JPH04203848A - Cooling device - Google Patents

Abstract

PURPOSE:To prevent a compressor from locking or breakage surely by a method wherein a cooling device is provided with an optical sensor, detecting two-phase separated condition of refrigerant and refrigerating machine oil optically and outputting the detection as detecting signals, a heat radiation promoting unit, for promoting the heat radiation of a condenser, and a heat radiation control unit, controlling the operation of the heat radiation promoting unit in accordance with the detecting signals. CONSTITUTION:The condition of two-phase separation of refrigerant and refrigerating oil, which flow between a receiver dryer 4 and an expansion valve 1a, is decided correctly by a heat radiation controller 7 in a condition that a detecting signal in accordance with the high-pressure liquid phase condition of mixed fluid from an optical sensor 5 is obtained. In a heat radiation control unit 7, receiving a detecting signal showing the change of the amount of permeating light when the mixed fluid has become two-phase separated condition from the optical sensor 5, a switch is put ON by the sudden change of an exciting magnetic field generated from an exciting coil 7a under excited condition, further, the operation of a condenser fan 6 is controlled continuously by the heat radiation control unit 7 in accordance with the detecting signals. According to this method, two-phase separation is avoided by the heat radiation promoting unit and the condensing effect of refrigerant in a condenser is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cooling device used for cooling a vehicle or cooling a freezer.

(Prior Art) This type of cooling device includes a refrigeration cycle in which a compressor, a condenser, a receiver dryer, a throttle device, and an evaporator are connected in this order via a conduit to form a closed circuit. This refrigeration cycle accommodates a mixed fluid made by mixing refrigerant such as fluorocarbon gas with refrigerating machine oil, and circulates the mixed fluid using a compressor. During the circulation of the mixed fluid, the refrigerant repeats a state change in which it condenses in the condenser and then evaporates in the evaporator. As a result, the evaporator absorbs heat, thereby providing a cooling effect. Note that the conduit disposed between the condenser and the evaporator is called a liquid line because the mixed fluid always flows in a liquid state.

On the other hand, condensers need to effectively radiate condensation heat. In order to promote this heat dissipation, a condenser fan is provided as a heat dissipation promoting device.

That is, heat radiation is promoted by applying wind generated by a condenser fan to the condenser.

It is important that the mixed fluid used be such that the mixed refrigerant and refrigerating machine oil are difficult to separate, regardless of load factors such as changes in pressure and temperature. This is to prevent fluorocarbon gas from being emitted into the outside air, whose use has been desired to be significantly regulated due to environmental destruction issues in recent years.

Recently, new refrigerants have been developed mainly in consideration of pollution problems. In response to this, refrigeration oil is also being developed.

(Problems to be Solved by the Invention) However, when the developed mixed fluid consisting of refrigerant and refrigeration oil is circulated under conditions of a predetermined temperature or higher, bubbles may be generated while flowing in the liquid line, or the refrigerant and refrigeration oil may The machine oil is separated into a solid-liquid two-phase state (at this time, the mixed fluid in the liquid state becomes cloudy), and condensation of the refrigerating machine oil adheres to the inside of the cooling system, preventing it from circulating smoothly. In the case of conventional cooling systems, two or three stages of pressure switches are installed in the high-pressure line of the refrigeration cycle, and the output from this pressure switch This allows you to adjust the rotation speed of the condenser fan.

However, in a mixed fluid that is smoothly circulating in a refrigeration cycle, the volume expands after the temperature rises, so the output from the pressure switch to adjust the rotation speed of the cooling fan is I'm always late.

For this reason, usually priority is given to condensing the mixed fluid, and the rotational speed of the cooling fan is not sufficiently adjusted to prevent the condenser itself from generating heat. As a result, condensation of the mixed fluid by the condenser tends to become unstable.

The present invention was made in view of the above circumstances, and its purpose is to provide a cooling device that can accurately detect the state of a mixed fluid flowing in a conduit and condense the mixed fluid in a condenser with good stability. There is a particular thing.

(Means for Solving the Problems) The present invention includes a refrigeration cycle that accommodates and circulates a mixed fluid made by mixing refrigerant with refrigeration oil, and a heat radiation promotion device that promotes heat radiation of a condenser of the refrigeration cycle. In the cooling device, an optical sensor is connected to a high-pressure side portion of the refrigeration cycle and outputs a detection signal representing the state of the mixed fluid in the high-pressure side portion; The cooling device is characterized by comprising a control device that controls the operation of the heat dissipation promotion device.

(Example) The cooling device of the present invention will be described in detail with reference to Examples below.

FIG. 1 shows the basic configuration of a cooling device mounted on a vehicle as an embodiment of the cooling device of the present invention. As shown in the figure, the vehicle cooling system, like the conventional cooling system described above, uses a mixed fluid in which the mixed refrigerant and refrigeration oil are separated into a solid-liquid two-phase state when the temperature is above a predetermined temperature. .

This vehicle cooling system includes a compressor 1, a condenser 3, a receiver dryer 4, and an expansion valve 1 as a throttle device.
The refrigeration cycle includes a refrigeration cycle similar to the conventional one, in which the evaporator 1 and the evaporator 1 are connected in this order through a conduit to form a closed circuit. Furthermore, in order to effectively radiate the condensed heat of the condenser 3, a condenser fan 6 is provided as a heat dissipation promoting device.

This vehicle cooling system further includes an optical sensor 5, which generates a detection signal indicating the presence or absence of a separated state of the mixed fluid, in a conduit between the receiver dryer 4 and the expansion valve 1a. The optical sensor 5 includes a light emitting section and a light receiving section that face each other with a mixed fluid in between. A determination as to whether the mixed fluid is in a separated state is made based on a change in the amount of transmitted light received by the light receiving section after the light irradiated from the irradiation light section passes through the mixed fluid.

The optical sensor 5 has a dedicated sensor amplifier 5a as shown in the figure.
One end is grounded and the other end of the signal line with the excitation coil 7a inserted is connected thereto. Excitation coil 7a
At opposite positions within the excitation field, one end is grounded and another signal line with a switch 7b and a resistor inserted in parallel is connected to the condenser fan 6 at the other end. The excitation coil 7a and the switch 7b together constitute a control device 7.

As will be understood from the following text, the control device 7 controls the operation of the condenser fan 6 in response to the detection signal from the sensor 5.

According to this configuration, the state of the mixed fluid flowing in the conduit of the liquid line can be accurately detected by the optical sensor 5, and the control device 7 that has received the detection signal from the optical sensor 5 (specifically Specifically, the switch 7b is turned on by the excitation field generated from the excitation coil 7a in an excited state), and the condensation effect on the mixed fluid in the capacitor 3 can be performed with good stability.

In particular, when the mixed fluid in a liquid state is circulated in a conduit (liquid line) disposed between the condenser 3 and the evaporator 1 at a predetermined temperature or higher, the refrigerant and refrigeration oil become solid and liquid. It separates into a two-phase state, resulting in a cloudy white state. The optical sensor 5 can accurately detect this state by detecting a change in the amount of light transmitted through the mixed fluid (it hardly changes when it is in a normal transparent state, but it is significantly reduced when it becomes cloudy).

FIG. 2 shows the physical characteristics of a mixed fluid as a curve C based on the correlation between pressure change P and temperature change T.

Here, the mixed fluid is in a liquid state regardless of the pressure change P when the temperature is below T1, but when the temperature is above 12, the pressure change P
It can be seen that depending on the amount of water, it is separated into two phases: solid and liquid. Specifically, under the condition of pressure PX, the mixed fluid is in a liquid state at temperature T1 (i.e., point X2), and in a solid-liquid state at temperature T2 (i.e., point X1). Two phases are separated.

That is, FIG. 2 shows that the mixed fluid, which is in a solid-liquid two-phase state at a temperature T2 under a pressure PX condition, becomes a liquid state when it is cooled to a temperature T1.

Therefore, even if such a mixed fluid is used, the condenser fan 6
Since the condenser 3 is cooled to cool the mixed fluid in the conduit, the mixed fluid is less likely to be separated into a solid-liquid two-phase state. Furthermore, even if the mixed fluid is separated into a solid-liquid two-phase state, the optical sensor 5 accurately detects the state and controls the cooling of the condenser 3 by the condenser fan 6, so that the mixed fluid is not solid-liquid in the first place. It becomes difficult to separate into two-phase state.

Note that the cooling device of the present invention can be used not only for vehicles but also for cooling the inside of a commercial freezer in which food products are stored, so the present invention is not limited to the embodiments.

(Effects of the Invention) As described above, according to the present invention, it is difficult for a mixed fluid to separate into a solid-liquid two-phase state, and even if the mixed fluid is separated, the cooling of the condenser is controlled and the solid-liquid two-phase state is immediately achieved. A highly useful cooling device capable of cooling a mixed fluid in a liquid state is realized. That is, since the cooling control section appropriately cools the high-pressure side condenser in the cooling device, there is an advantage that the cooling device itself can be constructed at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a cooling device of the present invention, and FIG. 2 is a diagram shown for explaining the physical characteristics of a mixed fluid used in the cooling device. Toeva volator, 2...Compressor, 3...Condenser, 4...Rember dryer, 5...Optical sensor, 6...Condenser fan, 7...Control device, 7
a...Excitation coil, 7b...Switch. Figure 1 Figure 2

Claims (2)

[Claims] (1) A cooling device including a refrigeration cycle that accommodates and circulates a mixed fluid made by mixing refrigerant with refrigeration oil, and a heat radiation promotion device that promotes heat radiation of a condenser of the refrigeration cycle, on the high-pressure side of the refrigeration cycle. connected to the part,
An optical sensor that outputs a detection signal representing the state of the mixed fluid in the high-pressure side portion, and a control device that is connected to the sensor and controls the operation of the heat dissipation promotion device in accordance with the detection signal. A cooling device featuring: (2) The sensor includes a light emitting section and a light receiving section that face each other with the mixed fluid in between, and the light receiving section outputs a signal corresponding to the amount of received light as the detection signal. cooling system.