cooling capacity can also be determined. Therefore, as shown in Fig. 11, the opening time of the injection valve is varied within a range exceeding the set capacity, the heating capacity or cooling capacity is calculated as described above, and the electrical input to the compressor is measured. The liquid refrigerant injection amount G1 at which the ratio becomes maximum, that is, the opening time of the injection valve 22 is determined. By then adjusting the injection timing as described above to minimize compression power, the maximum energy efficiency of the cycle can be found.

As described above, according to this embodiment, minute droplets of liquid refrigerant can be injected into the compression chamber of the compressor at any timing during the compression stroke and for an arbitrary period of time.

Therefore, even when the compressor is operating at high speed, all of the liquid refrigerant injected during the compression stroke can be evaporated within the compression chamber, which prevents liquid compression and brings the compression closer to isothermal compression, reducing compression power. . In addition, as an accompanying effect, damage to the discharge valve due to liquid compression can be prevented,
It is possible to prevent the bearing from seizing due to a decrease in the bearing temperature, improving reliability, and the motor is also cooled, which lowers the winding temperature and reduces the resistance value (which improves the motor efficiency. You can set the injection timing that minimizes the power, or you can set the injection time and injection timing to maximize the energy efficiency of the cycle, so you can operate the room air conditioner at the highest efficiency point.

[Effects of the Invention] According to the present invention, minute droplets of liquid refrigerant can be injected into the compression chamber of the compressor during the compression stroke at any timing. Therefore, the evaporation rate of the liquid droplets is fast and all of them evaporate during the compression stroke, so liquid compression can be prevented even during high-speed operation of the compressor, and the refrigerant gas during the compression stroke is cooled, making the compression stroke more isothermal compression. The motor, which is cooled by compressed refrigerant gas, can be cooled more effectively, improving motor efficiency, preventing damage to the compressor discharge valve, improving reliability by lowering bearing temperature, and increasing compression power. This has the effect of reducing Furthermore, since the liquid refrigerant injection time and injection timing can be freely changed, it is possible to minimize the pressure and the geometrical force, and furthermore, to maximize the energy efficiency of the cycle.

[Brief explanation of the drawing]

Fig. 1 is an air conditioner cycle configuration diagram according to an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view of a rotary compressor according to an embodiment of the present invention, and Fig. 3 is a cross-sectional view of a rotary compressor according to the embodiment. FIG. 4 is a vertical cross-sectional view of a liquid refrigerant injection device according to an embodiment of the present invention; FIG. The figure shows changes in compressor cylinder internal pressure due to liquid refrigerant injection, and FIGS. 7 and 8 are map charts for determining the opening time of the injection valve of the liquid refrigerant injection device. Fig. 9 is a flowchart for calculating the opening time of the injection valve in real time, Fig. 10 is a diagram showing a control system to minimize the If, I and I power, and Fig. 11 is the flowchart for calculating the opening time of the injection valve in real time. Diagrams showing control procedures, Figures 1-2 (a), (
b) is a diagram for explaining a control method that maximizes cycle efficiency. 1: Compressor 2: Four-way valve 3: Outdoor heat exchanger 4: Expansion valve 5 Near: 8: 9: 10: 12: 14: 16: 18: 20: 22: 24: 26 = 27: 28: Indoor heat exchange 6: Switching valve microcomputer inverter I prime mover Beating circuit casing for liquid refrigerant injection device 11 Nigilinder roller 13: Upper + 1 lower bearing 15: Shaft motor J7: Liquid refrigerant injection device Liquid refrigerant introduction pipe 19: Vane compression Chamber 21: Suction chamber valve body 23: Nozzle swirler 25: Electromagnetic armature gear pressure regulating stopper External body Attachment 1 Figure 3 Figure 4? , ) Nδ U Atsushi 2 Figure 5 Figure 5 Night Grain 4 Ki d (p, m) Rice presentation member VC (C7rL3) Figure 7 Compressor rotation speed N (, (rρ Town Compressor rotation Speed N(: (rpm) Fig. 10￥11

Claims (1)

[Claims] 1. The volume of the compression chamber formed between the rotating body and the fixed body, which is rotated by the rotation of the shaft, decreases with the rotation of the shaft, so that the refrigerant gas in the compression chamber is compressed and discharged. The compressor is equipped with a liquid refrigerant injection device that injects liquid refrigerant into a compression chamber in the form of a fine mist during the compression stroke, and the liquid refrigerant injection device includes an injection nozzle with a small hole diameter and a high-pressure liquid refrigerant injected into the injection nozzle. It consists of a swirler that introduces the injector as a swirling flow, a valve that opens and closes the injection nozzle, and a valve operating means that operates the valve in response to a pulse electric signal. A compressor characterized by being located as if facing the 2 Based on the detected values of the compressor rotation speed (rotation speed of the shaft) and discharge pressure, the compressor rotation speed, discharge pressure,
A necessary valve opening time is calculated by interpolation from a database that three-dimensionally maps the required cooling amount or valve opening time, and pulse electricity is applied to the valve operating means to open the injection nozzle for the calculated required valve opening time. The compressor according to claim 1, further comprising arithmetic control means for providing a signal. 3 Discharge temperature, enthalpy,
Calculate the amount of refrigerant circulation, calculate the required cooling amount, calculate the required valve opening time from the calculated value in real time, and direct the valve operating means to open the injection nozzle for the calculated required valve opening time. 2. A compressor according to claim 1, further comprising arithmetic control means for providing a pulsed electrical signal. 4. The calculation control means calculates compression power from a detected value of a drive current of a motor that rotates the shaft, and controls the timing of applying a pulse electric signal to the valve operation means so that the compression power is minimized. Compressor according to 2 or 3. 5. The calculation control means adjusts the valve opening time so as to maximize the ratio between the measured value of the heating or cooling capacity of the refrigeration cycle using the compressor and the detected value of the drive current of the motor. Compressor as described.