JP2002147873A - Co2 refrigeration cycle and method for controlling operation of compressor of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CO2 refrigeration cycle and a method of controlling the operation of a compressor of the CO2 refrigeration cycle where pressure rise of CO2 refrigerant in a high pressure refrigerant path region accompanying rise in the rotational speed of the compressor, temperature of a gas cooler or the like is suppressed, and the circulation flow rate of the refrigerant is prevented from becoming excessively high. SOLUTION: The compressor 22 is provided with a first bypass port 100, a second bypass port 101 and a bypass port opening/closing mechanism 102. The bypass port opening/closing means 102 controls the first bypass port 100 and the second bypass port 101, in such a manner as to open and close the ports on the basis of the conditions of the rotational speed of the compressor 22 and the pressure of the CO2 refrigerant flowing in the high-pressure refrigerant flow path region. Thus, the pressure of the CO2 refrigerant flowing in the high-pressure refrigerant flow path region is controlled by a combination of the bypass port opening/closing mechanism 102 and a high-pressure control valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates includes a CO ₂ refrigeration cycle for the CO ₂ refrigerant, and to a compressor operation control method of the CO ₂ refrigeration cycle.

[0002]

2. Description of the Related Art In recent years, there has been an increasing interest in preserving the global environment. However, there is a concern that an alternative chlorofluorocarbon, such as R134a, which is conventionally used as a refrigerant for an air conditioner for a vehicle, will have an effect on global warming. Have been. For this reason, as a substitute for the alternative CFC refrigerant, a vehicle air conditioner using a substance originally existing in the natural world, a so-called natural refrigerant, has been studied. As a candidate for such a natural refrigerant, carbon dioxide (CO ₂ ) has attracted attention. This CO ₂ has the advantage that it not only contributes significantly less to global warming than CFC alternatives, but also is not flammable and is basically harmless to the human body.

[0003] From such a background, a vapor compression refrigeration cycle using carbon dioxide (hereinafter abbreviated as CO ₂ refrigeration cycle) has been proposed. An example of this conventional CO ₂ refrigeration cycle will be described with reference to FIG.

[0004] Reference numeral 1 in the figure denotes a compressor for compressing CO ₂ in a gaseous state, which is driven by obtaining a driving force from a driving source (not shown) (for example, an internal combustion engine). I have. Reference numeral 2 denotes a gas cooler (radiator) that cools CO ₂ compressed by the compressor 1 by exchanging heat with external air or the like.
Reference numeral 3 denotes a high-pressure control valve provided on a pipe on the outlet side of the intercooler 7 described later. The high-pressure control valve 3 is provided at the outlet side of the gas cooler 2 in accordance with the CO ₂ temperature (refrigerant temperature) detected by the temperature-sensitive cylinder 11 described later (the outlet pressure of the intercooler 7 in this example). Side pressure (high side pressure). Incidentally, the high pressure control valve 3, which together with pressure control also serves as a pressure reducer, CO ₂ refrigerant, the high pressure control valve 3
, And becomes CO ₂ in a low-temperature, low-pressure gas-liquid two-phase state, and further reduced by the throttle resistor 4 a (throttle means).

[0005] Reference numeral 4 denotes an evaporator (evaporator) that functions as an air cooling means (cooler) in the vehicle compartment, and is used when CO _{2 in} a gas-liquid two-phase state is vaporized (evaporated) in the evaporator 4. Then, the latent heat of evaporation is taken from the air inside the vehicle to cool the air inside the vehicle. Reference numeral 5 denotes a liquid storage container for storing the liquid refrigerant 5a.
The pipe 6 on the outlet side is vertically penetrated so that the liquid refrigerant 5a in the liquid reservoir 5 and the liquid refrigerant in the pipe 6 exchange heat. The penetrating portion of the pipe 6 of the liquid reservoir 5 is sealed (not shown) so that the inside of the liquid reservoir 5 is a closed space. The bottom of the liquid reservoir 5 communicates with a pipe 6 between the high-pressure control valve 3 and the throttle resistor 4a by a communication pipe 5b. The intercooler 7 is a counter-current heat exchanger that exchanges heat between a high-temperature and high-pressure refrigerant from the outlet of the gas cooler 2 and a low-temperature and low-pressure refrigerant from the outlet of the evaporator 4.
₍₂ ) It has a function to improve the response speed to the capacity increase requirement of the refrigeration cycle.

The compressor 1, gas cooler 2, intercooler 7, high-pressure control valve 3, throttle resistor 4a, and evaporator 4 described above are connected by a pipe 6 to form a closed circuit (CO ₂ refrigeration cycle). Has formed.
Reference numeral 8 denotes an oil separator that collects lubricating oil from the refrigerant gas discharged from the compressor 1 so that the collected lubricating oil is returned into the compressor 1 through the oil return pipe 9. Has become.

[0007]

The conventional CO ₂ refrigeration cycle described above has the following problems. That is, in designing the compressor 1,
In order to achieve high compression efficiency even at low speed rotation, the compressor is designed to have a large displacement amount per rotation at low speed rotation (compression chamber volume at the start of compression in the compressor 1). On the other hand, in a CO ₂ refrigeration cycle using CO ₂ as a refrigerant, compared with other refrigeration cycles using alternative Freon as a refrigerant, a high-pressure refrigerant flow path region (from the compressor 1 through the gas cooler 2 and the intercooler 7). between leading up to the high pressure control valve 3, that the thick line area through which CO ₂ refrigerant which has high pressure. hereinafter, the same. since it is highly necessary for pressure control), with only the pressure control by the throttle mechanism CO ₂ refrigeration There was a risk that the refrigerant circulation flow rate during the cycle would be excessive.

The present invention has been made in view of the above circumstances, and suppresses a rise in the pressure of the CO ₂ refrigerant in the high-pressure refrigerant flow path region due to a rise in the compressor rotation speed, a rise in the gas cooler temperature, and the like. An object of the present invention is to provide a CO ₂ refrigeration cycle and a compressor operation control method for the CO ₂ refrigeration cycle that can prevent the circulation flow rate from becoming excessive.

[0009]

The present invention employs the following means in order to solve the above-mentioned problems. C according to claim 1
O ₂ refrigeration cycle includes a compressor for compressing a CO ₂ refrigerant, a gas cooler for cooling the CO ₂ refrigerant after being compressed in the compressor, the pressure control of the CO ₂ refrigerant after being cooled in the gas cooler And a cooler that takes in the CO ₂ refrigerant after passing through the high-pressure control valve and cools an object to be cooled, wherein the compressor is provided in a spiral shape on one side of an end plate. A fixed scroll fixed at a fixed position with the wall of the other end plate, and another spiral wall standing on one side surface of the other end plate to engage with each other to rotate the wall. In a CO ₂ refrigeration cycle which is a scroll compressor having a revolving scroll supported so as to be capable of revolving orbiting while being prevented, an end plate of the fixed scroll has a compression chamber formed between the revolving scroll and the fixed scroll. A communication bypass port; A bypass port opening / closing mechanism for opening / closing the bypass port, wherein the bypass port opening / closing mechanism is configured to control a rotational speed condition of the compressor and a high-pressure refrigerant from the compressor to the high-pressure control valve via the gas cooler. performs opening and closing control of the bypass port by the pressure conditions of the CO ₂ refrigerant flowing through the channel region, the pressure of the CO ₂ refrigerant flowing through the high-pressure refrigerant passage area, and the bypass port opening and closing mechanism and the high-pressure control valve Characterized by being controlled by a combination of

[0010] The CO according to claim 1_TwoFor refrigeration cycle
According to the CO flowing through the high-pressure refrigerant flow path region,_TwoRefrigerant pressure
Adjustment is done by high pressure control valve and bypass port.
This is performed by adjusting the pressure by an opening / closing mechanism. And
By these controls, CO flowing through the high-pressure refrigerant flow path region_Twocold
The pressure rise of the medium can be suppressed. That is, high pressure
The pressure adjustment by the control valve is performed, for example, by controlling CO 2 at the gas cooler outlet.
_TwoBy detecting the refrigerant temperature, etc., CO_Twocold
The medium pressure is detected, and the high pressure control valve
By adjusting CO, the CO downstream of the gas cooler_TwoRefrigerant pressure
Perform force adjustment. The pressure by the bypass port opening / closing mechanism
The force adjustment is performed in the following flow. (1) First, the number of rotations of the compressor is set to a predetermined number of rotations.
Judgment as to whether it is high rotation or low rotation
If it is determined that the engine speed is low, the bypass port
Fully closed and maximum displacement (all that is sucked into the compression chamber
CO_TwoThe refrigerant is compressed to the end and flows into the high-pressure refrigerant flow path.
The compression chamber volume at the start of compression)
The machine is operated. (2) Conversely, the rotation speed of the compressor is higher than the rotation speed condition
If it is determined that the high pressure refrigerant flow path
Detect the pressure in the area (for example, CO at the gas cooler outlet) _TwoRefrigerant
This is detected based on the temperature.)
Open bypass port if higher than force condition and compress
Indoor CO_TwoRelieves part of the refrigerant, lower than pressure conditions
In this case, close the bypass port and_TwoStop refrigerant from escaping
Perform the operation of Open / close operation of this bypass port
Due to the decrease in displacement, CO in the high pressure refrigerant flow path area_Two
Adjust the pressure of the refrigerant.

[0011] compressor operation control method of the CO ₂ refrigeration cycle according to claim 2 includes a compressor for compressing a CO ₂ refrigerant, a gas cooler for cooling the CO ₂ refrigerant after being compressed in the compressor, the A compressor configured to control a pressure of the CO ₂ refrigerant after being cooled by the gas cooler, and a cooler that cools an object to be cooled by taking in the CO ₂ refrigerant after passing through the high pressure control valve; Is a fixed scroll fixed at a fixed position with a spiral wall body erected on one side surface of the end plate, and another spiral wall body erected on one side surface of the other end plate. in the compressor operation control method of the CO ₂ refrigeration cycle a scroll compressor comprising a revolving movably supported orbiting scroll being prevented rotation by engaging the respective wall to each other have, the fixed Orbiting on the scroll end plate A bypass port communicating with a compression chamber formed between the compressor and a crawl; and a bypass port opening / closing mechanism for opening / closing the bypass port. Based on the pressure condition of the CO ₂ refrigerant flowing through the high-pressure refrigerant flow path area up to the control valve, the bypass port opening / closing mechanism performs opening / closing control of the bypass port, and flows through the high-pressure refrigerant flow path area. The CO
₍₂₎ The pressure of the refrigerant is controlled by a combination of the bypass port opening / closing mechanism and the high-pressure control valve.

[0012] compressor operation control method of the CO ₂ refrigeration cycle according to claim 3, wherein, in the compressor operation control method of the CO ₂ refrigeration cycle according to claim 2, the opening and closing control of the bypass port by the bypass port opening and closing mechanism At least, a compressor rotation speed determining step of determining whether the rotation speed of the compressor is higher or lower than a preset rotation speed condition; and a high rotation speed in the compressor rotation speed determination step. The pressure of the CO ₂ refrigerant flowing through the high-pressure refrigerant flow path region is determined based on a refrigerant pressure determination step of determining whether the pressure is higher or lower than a predetermined pressure condition. It is characterized by being performed.

The CO _{2 according to} claim 2 or 3
According to a compressor operation control method for a refrigeration cycle, claim 1 is provided.
As in the case of the operation of (1), the pressure and flow rate of the CO ₂ refrigerant flowing through the high-pressure refrigerant flow path region can be efficiently controlled.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a CO ₂ refrigeration cycle and a compressor operation control method for the same according to the present invention will be described below with reference to FIGS. 1 to 6, but the present invention is not limited thereto. Of course, it is not. FIG.
FIG. 1 is a configuration diagram illustrating an embodiment of an on-vehicle air conditioner including a CO ₂ refrigeration cycle of the present embodiment. FIG.
FIG. ₂ is a configuration diagram of the CO ₂ refrigeration cycle. FIG.
Is a diagram showing a compressor of the same CO ₂ refrigeration cycle,
It is sectional drawing seen from the cross section which passes along the axis. FIG.
3A and 3B are diagrams illustrating a peripheral portion of a fixed scroll of the compressor, in which FIG. 3A is a cross-sectional view as viewed from a cross section different from FIG. 3, and FIG. 3B is a view as viewed from a scroll tooth side. FIGS. 5A and 5B are diagrams showing the operation of the bypass port opening / closing mechanism of the compressor, wherein FIG. 5A is a state diagram in which the bypass port is completely opened, and FIG. 5B is a diagram in which the bypass port is completely closed. It is a state diagram. FIG. 6 is a flowchart showing the operation of the bypass port opening / closing mechanism of the compressor.

As shown in FIG. 1, a vehicle air conditioner equipped with a CO ₂ refrigeration cycle 20 according to the present embodiment has a casing 50 in which an internal space serves as a flow path of air a introduced into a vehicle interior.
Is used as an air conditioner main body, and various components described below are accommodated in the internal space of the casing 50.

That is, inside the casing 50, an inside / outside air switching damper 53 for switching an air intake passage to either the inside air port 51 or the outside air port 52, and air inside the casing 50 through the inside air port 51 or the outside air port 52. and a cooler for cooling the air a introduced by the blower 54, and the CO ₂ refrigeration cycle 2
0, and the evaporator 2
Heater core 5 which is an air heater disposed downstream of
6, an air mix damper 57 for adjusting the flow rate of the air a passing through the heater core 56, a face damper 61 and a foot damper 62 for opening and closing the face outlet 58, the foot outlet 59, and the defrost outlet 60, respectively, and a defrost damper 63. And are provided. The outlets 58, 59, and 60 communicate with the interior of the vehicle through ducts (not shown). The control device 64 controls the blower blower 54, controls motors (not shown) for driving the dampers 53, 57, 61, 62, 63, and further controls the operation of the CO ₂ refrigeration cycle 20. is there.

In the vehicle air conditioner thus constructed, the air a introduced from the inside air port 52 or the outside air port 53
, The total amount through the evaporator 21 is cooled by CO ₂ refrigerant exchanges heat with CO ₂ refrigeration cycle 20. Thereafter, the amount of air that passes through the heater core 56 and is heated is distributed according to the opening degree of the air mix damper 57.
The temperature is adjusted to a predetermined value, and the air is introduced into the passenger compartment from at least one of the outlets 58, 59, and 60. The heater core 57 is generally supplied with cooling water, which cools a drive source of an internal combustion engine (not shown) and has a high temperature.

As shown in FIG. 2, the CO ₂ refrigeration cycle 2
The 0, a compressor 22 for compressing a CO ₂ refrigerant r, a gas cooler 23 for cooling the CO ₂ refrigerant r after being compressed by the compressor 22, CO ₂ after being cooled in the gas cooler 23
A high-pressure control valve 24 that controls the pressure of the refrigerant r, and the evaporator 21 that takes in the CO ₂ refrigerant r that has passed through the high-pressure control valve 24 and cools the air a in the casing 50 to be cooled. ing. Furthermore, this CO ₂
The refrigeration cycle 20 includes an oil separator 25 provided between the compressor 22 and the gas cooler 23, a temperature-sensitive cylinder 26 provided on the outlet side of the gas cooler 23, and a gas cooler 2.
3, an intercooler 27 provided between the high-pressure control valve 24, a liquid reservoir 28 provided between the intercooler 27 and the evaporator 21, and a throttle resistor 21a provided on the upstream side of the evaporator 21. Is provided.

The compressor 22 is a scroll compressor that compresses a CO ₂ refrigerant r in a gaseous state, and is driven by obtaining a driving force from a driving source (not shown) (for example, an internal combustion engine). I have. The details of the compressor 22 will be described later. The gas cooler 23 is a radiator that cools the CO ₂ refrigerant r compressed by the compressor 22 by exchanging heat with the outside air or the like. Also, the high pressure control valve 24
Controls the outlet pressure of the gas cooler 23 (high side pressure on the outlet side of the intercooler 27 in this example) in accordance with the CO ₂ temperature (refrigerant temperature) detected by the temperature-sensitive cylinder 26 at the outlet side of the gas cooler 23. It is supposed to. The high-pressure control valve 24 serves as a pressure reducer as well as pressure control. The CO ₂ refrigerant r is depressurized by the high-pressure control valve 24 to become low-temperature low-pressure CO _{2 in} a gas-liquid two-phase state. The pressure is reduced by 21a.

The evaporator 21 is an evaporator functioning as air cooling means in the vehicle compartment. When the CO ₂ refrigerant in a gas-liquid two-phase state evaporates (evaporates) in the evaporator 21, the evaporator 21 evaporates from the vehicle interior air. It takes away latent heat to cool the air in the cabin. The liquid storage container 28 is a liquid storage container that stores the liquid refrigerant 28a.
A pipe 29 on the outlet side of the evaporator 21 penetrates vertically, and is connected to the liquid refrigerant 28 a in the liquid reservoir 28 and the pipe 29.
The heat exchange is performed with the liquid refrigerant r in the inside. The penetration part of the pipe 29 of the liquid storage container 28 is sealed (not shown) so that the inside of the liquid storage container 28 becomes a closed space. In addition, the bottom of the liquid reservoir 28 communicates with a pipe 29 between the high-pressure control valve 24 and the throttle resistor 21a by a communication pipe 28b.

The intercooler 27 is a counter-current heat exchanger for exchanging heat between the high-temperature and high-pressure CO ₂ refrigerant r from the outlet of the gas cooler 23 and the low-temperature and low-pressure CO ₂ refrigerant r from the evaporator 21. It has a function of improving the response speed to the requirement for increasing the capacity of the CO ₂ refrigeration cycle 20. Further, the oil separator 25 is provided with the compressor 2.
The lubricating oil is collected from the CO ₂ refrigerant gas r discharged from the compressor ₂ , and the collected lubricating oil is returned into the compressor 22 through the oil return pipe 25 a. The compressor 22, the gas cooler 23, the intercooler 27, the high-pressure control valve 24, the throttle resistor 21a, and the evaporator 21 described above are connected by a pipe 29 to form a closed circuit (a CO ₂ refrigeration cycle). I have.

Next, the compressor 22 will be described in detail with reference to FIG. In addition, the compressor 22 of the present embodiment includes:
It is particularly characterized in that it has a bypass port and a bypass port opening / closing mechanism (both will be described later) provided in the fixed scroll. First, an overall configuration will be described with reference to FIG. The description of the bypass port opening / closing mechanism will be continued.

In FIG. 3, reference numeral 31 denotes a housing. The housing 31 includes a housing main body 31a formed in a cup shape and a lid plate 31b fixed to the opening end side of the housing main body 31a. Have been.
A scroll compression mechanism including a fixed scroll 32 and an orbiting scroll 33 is provided inside the housing 31. The fixed scroll 32 has a configuration in which a spiral wall 32b is erected on one side surface of an end plate 32a. Similar to the fixed scroll 32, the orbiting scroll 33 has a configuration in which a spiral wall 33b is erected on one side surface of an end plate 33a, and the wall 33b is substantially the same as the wall 32b on the fixed scroll 32 side. Have the same shape.
Further, tip seals 47 and 48 for increasing the airtightness of the compression chamber C are provided on the upper edges of the walls 32b and 33b.

The fixed scroll 32 is fastened to the housing body 31a by bolts 34. Further, the orbiting scroll 33 is assembled by engaging the walls 32b and 33b with each other in a state where the orbiting scrolls 33 are eccentric with respect to the fixed scroll 32 by the orbital revolving radius and shifted in phase by 180 °. The rotation is prevented by a rotation prevention mechanism 35 provided between the end plate 33a and the end plate 33a, and the rotation is supported so as to be able to revolve.

A rotary shaft 36 having a crank 36a is penetrated through the cover plate 31b, and bearings 37a, 37
b, it is rotatably supported by the lid plate 31b. A boss 38 is provided at the center of the other end surface of the end plate 33a on the orbiting scroll 33 side. The boss 38 has a crank 36a
Of the bearing 39 and the drive bush 40
The rotary scroll 3
Numeral 3 revolves around the rotating shaft 36 to rotate. Further, a balance weight 41 for canceling an unbalance amount given to the orbiting scroll 33 is attached to the rotating shaft 36.

Further, inside the housing 31, a suction chamber 42 is formed around the fixed scroll 32, and further, a discharge cavity 43 defined by a bottom surface inside the housing main body 31a and another side surface of the end plate 32a is formed. ing. The housing main body 31a is provided with a suction port 44 for guiding the low-pressure CO ₂ refrigerant toward the suction chamber 42. At the center of the end plate 32a on the fixed scroll 32 side, the volume gradually decreases and moves toward the center. A discharge port 45 for guiding high-pressure CO ₂ refrigerant from the compression chamber C to the discharge cavity 43 is provided. In addition, a discharge valve 45a that opens the discharge port 45 only when a pressure equal to or more than a predetermined magnitude is applied is provided at the center of the other side surface (the center of the back surface) of the end plate 32a.

According to the scroll compressor 22 having the configuration described above, when the rotary shaft 36 is driven to rotate around its axis by a motor (not shown), the eccentric shaft 36b
Makes the orbiting scroll 33 revolve around the fixed scroll 32 while preventing its rotation. Then, the low-pressure CO ₂ refrigerant gas taken in from the suction port 44 becomes
While gradually decreasing the volume and gradually increasing the pressure in each compression chamber C, the compression chamber C moves from the outer peripheral end toward the center, and finally is discharged to the discharge cavity 43 through the discharge port 45. . The compressed CO ₂ refrigerant gas discharged to the discharge cavity 43 is supplied to the gas cooler 23 through the oil separator 25.

The overall configuration and operation of the compressor 22 according to this embodiment have been described above. Next, the bypass port and the bypass port opening / closing mechanism will be described below with reference to FIGS. . As shown in FIG. 4A, a pair of first bypass ports (30% ports) communicating with a compression chamber C formed between the end scroll 32 and the orbiting scroll 33 are provided on the end plate 32a of the fixed scroll 32. 100
And a second bypass port (50% port) 101 and a bypass port opening / closing mechanism 102 for opening and closing these bypass ports 100 and 101. And
The bypass port opening / closing mechanism 102 includes a high-pressure refrigerant flow path region HP (shown by a bold line in FIG. 2) between the compressor 22 and the high-pressure control valve 24 through the gas cooler 23 and the high-pressure control valve 24. Depending on the pressure condition of the CO ₂ refrigerant flowing through the flow path region).
It is configured to perform the opening / closing control.

The pair of bypass ports 10
0, 101 and its bypass port opening / closing mechanism 102 constitute a set of high-pressure control units as shown in FIG.
As shown, two sets are provided with the discharge port 45 of the fixed scroll 32 interposed therebetween. These high-pressure control units B1, B2
Have the same configuration, and therefore, in the following description, only one of them will be described.

As shown in FIG. 4B, when the volume of the compression chamber at the start of compression is 100%, the first bypass port 100 compresses the CO ₂ refrigerant in the compression chamber to a volume of about 30%. It is formed at a spiral position. The one first bypass port 100 is formed at a position (180-degree position) opposed to the other first bypass port 100 with the discharge port 45 interposed therebetween. The second bypass port 101 is formed at a spiral position where the volume of the CO ₂ refrigerant in the compression chamber is compressed to about 50% when the volume of the compression chamber at the start of compression is 100%. Then, the one first bypass port 1
00 is formed at a position (180-degree position) facing the other first bypass port 100 with the discharge port 45 interposed therebetween. The first bypass port 100 and the second
Since the bypass port 101 also communicates with the bypass flow passage 104 formed in the fixed scroll 32, the first bypass port 100 and the second bypass port 10
A part of the CO ₂ refrigerant in the compression chamber C flows out to the bypass flow path 104 via 1 and is returned to the suction port 44 (low pressure side).

As shown in FIG. 4A, the bypass port opening / closing mechanism 102 includes a piston 102a that opens and closes the first bypass port 100 and the second bypass port 101 by moving the piston in the bypass flow path 104, A spring 102b for urging the piston 102a toward an open state, and a spring fixing part 102 for fixing one end of the spring 102b in the bypass flow passage 104
c, and a pressure regulating valve 102d for inducing the pressure (high pressure) of the CO ₂ refrigerant in the high-pressure refrigerant flow path region HP to close the piston 102a and reducing the pressure to a preset pressure value. Reference numeral 102e denotes a piston pressurizing flow path communicating between the pressure regulating valve 102d and the bypass refrigerant flow path 104, and reference numeral 102f denotes a seal component fixed to the piston 102a.

The bypass port opening / closing mechanism 10
According to No. 2, the bypass port open state shown in FIG. 5A and the bypass port closed state shown in FIG. 5B can be selected. That is, the pressure regulating valve 102d
In an operation state in which the pressure of the CO ₂ refrigerant r1 is smaller than the urging force of the spring 102b, as shown in FIG. 5A, the piston 102a slides to the left in the drawing, and the first bypass port 100 and the second Bypass port 101
Fully open both. As a result, the CO ₂ refrigerant r2 in the compression chamber C passes through the opened first bypass port 100 and the second bypass port 101, and the bypass passage 104
And the suction port 44 (low pressure side)
Is to be returned to.

Conversely, when the pressure of the CO ₂ refrigerant r1 from the pressure regulating valve 102d is higher than the urging force of the spring 102b, the piston 1 is operated as shown in FIG.
02a slides to the right in the drawing, and both the first bypass port 100 and the second bypass port 101 are fully closed. Thereby, the first bypass port 100 and the second
The bypass of the CO ₂ refrigerant r2 through the bypass port 101 is prohibited.

The setting of pressure reduction by the pressure regulating valve 102d (that is, the setting of the pressure value for pressurizing the piston 102a to the closed state through the piston pressurizing flow path 102e) is set by the control device 64. I have. Then, the control device 64 in the operating state checks the pressure of the CO ₂ refrigerant flowing in the high-pressure refrigerant flow path area HP in real time,
The pressure of the O ₂ refrigerant is maintained at an appropriate pressure by a combination of control by the bypass port opening / closing mechanism 102 (hereinafter, referred to as first control) and control by the high-pressure control valve 24 (hereinafter, referred to as second control). It can be controlled as follows. The pressure of the CO ₂ refrigerant flowing through the high-pressure refrigerant flow path region HP can be controlled by the first and second controls.

The details of the compressor operation control method for the CO ₂ refrigeration cycle according to this embodiment will be described below. In the second control by the above-described high-pressure control valve 24, the CO ₂ refrigerant pressure in the high-pressure refrigerant flow path region HP is detected by, for example, detecting the temperature of the CO ₂ refrigerant at the outlet of the gas cooler 23 by the temperature-sensitive cylinder 26, The high-pressure control valve 24 adjusts the opening thereof as necessary, so that the CO ₂ in the high-pressure refrigerant flow path region HP
Excessive pressure increase of the refrigerant is suppressed.

The above-described bypass port opening / closing mechanism 10
The first control (opening / closing control of the first bypass port 100 and the second bypass port 101) according to 2 is performed according to the flow shown in FIG. That is, the first bypass port 100
The opening and closing control of the second bypass port 101 is performed by the compressor 2
A step of determining whether the number of rotations 2 is higher or lower than a predetermined number of rotations, and a case where it is determined that the number of rotations is high in the compressor number determination step. A refrigerant pressure determination step of determining whether the pressure of the CO ₂ refrigerant flowing through the high-pressure refrigerant flow path region HP is higher or lower than a preset pressure condition;
It is performed based on. This is described in detail below.

(1) First, in the compressor rotational speed determination step, the control device 64 determines whether the rotational speed of the compressor 22 is higher or lower than a preset rotational speed condition. (Step S1), and when it is determined that the rotation is low, the control device 64 operates the pressure adjusting valve 102
d, the set pressure in the piston pressurization flow path 102e is increased, and both the first bypass port 100 and the second bypass port 101 are completely closed to achieve the maximum displacement (all the CO ₂ sucked into the compression chamber). The compressor 22 is operated at full load with the compression chamber volume at the start of compression when the refrigerant is completely compressed and flows into the high-pressure refrigerant flow path region HP (step S2). Thus, even under the operating condition in which the rotational speed of the compressor 22 is low and the capacity is expected to be insufficient, the compressor 22 is operated at full load, so that it is possible to prevent the capacity from being insufficient.

(2) Conversely, in the compressor speed determination step, if the control device 64 determines that the speed of the compressor 22 is higher than the speed condition, the process proceeds to step S1. Subsequently, the pressure in the high-pressure refrigerant flow path region HP is detected (for example, by detecting the temperature of the CO ₂ refrigerant at the outlet of the gas cooler 23 with the temperature-sensitive cylinder 26), and this pressure is higher or lower than a preset pressure condition. The refrigerant pressure determination step (step S3) for determining whether the refrigerant pressure is higher or lower is performed.

When it is determined that the pressure is high, the control device 64 instructs the pressure adjusting valve 102d to reduce the set pressure in the piston pressurizing flow path 102e, and the first bypass port 100 and the second bypass port 101 When opened, a part of the CO ₂ refrigerant in the compression chamber C is released to the suction port 44 (Step S4). On the other hand, if it is determined that the pressure is lower than the pressure condition, the control device 64 instructs the pressure adjusting valve 102d to increase the set pressure in the piston pressurizing flow path 102e, and
An operation of closing the bypass port 100 and the second bypass port 101 to stop the escape of the CO ₂ refrigerant is performed (Step S5). In this manner, by continuously adjusting the displacement amount by the opening and closing operation of the first bypass port 100 and the second bypass port 101, C in the high-pressure refrigerant flow path area HP
The pressure of the O ₂ refrigerant is adjusted.

According to the CO ₂ refrigeration cycle and the compressor operation control method of the present embodiment described above, the first bypass port 100 and the second bypass port 101 are provided to the compressor 22.
And a bypass port opening / closing mechanism 102, and the bypass port opening / closing mechanism 102 is configured to control the first bypass port 100 and the second bypass by the rotational speed condition of the compressor 22 and the pressure condition of the CO ₂ refrigerant flowing through the high-pressure refrigerant flow path region HP. The opening / closing control of the port 101 is performed, and the pressure of the CO ₂ refrigerant flowing through the high-pressure refrigerant flow path region HP is reduced by the bypass port opening / closing mechanism 10.
2 and the high-pressure control valve 24. According to this, it is possible to suppress an increase in the pressure of the CO ₂ refrigerant in the high-pressure refrigerant flow path region HP due to an increase in the number of rotations of the compressor, an increase in the temperature of the gas cooler, and the like. It is possible to prevent a case in which the refrigerant circulation flow rate is wide open and the refrigerant circulation flow rate is excessive. In addition, under operating conditions where the rotational speed of the compressor 22 is low and capacity shortage is expected, the compressor 22 is operated at full load, so that the capacity shortage can be avoided.

In the above embodiment, the description has been made on the assumption that a CO ₂ refrigerant is used. However, the present invention is not limited to this. For example, the present invention is applied to a refrigerant using another refrigerant having a low critical temperature such as a CO ₂ refrigerant. Is also possible.

[0042]

According to the CO ₂ refrigeration cycle of the present invention, the compressor is provided with a bypass port and a bypass port opening / closing mechanism. opens and closes the control of the bypass port by the pressure conditions of the CO ₂ refrigerant flowing through the channel region, the pressure of the CO ₂ refrigerant flowing through the high-pressure refrigerant passage area is controlled by the combination of the bypass port opening and closing mechanism and the high-pressure control valve The configuration was adopted. According to this configuration, it is possible to suppress a rise in the pressure of the CO ₂ refrigerant in the high-pressure refrigerant flow path region due to a rise in the compressor rotation speed, a rise in the gas cooler temperature, and the like without extremely increasing the refrigerant circulation amount. Become.

Further, according to the second or third aspect of the present invention,
₍₂ ) According to the compressor operation control method of the refrigeration cycle, similarly to the effect of claim 1, the pressure increase of the CO ₂ refrigerant in the high-pressure refrigerant flow path region due to an increase in the compressor rotation speed, an increase in the gas cooler temperature, and the like. Can be suppressed without extremely increasing the amount of circulating refrigerant.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a vehicle-mounted air conditioner including a CO ₂ refrigeration cycle of the present invention.

FIG. 2 is a configuration diagram of the CO ₂ refrigeration cycle.

FIG. 3 is a view showing the compressor of the CO ₂ refrigeration cycle, and is a cross-sectional view as viewed from a cross-section passing through the axis thereof.

4A and 4B are diagrams showing a peripheral portion of a fixed scroll of the compressor, wherein FIG. 4A is a cross-sectional view as viewed from a cross section different from FIG. 3, and FIG. 4B is a view as viewed from a scroll tooth side. is there.

5A and 5B are diagrams showing an operation of a bypass port opening / closing mechanism of the compressor, in which FIG. 5A is a diagram in a state where the bypass port is completely opened, and FIG. 5B is a diagram in which the bypass port is completely closed. FIG.

FIG. 6 is a flowchart showing an operation of a bypass port opening / closing mechanism of the compressor.

FIG. 7 is a configuration diagram showing a conventional CO ₂ refrigeration cycle.

[Explanation of symbols]

20 ... CO ₂ refrigeration cycle 21 ... evaporator (cooler) 22 ... compressor 23 ... gas cooler 24 ... high-pressure control valve 32 ... fixed scroll 32a ... end plate 32 b · · · Wall body 33 ··· Orbiting scroll 33a ··· Other end plate 33b ··· Other wall bodies 100 and 101 ··· First bypass port and second bypass port (bypass port) 102 ··· Bypass port Opening / closing mechanism HP: High-pressure refrigerant flow path area

Claims (3)

[Claims] And 1. A compressor for compressing a CO ₂ refrigerant, a gas cooler for cooling the CO ₂ refrigerant after being compressed in the compressor, the pressure control of the CO ₂ refrigerant after being cooled in the gas cooler A high-pressure control valve to perform, and a cooler that cools an object to be cooled by taking in the CO ₂ refrigerant after passing through the high-pressure control valve, wherein the compressor has a spiral shape that is provided upright on one side of an end plate. It has a fixed scroll having a wall and fixed at a fixed position, and another spiral-shaped wall standing upright on one side surface of the other end plate to engage with each other to prevent rotation. In the CO ₂ refrigeration cycle, which is a scroll compressor having a revolving scroll supported so as to be able to revolve and revolve, the end plate of the fixed scroll communicates with a compression chamber formed between the revolving scroll and the fixed scroll. And the bypass port A bypass port opening / closing mechanism for opening / closing a sport; the bypass port opening / closing mechanism includes: a compressor rotation speed condition; and a high-pressure refrigerant flow from the compressor to the high-pressure control valve via the gas cooler. Said C flowing through the road area
Open / close control of the bypass port is performed according to the pressure condition of the O ₂ refrigerant, and the pressure of the CO ₂ refrigerant flowing through the high-pressure refrigerant flow path region is controlled by a combination of the bypass port opening / closing mechanism and the high-pressure control valve. A CO ₂ refrigeration cycle characterized in that: 2. CO_TwoA compressor for compressing the refrigerant;
CO after being compressed by a press_TwoGas cooler for cooling refrigerant
And the CO after being cooled by the gas cooler._TwoRefrigerant
A high-pressure control valve for performing pressure control, and after passing through the high-pressure control valve,
The CO_TwoA cooler that takes in the refrigerant and cools the object to be cooled
And the compressor has a spiral wall erected on one side surface of the end plate.
A fixed scroll that has a body and is fixed in place, and another
With another spiral wall standing on one side of the end plate
The walls are engaged with each other to prevent rotation and
And a revolving scroll supported so as to be able to revolve.
CO that is a scroll compressor_TwoRefrigeration cycle compressor operation
In the rotation control method, an end plate of the fixed scroll is provided with an orbiting scroll.
A bypass port communicating with a compression chamber formed therebetween;
Bypass port opening / closing mechanism for opening / closing the bypass port
And the number of revolutions of the compressor and the gas
High-pressure refrigerant flow through the heat exchanger to the high-pressure control valve
The CO flowing through the road area_TwoBased on refrigerant pressure conditions
The bypass port by the bypass port opening / closing mechanism.
Control the opening and closing of the port, the CO flowing through the high-pressure refrigerant flow path region_TwoRefrigerant pressure
Between the bypass port opening / closing mechanism and the high pressure control valve.
CO controlled by combination _Twofrozen
Cycle compressor operation control method. 3. The compressor operation control method for a CO ₂ refrigeration cycle according to claim 2, wherein the bypass port opening / closing control by the bypass port opening / closing mechanism includes at least a rotation number of the compressor set in advance. A compressor rotation speed determining step of determining whether the rotation speed is higher or lower than the number of conditions; and a high rotation speed is determined in the compressor rotation speed determination step.
The pressure of the CO ₂ refrigerant flowing through the high-pressure refrigerant flow path region is determined based on a refrigerant pressure determining step of determining whether the pressure is higher or lower than a preset pressure condition. Compressor operation control method for a CO ₂ refrigeration cycle.