JP2010192141A - Coolant circuit system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coolant circuit system capable of preventing sudden drop of insulation resistance in a fuel cell system accompanying coupling, in one built in the fuel cell system and other systems respectively, and equipped with two coolant circuits capable of coupling or interrupting each other. <P>SOLUTION: The coolant circuit system 10 includes: a coolant circuit for a cell 12, controlling flow of coolant used in the fuel cell system; and a coolant circuit for air conditioning 13, controlling flow of coolant used in an air conditioning system 110. A coolant flow channel for a cell 14 fitted in the coolant circuit for a cell 12 is provided with an ion exchanger 18. A coolant flow channel for air conditioning 30, fitted in the coolant circuit for air conditioning 13, is provided with an ion concentration detector 38 for detecting ion concentration (eventually, conductivity). A control part controls operation of a connection valve 40 fitted between both flow channels based on a detection result detected at the ion concentration detector 38 to couple or interrupt both flow channels. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the present invention, a refrigerant circuit for a battery through which a refrigerant used in a fuel cell system passes and a refrigerant circuit for another system through which a refrigerant used in another system (for example, an air conditioning system) passes are connected or disconnected. The present invention relates to a refrigerant circuit system.

  Since it has little influence on the environment, the use of fuel cells is considered as a power source for vehicles and the like. In the fuel cell, for example, a fuel gas such as hydrogen is supplied to the anode side of the fuel cell stack, an oxidizing gas containing oxygen such as air is supplied to the cathode side, and necessary electric power is taken out by a reaction through the electrolyte membrane. The fuel cell generates heat due to this reaction. Since this heat generation causes an increase in battery temperature and, in turn, a decrease in power generation efficiency and component life, a conventional fuel cell system has been provided with a refrigerant circuit through which a refrigerant for cooling the fuel cell passes. The fuel cell is cooled (heat exchange) by the refrigerant flowing through the refrigerant circuit, and the refrigerant whose temperature has been increased by heat exchange with the fuel cell is cooled by a radiator or the like provided in the middle of the refrigerant circuit. .

  Here, in addition to the fuel cell system, a vehicle having such a fuel cell system is provided with a system having a refrigerant circuit, such as an air conditioning system. In recent years, for the purpose of effective use of heat quantity, a technique has been proposed in which such a refrigerant circuit of another system and a refrigerant circuit of a fuel cell system can be connected.

  For example, Patent Document 1 discloses a cooperative cooling system that performs cooperative control by sharing a refrigerant between a fuel cell cooling system and an air conditioning cooling system. In this cooperative cooling system, when a high-temperature refrigerant is required in the air-conditioning cooling system as in heating, the fuel cell cooling system and the air-conditioning cooling system are connected, and the refrigerant heated by the fuel cell flows into the air-conditioning cooling system. I am doing so. Even when a high-temperature refrigerant is not required in the air-conditioning cooling system, the fuel cell cooling system and the air-conditioning cooling system are appropriately connected to prevent an excessive increase in the ion concentration of the refrigerant in the air-conditioning cooling system. The refrigerant of the air conditioning cooling system flows into the fuel cell cooling system having the ion exchanger. After the connection, the ion concentration is monitored by an ion concentration detector mounted on the ion exchanger, and both cooling systems are shut off if the ion concentration is below a predetermined reference value.

JP 2008-130476 A

  However, the technique described in Patent Document 1 has a problem that only the ion concentration of the refrigerant flowing in the fuel cell cooling system is monitored. That is, in the technique described in Patent Document 1, the ion concentration is detected by an ion concentration detector integrated with the ion exchanger. Here, normally, the ion exchanger has to be provided on the fuel cell side where the amount of ions tends to be relatively large. Therefore, as a result, an ion concentration detector integrated with the ion exchanger is also provided on the fuel cell side, and only the ion concentration on the fuel cell side can be monitored.

  In this case, since the ion concentration of the air-conditioning cooling system refrigerant is unknown, in some cases, the air-conditioning cooling system and the fuel cell cooling system are connected even though the ion concentration of the air-conditioning cooling system refrigerant is very high. It was sometimes done. In this case, the refrigerant of the air conditioning cooling system having a very high ion concentration flows into the fuel cell cooling system, and the ion concentration of the refrigerant of the fuel cell cooling system suddenly increases (as a result, between the fuel cell component and the ground). There was a risk of causing a sharp drop in insulation resistance).

  Therefore, an object of the present invention is to provide a circuit system that can prevent a sudden drop in insulation resistance due to connection.

  A refrigerant circuit system of the present invention includes a refrigerant circuit for a battery that controls the flow of refrigerant used in a fuel cell system, and a refrigerant circuit for another system that controls the flow of refrigerant used in another system. A circuit system, wherein the battery refrigerant flow path provided in the battery refrigerant circuit and the other system refrigerant flow path provided in the other system refrigerant circuit are blocked, and the battery refrigerant flow path A connection valve that can be switched to a connected state that connects the refrigerant flow path for the other system and one of the refrigerant circuit for the battery or the refrigerant circuit for the other system, and ions from the refrigerant that flows in the one refrigerant flow path An ion exchanger to be removed, a conductivity detector provided on the other of the battery refrigerant circuit or the other system refrigerant circuit and detecting the conductivity of the refrigerant flowing in the other refrigerant flow path; On the basis of the detection result at the rate detector, characterized in that it comprises a control means for controlling the operation of said connection valve.

  In a preferred aspect, the ion exchanger is provided in the battery refrigerant circuit, and the conductivity detector is provided in the other system refrigerant circuit. In this case, when the conductivity of the refrigerant flowing through the refrigerant circuit for the other system detected by the conductivity detector in the shut-off state exceeds a predetermined upper limit value, the control means enters the connected state. It is desirable to drive the connection valve as much as possible. The upper limit value is desirably a value that can maintain the insulation resistance value between the fuel cell and the ground at a specified reference value or more when the battery coolant channel and the other system coolant channel are connected.

  In another preferred aspect, the other system refrigerant circuit is an air conditioning refrigerant circuit that is used for air conditioning and has a heater core. In this case, it is desirable that the conductivity detector is provided on the downstream side of the heater core.

  In another preferred aspect, when the control means shifts from the cut-off state to the connected state, the connection means is connected according to the conductivity of the refrigerant flowing through the refrigerant circuit for the other system detected by the conductivity detector. The amount of refrigerant per unit time flowing from the other system refrigerant flow path into the battery refrigerant flow path is adjusted by controlling the valve opening / closing amount.

  In another preferred aspect, when the control means shifts from the cut-off state to the connected state, the control means is responsive to the conductivity of the refrigerant flowing in the refrigerant circuit for the other system detected by the conductivity detector in the cut-off state. The refrigerant amount per unit time flowing into the battery refrigerant flow path from the other system refrigerant flow path is adjusted by intermittently opening and closing the connection valve and adjusting the open / close interval.

  According to the present invention, the conductivity detector is provided in the refrigerant circuit not provided with the ion exchanger, and the drive of the connection valve is controlled in accordance with the detection result of the conductivity detector. . Therefore, it is possible to prevent the refrigerant on the circuit side where the ion exchanger is not provided from being left excessively high, thereby preventing a sudden drop in insulation resistance associated with the connection.

It is a schematic block diagram of the refrigerant circuit system which is embodiment of this invention. It is a figure which shows the flow-path structure in the interruption | blocking state. It is a figure which shows the flow-path structure in a connection state. It is a graph which shows an example of the electrical conductivity change accompanying interruption | blocking / connection. It is a flowchart which shows the flow of control, such as a connection valve. It is a graph which shows the relationship between the air-conditioning side electrical conductivity just before a connection, and the battery side electrical conductivity just after a connection.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a refrigerant circuit system 10 according to an embodiment of the present invention. The refrigerant circuit system 10 is a system that controls the flow of refrigerant, and is incorporated in a fuel cell system and an air conditioning system 110 that are mounted on a vehicle. Before describing the refrigerant circuit system 10 in detail, first, a fuel cell system and an air conditioning system 110 in which the refrigerant circuit system 10 is incorporated will be briefly described.

  The fuel cell system is a system for driving a fuel cell stack (hereinafter abbreviated as “FC stack”) 100. The FC stack 100 is formed by laminating a plurality of single cells (cells) sandwiched by placing separators on both outer sides of MEA (Mebrane Electrode Assembly) in which catalyst electrode layers are arranged on both sides of an electrolyte membrane.

  The fuel cell system is provided with a gas supply system (not shown) for supplying a fuel gas such as hydrogen gas to the cathode side of the FC stack 100 and an oxidizing gas such as compressed air to the anode side. When electric power is required, the control unit (not shown) of the fuel cell system drives this gas supply system to supply fuel gas such as hydrogen gas on the cathode side of the FC stack 100 and compressed air or the like on the anode side. Supply oxidizing gas. When the fuel gas and the oxidizing gas are supplied, an electrochemical reaction through the electrolyte membrane occurs in the FC stack 100, and the FC stack 100 generates power. The control unit of the fuel cell system takes out the electric power obtained by this power generation and uses it appropriately.

  Here, it is known that heat is generated as the FC stack 100 generates power. If the temperature of the FC stack 100 rises excessively due to such heat generation, problems such as a decrease in power generation efficiency and a decrease in the life of the FC stack 100 are caused. Therefore, conventionally, a battery refrigerant circuit 12 for cooling the FC stack 100 is incorporated in the fuel cell system.

  The battery refrigerant circuit 12 constitutes the refrigerant circuit system 10 in cooperation with the air conditioning refrigerant circuit 13 to be described later, and is a circuit that controls the flow of the refrigerant for adjusting the temperature of the FC stack 100. The battery refrigerant circuit 12 is provided on the battery refrigerant flow paths 14a, 14b, 14c through which the refrigerant flows (hereinafter, subscript alphabets are omitted unless otherwise distinguished) or on the path of the battery refrigerant flow path 14. The refrigerant pump 16, the radiator 22, the ion exchanger 18, the switching valve 20, and the like, which are provided, will be described in detail later.

  Next, the air conditioning system 110 will be briefly described. The air conditioning system 110 is a system for air conditioning a passenger compartment, and is broadly divided into an air conditioner circuit 50 that mainly cools the passenger compartment and an air conditioning refrigerant circuit 13 that mainly heats the passenger compartment.

  The air conditioning refrigerant circuit 13 constitutes the refrigerant circuit system 10 in cooperation with the battery refrigerant circuit 12 described above. The air conditioning refrigerant flow path 30 through which the refrigerant flows and the path of the air conditioning refrigerant flow path 30 are provided. The heater core 36, the electric heater 34, the refrigerant pump 32, and the like provided in the above are included. Although details of the configuration of the air conditioning refrigerant circuit 13 will be described later, basically, the vehicle interior is heated by radiating the heat of the heated refrigerant by the heater core 36.

  The air conditioner circuit 50 is provided on the air conditioner refrigerant flow path 52 through which the cooling refrigerant (separate from the refrigerant flowing in the battery refrigerant flow path and the air conditioning refrigerant flow path) flows, or on the path of the air conditioner refrigerant flow path 52. A condenser 54, an expansion valve 56, an evaporator 58, an electric compressor 60, and the like are provided. At the time of cooling execution, the cooling refrigerant is compressed by the electric compressor 60 and becomes vaporized gas at high temperature and high pressure. This high-temperature and high-pressure cooling refrigerant is liquefied by the condenser 54 and dissipated. The expansion valve 56 makes the liquefied cooling refrigerant into a mist by rapidly reducing the pressure. The evaporator 58 cools the air passing through the evaporator 58 by vaporizing the mist-like cooling refrigerant. The cooled air flows into the passenger compartment, thereby cooling the passenger compartment.

  Next, the refrigerant circuit system 10 incorporated in the fuel cell system and the air conditioning system 110 will be described. The refrigerant circuit system 10 is a system that controls the flow of refrigerant, and includes the battery refrigerant circuit 12, the air conditioning refrigerant circuit 13, and a control unit (not shown). The refrigerant handled in the refrigerant circuit system 10 is not particularly limited as long as it can transfer heat and can exchange heat with the FC stack 100 and the heater core 36, and may be gas or liquid. Therefore, for example, a 50% concentration ethylene glycol aqueous solution or the like can be used as a refrigerant in the refrigerant circuit system.

  The control unit controls the operations of the valves 20 and 40 and the refrigerant pumps 16 and 32 provided in the battery refrigerant circuit 12 and the air conditioning refrigerant circuit 13 and the like. To do. The control unit may be dedicated to the refrigerant circuit system 10, or a battery control unit that controls driving of the fuel cell system may be used as the control unit of the refrigerant circuit system 10.

  As described above, the battery refrigerant circuit 12 is a circuit incorporated in the fuel cell system in order to adjust the temperature of the FC stack 100. The battery refrigerant flow path 14, the refrigerant pump 16, the radiator 22, the ion exchanger 18, A switching valve 20 is provided. The battery coolant channel 14 can be further divided into a main channel 14a, a bypass channel 14b, an ion exchange channel 14c, and the like. The main flow path 14 a is a flow path that circulates between the FC stack 100 and the radiator 22. After the refrigerant flowing along the main flow path 14 a is cooled by the radiator 22, the refrigerant reaches the FC stack 100 and heat exchange with the FC stack 100 is performed, whereby the FC stack 100 is cooled. The refrigerant heated by heat exchange with the FC stack 100 reaches the radiator 22 again and is cooled.

  The bypass flow path 14 b branches from the main flow path 14 a at a position upstream of the radiator 22 and merges with the main flow path 14 a at a position downstream of the radiator 22. From another viewpoint, the bypass flow path 14b is a flow path for circulating the refrigerant without passing through the radiator 22. A switching valve 20 is provided at the junction of the bypass flow path 14b and the main flow path 14a so that the refrigerant path is switched to the radiator side or the bypass flow path side according to the operation of the switching valve 20. It has become. When aggressive cooling of the FC stack 100 is not required, for example, when the FC stack 100 is stopped or immediately after startup, the temperature of the FC stack 100 may be excessively lowered by flowing the refrigerant through the bypass passage 14b. Is prevented.

  The ion exchange channel 14 c is a channel that branches from the main channel 14 a on the upstream side of the FC stack 100 and merges with the main channel 14 a on the downstream side of the FC stack 100. From another viewpoint, the ion exchange channel 14 c can be said to be a channel provided in parallel with the FC stack 100. The ion exchange flow path 14c is provided with an ion exchanger 18 that removes ions present in the refrigerant and thus reduces the conductivity of the refrigerant. The refrigerant that has flowed into the ion exchange channel 14c is returned to the main channel 14a after ion removal (conductivity reduction) by the ion exchanger 18.

  Here, the reason for providing the ion exchanger 18 will be briefly described. Conventionally, in the fuel cell system, in order to adjust the temperature of the FC stack 100, the refrigerant is circulated along the battery refrigerant flow path 14, but ions are formed from the components constituting the battery refrigerant flow path 14. It is known to elute gradually. If these gradually eluting ions are allowed to stand, there is a problem that the conductivity of the refrigerant is gradually improved, and ultimately the insulation resistance between the FC stack 100 and the ground is excessively lowered. In order to avoid such a problem, an ion exchanger 18 is installed in the battery refrigerant flow path 14 to remove ions in the refrigerant. In this embodiment, the FC stack 100 and the ion exchanger 18 are connected in parallel. However, the FC stack 100 and the ion exchanger 18 are connected in series, that is, the ion exchanger 18 is connected to the main flow path 14a. You may make it install in. The ion exchanger 18 only needs to be able to remove ions in the refrigerant, and may not have an ion concentration detection function or the like.

  The refrigerant pump 16 is a pump that circulates the refrigerant, and is driven and controlled by the control unit. The control unit drives the refrigerant pump 16 to circulate the refrigerant along the flow path 14 when the FC stack 100 needs to be cooled or when ions in the refrigerant need to be removed.

  Next, the air conditioning refrigerant circuit 13 will be described. As described above, the air-conditioning refrigerant circuit 13 constitutes a part of the air-conditioning system 110 and is a circuit mainly for heating the passenger compartment. The air conditioning refrigerant circuit 13 is provided with an air conditioning refrigerant flow path 30 through which refrigerant flows, a refrigerant pump 32, an electric heater 34, a heater core 36, an ion concentration detector 38, and the like. The air conditioning refrigerant flow path 30 does not have a branch path or the like, and forms a single annular flow path. The electric heater 34 functions as a heat source for heating the refrigerant flowing through the air conditioning refrigerant flow path 30, and its driving is controlled by the control unit. The heater core 36 is provided in the vicinity downstream of the electric heater 34, performs heat exchange with the heated refrigerant, and radiates heat obtained by the heat exchange into the vehicle interior. This heat radiation allows the vehicle interior to be heated.

  The ion concentration detector 38 detects the ion concentration of the refrigerant flowing through the air conditioning refrigerant flow path 30. The ion concentration detected here is output to the control unit. The control unit calculates the conductivity (or electrical resistance value) of the refrigerant based on the obtained ion concentration, and controls the driving of the connection valve 40 described later based on this conductivity. This will be described in detail later. To do. Although the ion concentration is detected in this embodiment, other parameters such as the electric resistance of the refrigerant can be used instead of the ion concentration if the conductivity or electric resistance value of the refrigerant can be finally obtained. The value and the conductivity itself may be detected. Further, in the present embodiment, the ion concentration detector 38 is installed on the downstream side of the heater core 36, but naturally the ion concentration detector 38 may be installed at another position, for example, the upstream position of the heater core 36. Good. However, in consideration of the fact that ions often elute from the heater core 36 and the ion concentration (conductivity) tends to be highest on the downstream side in the vicinity of the heater core 36, the ion concentration detector 38 is provided on the downstream side of the heater core 36 (that is, It can be said that it is desirable to provide it at a position where the ion concentration is highest.

  The battery refrigerant circuit 12 and the air conditioning refrigerant circuit 13 configured as described above can be freely connected / disconnected as appropriate. That is, the battery coolant channel 14 and the air conditioning coolant channel 30 are connected via the first and second connection channels 42 and 44. Further, a connection valve 40 that is a three-way valve is provided at the junction of the first connection flow path 42 and the air conditioning refrigerant flow path 30, and the battery refrigerant flow is changed according to the state switching of the connection valve 40. The passage 14 and the air conditioning refrigerant passage 30 are connected or blocked. In other words, the connection valve 40 is in a connected state in which the battery refrigerant flow path 14 and the air conditioning refrigerant flow path 30 are connected, and in a blocked state in which the battery refrigerant flow path 14 and the air conditioning refrigerant flow path 30 are blocked (separated). And can be switched to.

  2 and 3 are views showing the state of the refrigerant circuit system 10 when the connection valve 40 is in a shut-off state or a connected state, respectively. In the shut-off state, the flow from the first connection flow path 42 to the air conditioning refrigerant flow path 30 is prohibited, and the circulation of the refrigerant along the air conditioning refrigerant flow path 30 (the flow indicated by the broken line arrow in FIG. 1). Permissible. In this case, the battery coolant channel 14 and the air conditioning coolant channel 30 function as separate channels independent of each other, as shown in FIG.

  On the other hand, in the connected state, the flow from the first connection flow path 42 to the air conditioning refrigerant flow path 30 is allowed, and the circulation of the refrigerant along the air conditioning refrigerant flow path 30 (in FIG. Flow shown) is prohibited. In this case, the battery coolant channel 14 and the air conditioning coolant channel 30 function as one large channel connected to each other as shown in FIG.

  The control unit controls the operation of the connection valve 40. Specifically, when the waste heat generated during power generation of the FC stack 100 is used for heating, the control unit brings the connection valve 40 into a connected state. That is, as described above, the FC stack 100 also generates heat (waste heat) with power generation. This waste heat is usually carried by a refrigerant and removed by the radiator 22. However, when heating is performed, it can be said that it is advantageous to use the waste heat of the FC stack 100 for heating rather than removing it. Therefore, when the waste heat is generated in the FC stack 100 (that is, when the FC stack 100 is generating power) and heating is performed, the control unit puts the connection valve 40 in the connected state. When the connection state is established and the flow path configuration is as shown in FIG. 3, the refrigerant heated by the waste heat of the FC stack 100 flows into the air conditioning refrigerant flow path 30. Then, by using the refrigerant heated by the waste heat for heating, it is possible to reduce the amount of heating by the electric heater 34 and consequently the power consumption. As a result, compared with the case where the two refrigerant flow paths 14 and 30 are not connected, the electric power consumed by the entire refrigerant circuit system 10 can be reduced.

  Here, as described above, since the power consumption can be reduced if the waste heat of the FC stack 100 is used for heating, a technique for connecting / blocking the air-conditioning refrigerant channel 30 and the battery refrigerant channel 14 has been conventionally possible. Many have been proposed. In many of these conventional techniques, the air conditioning refrigerant flow path 30 and the battery refrigerant flow path 14 are blocked when heating is not performed. However, with such a configuration, the shut-off state of both the flow paths 14 and 30 continues for a long time in summer and the like. In this case, there is no problem in the battery refrigerant flow path 14 because the refrigerant pump 16 operates every time the FC stack 100 is operated, and the ions are removed by the ion exchanger 18. On the other hand, in the air conditioning refrigerant flow path 30, unless heating or the like is performed for a long period of time, the refrigerant does not circulate for a long period. In this case, ions eluted from various parts such as the heater core 36 are accumulated in the refrigerant, and the conductivity of the refrigerant may be excessively increased. If this state is left as it is, the refrigerant having an excessively high conductivity will flow from the air conditioning refrigerant flow path 30 into the battery refrigerant flow path 14 when the flow paths 14 and 30 are connected next time, and the battery The conductivity of the refrigerant flowing through the refrigerant flow path 14 will increase rapidly. As a result, there is a risk that the insulation resistance between the FC stack 100 and the ground is drastically reduced. This will be briefly described with reference to FIG.

  FIG. 4 is a graph showing an example of the change in conductivity associated with the blocking / connection of the two flow paths 14 and 30. In FIG. 4, it is assumed that the two flow paths 14 and 30 are blocked at time t0 and connected at time t1. The thick solid line indicates the change in the conductivity of the refrigerant flowing through the battery refrigerant flow path 14 (hereinafter referred to as “battery side conductivity Cb”), and the thin solid line indicates the conductivity of the refrigerant flowing through the air conditioning refrigerant flow path 30 (hereinafter “ It shows the change in the air conditioning side conductivity Ca ”.

  As is clear from FIG. 4, even when the battery is cut off, the battery-side conductivity Cb hardly changes. This is because ions in the refrigerant are appropriately removed by the ion exchanger 18 provided in the battery refrigerant flow path 14. On the other hand, since the ion exchanger 18 is not provided in the air conditioning refrigerant flow path 30, after being switched off (that is, after being separated from the battery refrigerant flow path 14 provided with the ion exchanger 18). ), The air conditioning side conductivity Ca gradually increases.

  It is assumed that both flow paths 14 and 30 are connected at time t1 when the air-conditioning-side conductivity Ca becomes high. In this case, since the battery-side refrigerant having a low conductivity flows into the air-conditioning refrigerant flow path 30, the air-conditioning-side conductivity Ca rapidly decreases. At the same time, since the refrigerant on the air conditioning side having high conductivity flows into the battery refrigerant flow path 14, the battery side conductivity Cb increases rapidly. After both refrigerants are mixed, the conductivity gradually decreases due to the action of the ion exchanger 18.

  Here, normally, in order to keep the insulation resistance value between the FC stack 100 and the ground within a range where there is no problem, a battery-side upper limit value Cb_max that is an upper limit value of the battery-side conductivity Cb is defined in advance. The ion exchanger 18 having a capacity capable of keeping the battery side conductivity Cb below the battery side upper limit Cb_max is selected. However, as described above, when the air-conditioning-side refrigerant whose conductivity has excessively increased flows into the battery refrigerant flow path 14, the capacity of the ion exchanger 18 cannot catch up, and the battery-side conductivity Cb immediately after connection is the battery. The side upper limit value Cb_max was exceeded, and as a result, the insulation resistance might fall below the reference value.

  In order to cope with such a problem, Patent Document 1 discloses a technique of appropriately connecting two refrigerant flow paths to suppress an increase in ion concentration in the refrigerant even when heating is unnecessary. However, in this patent document 1, it is only determined the timing to shift to the connected state based on the length of the stop time of the refrigerant pump and the like, and it is said that the state has shifted to the connected state at an appropriate timing. It was difficult. As a result, there has been a case where the problem of a rapid decrease in the insulation resistance as described above may occur. Moreover, in patent document 1, since the ion concentration detector was provided only in the battery refrigerant flow path, there was a problem that the ion concentration (conductivity) in the air conditioning refrigerant flow path could not be detected. Here, since an ion exchanger is provided in the battery refrigerant flow path, it is unlikely that the ion concentration will rise excessively compared to the air conditioning refrigerant flow path, and the necessity to detect the ion concentration is necessary. Is low.

  In order to solve such a problem of the prior art, in this embodiment, an ion concentration detector 38 is provided in the air conditioning refrigerant circuit 13 to detect the ion concentration of the refrigerant flowing in the air conditioning refrigerant flow path 30, and consequently the conductivity. ing. And the drive of the connection valve 40 grade | etc., Is controlled based on this detected electrical conductivity. Hereinafter, the drive control of the connection valve 40 and the like based on the air conditioning side conductivity Ca will be described in detail.

  FIG. 5 is a flowchart showing a flow of drive control of the connection valve 40 and the like in the present embodiment. The control unit periodically detects the air conditioning conductivity Ca (S10). That is, the control unit periodically acquires the ion concentration detected by the ion concentration detector 38 installed in the air conditioning refrigerant flow path 30, and calculates the air conditioning side conductivity Ca based on the acquired ion concentration. . Here, it is desirable to always monitor the air-conditioning-side conductivity Ca as long as the vehicle is activated (ie, the ignition switch is turned on) even in the summer when heating is unnecessary. As will be described later, by constantly monitoring, it is possible to prevent the air-conditioning side conductivity from being left excessively increased, thereby preventing a sudden drop in insulation resistance when shifting from a shut-off state to a connected state. Because.

  If the air conditioning side conductivity Ca is obtained, it is subsequently determined whether or not the obtained air conditioning side conductivity Ca exceeds a predetermined air conditioning side upper limit Ca_max (S12). Here, the air conditioning side upper limit value Ca_max is a value at which the battery side conductivity Cb does not exceed the battery side upper limit value Cb_max when the state is shifted from the cut-off state to the connected state, and the refrigerant amount ratio of each of the flow paths 14 and 30 and the like. Is a value defined in advance based on

  Specifically, the determination of the air conditioning side upper limit Ca_max will be described with reference to FIG. FIG. 6 is a diagram showing the relationship between the air conditioning side conductivity Ca1 (see FIG. 4) just before the connection and the battery side conductivity Cb1 (see FIG. 4) just after the connection. In FIG. 6, the horizontal axis represents the air conditioning side conductivity Ca1 immediately before the connection, and the vertical axis represents the battery side conductivity Cb1 immediately after the connection.

  As described with reference to FIG. 4, the value of the battery-side conductivity Cb in the cut-off state is generally constant, and the ratio of the amount of refrigerant flowing through the two flow paths 14 and 30 is also substantially constant. Therefore, the battery side conductivity Cb1 immediately after the connection is generally proportional to the air conditioning side conductivity Ca1 immediately before the connection, as shown in FIG.

The air conditioning side upper limit value Ca_max is set based on the relationship between the two conductivity values Ca1 and Cb1. Specifically, the air conditioning side upper limit Ca_max is set to a value equal to or lower than the air conditioning side conductivity Ca1 ^* when Cb1 = Cb_max. The air conditioning side upper limit value Ca_max is not particularly limited as long as it is Ca1 ^* or less, but if the air conditioning side upper limit value Ca_max is excessively small, the flow of steps S16 to S22 to be described later frequently occurs, and the control becomes complicated. To do. Therefore, the air conditioning side upper limit value Ca_max is set to a value that is not excessively small (for example, about Ca1 ^* ≧ Ca_max> 0.5 × Ca1 ^* ) in consideration of an increase rate of the air conditioning side conductivity Ca in the shut-off state. It is desirable.

  Returning to FIG. 5 again, control of the connection valve 40 and the like will be described. If the detected air-conditioning-side conductivity Ca is equal to or less than the air-conditioning-side upper limit Ca_max, it means that there is no problem in the current state. Continue monitoring.

  On the other hand, when the detected air-conditioning-side conductivity Ca exceeds the air-conditioning-side upper limit Ca_max, the control unit subsequently determines whether or not the connection valve 40 is in the connected state (S14). As a result of the determination, if it is in the connected state, the process returns to step S10, and regular monitoring of the air conditioning side conductivity Ca is continued. On the other hand, as a result of the determination, when the connection valve is in a shut-off state, that is, when the air conditioning refrigerant flow path 30 and the battery refrigerant flow path 14 are separated, the connection valve 40 is brought into a connected state, and both flow paths 14 , 30 are connected (S16). Further, the refrigerant pumps 16 and 32 installed in the respective flow paths 14 and 30 are operated at a predetermined rotational speed to circulate the refrigerant (S18).

  From this circulation, the air-conditioning-side refrigerant flows into the battery refrigerant flow path 14. By this inflow, the battery side conductivity Cb temporarily rises. However, since the conductivity Ca of the air-conditioning-side refrigerant flowing into the battery refrigerant flow path 14 at this time is slightly higher than the air-conditioning-side upper limit Ca_max, the air-conditioning side refrigerant becomes the battery refrigerant flow path 14. Even if it flows into the battery, there is almost no risk that the battery-side conductivity Cb exceeds the battery-side upper limit Cb_max, and consequently there is almost no risk that the insulation resistance will drop rapidly. Further, with the circulation, a part of the refrigerant passes through the ion exchanger 18 and the ions are removed, so that the conductivity is also lowered.

  If a predetermined time elapses after the refrigerant pumps 16 and 32 are activated, the control unit stops driving the refrigerant pumps 16 and 32 (S20). Further, the connection valve 40 is switched to the shut-off state, and the air conditioning refrigerant flow path 30 and the battery refrigerant flow path 14 are separated (S22). And it returns to step S10 and the regular monitoring of the air-conditioning side electric conductivity Ca is restarted.

  As is apparent from the above description, in the present embodiment, even when heating is not required, if the air conditioning side conductivity Ca exceeds the air conditioning side upper limit Ca_max, the air conditioning refrigerant flow path 30 and the battery The refrigerant flow path 14 is connected to circulate the refrigerant. This effectively prevents the air conditioning side conductivity Ca from being left in a shut-off state even though it is excessively increased. As a result, it is possible to effectively prevent a sudden increase in the battery-side conductivity Cb during the transition from the shut-off state to the connected state, and thus a rapid decrease in the insulation resistance.

  In the above description, when the air-conditioning-side conductivity Ca exceeds the air-conditioning-side upper limit Ca_max, the state immediately shifts to the connected state, but may gradually shift to the connected state. Specifically, the valve body constituting the connection valve 40 is configured so that the amount of refrigerant per unit time flowing from the air conditioning refrigerant passage 30 into the battery refrigerant passage 14 is smaller than that in the fully connected state. The opening / closing amount may be adjusted. Alternatively, the connected state (that is, the connected state and the cut-off state) is intermittently set so that the amount of refrigerant per unit time flowing from the air-conditioning refrigerant channel 30 into the battery refrigerant channel 14 is smaller than that in the fully connected state. May be repeated at a predetermined cycle). In any case, the rate of increase in the battery-side conductivity Cb can be reduced by suppressing the amount of refrigerant per unit time flowing from the air-conditioning refrigerant channel 30 to the battery refrigerant channel 14 to be lower than that in the fully connected state. As a result, the insulation resistance is prevented from being below a predetermined standard.

  Further, the amount of refrigerant per unit time flowing from the air conditioning refrigerant flow path 30 to the battery refrigerant flow path 14 in accordance with the excess amount ΔCa (ΔCa = Ca−Ca_max) of the air conditioning side conductivity Ca with respect to the air conditioning side upper limit Ca_max. May be adjusted. That is, when the vehicle is being started (while the ignition switch is on), the air-conditioning side conductivity Ca is periodically detected. Therefore, the excess amount ΔCa does not become excessively large. However, when the vehicle is stopped for a long time (the ignition switch is turned off), monitoring of the air-conditioning side conductivity Ca or the like cannot be detected, and therefore the air-conditioning side conductivity Ca may be left excessively increased. . When the vehicle is started in this state, the air conditioning side conductivity Ca is detected. However, since the air conditioning side conductivity Ca at this time exceeds the air conditioning side upper limit Ca_max, the state shifts to the connected state. . However, if the air-conditioning-side refrigerant that has been left standing for a long time and the conductivity has increased excessively flows into the battery refrigerant flow path 14 at a stretch, the battery-side conductivity Cb rapidly increases, and as a result, the insulation resistance rapidly decreases. . Therefore, the larger the excess amount ΔCa of the air conditioning side conductivity Ca with respect to the air conditioning side upper limit Ca_max, the smaller the amount of refrigerant per unit time flowing from the air conditioning refrigerant channel 30 to the battery refrigerant channel 14. It is desirable to adjust the opening / closing amount of the valve body constituting the valve 40, the opening / closing interval of the valve body, and the like. With such a configuration, when the vehicle is stopped for a long time, in other words, even when the air-conditioning-side conductivity Ca cannot be detected for a long time, the battery-side conductivity Cb increases rapidly, and thus the insulation resistance rapidly increases. Resistance can be prevented.

  In the above description, the air conditioning refrigerant circuit 13 is illustrated as a refrigerant circuit that is connected / blocked to the battery refrigerant circuit 12, but other refrigerant circuits such as a refrigerant circuit mounted on a vehicle, for example, Alternatively, a refrigerant circuit for controlling the temperature of an electrical component (such as an inverter, a traveling motor, or a PCU) may be used.

  DESCRIPTION OF SYMBOLS 10 Refrigerant circuit system, 12 Battery refrigerant circuit, 13 Air conditioning refrigerant circuit, 14 Battery refrigerant flow path, 16, 32 Refrigerant pump, 18 Ion exchanger, 20 Switching valve, 22 Radiator, 30 Air conditioning refrigerant flow path, 34 Electric heater, 36 Heater core, 38 Ion concentration detector, 40 Connection valve, 42, 44 Connection flow path, 50 Air conditioner circuit, 52 Air conditioner refrigerant flow path, 54 Condenser, 56 Expansion valve, 58 Evaporator, 60 Electric compressor, 100 FC Stack, 110 Air conditioning system.

Claims (8)

A refrigerant circuit system comprising: a refrigerant circuit for a battery that controls a flow of refrigerant used in a fuel cell system; and a refrigerant circuit for another system that controls a flow of refrigerant used in another system,
A blocking state in which the battery refrigerant flow path provided in the battery refrigerant circuit and the other system refrigerant flow path provided in the other system refrigerant circuit are blocked; and the battery refrigerant flow path and the other system refrigerant flow path And a connection state that can be switched to a connected state,
An ion exchanger that is provided in one of the refrigerant circuit for the battery or the refrigerant circuit for another system and removes ions from the refrigerant flowing in the one refrigerant flow path;
A conductivity detector that is provided on the other side of the refrigerant circuit for the battery or the refrigerant circuit for another system and detects the conductivity of the refrigerant flowing in the other refrigerant flow path;
Control means for controlling the operation of the connection valve based on at least the detection result detected by the conductivity detector;
A refrigerant circuit system comprising: The refrigerant circuit system according to claim 1,
The ion exchanger is provided in the battery refrigerant circuit,
The conductivity detector is provided in the refrigerant circuit for the other system,
A refrigerant circuit system characterized by that. The refrigerant circuit system according to claim 2,
When the conductivity of the refrigerant flowing in the refrigerant circuit for the other system detected by the conductivity detector in the shut-off state exceeds a predetermined upper limit value in the shut-off state, the control means sets the connection valve to enter the connected state. A refrigerant circuit system that is driven. The refrigerant circuit system according to claim 3,
The upper limit value is a value that can keep the insulation resistance value between the fuel cell and the ground at a specified reference value or more when the battery coolant channel and the other system coolant channel are connected. Refrigerant circuit system. The refrigerant circuit system according to any one of claims 2 to 4,
The refrigerant circuit system for an other system is an air conditioning refrigerant circuit which is used for air conditioning and has a heater core. The refrigerant circuit system according to claim 5,
The refrigerant circuit system according to claim 1, wherein the conductivity detector is provided on a downstream side of the heater core. The refrigerant circuit system according to any one of claims 2 to 6,
The control means controls the opening / closing amount of the connection valve according to the conductivity of the refrigerant flowing in the refrigerant circuit for the other system detected by the conductivity detector when shifting from the shut-off state to the connected state. Thus, the refrigerant circuit system is characterized in that the refrigerant amount per unit time flowing into the battery refrigerant flow path from the other system refrigerant flow path is adjusted. The refrigerant circuit system according to any one of claims 2 to 7,
When the control means shifts from the cut-off state to the connected state, the control means intermittently turns the connection valve on the basis of the conductivity of the refrigerant flowing in the refrigerant circuit for other system detected by the conductivity detector in the cut-off state. The refrigerant circuit system is characterized in that the refrigerant amount per unit time flowing into the battery refrigerant flow path from the other system refrigerant flow path is adjusted by adjusting the opening and closing interval.

Images