JP2001354030A - Thermo-compression type refrigerating cycle for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a fuel economy for a vehicle by saving power in a refrigerating cycle. SOLUTION: A target gas-flowing volume is controlled in accordance with a fuel-saving control line η selected to bring the sum of consumed power in an alternater and consumed power in a compressor to the minimum, when a pressure switch 610 is OFF, and the target gas blowing volume (duty ratio) is increased compared with that when the pressure switch 610 is OFF, so as to reduce the target gas blowing volume (duty ratio) as a vehicle speed is increased, when the pressure switch 610 is ON. Refrigerating capacity (cooling capacity) is secured thereby while saving the power in the refrigerating cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor compression refrigeration cycle for a vehicle (hereinafter, abbreviated as a refrigeration cycle), and is effective when applied to a vehicle air conditioner.

[0002]

2. Description of the Related Art As is well known, a refrigeration cycle using chlorofluorocarbon as a refrigerant includes a compressor, a condenser, a decompressor, an evaporator, and a blower for blowing cooling air to the condenser.

Conventionally, in a vehicle air conditioner, when a high-pressure side refrigerant pressure of a refrigeration cycle is lower than a predetermined pressure, a predetermined constant voltage (for example, 6 V) is applied to an electric motor of a blower, When the refrigerant pressure becomes equal to or higher than a predetermined pressure, the applied voltage is increased (for example, up to 12 V) to increase the amount of cooling air to the condenser, thereby ensuring the cooling performance.

[0004]

In recent years, there has been an increasing demand for power saving (fuel saving) of vehicles including air conditioners. Therefore, an object of the present invention is to reduce the power of a refrigeration cycle.

[0005]

According to the present invention, in order to achieve the above object, according to the first aspect of the present invention, a compressor (100) for sucking and compressing a refrigerant and discharging the refrigerant from the compressor (100). A radiator (200) for exchanging heat between the refrigerant and air;
A decompressor (300) for decompressing the refrigerant flowing out of the radiator (200), an evaporator (400) for evaporating the refrigerant decompressed by the decompressor (300), and cooling air for the radiator (200). And a blower (510) for blowing air.
When the refrigerant pressure on the high pressure side from the discharge side of 0) to the inflow side of the decompressor (300) is equal to or higher than a predetermined pressure, the blower (510) is controlled to reach the target air flow rate determined based on the refrigerant pressure on the high pressure side. ), And when the refrigerant pressure on the high pressure side is lower than a predetermined pressure, the blower (510) is controlled so as to have a target air flow rate determined based on the vehicle speed.

According to a detailed study by the inventor, when the refrigerant pressure on the high pressure side is lower than a predetermined pressure, the refrigerant is cooled to a heat load (cooling capacity) of the radiator (200) determined by the refrigerant pressure on the high pressure side. It has been found that the refrigerant pressure on the high pressure side decreases and the power consumption of the compressor (100) can be reduced, so that power saving of the refrigeration cycle can be achieved.

According to the present invention, when the refrigerant pressure on the high pressure side is lower than the predetermined pressure, the blower (510) is controlled so as to have a target air flow rate determined based on the vehicle speed. The power consumption of the refrigeration cycle can be reduced while suppressing the power consumption of ()) from becoming excessively large.

When the high-pressure side refrigerant pressure is equal to or higher than a predetermined pressure, the radiator (200) is controlled by controlling the blower (510) so as to attain a target air flow rate determined based on the high-pressure side refrigerant pressure. Corresponding to the heat load.

It is desirable that the target air volume be determined so as to decrease as the vehicle speed increases, as in the second aspect of the present invention.

[0010] Further, the blower (510) may be controlled by controlling the voltage applied to the electric motor (512).

Incidentally, the reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present embodiment, the refrigeration cycle according to the present invention is applied to an air conditioner for a vehicle, and FIG. 1 is a schematic diagram of an air conditioner for a vehicle (a refrigeration cycle for a vehicle). In FIG. 1, reference numeral 100 denotes a compressor for suctioning and compressing a refrigerant (in this embodiment, CFC), and reference numeral 200 denotes a condenser (heat dissipation) mounted on the front end side of the vehicle for exchanging heat between the refrigerant discharged from the compressor 100 and air. Container). The compressor 100 operates by obtaining driving force from a traveling engine E / G.

Reference numeral 300 denotes a decompressor for decompressing the refrigerant cooled by the condenser 200, and reference numeral 400 denotes heat exchange between air depressurized by the depressurizer 300 and the refrigerant in a gas-liquid two-layer state blown into the vehicle interior. The evaporator cools air blown into the vehicle compartment by evaporating the liquid-phase refrigerant. The decompressor 300 is a temperature-type expansion valve that adjusts the opening so that the refrigerant heating degree at the refrigerant outlet side of the evaporator 400 (the suction side of the compressor 100) becomes a predetermined value.

Reference numeral 510 denotes a condenser fan (blower) for blowing cooling air to the condenser 200. The condenser fan 510 includes an axial fan 511 for blowing air and an electric motor 51 for driving the axial fan 511 to rotate.
2).

Reference numeral 520 denotes a blower (blower) for blowing conditioned air blown into the vehicle interior. This blower 520 is a centrifugal multi-blade fan (in FIG. 1, an axial fan is drawn to simplify the illustration in the drawing). 521) and an electric motor 522 that drives the centrifugal multi-blade fan 521.

610 is the high pressure side of the refrigeration cycle (compressor 1
The refrigerant pressure in the range from the discharge side of the pressure regulator 00 to the inflow side of the pressure reducer 300 is detected, and when the detected pressure becomes equal to or higher than a predetermined pressure (about 1.5 MPa in the present embodiment), an electronic control unit (ECU) ) Is a pressure switch (pressure detecting means) for sending a signal to 600;
10 and a vehicle speed sensor (vehicle speed detecting means) 6 for detecting a vehicle speed
The electric motor 512 (condenser fan 510) is controlled based on the 20 detection signals.

The ECU 600 includes an electric motor 512
(Condenser fan 510) and blower 520
(Electric motor 522), an air mix door (not shown) for adjusting the mixing ratio of the cool air cooled by the evaporator 400 and the warm air heated by the engine cooling water, and the blowing direction of the conditioned air. The air-conditioning control means such as a blowing mode door (not shown) is also controlled.

Next, control of the condenser fan 510 (electric motor 512) will be described with reference to the flowchart shown in FIG.

First, it is determined whether the start switch (A / C switch) of the air conditioner is turned on (ON or OFF) (S100). If the A / C switch is turned on, the pressure switch 610 and the pressure switch 610 are turned off. The signal from the vehicle speed sensor 620 is read (S110).

Then, it is determined whether the pressure switch 610 is in the ON state (the high-pressure side refrigerant pressure is higher than the predetermined pressure) or OFF (the high-pressure side refrigerant pressure is lower than the predetermined pressure) (S120). In the OFF state, the electric motor 5 is set so as to have a relationship shown by a thick solid line in FIG. 3 (hereinafter, this solid line is referred to as a fuel-saving control line η1).
12 is duty-controlled (S130), while when the pressure switch 610 is in the ON state, the relationship shown by the thick broken line in FIG. 3 (hereinafter, this broken line is referred to as an equal air volume control line η2). Thus, the duty control of the voltage applied to the electric motor 512 is performed (S140).

Here, the duty control is to control the electric motor 512 (condenser fan 510) by controlling the ratio (duty ratio) of the time during which the electric motor 512 is energized and the time during which the electric motor 512 is not energized.

The setting of the duty ratio to a predetermined value means that the condenser fan 510 is controlled so that the amount of air blown toward the condenser 200 by the condenser fan 510 becomes a predetermined amount of air. Determining the air volume is used to determine the duty ratio corresponding to the target air volume.

Next, the fuel efficiency control line η1 and the constant air volume control line η2 will be described.

The solid line in FIG. 3 (hereinafter, this solid line is referred to as an equal air volume control line ηo) indicates the air volume supplied to the condenser 200 (= vehicle speed air + target air volume) when the pressure switch 610 is OFF. This shows the relationship between the target airflow and the vehicle speed when the airflow is constant irrespective of the vehicle speed. The equal airflow control line η2 indicates the airflow supplied to the condenser 200 when the pressure switch 610 is ON. (=
It shows the relationship between the target air flow and the vehicle speed when the (air velocity + target air flow) is constant regardless of the vehicle speed.

Therefore, if the heat radiation capacity required by the condenser 200 (hereinafter, this heat radiation capacity is referred to as the required condenser capacity) is constant regardless of the vehicle speed, when the pressure switch 610 is OFF, the constant air volume control line As shown in ηo, the condenser fan 510 is controlled so that the target air volume decreases as the vehicle speed increases. When the pressure switch 610 is ON, the target air volume increases as the vehicle speed increases as indicated by the equal air volume control line η2. May be controlled so as to reduce the temperature.

Here, the target air volume (air volume supplied to the condenser 200) determined by the equal air volume control lines ηo and η2 is determined by the required capacity of the condenser, and the required capacity of the condenser is determined by the high pressure side refrigerant. Since the pressure increases as the pressure increases, in the present embodiment, the equal air volume control line η2 is determined based on the maximum high-pressure side refrigerant pressure expected in design, and the equal air volume control line ηo indicates that the pressure switch 610 is ON. This is determined based on a predetermined high-pressure side refrigerant pressure.

By the way, the inventor has set the target air flow rate, the compressor 1
After examining the relationship between the power consumption of No. 00 and the power consumption of the condenser fan 510, the following conclusions were obtained.
In this study, the condenser fan 510
The power consumed in the (electric motor 512) is supplied from an alternator (generator) that generates driving power by obtaining driving force from the engine E / G.
The consumed power of the alternator was used as the consumed power of 0 (electric motor 512).

That is, the power consumption of the compressor 100 (≒ discharge pressure × discharge flow rate) increases as the high-pressure side pressure increases, but as the power consumed by the condenser fan 510 (alternator) increases, the target air flow rate (duty rate) increases. Ratio) increases, the heat dissipation capacity of the condenser 200 increases, and the high-pressure side refrigerant pressure decreases, so that the power consumption (duty ratio) of the condenser fan 510 (alternator)
Increases, the power consumption of the compressor 100 decreases, as shown in FIG.

Therefore, as shown by the solid line in FIG. 4, a target that minimizes the sum of the power consumption of the compressor 100 and the power consumption of the condenser fan 510 (alternator) (hereinafter, this sum is referred to as air-conditioning power consumption). Ventilation volume (duty ratio)
Can exist. The relationship between the minimum air-conditioning power consumption and the target airflow (duty ratio) is the above-mentioned fuel-saving control line η1. Note that the fuel saving control line η1
Is appropriately selected according to the product specifications of the refrigeration cycle (air conditioner).

By the way, if the air-conditioning power consumption and the target air volume (duty ratio) are determined, the power consumption of the compressor 100 and the air volume supplied to the condenser 200 at the time of the minimum power consumption (= vehicle speed air + The target pressure can be calculated (estimated) from the high-pressure side refrigerant pressure.

Therefore, in this embodiment, the pressure switch 6
10 when the high pressure side refrigerant pressure is turned on, the fuel saving control line η1
The refrigerant pressure on the high-pressure side calculated (estimated) based on the following formula is used. When the pressure switch 610 is ON, the target air flow is controlled in accordance with the equal air volume control line η2. When the pressure switch 610 is OFF, the fuel saving control line is used. The target airflow is controlled according to η1.

Next, the features of this embodiment will be described.

According to the present embodiment, the pressure switch 610
Is OFF, the target air flow is controlled in accordance with the fuel efficiency control line η1, so that the power consumption for air conditioning can be reduced. Therefore, power saving of the refrigeration cycle can be achieved, so that vehicle power saving (fuel saving) can be achieved.

On the other hand, the pressure switch 610 is turned on,
When the heat load of the refrigeration cycle (condenser 200) increases, the target airflow rate (duty ratio) decreases as the vehicle speed increases, although it deviates from the fuel saving control line η1, as compared with when the pressure switch 610 is OFF. Since the target air flow rate (duty ratio) is increased, power saving of the refrigeration cycle can be achieved while securing refrigeration capacity (cooling capacity).

In this embodiment, when the vehicle speed exceeds a predetermined speed, the fuel saving control line η1 and the constant air volume control line η2 overlap, but the present invention is not limited to this.

The high-pressure side refrigerant pressure when the pressure switch 610 is turned on is not more than the high-pressure side refrigerant pressure calculated (estimated) strictly based on the fuel saving control line η1.

(Other Embodiments) In the above-described embodiment, the target air flow rate is controlled in two stages by turning on and off the pressure switch 610. However, the present invention is not limited to this. When the pressure is equal to or higher than the predetermined pressure, the equal air volume control line η2 may be variably controlled in multiple stages (stepless) according to the high-pressure side refrigerant pressure.

In the above-described embodiment, the duty of the condenser fan 510 (electric motor 512) is controlled. However, the present invention is not limited to this.
(Pulse width modulation) may be controlled by other control methods such as control.

In the above embodiment, the electric motor 5
Although the axial fan 511 is driven to rotate by 12, the present invention is not limited to this, and the blowing fan such as the axial fan 511 may be driven by other driving means such as a hydraulic motor.

Further, in the above embodiment, the refrigeration cycle using chlorofluorocarbon as the refrigerant is described. However, the present invention is not limited to this. It can also be applied to a supercritical refrigeration cycle at or above the critical pressure.

In the above embodiment, the compressor 100
Has obtained the driving force from the engine E / G, but may be a compressor that obtains the driving force from an electric motor like an electric compressor.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a refrigeration cycle according to an embodiment of the present invention.

FIG. 2 is a flowchart of a refrigeration cycle according to the embodiment of the present invention.

FIG. 3 is a graph showing a relationship between a duty ratio and a vehicle speed in a refrigeration cycle according to the embodiment of the present invention.

FIG. 4 is a graph showing a relationship between a duty ratio and a loss power in the refrigeration cycle according to the embodiment of the present invention.

[Explanation of symbols]

510: condenser fan (blower), 600: EC
U, 610: pressure sensor, 620: vehicle speed sensor.

Claims (3)

[Claims] 1. A compressor (100) for sucking and compressing a refrigerant.
A radiator (200) for exchanging heat between the refrigerant discharged from the compressor (100) and air; a decompressor (300) for decompressing the refrigerant flowing out of the radiator (200); A vapor compression refrigeration cycle for a vehicle, comprising: an evaporator (400) for evaporating the refrigerant decompressed in (300); and a blower (510) for blowing cooling air to the radiator (200). From the discharge side of the compressor (100),
When the refrigerant pressure on the high pressure side reaching the inflow side of 0) is equal to or higher than a predetermined pressure, the blower (510) is controlled so as to have a target air flow rate determined based on the refrigerant pressure on the high pressure side, When the refrigerant pressure on the high pressure side is lower than a predetermined pressure, the blower (510) is controlled so as to have a target air flow rate determined based on a vehicle speed. . 2. The vapor compression refrigeration cycle for a vehicle according to claim 1, wherein the target air flow is determined so as to decrease as the vehicle speed increases. 3. The blower (510) includes a blower fan (511) and an electric motor (512) for driving the blower fan (511). The vapor compression refrigeration cycle for a vehicle according to claim 1 or 2, wherein the blower (510) is controlled by controlling an applied voltage.