JPH0331670A - Cooling device for loading on vehicle - Google Patents

Abstract

PURPOSE:To prevent the generation of flash gas in a refrigerant pipeline by a method wherein a temperature detecting means is provided near a condenser while the temperature detecting means is connected electrically to the control circuit of a driving device for a cooling fan. CONSTITUTION:A temperature switch 7 is provided near a condenser 12 and is formed so that the contact thereof is opened at a temperature lower than 15 deg.C, for example. Air stream for cooling is passed through the condenser 12 by the rotation of a motor 5 for driving a cooling fan to cool and condense refrigerant. When a temperature near the condenser 12 is reduced to a temperature lower than 15 deg.C, the contact of the temperature switch 7 is opened and the motor 5 is stopped. According to this method, the flow of air for cooling into the condenser 12 may be stopped to prevent the over-cooling of the refrigerant in the condenser 12 whereby the generation of flash gas in a discharging pipe 31 and/or a capillary tube 32 may be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to 1) a high-pressure unit consisting of a compressor and an air-cooled condenser, and an evaporator, such as an on-vehicle refrigerator that can be installed in a passenger car; This invention relates to an on-vehicle cooling system in which a low-pressure unit and a low-pressure unit are provided in isolation from each other (for example, in a trunk room and a passenger seat), and the two units are connected via refrigerant piping.

[Conventional technology]

FIG. 4 is an explanatory diagram showing an example of the configuration of a conventional vehicle-mounted refrigerator. In the figure, 1 is a high pressure unit.

Reference numeral 2 designates low-pressure units, each of which is installed separately in, for example, a trunk room or a passenger compartment, and the units 1 and 2 are connected via a refrigerant pipe 3 so that refrigerant (not shown) can be circulated in the direction of the arrow. . First, the high-pressure unit 1 is constructed by connecting components such as a compressor 11, a condenser 12, and a strainer 13 in series. The condenser 12 is formed, for example, by interposing a large number of cooling fins 12b in a refrigerant pipe 12a formed in a zigzag shape.
The zero-order low-pressure unit 2 is usually configured to allow air flow from a cooling fan (not shown) to flow between the two. . Note that the evaporator 22 is, for example, the condenser 12.
Similarly, fin-tube types are often used to increase the heat transfer area. The refrigerant pipe 3 includes a discharge pipe 31 and a capillary tube 32 that supply liquid refrigerant.

It is composed of a suction pipe 33 that supplies gaseous refrigerant.

34 is a coupler, and 4 is a partition.

With the above configuration, the gaseous refrigerant is first compressed by the compressor 11 to a high temperature and high pressure state, and then is sent to the condenser 12, where it is condensed into a high pressure liquid by heat exchange, and foreign matter is removed via the strainer 13. A certain pressure loss is applied in the capillary tube 32 that is removed and fed through the discharge pipe 31, and the heat is removed from the cabinet 21 by being vaporized in the evaporator 22. can function as a so-called refrigerator. The gaseous refrigerant then returns to the compressor 11 via the suction pipe 33, where it is compressed again and used for circulation.

[Problem to be solved by the invention]

In the 5CQT type cooling device as described above, the discharge pipe 31 can be arranged along the suction pipe 33, so that the high pressure unit 1 and the low pressure unit 2 can be connected at least once.
However, since the capillary tube 32 passes through the atmosphere in which the low-pressure unit 2 is installed, there is a possibility that it will be exposed to a temperature Tc higher than the ambient temperature Tu of the condenser 12. be. In this case Tc
>Tu, and when the temperature difference between Tc and Tu exceeds a certain value, the refrigerant that has been heated to one isopressure crosses the saturated liquid line on the Molière diagram and enters a so-called two-phase mixed state. That is, there is a problem in that a part of the liquid refrigerant evaporates while remaining at an equal pressure, and a so-called flash gas is generated within the capillary tube 32. If such flash gas is generated within the capillary tube 32, it will block the discharge pipe 31, making it impossible to feed the refrigerant, which will not only cause a significant decrease in cooling capacity but also stop the operation of the entire cooling device. This may also lead to damage to the equipment and equipment.

The present invention solves the problems existing in the prior art described above, and provides an on-vehicle cooling device that can prevent the generation of flash gas in refrigerant piping in an on-vehicle cooling device in which a high-pressure unit and a low-pressure unit are installed separately. The purpose is to provide.

[Means to solve the problem]

In order to achieve the above object, in the first invention, a high-pressure unit consisting of a compressor and an air-cooled condenser and a low-pressure unit consisting of an evaporator are provided in isolation from each other, and a connection between the two units is provided. In an on-vehicle cooling system connected via refrigerant piping.

Temperature detection means is provided near the condenser.

This temperature detection means is electrically connected to a control circuit of a cooling fan drive device, and is configured to prevent overcooling of the refrigerant in the condenser. A technical method was adopted.

Next, in a second invention, in addition to the technical means in the first invention, an electric heating means is provided in the condenser, and the control circuit of the electric heating means and the temperature detection means are electrically connected.

Added a technical means.

Furthermore, in the third invention, a high pressure unit consisting of a compressor and an air-cooled condenser and a low pressure unit consisting of an evaporator are provided in isolation from each other, and both units are connected via a refrigerant pipe. In an on-vehicle cooling system.

Temperature detection means are installed near the A11 unit and the refrigerant pipe, respectively.
An output means for comparing the electric signals from both temperature detection means and outputting the result is provided, and this output means is electrically connected to the control circuit of the cooling fan drive device, and the refrigerant in the condenser is Constructed to prevent cooling. A technical method was adopted.

Further, in a fourth aspect of the invention, in addition to the technical means in the third aspect, an electric heating means is provided in the condenser, and a control circuit of the electric heating means and the output means are electrically connected.

Added a technical means.

[For production]

With the above configuration, in the first invention, when the temperature near the condenser falls below a predetermined temperature, that is, the temperature at which flash gas is generated, the cooling fan is stopped by an electric signal from the temperature detection means. This can be expected to prevent the refrigerant in the condenser from being overcooled.

In the second aspect of the invention, in addition to the above action, the temperature of the refrigerant in the condenser can be quickly recovered to a predetermined temperature by simultaneously operating the electric heating means attached to the condenser.

In the third invention, even if the temperature near the refrigerant pipe changes, if the difference between the temperature near the condenser and the temperature near the condenser is below a predetermined value, the operation is continued and the temperature exceeds the predetermined value. It is expected that the cooling fan will be stopped only in such a case that the refrigerant in the condenser will be prevented from being overcooled.

In addition to the effect of the third invention, the fourth invention can be expected to have an effect of quickly recovering the temperature of the refrigerant in the condenser to a predetermined value.

〔Example〕

FIG. 1 is an electrical circuit diagram showing a first embodiment of the present invention.

In the figure, reference numeral 5 denotes a motor, which is provided to drive a cooling fan (not shown) for circulating a cooling air flow to the condenser 12 shown in FIG. 4. A temperature switch 7 electrically connects the motor 5 to a power source 10. The temperature switch 7 is provided near the condenser 12 shown in FIG. 4, and is formed so that its contacts open at a temperature of, for example, 15° C. or lower. When R-12 is used as the refrigerant, if the temperature near the condenser 12 drops below 15°C, there is a risk that flash gas will occur in the discharge pipe 31 and/or capillary tube 32 shown in FIG. Because it is known.

The contact opening temperature is set as described above.

With the above configuration, 1. During normal operation, the temperature switch 7 closes its contacts as shown in FIG. The zero-order condenser 1 performs cooling and condensation of the refrigerant.
When the temperature near 2 falls below 15° C., the contacts of the temperature switch 7 shown in FIG. 1 are opened and the motor 5 is stopped. As a result, it is possible to stop the flow of cooling air to the condenser 12 shown in FIG. This can prevent the generation of flash gas.

FIG. 2(a) is an explanatory diagram of main parts showing a second embodiment of the present invention,
FIG. 2(b) is a cross-sectional view taken along the line A-A in FIG. 2(a). In FIG. 2(b), the condenser 12 is formed by fixing a refrigerant pipe 12a to the surface of cooling fins 12b.

The arrow indicates the flow direction of the refrigerant (not shown). Reference numeral 8 denotes a heater, in which a wire rod made of an electrical resistance material such as Nl-Cr alloy is arranged along the refrigerant pipe 12a, and is connected to a heating power source via a thermostat 9 installed near the condenser 2. electrically connected to 10.

Note that the thermostat 9 is formed to close its contacts at 15° C. or lower when, for example, R-12 is used as the refrigerant. The heater 8 may be provided on both sides of the cooling fin 12b.

With the above configuration, the conditions are reached such that flash gas is generated in the discharge pipe 31 and/or the capillary tube 32 in FIG. 4.

When the temperature near the condenser 12 shown in FIG. 2(a) falls below 1, for example, 15° C., the contacts of the thermostat 9 close. As a result, the heater 8 is activated by the heating power source 10, and the refrigerant (not shown) is heated through the cooling fins 12b and the refrigerant pipe 12a, thereby preventing overcooling of the refrigerant and the generation of flash gas associated with this. be. By providing the heater 8 in conjunction with the condenser 12 in this way, the cooling efficiency of the entire device is slightly reduced, but it is possible to completely avoid loss of functionality of the entire device due to generation of flash gas.

FIG. 3 is an electrical circuit diagram showing a third embodiment of the present invention.

In FIG. 3, a transistor 51 is connected in series with the motor 5, and is configured to receive the output voltage of the comparator 6 as a base voltage. Thermistors 71 and 72 each have negative characteristics, and are arranged to be able to measure the temperature Tu near the condenser 12 and the temperature Tc near the refrigerant pipe 3 in FIG. The output sides of these thermistors 71 and 72 are connected to the input side of the comparator 6.

With the above configuration, 1. In a normal state, the output voltage of the comparator 6 applies the base voltage to the transistor 51, so the motor 5 operates to drive the cooling fan (not shown), and as shown in FIG. A cooling air flow is passed through the condenser 12 shown in FIG. 3 to cool and condense the refrigerant.
When the difference Tc-Tu between the temperature Tu near the refrigerant pipe 3 (see FIG. 4) and the temperature Tc near the refrigerant pipe 3 exceeds, for example, 10°C, the output voltage of the comparator 6 in FIG. 3 becomes 0. , the base voltage of transistor 51 decreases, causing motor 5 to stop. This prevents the refrigerant in the condenser 12 shown in FIG. 4 from being overcooled.

This makes it possible to avoid loss of function of the cooling device due to the generation of flash gas. Note that when the temperature Tc near the refrigerant pipe 3 in FIG. 4 is substantially constant, there is no problem because the temperature Tu near the compressor 9a is also substantially constant.
If the temperature Tc changes, especially if this temperature Tc increases, the temperature Tu near the condenser 12 where flash gas is generated will also increase, and the cooling fan may not stop.
By configuring as shown in the figure, the motor 5
It is effective because it can stop the

In the second embodiment of the present invention, an example is shown in which the condenser lacks a cooling fan, but a cooling fan may be provided as in the other embodiments, and in each of the above embodiments, the capillary tube may be replaced. Even if an expansion valve is provided, the effect is the same. Note that although the low-pressure unit has been described as a refrigerator, it may also be a small-sized freezer (or may also be used as an air-conditioning device for supplying cold air to a passenger compartment, for example).

〔Effect of the invention〕

Since the present invention has the structure and operation as described below, the following effects can be expected.

(1) Preventing the generation of flash gas due to overcooling of the refrigerant in the condenser constituting the high pressure unit.

The cooling device can be operated smoothly.

(2) Even if the atmospheric temperature difference between the high pressure unit and the low pressure unit is large, generation of flash gas can be prevented.

(3) There is no need to install special complicated equipment to prevent the generation of flash gas, and the function of the small and lightweight in-vehicle cooling system can be maintained.

[Brief explanation of drawings]

FIG. 1 is an electrical circuit diagram showing a first embodiment of the present invention. FIG. 2(a) is an explanatory diagram of main parts showing a second embodiment of the present invention. FIG. 2(b) is a sectional view taken along line A-A in FIG. 2(a), FIG. 3 is an electric circuit diagram showing a third embodiment of the present invention, and FIG. 4 is an example of the configuration of a conventional in-vehicle refrigerator. FIG. 1; High pressure unit. 2: Low pressure unit 3: Refrigerant piping. ;Temperature switch. ;heater. 9: Thermostat. : Comparator 71, 72 : Thermistor.

Claims (4)

[Claims] (1) A vehicle cooling system in which a high-pressure unit consisting of a compressor and an air-cooled condenser and a low-pressure unit consisting of an evaporator are provided in isolation from each other, and both units are connected via refrigerant piping. The temperature detection means is provided near the condenser, and the temperature detection means is electrically connected to the control circuit of the cooling fan drive device to prevent overcooling of the refrigerant in the condenser. An in-vehicle cooling device featuring: (2) Claim in which the condenser is provided with an electric heating means, and the control circuit of the electric heating means and the temperature detection means are electrically connected.
1) The vehicle cooling device described above. (3) An on-vehicle cooling system in which a high-pressure unit consisting of a compressor and an air-cooled condenser and a low-pressure unit consisting of an evaporator are provided in isolation from each other, and both units are connected via refrigerant piping. In this method, a temperature detection means is provided near the condenser and the refrigerant pipe, and an output means for comparing electrical signals from both temperature detection means and outputting the result, and this output means is connected to the cooling fan drive device. An on-vehicle cooling device characterized by being electrically connected to a control circuit and configured to prevent overcooling of refrigerant in a condenser. (4) Claim (4) wherein the condenser is provided with an electric heating means, and the control circuit of the electric heating means and the output means are electrically connected.
3) The vehicle cooling device described above.