JPH04225770A - Cooler for automobile - Google Patents

Abstract

PURPOSE:To allow a driver to judge the propriety of the amount of refrigerant while the driver stays in the cabinet of a car, by a method wherein a temperature gradient in the cabinet is calculated from a specified time elapsed, the initial temperature and the progressive temperature to obtain a state signal corresponding to the state of a refrigerating circuit. CONSTITUTION:In a refrigerating circuit for a car, which includes a liquid refrigerant pipe P along which liquid refrigerant substantially containing liquid and vapor phase refrigerant flows, a self-heat-generating thermistor 10 is provided as a circuit state monitoring device, and thermally comes in contact with the liquid refrigerant to output electric resistance values OMEGA corresponding to the amount of liquid phase refrigerant in the liquid refrigerant pipe P. A controller calculates a temperature gradient in a cabinet s=(To-T1)/t from the initial temperature To at the start-up of cooling operation of the refrigerating circuit, a progressive temperature T1 a specified time period t after the start-up cooling operation, and the specified time elapsed t. A state signal corresponding to the state of refrigerating circuit is output based on the electric resistance value and the temperature gradient s, and indicated on a display panel 34.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant amount detection device used in an automobile cooling system, which is capable of determining whether or not the amount of refrigerant in a cooling circuit is appropriate in a vehicle interior.

0002

[Prior Art] Generally, refrigerant circulating in a cooling circuit is
If the amount of refrigerant is appropriate, the bubbles will disappear a few minutes after the refrigerant compressor starts operating, and the refrigerant will become transparent.
Conversely, if the amount of refrigerant is insufficient, the refrigerant remains in a white mist-like state. For this reason, conventional judgments about the appropriateness of the amount of refrigerant in the cooling circuit have been made by installing a sight glass in the liquid tank or high-pressure piping for people to look through, and visually checking the state of the refrigerant flowing in the cooling circuit.

0003

[Problems to be Solved by the Invention] However, in the conventional method using a sight glass, since it is necessary to rely on visual confirmation of the sight glass, the judgment of the appropriateness of the amount of refrigerant is subjective and largely influenced by empirical rules. It was inaccurate and dangerous. Since the sight glass must necessarily be installed in the engine compartment along with the liquid tank or high-pressure piping, it is necessary to look through the sight glass after opening the heavy bonnet each time, which not only takes time but also It was inconvenient to handle, as there was a risk of the bonnet falling off, and hands were also dirty.

Therefore, the technical problem of the present invention is to objectively and accurately detect the state of the refrigerant in the refrigerant circuit in view of the above-mentioned drawbacks, and to detect the state of the refrigerant in the refrigerant circuit while in the car without opening the heavy hood. The present invention provides a refrigerant amount detection device that can safely determine whether the amount of refrigerant is appropriate.

[0005]

[Means for Solving the Problems] According to the present invention, an air conditioner for an automobile, which has a liquid refrigerant piping section through which a liquid refrigerant substantially containing a liquid phase and a gas phase passes, is used for cooling the interior of a vehicle. In an automotive cooling device comprising a circuit and a circuit state monitoring means for monitoring the state of the automotive cooling circuit, the circuit state monitoring means is in thermal contact with the liquid refrigerant, and the circuit state monitoring means is in thermal contact with the liquid refrigerant in the liquid refrigerant pipe section. a self-heating type thermistor that outputs an electrical resistance value Ω corresponding to the amount of the liquid phase; an initial temperature To in the vehicle interior at the time when the cooling of the automotive cooling circuit is started; and a predetermined elapsed time t after the start of the cooling. a temperature detection unit that actually measures the elapsed temperature T1 in the vehicle interior;
From the predetermined elapsed time t, the initial temperature To, and the elapsed temperature T1, the temperature gradient s in the vehicle interior is determined as (To−T1).
/t; and a status signal output unit that outputs a status signal corresponding to the status of the automotive cooling circuit based on the electrical resistance value Ω and the temperature gradient s. A characteristic automobile cooling device is obtained. Further, according to the present invention, in the automotive cooling device, the electrical resistance value Ω is equal to the first, second, and third resistance values Ω1.
, Ω2 and Ω3, the self-heating type thermistor outputs the first resistance value Ω1 when the amount of the liquid phase is a predetermined appropriate amount of liquid phase, and the self-heating type thermistor outputs the first resistance value Ω1 when the amount of the liquid phase is a predetermined appropriate amount. The second resistance value Ω is substantially 50% of the liquid phase amount.
2, and outputs the third resistance value Ω3 when the amount is substantially 20% of the predetermined appropriate liquid phase amount, and the state signal includes first, second, and third state signals. , the state signal output section is configured such that the temperature gradient s is a predetermined suitable temperature gradient s.
0 or less and the electrical resistance value Ω is the first resistance value Ω1, outputting the first state signal;
When the temperature gradient s is less than or equal to a predetermined appropriate temperature gradient s0 and the electrical resistance value Ω is the second resistance value Ω2, the second state signal is output, and the temperature gradient s
is less than or equal to a predetermined suitable temperature gradient s0, and the electrical resistance value Ω is the third resistance value Ω3, the automotive cooling device is characterized in that it outputs the third state signal. It will be done. Further, according to the present invention, in the automotive cooling device, the automotive cooling circuit includes an evaporator fan that sends air to the evaporator, and a compressor that is driven and stopped via an electromagnetic clutch. The circuit condition monitoring means is
the circuit status display unit receives the status signal, and when the status signal is the first status signal, displays a message indicating that the evaporator fan needs to be inspected; If it is a status signal, a display indicating that the amount of refrigerant needs to be refilled is displayed, and if it is the second status signal, the electromagnetic clutch is disengaged and the refrigerant is turned off to prevent seizure of the compressor. A cooling device for an automobile is obtained, which is characterized by displaying the following information. Further, according to the present invention, there is obtained the automobile cooling device, wherein the circuit status display section is arranged so as to be visible in the garage.

[0006]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, an automotive cooling system includes a compressor 1
, condenser 3, receiver dryer 5, expansion valve 7, evaporator 9
a cooling circuit section configured with a closed circuit that circulates in the order of;
It is comprised of a circuit state monitoring section (not shown) that monitors the state of this cooling circuit section. The compressor 1 is driven by an automobile engine via an electromagnetic clutch. Note that 31 is an evaporator fan, which is connected from the receiver dryer 5 to the expansion valve 9 by a liquid refrigerant pipe P. As shown in FIG. 2, the circuit state monitoring section includes a self-heating type thermistor 10 as a refrigerant sensor at a predetermined position of the liquid refrigerant pipe P. Note that 11 is a holder for holding the thermistor 10 in the conduit P. The thermistor 10 self-generates heat through the passage of a minute current, and the temperature changes due to the difference in the amount of electric heat when it comes into contact with liquid-phase refrigerant and when it comes into contact with gas-phase refrigerant and the change in electrical resistance value Ω cause the refrigeration cycle to change. This is to detect the amount of refrigerant in the tank. Now, when current is passed through the self-heating type thermistor 10, the temperature of the thermistor 10 itself rises above the ambient temperature. This increase causes the resistance value of the thermistor 10 to decrease. Here, the liquid thermal conductivity of the refrigerant (0.061 Kcal/mh °C for CFC-12) and the vapor thermal conductivity (
0.0083Kcal/mh (°C), a current is applied to the thermistor 10 to generate heat. As shown in FIG. 3, if the amount of refrigerant sealed is appropriate, the refrigerant state will be predominant in the liquid phase state, and the liquid phase refrigerant with high surface thermal conductivity will come into contact with the thermistor 10, and the temperature of the self-heating type thermistor 10 will increase. The resistance value of the thermistor 10 increases. Conversely, when the gas phase state is predominant, the temperature of the self-heating thermistor 10 does not drop because the gas phase refrigerant with low surface thermal conductivity comes into contact with the thermistor 10 more frequently.
The resistance value of the thermistor 10 becomes smaller. This self-heating type thermistor 10 outputs a first resistance value Ω1 when the amount of liquid phase is an appropriate amount of liquid phase, and substantially 50% of the amount of appropriate liquid phase.
%, outputs a second resistance value Ω2, and outputs a third resistance value Ω2 when it is substantially 20% of the appropriate liquid phase amount.
Outputs 3.

Furthermore, this circuit state monitoring unit includes a memory (not shown) that stores the first, second and third resistance values Ω1, 2 and 3 in advance, and a memory (not shown) that stores the first, second and third resistance values Ω1, 2 and 3 in advance, and A counter (not shown) that counts the cooling operation time of
, the initial temperature To in the vehicle interior at the time of starting the cooling, and the elapsed temperature T in the vehicle interior after a predetermined elapsed time t from the time the cooling started.
1 and a predetermined elapsed time t.
a temperature gradient calculation unit (not shown) that calculates the temperature gradient s=(To−T1)/t in the vehicle interior from the initial temperature To and the elapsed temperature T1; and an electric resistance output from the self-heating thermistor 10. It has a status signal output unit (not shown) that outputs a status signal corresponding to the status of the automotive cooling circuit based on the value Ω and the temperature gradient s.

Here, in the state signal output section, the temperature gradient s is less than or equal to the appropriate temperature gradient s0, and the electrical resistance value Ω is the first
outputs a first state signal when the resistance value is Ω1, and outputs a second state signal when the temperature gradient s is less than or equal to the appropriate temperature gradient s0 and has a second resistance value Ω2;
and the temperature gradient s is less than or equal to the appropriate temperature gradient s0,
When the third resistance value is Ω3, a third status signal is output.

[0009] Furthermore, the circuit state monitoring section includes a display panel 34.
is installed in the vehicle interior, and when the status signal is the first status signal, a display indicating that the evaporator fan 31 needs to be inspected is displayed, and when it is the second status signal, a display indicating that refrigerant amount replenishment is required is displayed. If it is the second status signal, the electromagnetic clutch is disengaged to prevent seizure of the compressor 1, and a display indicating that there is no refrigerant is displayed.

0010

[Effects of the Invention] According to the present invention, the state of the refrigerant in the refrigerant circuit is objectively and accurately detected, and the state of the refrigerant is displayed on the display inside the vehicle, so that the occupant can immediately Since it is possible to immediately judge whether the amount of refrigerant is appropriate or not, there is no need to open the bonnet or get your hands dirty each time, which is extremely safe and useful.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an outline of a refrigeration circuit in the present invention.

FIG. 2 is an explanatory diagram showing an example of an installed state of the self-heating type thermistor of the present invention.

FIG. 3 is a temperature-resistance characteristic diagram of the thermistor used in the present invention.

[Explanation of symbols]

1 Compressor 3 Condenser 5 Receiver dryer 7. Expansion valve 9 Evaporator 10 Self-heating thermistor P Liquid refrigerant piping 31 Evaporator fan 33 Vehicle interior temperature sensor 34 Display panel

Claims (4)

[Claims] Claim 1: An automotive cooling circuit that has a liquid refrigerant piping section through which a liquid refrigerant substantially including a liquid phase and a gaseous phase passes, and is used to cool the interior of a vehicle, and the state of the automotive cooling circuit. In the automotive cooling device, the circuit state monitoring means is in thermal contact with the liquid refrigerant and has an electrical resistance value corresponding to the amount of the liquid phase in the liquid refrigerant piping section. A self-heating type thermistor that outputs Ω, an initial temperature To in the vehicle interior when cooling is started in the automotive cooling circuit, and an elapsed temperature T1 in the vehicle interior after a predetermined elapsed time t from the time the cooling is started are actually measured. a temperature detection unit that calculates a temperature gradient s=(To−T1)/t in the vehicle interior from the predetermined elapsed time t, the initial temperature To, and the elapsed temperature T1; Based on the resistance value Ω and the temperature gradient s,
A cooling device for a motor vehicle, comprising: a state signal output section that outputs a state signal corresponding to a state of the cooling circuit for a motor vehicle. 2. The automobile cooling device according to claim 1, wherein the electrical resistance value Ω is comprised of first, second, and third resistance values Ω1, Ω2, and Ω3, and the self-heating type thermistor includes the outputting the first resistance value Ω1 when the amount of the liquid phase is a predetermined appropriate amount of liquid phase; the third resistance value Ω3 is output when the predetermined suitable liquid phase amount is substantially 20%; The state signal output section is configured to include a state signal, and the state signal output section is configured such that the temperature gradient s is less than or equal to a predetermined suitable temperature gradient s0, and the electrical resistance value Ω is
When the first resistance value is Ω1, the first state signal is output, and the temperature gradient s is a predetermined appropriate temperature gradient s.
0 or less, and when the electrical resistance value Ω is the second resistance value Ω2, outputting the second state signal;
For automobiles, the third status signal is output when the temperature gradient s is less than or equal to a predetermined suitable temperature gradient s0 and the electrical resistance value Ω is the third resistance value Ω3. Cooling device. 3. The automotive cooling system according to claim 2, wherein the automotive cooling circuit includes an evaporator fan that sends air to the evaporator, and a compressor that is driven and stopped via an electromagnetic clutch. , the circuit status monitoring means includes a circuit status display unit, the circuit status display unit receiving the status signal, and indicating that the evaporator fan requires inspection when the status signal is the first status signal. If it is the second status signal, a display indicating that the refrigerant amount needs to be refilled is displayed, and if it is the second status signal, to prevent seizure of the compressor,
A cooling device for an automobile, characterized in that when the electromagnetic clutch is disengaged, a display indicating that there is no refrigerant is displayed. 4. The automobile cooling device according to claim 3, wherein the circuit status display section is arranged so as to be visible within the garage.