JPS61190269A - Air conditioner having refrigeration function for automobile - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an air conditioner for an automobile, and in particular to an air conditioner with a refrigeration function in which an evaporator constituting a cooling device of the air conditioner also serves as an evaporator of a refrigeration device. Relating to a harmonizing device.

[Background of the invention]

It is already known from Utility Model Application Publication No. 55-13190 etc. that the evaporator of a cooling device for cooling the interior of a vehicle also serves as the evaporator of a refrigeration device for cooling objects to be cooled, such as canned juice.

By the way, in general, in a cooling system, in order to prevent freezing on the surface of the evaporator, for example, the surface temperature of the evaporator is detected, and when the temperature drops to, for example, zero degrees, for example, the compressor of the refrigeration cycle is stopped and the cooling capacity of the evaporator is reduced. Freeze protection means are provided to reduce and prevent further reduction of the evaporator surface temperature.

However, when this anti-freezing means is used in the above-mentioned conventional example, the outlet temperature of the evaporator cannot be lowered below zero degrees, and when operated as a refrigeration device, there is a problem that the cooling capacity for cooling the object to be cooled is insufficient.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide an air conditioner with a refrigeration function for automobiles that has a high cooling capacity and does not cause freezing of the evaporator.

[Summary of the invention]

In order to achieve the above object, the present invention guides the cooling air that has passed through the evaporator only into the refrigerator when operating the refrigerator alone, and forms the air that has passed through the refrigerator so that it is cooled again by the evaporator. The structure is designed to prevent excess moisture from being brought into the air passing through the compartment from inside the vehicle, and the cooling capacity enhancement means that operates by detecting that the refrigerator is operating alone will eventually prevent evaporation. The apparatus is characterized in that the freezing prevention means is prevented from operating until the temperature of the cold air blown from the container becomes lower than that when the apparatus is used as a cooling device.

[Embodiments of the invention] An embodiment of the present invention will be described with reference to FIGS. 1 to 4.

In FIG. 1, 1 indicates a compressor 2, a condenser 3, an expansion valve 4,
This is a refrigeration cycle constructed by connecting evaporators 5, and performs cooling by circulating the refrigerant sealed in the cycle in the above connection order and evaporating it in the evaporator.

Next, the evaporator 5 is arranged in series in the unit case 10 together with the blower 11 and the refrigerator compartment 13 containing the objects to be cooled 12, and at the front and rear of the unit case 10 there are suction air passages 14 whose ends open into the room; The blowout air passages 15 are connected to each other.

Further, inside the unit case, there is a recirculation air passage 16 that connects the downstream side of the refrigerator compartment 13 and the upstream side of the blower 11, and a recirculation air passage 16 for controlling the switching of air distribution to the blowout air passage 15 and the recirculation air passage 16. A ventilation selection door 17 is provided.

In the 20 thermometer calculation circuit, the thermometer U20 includes a thermistor 21 for detecting the fin surface temperature t of the evaporator 5.
, a position detection switch 22 that detects the position of the selection door 17, a relay 23 that turns on and off the electromagnetic clutch 2a that controls the vertical movement of the compressor 2, and a power source and ground.

Further, as shown in the operating principle diagram shown in FIG. 2, the thermoarithmetic operation circuit 20 includes a Zener diode ZD and resistors R, ! for generating a constant voltage. , a resistor R2rRs+R4*RsrRII for setting the operating value of the thermostat, an operational amplifier OP for performing comparison and judgment, a transistor T2 for controlling energization to the relay 23, and a resistance ratio of 7.

Next, the operation of the first embodiment having the above configuration will be explained.

First, the cooling operation for cooling the room starts with the air distribution selection door 17.
is controlled to the 9th position and dehumidified using the evaporator 5.

Since the cooled air is blown into the room from the blowout air path 15, thermo control is performed according to the flow on the cooling operation side of 0FFL FIG. 3. Here, the inverting input terminal voltage V of the operational amplifier OP in the thermo-operational circuit is the evaporator temperature t,
Letting Ri be the resistance of the thermistor 21 that correlates to
It is expressed by the following formula.

On the other hand, the non-inverting input terminal voltage door of the operational amplifier OP is expressed by the following equation corresponding to the output state of the operational amplifier OP.

During HIGH output and LOW output, these terminal voltage signals are compared and judged by the operational amplifier OP, ■, ≦V. In this case, the output of operational amplifier OP is HI G
When the voltage is H, the contact of the ONL relay 23 closes the transistor T, while when V>V, its output becomes LOW, turning off the transistor Tr, stopping the current flow to the IJ flyer 3, and opening the contact.

Therefore, when the evaporator temperature t is higher than tbl and the thermistor resistance ratio t is small as shown in FIG. According to the flow shown in FIG. 3, a HIGH signal is output and the relay 23 closes its contact, so that the electromagnetic clutch 2a is turned on and the refrigeration cycle 1 is operated to perform cooling. As this cooling operation continues, the thermistor resistance Rt increases as the evaporator temperature t decreases, and the terminal voltage V shown by equation (1) increases.

becomes high and reaches 31 points and becomes Vp) Vr[1, the operational amplifier OP is inverted, outputs LOWt, the electromagnetic clutch 28t is turned off, and the refrigeration cycle lt is stopped.

Here, the resistance value of the resistor R3+R4+Rs and the characteristic value of the thermistor resistor R0 are set so that t, l, which is the evaporator temperature t when the operational amplifier OP becomes vP=v, HI and inverts, becomes approximately OC. When the evaporation temperature t becomes t, 1 (abbreviated OC), the refrigeration cycle 1 is stopped,
This prevents the condensed water generated in the evaporator 5 from freezing.

Note that the resistor R2 provided in the thermo calculation circuit 20 is for providing a differential tDIFF in the operation of the circuit, and once the operational amplifier OP is inverted and the output terminal becomes LOW and the refrigeration cycle l is stopped, At the same time, the terminal voltage Vr moves to VrLo, indicated by (2)', which is lower than the previous terminal voltage vr HE .

Therefore, when the refrigeration cycle 1 is stopped, the evaporator temperature t,
increases at tbl 'i, the terminal voltage Vp decreases, and vl,
=vrLo Cb1 point) until the electromagnetic clutch 2a is reached.
continues at 0FFL to prevent frequent disconnection of the electromagnetic clutch 2a.

Next, in a refrigeration operation in which only the object 12 to be cooled is cooled, the air distribution selection door 17 is controlled to position b, and the dehumidified cold air coming out of the refrigerator compartment 13'r is transferred to the recirculation air path 12.
The object to be cooled 12 is refrigerated by circulating the entire inside of the unit case 10. Here, the position detection switch 22 is turned ON because the air distribution selection door 17 is in the b position.
, connect the resistor R61 in the thermo calculation circuit to the ground,
Thermo control is performed according to the refrigeration operation flow shown in FIG.

Therefore, the inverting input terminal voltage vp2 of the operational amplifier OP in the thermo-operational circuit is expressed by the following equation, and has a much lower characteristic as shown in FIG. 4 than the terminal voltage vp1 during cooling operation in equation (1). Become.

On the other hand, the non-inverting input terminal voltage V is the same as during cooling operation (
2) Since it is expressed by equation (3), Vp 2 = Vr
It becomes larger than wx. Here, since the thermistor resistance hole t exhibits a negative characteristic relationship with respect to the evaporator temperature t as shown in FIG. 4, the evaporator temperature t at which the operational amplifier OP is reversed and the refrigeration cycle I is stopped is 1.2. Therefore, t during cooling moves to a value lower than 1 (approximately OCI), for example, -5C.

Therefore, during refrigeration operation where dehumidified air is recirculated so that freezing does not occur, the refrigeration cycle 1 is operated even if the evaporator temperature t falls below OC to generate low-temperature cold air and cool the object 12. It can be cooled rapidly.

In the above embodiment, the capacity of the evaporator is adjusted to prevent freezing by controlling the operation of the compressor during the refrigeration cycle. It can also be combined with so-called capacity control operation that controls the refrigerant discharge force.

Another embodiment shown in FIG. 5 will be described below.

They are installed in parallel. Here, 6 is an electromagnetic valve that controls the refrigerant supply to the evaporator 5, 7 is an expansion valve that controls the degree of superheating of the refrigerant at the outlet of the evaporator 8, and 9 is an expansion valve inside the evaporator 8 to prevent the evaporator 8 from freezing. This is an evaporation pressure control valve for maintaining the refrigerant pressure above a predetermined value.

The thermo calculation circuit 20 in this embodiment is exactly the same as in the above-mentioned embodiment, but uses its output signal to control ON/OFF of the electromagnetic valve 6 to control the refrigerant supply to the evaporator 5. The ability of 5 was adjusted to prevent freezing.

That is, when the antifreeze state is reached, the solenoid valve 6 is closed to stop the supply of refrigerant to the evaporator 5, but the switch 22
When the refrigerator is operating independently with the casing closed, the temperature detected by the thermostat 21 is lower (e.g. -51Z') than the temperature when operating as a cooling device (e.g. zero degrees), and the closing output of the solenoid valve 6 is It is controlled so that it does not occur.

Furthermore, as an application example of the present invention, if any one of the resistors R3, R4, and Rs of the thermo-operation circuit 20 is made a variable resistor and the resistance value can be manipulated, the inversion voltage of the operational amplifier OF can be changed, and the evaporation The evaporator temperature 1 ml T t,2 at which the capacity control of the vessel 5 begins can be varied. In this way, the indoor temperature can be adjusted by changing the temperature of the cold air blown out during cooling operation, and the temperature of the cooled air can also be adjusted during refrigeration operation to keep the object 12 to be cooled at the desired temperature at all times. .

In this embodiment, the passage is closed by the electromagnetic valve 6, but the expansion valve 4 is composed of an electronically controlled expansion valve.
If the expansion valve 1 has a function of closing the passage by itself by switching an electric signal, the expansion valve 1 can be used as a valve body for preventing freezing in place of the electromagnetic valve 6.

As described above, according to the embodiment described above, the operation of the refrigeration cycle is controlled by the thermo calculation circuit 20 so as to maintain the evaporator temperature t at approximately OC or higher during cooling operation, and the phenomenon of freezing of the evaporator 5 due to condensed water is prevented. On the other hand, during a refrigeration operation in which dehumidified cold air is recirculated, there is an effect that a large refrigeration capacity can be obtained by keeping the evaporator temperature t below OC.

By the way, to explain the effects of the example shown in Figure 5, the running speed is 40 km/h, the outside air is 35C9, and the solar radiation is 660Kcat/m.
When the refrigerator was operated alone at a circulating air volume of 0.8 m37Mh for 1 hour under the conditions of 250rn
According to the present invention, five liter cans of juice could be cooled down to 3-4C, whereas with the conventional device, it could only be cooled down to 7-8C.

〔Effect of the invention〕

According to the present invention, when the evaporator is operating as a refrigerator alone, air containing moisture is not substantially sucked in from the outside, and when the anti-freezing means is operating as a cooling device, As a result, since the evaporator does not operate until the outlet temperature drops to a low temperature, the cooling capacity during refrigerator operation can be increased without worrying about the evaporator freezing.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram showing one embodiment of the present invention;
The diagrams are a diagram of the operating principle of the thermo calculation circuit used in Figure 1, and Figure 3.
FIG. 4 is a flowchart showing the thermo control of the present invention; FIG. 4 is an explanatory diagram of the operation of the thermo calculation circuit shown in FIG. l... Refrigeration cycle, 2... Compressor, 2a... Electromagnetic clutch, 3... Condenser, 4... Expansion valve, 5...
・Evaporator, lO...Unit case, ll...Blower, 12...Object to be cooled, 13...Refrigerating room, 14...
- Suction air path, 15... Outlet air path, 16... Recirculation air path, 17... Air distribution selection door, 20... Thermo calculation circuit, 21... Thermistor, 22... Position Detection switch, 23... Relay, 6... Solenoid valve, 7... Expansion valve, 8... Evaporator, 9... Evaporation pressure control valve.

Claims (1)

[Claims] 1. A cooling device that cools the air blown into the vehicle interior, an evaporator constituting the cooling device, and antifreeze means that adjusts the cooling capacity of the cooling device according to the operating state of the cooling device so that the evaporator does not freeze. A refrigeration device that guides the cold air that has passed through the evaporator into the refrigerator to cool objects to be cooled in the refrigerator, wherein the cold air that has passed through the evaporator is substantially guided only into the refrigerator. and a means for forming an independent operating state of the refrigerator in which the cold air that has passed through the refrigerator is cooled again by the evaporator, which operates when the refrigerator is operating independently, and the blowing temperature of the evaporator eventually changes to the operating state of the cooling device. 1. An air conditioner with a refrigeration function for an automobile, characterized in that a cooling capacity enhancing means is provided for inhibiting the operation of the anti-freezing means until the temperature reaches a value lower than the evaporator outlet temperature.