JP2008215712A - Refrigerant leakage detecting device of air conditioner for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine refrigerant leakage in a refrigerating cycle device with high accuracy. <P>SOLUTION: The difference ▵d between sampling data X(t) of detected concentration of carbon dioxide and an estimated value C(t) of the concentration of carbon dioxide in a compartment under a condition that a refrigerant (carbon dioxide) does not leak from the refrigerating cycle device, is found, and the refrigerant leakage is determined on the basis of the comparison of the difference ▵d with a reference value S. According to this embodiment, the refrigerant leakage can be determined with high accuracy in comparison with a case when the refrigerant leakage is determined on the basis of the comparison of the sampling data X(t) of the detected concentration with the reference value. The reference value S1 in executing the inside air circulation mode is more than a reference value S2 in executing the outside air introduction mode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigerant leakage determination device for a vehicle air conditioner that determines whether or not carbon dioxide used as a refrigerant in a vehicle air conditioner leaks.

2. Description of the Related Art Conventionally, in a refrigerant leakage determination device for a vehicle air conditioner, a gas sensor for detecting the concentration of carbon dioxide is provided in the passenger compartment in order to determine the presence or absence of carbon dioxide leakage as a refrigerant in a refrigeration cycle device. When the measured value exceeds a preset reference value, it is determined that carbon dioxide has leaked and an alarm is issued (see, for example, Patent Document 1).
JP-A-288429

  In the above-described vehicle air conditioner, when the inside air circulation mode for circulating the cabin air is performed, carbon dioxide discharged from the occupant is circulated in the cabin. The concentration of carbon dioxide in the passenger compartment is higher than when the introduction mode is performed.

  Therefore, if the same value is used as the reference value in the case where the inside air circulation mode is executed and the case where the outside air introduction mode is executed, the leakage of carbon dioxide may be erroneously determined.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a refrigerant leakage detection device for a vehicle air conditioner that can accurately determine the leakage of carbon dioxide as a refrigerant.

  To achieve the above object, according to the present invention, a gas sensor (17) for detecting the concentration of carbon dioxide in at least one of an air conditioning duct and a vehicle interior of a vehicle air conditioner and a refrigerant of a refrigeration cycle device of the vehicle air conditioner. The difference (Δd) between the estimated value of the concentration of carbon dioxide in the vehicle interior and the detected concentration of the gas sensor in a state where the carbon dioxide does not leak into the vehicle interior is calculated, and the calculated difference is the reference Determining means (S130, S140) for determining whether or not the carbon dioxide is leaked, and an inside air circulation mode in which the vehicle air conditioner circulates vehicle interior air In the first feature, the reference value used in the determination means is larger than that in the case where the outside air introduction mode for introducing outside air into the vehicle interior is carried out. To.

  Therefore, it is determined whether or not carbon dioxide is leaked using the difference (Δd) between the estimated value of the carbon dioxide concentration in the passenger compartment when the carbon dioxide is not leaking into the passenger compartment and the detected concentration of the gas sensor. Therefore, the leakage of the refrigerant can be accurately determined as compared with the case where the detection concentration of the gas sensor is compared with the reference value to determine whether or not carbon dioxide is leaking.

  In addition, since the reference value used in the determination means is larger when the inside air circulation mode is performed than when the outside air introduction mode is performed, the inside air circulation mode and the outside air It is possible to suppress erroneous determination of refrigerant leakage due to switching of the introduction mode.

  Based on the above, it is possible to accurately determine leakage of carbon dioxide as a refrigerant.

  The present invention provides a gas sensor (17) for detecting the concentration of carbon dioxide in at least one of an air conditioning duct and a vehicle interior of a vehicle air conditioner, and a concentration of the carbon dioxide as a refrigerant of a refrigeration cycle device of the vehicle air conditioner. Whether or not the carbon dioxide concentration as a refrigerant of the refrigeration cycle device of the vehicle air conditioner leaks by determining whether or not the slope of the carbon dioxide concentration is equal to or higher than a reference value. Determination means (S200, S210) for determining whether or not, and when the vehicle air conditioner is in an inside air circulation mode for circulating the inside air of the vehicle interior, the introduction of outside air into the vehicle interior The second feature is that the reference value used in the determination means is larger than that in the case where the mode is implemented.

  Therefore, since it is determined whether or not carbon dioxide is leaking using the slope of the concentration of carbon dioxide, it is determined whether or not carbon dioxide is leaking by comparing the detected concentration of the gas sensor with a reference value. Compared to the case, the leakage of the refrigerant can be determined with higher accuracy.

  In addition, since the reference value used in the determination means is larger when the inside air circulation mode is performed than when the outside air introduction mode is performed, the inside air circulation mode and the outside air It is possible to suppress erroneous determination of refrigerant leakage due to switching of the introduction mode.

  Based on the above, it is possible to accurately determine leakage of carbon dioxide as a refrigerant.

  In addition, the code | symbol in the bracket | parenthesis of each means described in a claim and this column shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
FIG. 1 shows a first embodiment of a vehicle air conditioner to which a refrigerant leakage detection device according to the present invention is applied.

  The vehicle air conditioner includes an air conditioning casing 1 that allows air to flow into the vehicle interior, an inside / outside air switching door 2 that selectively opens and closes the inside air introduction port 2a and the outside air introduction port 2b in the air conditioning casing 1, and an inside air introduction port 2a. The blower unit 3 that blows air from one of the outside air inlets 2b toward the vehicle interior, the cooling heat exchanger 4 that cools the air blown from the blower unit 3, and the cooling heat exchange And a heating heat exchanger 5 for heating the cooling air cooled by the vessel 4.

  The cooling heat exchanger 4 constitutes a well-known refrigeration cycle apparatus that circulates refrigerant together with the compressor 4a, the condenser 4b, and the decompressor 4c, and exchanges heat with the blown air from the blower unit 3 by evaporation of the refrigerant. Cool down. Carbon dioxide is used as the refrigerant. The heating heat exchanger 5 heats cold air from the cooling heat exchanger 4 by circulating engine cooling water (heat source hot water) from the traveling engine 5a.

  In the air conditioning casing 1, there is provided a cold air bypass passage 1 a that bypasses the heating heat exchanger 5 and flows cooling air. An air mix door 6 is provided in the air conditioning casing 1 to adjust the ratio of the amount of air flowing through the cold air bypass passage 1a and the amount of air flowing through the heating heat exchanger 5 to adjust the temperature of air blown into the passenger compartment. ing.

  On the downstream side of the cold air bypass passage 1 a and the heating heat exchanger 5, a mixing chamber 7 for mixing the cold air from the cold air bypass passage 1 a and the hot air from the heating heat exchanger 5 is provided. The air mixed in the mixing chamber 7 is blown out from the face air outlet 8a, the foot air outlet 8b, or the differential air outlet 8c toward the vehicle interior. Mode doors 9a, 9b, and 9c for opening and closing the air outlets 8a, 8b, and 8c, respectively, are provided.

  Next, an outline of the electrical configuration of the present embodiment will be described.

  The vehicle air conditioner includes an air conditioner ECU 10, servo motors 12, 13, 14, an inside air sensor 16, an outside air sensor 17, a CO2 sensor 18, a water temperature sensor 19, seating sensors 20a to 20d, a temperature setting device 21, a warning lamp 22, and a speaker. 23.

  The air conditioner ECU 10 is an electronic control device including a microcomputer, a memory, and the like. The air conditioner ECU 10 calculates a necessary blowing temperature TAO based on output signals from the sensors 16 to 19, 20 a to 20 d, the temperature setter 21, etc. The servo motors 12, 13, 14 and the blower motor 3a of the blower unit 3 are controlled on the basis of the required blowing temperature TAO.

  Here, the required blowing temperature TAO is the blowing air temperature necessary for maintaining the vehicle interior at the set temperature test regardless of the change in the environment in the vehicle interior.

  The blower motor 3a is an electric motor for rotationally driving the impeller of the blower unit 3, and the number of rotations (i.e., the amount of blown air) of the blower motor 3a is determined based on the required blowing temperature TAO as is well known.

  The servo motor 12 is an electric motor for driving the inside / outside air switching door 2 via a link mechanism. When the electric motor is controlled, as is well known, the inside air circulation mode and the outside air introduction mode are based on the required blowing temperature TAO. One of them is determined as the inside / outside air switching mode, and the inside / outside air switching door 2 is opened / closed based on the determined mode.

  The inside air circulation mode is a mode in which the inside air introduction port 2a is fully opened by the inside / outside air switching door 2 and the outside air introduction port 2b is fully closed to circulate the inside air in the vehicle interior. The outside air introduction mode is a mode in which the inside air introduction port 2a is fully closed by the inside / outside air switching door 2 and the outside air introduction port 2b is fully opened to introduce outside air into the vehicle interior.

  The servo motor 13 is an electric motor for driving the air mix door 6 via a link mechanism. When the electric motor is controlled, the air is controlled based on the required blowing temperature TAO and the temperature detected by the water temperature sensor 19, as is well known. The mix door 6 is controlled. The water temperature sensor 19 is a temperature sensor that detects the temperature of engine cooling water.

  The servo motor 14 drives the mode doors 9a, 9b, and 9c independently through the link mechanism.

  The inside air sensor 16 is a temperature sensor that detects the air temperature in the passenger compartment. The outside air sensor 17 is a temperature sensor that detects the air temperature outside the passenger compartment. The CO2 sensor 18 is a gas sensor that is disposed in at least one of the air conditioning casing 1 and the passenger compartment and detects the concentration of carbon dioxide.

  The seating sensors 20a to 20d are sensors for detecting whether or not an occupant is seated for each seat. As the seating sensors 20a to 20d, for example, switches that are turned on or off when a passenger is seated are used.

  The temperature setting device 21 is a switch for setting a set temperature test in the passenger compartment, and the warning lamp 22 is a lamp arranged toward the passenger on the instrument panel in the passenger compartment. The speaker 23 outputs sound for warning the passenger.

  The air conditioner ECU 10 performs a process for determining the presence or absence of refrigerant leakage from the refrigeration cycle apparatus, as will be described later, based on the concentration of carbon dioxide detected by the CO 2 sensor 17.

  Next, a process for determining the presence or absence of refrigerant leakage in the refrigeration cycle apparatus, which is a feature of the present embodiment, will be described with reference to FIGS. FIG. 2 is a flowchart showing a process for determining the presence or absence of refrigerant leakage. The air conditioner ECU 10 starts executing the process for determining whether or not the refrigerant has leaked when the ignition switch IG is turned on, and this execution is repeated at regular intervals.

  First, in step S100, sampling of the concentration of carbon dioxide by the CO2 sensor 17 is started. The sampling of the carbon dioxide concentration is performed at regular intervals.

  Next, in step S110, a reference value S used to determine whether or not refrigerant (ie, carbon dioxide) has leaked is determined. That is, S = S1 when the inside air circulation mode is being implemented, and S = S2 when the outside air introduction mode is being implemented.

  Here, the reference value S1 when the inside air circulation mode is implemented is larger than the reference value S2 when the outside air introduction mode is implemented.

  Next, in step S120, sampling data X (t) of the detected concentration of carbon dioxide by the CO2 sensor 17 is captured. X (t) is sampling data at time t.

  Next, in step S130, an estimated value C (t) of the concentration of carbon dioxide in the passenger compartment when refrigerant (carbon dioxide) does not leak from the refrigeration cycle apparatus is calculated. C (t) is a function indicating the estimated value of the carbon dioxide concentration at time t. Details of the function C (t) will be described later.

  Next, in step S140, a difference Δd (= X (t) −C (t)) between X (t) and C (t) is obtained, and the difference Δd is compared with the reference value S to leak the refrigerant. It is determined whether or not.

  Here, the reference value S varies depending on whether the inside air circulation mode or the outside air introduction mode is implemented as the inside / outside air switching mode. Therefore, when determining whether or not the refrigerant is leaking, when the inside air circulation mode is being performed, the difference Δd is compared with the reference value S1, as shown in FIG. 3, and the outside air introduction mode is being performed. Sometimes, as shown in FIG. 4, the difference Δd is compared with the reference value S2.

  That is, when the inside air circulation mode is being executed, when the difference Δd (= X (t) −C (t)) is larger than the reference value S1, it is determined as YES in Step 140 and it is determined that the refrigerant is leaking.

  On the other hand, when the outside air introduction mode is being implemented, when the difference Δd (= X (t) −C (t)) is larger than the reference value S2, it is determined as YES in Step 140 and it is determined that the refrigerant is leaking.

  3 (a) and 4 (a) are graphs showing X (t) and C (t), where the vertical axis represents carbon dioxide concentration and the horizontal axis represents time, and FIG. 3 (a) and FIG. 4 (a) is a graph in which the vertical axis represents the difference Δd (= X (t) −C (t)) and the horizontal axis represents time.

  Thus, when the difference Δd (= X (t) −C (t)) is larger than the reference value S (= S1, S2), the process proceeds to step S160, where the warning lamp 22 is turned on and the refrigerant leaks. Alert the passenger to the effect. In addition to this, a buzzer sounds from the speaker 23.

  Further, in step 140, when the inside air circulation mode is being executed and the difference Δd (= X (t) −C (t)) is smaller than the reference value S1, it is determined as NO and it is determined that the refrigerant has not leaked. When the outside air introduction mode is being implemented, it is determined that the refrigerant has not leaked when the difference Δd (= X (t) −C (t)) is smaller than the reference value S2.

  When it is determined that the refrigerant has not leaked, the process proceeds to step S160, where it is determined whether the sampling data X (t) of the detected concentration of carbon dioxide is larger than the set value Z.

  Here, when the sampling data X (t) is larger than the set value Z, it is determined that the refrigerant is leaking, and the process proceeds to step S160. When the sampling data X (t) is smaller than the set value Z, it is determined that the refrigerant has not leaked, and the process returns to step S110.

  Next, details of the function C (t) will be described.

  The function C (t) of this embodiment is calculated based on the following formula 1.

C (t) * V = C (0) * V + B * D
+ Cout · ∫ (Q1 (t) + Q2 (t)) dt
−C (t) · ∫ (Q1 (t) + Q2 (t)) dt ............ Formula 1
Here, Cout is the concentration (ppm) of carbon dioxide in the outside air, and a predetermined constant value is used. As Cout, a detection value of a CO2 sensor that detects the concentration of carbon dioxide in the outside air may be used. C (0) is the initial concentration (ppm) of carbon dioxide in the passenger compartment, and a predetermined value is used as C (0).

  B is the number of passengers (persons). As the number of passengers B, the number of seated passengers detected by the seating sensors 20a to 20d is used. D is the carbon dioxide emission (m / h / person) by exhalation per person, and a predetermined value is used as D. V is the vehicle interior volume (m ^ 3).

  Q1 (t) is a function representing the outside air introduction amount (m ^ 3 / h) at time t, and increases with an increase in the rotation speed of the blower motor 3a. In addition to this, Q1 (t) also changes depending on the state of the inside / outside air switching door 2. That is, the value of Q1 (t) increases when the outside air introduction mode is implemented, and the value of Q1 (t) decreases when the inside air circulation mode is implemented. Q2 (t) is a dynamic pressure ventilation volume (m ^ 3 / h) calculated based on the vehicle speed, and increases as the vehicle speed increases.

  Next, the effect of this embodiment is demonstrated.

  First, when the inside air circulation mode is performed, the concentration of carbon dioxide in the passenger compartment is higher than when the outside air introduction mode is performed. Therefore, if the same value is used as the reference value in the case where the inside air circulation mode is executed and the case where the outside air introduction mode is executed, the leakage of carbon dioxide may be erroneously determined.

  On the other hand, in the present embodiment, the reference value S1 when the inside air circulation mode is implemented is larger than the reference value S2 when the outside air introduction mode is implemented. Therefore, it is possible to make it difficult to make an erroneous determination of refrigerant leakage by switching between the inside air circulation mode and the outside air introduction mode.

  In this embodiment, the sampling data X (t) of the detected concentration of carbon dioxide, and the estimated value C (t) of the concentration of carbon dioxide in the passenger compartment when refrigerant (carbon dioxide) does not leak from the refrigeration cycle apparatus. The difference Δd is obtained, and leakage of the refrigerant is determined based on a comparison between the difference Δd and the reference value S.

  Therefore, according to the present embodiment, the value of the carbon dioxide concentration that is high enough to adversely affect the human body is set as the set value Z, and the leakage of the refrigerant is determined by comparing the set value Z with the sampling data X (t). Compared with the case where it does, the presence or absence of the leakage of a refrigerant | coolant can be determined at an early stage.

(Second Embodiment)
In the first embodiment described above, the sampling data X (t) of the detected concentration of carbon dioxide and the estimated value C () of the concentration of carbon dioxide in the passenger compartment when refrigerant (carbon dioxide) does not leak from the refrigeration cycle apparatus. Although the example in which the refrigerant leak is determined based on the difference Δd with respect to t) has been described, instead of this, in the second embodiment, the refrigerant leak is determined based on the slope of the detected concentration of carbon dioxide. .

  FIG. 5 shows a flowchart of the refrigerant leak detection process of the present embodiment. Hereinafter, the refrigerant leakage detection process of the present embodiment will be described.

  First, in step S100, sampling of the concentration of carbon dioxide by the CO2 sensor 17 is started. The sampling of the carbon dioxide concentration is performed at regular intervals.

  Next, in step S110, a reference value K used for determining whether or not refrigerant (ie, carbon dioxide) has leaked is determined. That is, when the inside air circulation mode is being implemented, K = K1, and when the outside air introduction mode is being implemented, K = K2.

  Here, the reference value K1 when the inside air circulation mode is implemented is larger than the reference value K2 when the outside air introduction mode is implemented.

  Next, in step S120, sampling data X (t) of the detected concentration of carbon dioxide by the CO2 sensor 17 is captured.

  Next, in step S200, it is determined whether or not the concentration of carbon dioxide by the CO2 sensor 17 is increasing. Specifically, a difference ΔX (= X (t) −X (t−1)) between the previous sampling data X (t−1) and the current sampling data X (t) is obtained, and the difference ΔX is a positive value. When the difference ΔX is a positive value (ΔX> 0), it is determined as YES in Step S200 and it is determined that the concentration of carbon dioxide is increasing.

  Next, in step S200, the difference ΔX and the reference value K are compared to determine whether or not the refrigerant is leaking. Here, the reference value K changes depending on whether the inside air circulation mode or the outside air introduction mode is performed as the inside / outside air switching mode. Therefore, when determining whether or not the refrigerant is leaking, the difference ΔX is compared with the reference value K1 when the inside air circulation mode is being executed, and the difference ΔX and the reference value K2 are compared when the outside air introduction mode is being executed. Compare

  That is, if the difference ΔX is larger than the reference value K1 when the inside air circulation mode is being performed, it is determined as YES that the refrigerant is leaking. If the difference ΔX is larger than the reference value K2 when the outside air introduction mode is being executed, it is determined as YES that the refrigerant is leaking.

  Thus, when the difference ΔX (= X (t) −X (t−1)) is larger than the reference value K (= K1, K2), it is determined as YES in Step 210 and it is determined that the refrigerant is leaking. At this time, the process proceeds to step S160, where the warning lamp 22 is turned on to warn the occupant that the refrigerant is leaking. In addition, a buzzer sound (warning sound) is generated from the speaker 23.

  In step S210, if the difference ΔX is smaller than the reference value K1 when the inside-air circulation mode is being implemented, it is determined that the refrigerant has not leaked as NO. If the difference ΔX is smaller than the reference value K2 when the outside air introduction mode is being implemented, it is determined that the refrigerant is leaking as NO.

  Thus, when the difference ΔX (= X (t) −X (t−1)) is smaller than the reference value K (= K1, K2), it is determined as NO in step 210 and it is determined that the refrigerant has not leaked.

  In step 200 described above, when the difference ΔX is zero or a negative value (ΔX ≦ 0), it is determined as NO that the concentration of carbon dioxide is stagnating or decreasing, and the process proceeds to step S110.

  According to the present embodiment described above, the refrigerant leakage is determined based on the slope of the change in the concentration of carbon dioxide. Therefore, according to the present embodiment, it is possible to accurately determine the refrigerant leakage as compared with the case where the refrigerant leakage is determined based on the comparison between the detected concentration sampling data X (t) and the reference value.

  In the present embodiment, the reference value K1 when the inside air circulation mode is implemented is larger than the reference value K2 when the outside air introduction mode is implemented. Therefore, it is possible to make it difficult to make an erroneous determination of refrigerant leakage by switching between the inside air circulation mode and the outside air introduction mode.

It is a schematic diagram which shows the structure of 1st Embodiment of the vehicle air conditioner which concerns on this invention. It is a flowchart which shows the refrigerant | coolant leak detection process of the air-conditioner ECU of FIG. It is a graph for demonstrating the refrigerant | coolant leak detection process of FIG. It is a graph for demonstrating the refrigerant | coolant leak detection process of FIG. It is a flowchart which shows the refrigerant | coolant leak detection process of air-conditioner ECU of 2nd Embodiment which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Air-conditioning casing, 2a ... Inside air introduction port, 2b ... Outside air introduction port,
2 ... Inside / outside air switching door, 3 ... Blower unit, 4 ... Heat exchanger for cooling,
5 ... Heat exchanger for heating, 4a ... Compressor, 4b ... Condenser, 4c ... Decompressor,
5a ... engine for running, 1a ... cold air bypass passage, 6 ... air mix door,
7 ... mixing chamber, 8a, 8b, 8c ... outlet
9a, 9b, 9c ... mode door, 10 ... air conditioner ECU,
12, 13, 14 ... servo motors, 16-19, 20a-20d ... sensors,
21 ... Temperature setter, 22 ... Warning lamp, 23 ... Speaker.

Claims (3)

A gas sensor (17) for detecting the concentration of carbon dioxide in at least one of the air conditioning duct and the passenger compartment of the vehicle air conditioner;
A difference (Δd) between an estimated value of the concentration of carbon dioxide in the vehicle interior in a state where the carbon dioxide as a refrigerant of the refrigeration cycle device of the vehicle air conditioner does not leak into the vehicle interior and a detected concentration of the gas sensor Determining means (S130, S140) for determining whether or not the calculated difference is larger than a reference value and determining whether or not the carbon dioxide is leaked,
In the case where the vehicle air conditioner implements the inside air circulation mode for circulating the air in the vehicle interior, the criterion used in the determination means is compared with the case where the outside air introduction mode for introducing outside air into the vehicle interior is implemented. A refrigerant leakage detection device for a vehicle air conditioner, characterized in that the value is increased. A gas sensor (17) for detecting the concentration of carbon dioxide in at least one of the air conditioning duct and the passenger compartment of the vehicle air conditioner;
When the concentration of the carbon dioxide as the refrigerant of the refrigeration cycle device of the vehicle air conditioner increases with time, it is determined whether or not the gradient of the carbon dioxide concentration is greater than or equal to a reference value, Determination means (S200, S210) for determining whether or not the carbon dioxide as a refrigerant of the refrigeration cycle apparatus of the air conditioner is leaked,
In the case where the vehicle air conditioner implements the inside air circulation mode for circulating the air in the vehicle interior, the criterion used in the determination means is compared with the case where the outside air introduction mode for introducing outside air into the vehicle interior is implemented. A refrigerant leakage detection device for a vehicle air conditioner, characterized in that the value is increased. 3. The apparatus according to claim 1, further comprising a warning unit that warns a passenger that the carbon dioxide is leaked when the determination unit determines that the carbon dioxide is leaking. A refrigerant leakage detection device for a vehicle air conditioner characterized by the above.

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