JP5626459B2 - Cooling system and vehicle equipped with the same - Google Patents

Description

  The present invention relates to a cooling system and a vehicle including the cooling system, and more particularly to a technique for diagnosing a partial abnormality of the cooling system.

  In an electric vehicle using an electric motor as a drive source, a cooling system for cooling the electric motor and the driving device is mounted in order to prevent overheating of the electric motor and a driving device such as an inverter that drives the electric motor.

  Japanese Patent Laying-Open No. 2008-256313 (Patent Document 1) discloses a cooling system including a cooling water circulation path, a pump for circulating cooling water through the circulation path, and a radiator for cooling the cooling water. The cooling system control device described in Patent Document 1 is a technology for determining whether or not an abnormality has occurred in the cooling system, and the temperature of the cooling water obtained from a temperature sensor provided in the circulation path of the cooling water, and a water pump And an abnormality determination unit that determines the type of abnormality that has occurred in the cooling system based on the number of rotations. If the temperature of the cooling water is equal to or higher than a preset threshold value, the abnormality determination unit determines whether there is an abnormality such as a radiator abnormality, a circulation path blockage, or a water pump failure based on the rotation speed of the water pump. Determine the type.

JP 2008-256313 A JP 2005-20881 A JP 2004-332988 A

  In the technology for determining whether or not an abnormality has occurred in the cooling system based on the temperature of the cooling water and the rotation speed of the water pump, as described in Patent Document 1, the type of abnormality that has occurred in the cooling system can be determined. It is difficult to determine the cause of the abnormality. Therefore, in the technique described in Patent Document 1, fail-safe processing such as limiting the output torque of the electric motor or stopping the water pump can be performed according to the type of abnormality, but the cause of the abnormality is removed. Cannot be processed.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to identify a cause of an abnormality that has occurred in the cooling system and to eliminate the cause of the abnormality. A system and a vehicle including the system are provided.

  According to one aspect of the present invention, there is provided a cooling system for cooling a heat generation source, a flow path for circulating a liquid medium for cooling the heat generation source, and a pump for circulating the liquid medium provided on the flow path With. The flow path includes a plurality of branch paths arranged in parallel with the flow direction of the liquid medium between the upstream side and the downstream side of the heat generation source. The cooling system detects an abnormality occurring in one of the plurality of branch paths by detecting an imbalance in the flow rate of the liquid medium flowing through each of the plurality of branch paths, and also detects an imbalance in the flow rate of the liquid medium. And a control device for diagnosing the cause of the abnormality based on the state of the cooling system at the time.

  Preferably, the control device diagnoses the cause of the abnormality based at least on the number of rotations of the pump when an imbalance in the flow rate of the liquid medium is detected.

  Preferably, the cooling system further includes a rotational speed sensor for detecting the rotational speed of the pump. When the first condition that the detected value of the rotational speed sensor when the pump is driven rises above the control target value when an imbalance in the flow rate of the liquid medium is detected, the control device Diagnose that air is mixed in.

  Preferably, the cooling system further includes a temperature sensor for detecting the temperature of the liquid medium. When the first condition is not satisfied, the control device determines whether or not the second condition that the detected value of the temperature sensor is lower than a predetermined threshold is satisfied, and when the second condition is satisfied Diagnose that the flow path is frozen.

  Preferably, when the second condition is satisfied, the control device determines whether or not the flow rate of the flow path is within the control range, and the third condition that the flow rate of the flow path is within the control range. When is established, it is diagnosed that one of the plurality of branch paths is frozen.

  Preferably, when the first condition is not satisfied and the second condition is not satisfied, the control device diagnoses that a foreign substance is mixed in any of the plurality of branch paths.

  Preferably, the control device temporarily increases the rotational speed of the pump when it is diagnosed that air or foreign matter is mixed in any of the plurality of branch paths.

  Preferably, when it is diagnosed that any of the plurality of branch paths is frozen, the control device temporarily increases the heat generation amount of the heat source corresponding to the branch path where the freezing is diagnosed.

  Preferably, the heat generation source is a drive device having an electric motor and an inverter for driving the electric motor. The cooling system further includes an element temperature sensor that detects the temperature of the power control element in the inverter. The control device reduces the heat generation of the power control element after temporarily heating the power control element in the inverter under a condition that does not issue another drive command to the inverter, and detects the detected value of the element temperature sensor. In addition to estimating the flow rate of each of the plurality of branch paths according to the degree of decrease, the flow rate of the liquid medium is detected based on the estimated value of the flow rate of each of the plurality of branch paths.

Preferably, the plurality of branch paths are configured to have an equal flow rate.
According to another aspect of the present invention, a vehicle includes a drive device that uses an electric motor as a drive source, and a cooling system for cooling the drive device. The cooling system includes a flow path for circulating a liquid medium for cooling the drive device, and a pump for circulating the liquid medium provided on the flow path. The flow path includes a plurality of branch paths that are arranged in parallel with the flow direction of the liquid medium between the upstream side and the downstream side of the heat generation source and are configured to have the same flow rate. The vehicle further includes a control device for detecting an abnormality occurring in the cooling system by detecting an imbalance in the flow rate of the liquid medium flowing through each of the plurality of branch paths.

  According to the present invention, when an abnormality occurring in the cooling system is detected, the cause of the abnormality can be specified and the cause of the abnormality can be removed. Thereby, even when an abnormality occurs in the cooling system, it is possible to prevent the determination of the abnormality from being immediately confirmed. As a result, it is possible to avoid the output of the drive device being limited or unnecessary replacement of the water pump.

1 is a schematic configuration diagram of a vehicle equipped with a cooling system according to an embodiment of the present invention. It is a figure which extracts and shows the structure of a cooling system among the structures of the vehicle of FIG. It is a conceptual diagram explaining the structure of the flow path which passes along PCU. It is the flowchart which showed roughly the processing structure of the control apparatus. 5 is a flowchart for realizing the abnormality cause removal control shown in step S04 of FIG. 4. It is a wave form diagram for demonstrating the diagnosis time of the cooling system which concerns on this example of a change. It is a flowchart for demonstrating control of the diagnostic time of the cooling system shown in FIG. It is a flowchart for demonstrating the flow volume detection process used at the time of the diagnosis of the cooling system of step S20 of FIG. It is the figure which showed an example of the water temperature-command torque map referred in step S23 of FIG. It is a figure for demonstrating the measurement of the fall rate of temperature. It is a figure which shows an example of a descent | fall rate flow map.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

(Vehicle configuration)
FIG. 1 is a schematic configuration diagram of a vehicle 100 equipped with a cooling system according to an embodiment of the present invention. In addition, although the vehicle 100 showed the example of the electric vehicle, as long as it is a vehicle carrying a cooling system, this invention is applicable also to the hybrid vehicle and fuel cell vehicle which use an internal combustion engine together other than an electric vehicle.

  Referring to FIG. 1, vehicle 100 includes a battery B that is a power storage device, a voltage sensor 10, a power control unit (PCU) 40, a motor generator MG, and a control device 30. PCU 40 includes a voltage converter 12, smoothing capacitors C 0 and C 1, a voltage sensor 13, and an inverter 14. Note that the PCU 40 may include only the inverter 14 without providing the voltage converter 12. Vehicle 100 further includes a positive bus PL2 for supplying power to inverter 14 that drives motor generator MG.

  Smoothing capacitor C1 is connected between positive bus PL1 and negative bus SL2. The voltage converter 12 boosts the voltage across the terminals of the smoothing capacitor C1. The smoothing capacitor C0 smoothes the voltage boosted by the voltage converter 12. The voltage sensor 13 detects the voltage VH between the terminals of the smoothing capacitor C0 and outputs it to the control device 30.

  Vehicle 100 further includes a system main relay SMRB connected between the positive electrode of battery B and positive bus PL1, and a system main relay SMRG connected between the negative electrode of battery B (negative bus SL1) and node N2. With.

  System main relays SMRB and SMRG are controlled to be in a conductive / non-conductive state in accordance with control signal SE provided from control device 30. The voltage sensor 10 detects a voltage VB between the terminals of the battery B. Although not shown, a current sensor for detecting the current IB flowing through the battery B is provided together with the voltage sensor 10 in order to monitor the state of charge of the battery B.

  As the battery B, for example, a secondary battery such as a lead storage battery, a nickel metal hydride battery, or a lithium ion battery, or a large capacity capacitor such as an electric double layer capacitor can be used. Negative bus SL2 extends through voltage converter 12 to inverter 14 side.

  Voltage converter 12 is a voltage converter that is provided between battery B and positive bus PL2 and performs voltage conversion. Voltage converter 12 has one end connected to reactor L1 connected to positive bus PL1, IGBT devices Q1 and Q2 connected in series between positive bus PL2 and negative bus SL2, and IGBT devices Q1 and Q2, respectively. Diodes D1 and D2.

  Reactor L1 has the other end connected to the emitter of IGBT element Q1 and the collector of IGBT element Q2. The cathode of diode D1 is connected to the collector of IGBT element Q1, and the anode of diode D1 is connected to the emitter of IGBT element Q1. The cathode of diode D2 is connected to the collector of IGBT element Q2, and the anode of diode D2 is connected to the emitter of IGBT element Q2.

  Inverter 14 is connected to positive bus PL2 and negative bus SL2. Inverter 14 converts the DC voltage output from voltage converter 12 into a three-phase AC voltage and outputs the same to motor generator MG driving wheel 2. Further, the inverter 14 returns the electric power generated in the motor generator MG to the voltage converter 12 along with the regenerative braking. At this time, the voltage converter 12 is controlled by the control device 30 so as to operate as a step-down circuit.

  Inverter 14 includes a U-phase arm 15, a V-phase arm 16, and a W-phase arm 17. U-phase arm 15, V-phase arm 16 and W-phase arm 17 are connected in parallel between positive bus PL2 and negative bus SL2.

  U-phase arm 15 includes IGBT elements Q3 and Q4 connected in series between positive bus PL2 and negative bus SL2, and diodes D3 and D4 connected in parallel with IGBT elements Q3 and Q4, respectively. The cathode of diode D3 is connected to the collector of IGBT element Q3, and the anode of diode D3 is connected to the emitter of IGBT element Q3. The cathode of diode D4 is connected to the collector of IGBT element Q4, and the anode of diode D4 is connected to the emitter of IGBT element Q4.

  V-phase arm 16 includes IGBT elements Q5 and Q6 connected in series between positive bus PL2 and negative bus SL2, and diodes D5 and D6 connected in parallel with IGBT elements Q5 and Q6, respectively. The cathode of diode D5 is connected to the collector of IGBT element Q5, and the anode of diode D5 is connected to the emitter of IGBT element Q5. The cathode of diode D6 is connected to the collector of IGBT element Q6, and the anode of diode D6 is connected to the emitter of IGBT element Q6.

  W-phase arm 17 includes IGBT elements Q7, Q8 connected in series between positive bus PL2 and negative bus SL2, and diodes D7, D8 connected in parallel with IGBT elements Q7, Q8, respectively. The cathode of diode D7 is connected to the collector of IGBT element Q7, and the anode of diode D7 is connected to the emitter of IGBT element Q7. The cathode of diode D8 is connected to the collector of IGBT element Q8, and the anode of diode D8 is connected to the emitter of IGBT element Q8.

  Motor generator MG is a three-phase permanent magnet synchronous motor, and one end of each of three stator coils of U, V, and W phases is connected to a neutral point. The other end of the U-phase coil is connected to a line drawn from the connection node of IGBT elements Q3 and Q4. The other end of the V-phase coil is connected to a line drawn from the connection node of IGBT elements Q5 and Q6. The other end of the W-phase coil is connected to a line drawn from the connection node of IGBT elements Q7 and Q8.

  Current sensor 24 detects a current flowing through motor generator MG as motor current MCRT, and outputs motor current MCRT to control device 30.

  Control device 30 receives the accelerator opening from accelerator sensor 111 and the set position of the shift lever from shift position sensor 113. Further, control device 30 receives a rotational speed (motor rotational speed) Nm of motor generator MG, values of current IB and voltages VB and VH, motor current MCRT, and activation signal IGON. Then, control device 30 controls voltage converter 12 and inverter 14 based on these pieces of information.

  Specifically, control device 30 outputs, to voltage converter 12, control signal PWU for instructing step-up, control signal PWD for instructing step-down, and a shutdown signal instructing operation inhibition.

  Further, control device 30 provides control signal PWMI for instructing inverter 14 to convert the DC voltage output from voltage converter 12 into an AC voltage for driving motor generator MG, and motor generator MG. A control signal PWMC for performing a regeneration instruction for converting the generated AC voltage into a DC voltage and returning it to the voltage converter 12 side is output.

(Cooling system configuration)
In the configuration shown in FIG. 1, vehicle 100 further includes a radiator 102, a reservoir tank 106, and a water pump 104 as a cooling system for cooling PCU 40 and motor generator MG. FIG. 2 shows the configuration of the cooling system extracted from the configuration of the vehicle 100 of FIG.

  The radiator 102, the PCU 40, the reservoir tank 106, the water pump 104, and the motor generator MG are annularly connected in series by a flow path 116.

  The water pump 104 is a pump for circulating cooling water such as antifreeze. Water pump 104 sucks the cooling water from reservoir tank 106 and circulates the cooling water toward motor generator MG. The rotation speed sensor 114 detects the rotation speed (hereinafter referred to as W / P rotation speed) NW of the water pump 104 and outputs the detected W / P rotation speed NW to the control device 30.

  Radiator 102 receives cooling water after cooling voltage converter 12 and inverter 14 inside PCU 40 from flow path 116, and cools the received cooling water using a radiator fan (not shown).

  In the vicinity of the cooling water inlet of the PCU 40, a temperature sensor 108 for detecting the cooling water temperature is provided. The cooling water temperature TW is transmitted from the temperature sensor 108 to the control device 30. In addition, a temperature sensor 110 that detects the temperature TC of the voltage converter 12 and a temperature sensor 112 that detects the temperature TI of the inverter 14 are provided inside the PCU 40. As the temperature sensors 110 and 112, a temperature detection element or the like built in the intelligent power module is used.

  Control device 30 generates signal SP for driving water pump 104 based on temperature TC from temperature sensor 110 and temperature TI from temperature sensor 112, and outputs the generated signal SP to water pump 104. To do.

  In the configuration shown in FIG. 2, in the flow path 116, a section from the upstream side to the downstream side of the PCU 40 is branched into a plurality of branch paths. FIG. 3 is a conceptual diagram illustrating the configuration of the flow path 116 that passes through the PCU 40. Referring to FIG. 3, power element substrate 400 on which power control elements (such as IGBT elements) of voltage converter 12 and inverter 14 are mounted is provided inside PCU 40. On the back surface of the power element substrate 400, a flow path 122 for cooling the power element substrate 400 is provided. The flow path 122 communicates with the cooling water inlet 120 and the cooling water outlet 124.

  In FIG. 3, the plurality of power control elements mounted on the power element substrate 400 are divided into three element parts (element parts 1 to 3). The flow path 122 is branched into three branch paths B1 to B3 so as to pass through these three element portions, respectively. These three branch paths B1 to B3 are arranged between the cooling water inlet 120 and the cooling water outlet 124 in parallel with respect to the flow direction of the cooling water, and are configured to have the same flow rate. . Therefore, when the cooling water introduced from the cooling water inlet 120 is divided into three equal parts, the cooling water flows through the respective branch paths B1 to B3 along the directions indicated by the arrows P1 to P3. At this time, the power control element included in the element unit is cooled by heat exchange between the cooling water flowing through each branch path and the element unit.

  The branch paths B1 to B3 are provided with flow rate sensors 131 to 133 for detecting the flow rate of the cooling water, respectively. A flow rate Fa of the cooling water in the branch path B1 is transmitted from the flow rate sensor 131 to the control device 30. From the flow sensor 132, the flow rate Fb of the cooling water in the branch path B2 is transmitted to the control device 30. From the flow rate sensor 133, the flow rate Fc of the cooling water in the branch path B3 is transmitted to the control device 30.

  The control device 30 diagnoses a partial abnormality of the cooling system based on the flow rates Fa, Fb, and Fc input from the flow rate sensors 131 to 133, respectively. The partial abnormality of the cooling system in the present embodiment means that an abnormality occurs in any of a plurality of branch paths. FIG. 3 shows a case where foreign matter is mixed in the branch path B1 as an example of the partial abnormality. In this case, since the flow rate of the cooling water flowing through the branch path B1 is reduced, the flow rate is unbalanced between the branch paths B1 to B3. When such flow rate imbalance occurs, a difference in cooling capacity occurs between the element units 1 to 3, which may cause a problem that the element temperature partially becomes high. In the case of FIG. 3, the element temperature T <b> 1 of the element unit 1 may be higher than the element temperature T <b> 2 of the element unit 2 and the element temperature T <b> 3 of the element unit 3. Therefore, it is necessary to quickly detect a partial abnormality of the cooling system and to eliminate the flow rate imbalance due to the partial abnormality.

  In the cooling system according to the present embodiment, in accordance with FIGS. 4 and 5 described below, the control device 30 determines the flow rates Fa and Fb based on the detection values (flow rates Fa, Fb, and Fc) of the flow sensors 131 to 133. , Fc is detected whether an imbalance has occurred. When the flow rate imbalance occurs, the control device 30 determines that the cooling system is partially abnormal.

  And if it determines with the partial abnormality of a cooling system, the control apparatus 30 will diagnose the cause of the said partial abnormality based on the state of the cooling system at the time of partial abnormality generation | occurrence | production. When the cause of the partial abnormality is diagnosed, the control device 30 further eliminates the partial abnormality by executing control for removing the diagnosed cause.

  FIG. 4 is a flowchart schematically showing the processing structure of the control device 30. Note that the processing of this flowchart is executed at regular time intervals or whenever a predetermined condition is satisfied.

  Referring to FIG. 4, in step S01, control device 30 reads flow rates Fa, Fb, Fc of branch paths B1-B3 detected by flow rate sensors 131-133 (FIG. 3). Subsequently, in step S02, the control device 30 monitors the rotational speed (W / P rotational speed) NW of the water pump 104 detected by the rotational speed sensor 114 (FIG. 1).

  In step S03, the control device 30 determines whether a partial abnormality of the cooling system has occurred based on the flow rates Fa, Fb, and Fc. Specifically, the control device 30 determines whether or not an imbalance has occurred between the flow rates Fa, Fb, and Fc. For example, the control device 30 calculates the ratio of each flow rate Fa, Fb, Fc to the total value (corresponding to the flow rate Ft of the flow path 116) of the flow rate Fa, the flow rate Fb, and the flow rate Fc. And the control apparatus 30 determines whether the imbalance of flow volume has generate | occur | produced by comparing the calculated ratio.

  When the calculated ratio is different among the flow rates Fa, Fb, and Fc, that is, when the ratio of each flow rate is out of 1/3, the control device 30 has a partial abnormality of the cooling system. Is determined. At this time, the control device 30 determines that an abnormality has occurred in the branch path in which the flow rate is smaller than that of other branch paths.

  If it is determined in step S03 that there is a partial abnormality of the cooling system, the control device 30 diagnoses the cause of the partial abnormality in step S04 based on the state of the cooling system when the partial abnormality occurs. Then, the control device 30 executes control for removing the diagnosed cause (hereinafter referred to as “abnormal cause removal control”). If the partial abnormality is not resolved even by the execution of the abnormality cause removal control, the control device 30 determines the abnormality of the cooling system through step S05. When the abnormality of the cooling system is determined, the control device 30 displays a warning on a display device, a warning lamp, or the like.

  FIG. 5 is a flowchart for realizing the abnormality cause removal control shown in step S04 of FIG. Note that the processing in steps S01 and S02 in FIG. 5 is the same as the processing in steps S01 and S02 in FIG. Further, the processing in steps S031, S032, and S033 in FIG. 5 corresponds to the processing in step S03 in FIG.

  Referring to FIG. 5, control device 30 reads flow rates Fa, Fb, Fc of branch paths B1-B3 detected by flow rate sensors 131-133 (FIG. 3) in step S01, and in step S02, The rotational speed (W / P rotational speed) NW of the pump 104 is monitored.

  Whether or not an imbalance has occurred between the flow rates Fa, Fb, and Fc based on the result of comparing the ratios of the flow rates Fa, Fb, and Fc with respect to the flow rate Ft of the flow path 116 in step S031. Determine whether. When the flow rates Fa, Fb, and Fc are not unbalanced (NO in step S031), the control device 30 determines that the cooling system is normal in step S033.

  On the other hand, when the imbalance of the flow rates Fa, Fb, and Fc is occurring (when YES is determined in step S031), the control device 30 determines that the cooling system is partially abnormal in step S032. The control device 30 determines that an abnormality has occurred in a branch path having a small flow rate ratio relative to the flow rate Ft among the plurality of branch paths B1 to B3. When it is determined in step S032 that the cooling system has a partial abnormality, the control device 30 performs the processes in steps S041 to S050, thereby executing the diagnosis of the cause of the partial abnormality and the abnormal cause removal control of the cooling system.

  Specifically, first, in step S041, the control device 30 determines whether or not the W / P rotational speed NW has increased based on the monitored W / P rotational speed NW. When W / P rotation speed NW increases (when YES is determined in step S041), control device 30 may have air mixed in the branch path determined to be abnormal in step S045. Diagnose. “Air is mixed into the branch path” means that a lump of air exists in the branch path. When air is mixed in the flow path, the load applied to the water pump 104 is smaller than when air is not mixed. Therefore, the actual rotational speed of the water pump 104 is larger than the control rotational speed specified by the signal SP. When the state where the W / P rotation speed NW is higher than the control rotation speed continues for a predetermined time or longer, the control device 30 diagnoses that air may be mixed in the branch path.

  If it is diagnosed in step S045 that air may be mixed in the branch path, the control device 30 temporarily increases the output of the water pump 104 in step S044. For example, the control device 30 drives the water pump 104 at the maximum rotation speed for a certain time. By increasing the number of revolutions of the water pump 104, the discharge flow rate of the water pump 104 increases, so that the air remaining in the branch path is pushed into the reservoir tank 106 together with the cooling water. In the reservoir tank 106, air and cooling water are separated, and the air is released to the atmosphere. Thereby, the air remaining in the branch path can be removed.

  On the other hand, when the W / P rotation speed NW has not increased in step S041 (when NO is determined in step S041), the control device 30 detects the coolant temperature TW detected by the temperature sensor 108 in step S042. Is less than or equal to a predetermined threshold. For example, the predetermined threshold is set to a temperature at which the cooling water in the flow path is frozen. Instead of the cooling water temperature TW detected by the temperature sensor 108, the determination may be made based on the detection value of the temperature sensor for detecting the outside air temperature.

  When cooling water temperature TW is equal to or lower than the predetermined threshold (when YES is determined in step S042), control device 30 subsequently determines whether or not the flow rate Ft of the cooling water flowing through flow path 116 is normal in step S046. Determine whether. The control device 30 calculates the total value of the flow rates Fa, Fb, and Fc detected by the flow rate sensors 131 to 133 as the flow rate Ft. And the control apparatus 30 determines with the flow volume Ft being normal, when the flow volume Ft exists in the control range of the flow volume according to the control rotation speed of the water pump 104. FIG.

  When it is determined in step S046 that the flow rate Ft is normal (YES in step S046), the control device 30 determines that the cooling water temperature is low in step S047, and therefore the branch paths B1 to B3 shown in FIG. Diagnose that may be partially frozen. The control device 30 estimates that among the plurality of branch paths B1 to B3, a branch path having a smaller flow rate relative to the total flow rate than the other branch paths is frozen. Therefore, in step S048, control device 30 forcibly generates heat at the element portion corresponding to the branch path where freezing is estimated. Specifically, the control device 30 outputs a control signal for setting the energized state for a short time to the power control element included in the element unit corresponding to the branch path. Since this control signal is for generating heat in the power control element, it does not generate torque for driving the vehicle unlike the control signals PWMI and PMWC. Since the power control element self-heats for a short time, the freezing of the branch path can be eliminated.

  On the other hand, when it is determined in step S046 that the flow rate Ft is not normal (when NO is determined in step S046), the control device 30 causes the flow path 116 including a plurality of branch paths B1 to B3 in step S049. Is diagnosed as freezing. In this case, the control device 30 forcibly causes all of the element units 1 to 3 to generate heat in step S050. Specifically, control device 30 outputs a control signal for making the power control elements included in element units 1 to 3 energized for a short time. All power control elements mounted on the power element substrate 400 self-heat for a short time, so that the freezing of the flow path can be eliminated.

  Returning to step S042, if the cooling water temperature TW is not equal to or lower than the predetermined threshold value (NO determination in step S042), the control device 30 has foreign matter or air mixed in some of the plurality of branch paths B1 to B3. Diagnose it as possible. The control device 30 estimates that foreign matter or air is mixed in a branch path having a small flow rate ratio with respect to the total flow rate among the plurality of branch paths B1 to B3. In addition, mixing of air into the branch path in step S043 means that an air mass is present in the branch path as in step S045. However, step S043 assumes a case where the flow area of the branch path is reduced because an infinite number of air masses having smaller sizes exist in the branch path compared to step S045. It is different in point.

  If it is diagnosed in step S041 that there is a possibility that foreign matter or air is mixed in the branch path, the control device 30 temporarily increases the output of the water pump 104 in step S044. As described above, by increasing the discharge flow rate of the water pump 104, foreign matters or air remaining in the branch path can be removed.

  As described above, if the cause of the partial abnormality of the cooling system is diagnosed based on the rotation speed of the water pump 104 and the cooling water temperature, the abnormality cause removal control is executed in the optimal control mode for removing the diagnosed cause. To do. Then, in step S051, the control device 30 determines whether or not the unbalance of the flow rates Fa, Fb, and Fc has been eliminated. If the flow rate imbalance has not been eliminated (NO in step S051), control device 30 determines an abnormality in the cooling system in step S05.

  On the other hand, if the flow rate imbalance is eliminated by the abnormality cause removal control (YES in step S051), the controller 30 eliminates the partial abnormality of the cooling system in step S06, and the cooling system is normal. Judged as having returned to the state.

  As described above, according to the cooling system according to the present embodiment, whether or not the flow rate of the cooling water is unbalanced between the plurality of branch paths connected in parallel to the flow direction of the cooling water. By determining whether or not, a partial abnormality of the cooling system can be detected.

  Here, as described above, when an imbalance in the flow rate of the cooling water occurs between the plurality of branch paths, there is a possibility that a problem that the element temperature partially becomes high may occur. Therefore, the abnormality of the cooling system may be determined based on the detection values of the temperature sensor 110 that detects the temperature TC of the voltage converter 12 and the temperature sensor 112 that detects the temperature TI of the inverter 14 (see FIG. 1). it can.

  However, in the configuration in which the abnormality of the cooling system is determined based on the detection value of the temperature sensor, whether the temperature increase of the power control element is due to an increase in the amount of heat generated by the power control element due to overcurrent or air in the flow path Alternatively, it cannot be determined whether the flow rate is reduced due to foreign matter mixed in or due to a failure of the water pump 104. Therefore, the load factor of motor generator MG may be limited in order to suppress the temperature rise of the power control element. Alternatively, there is a possibility that the water pump 104 is erroneously replaced even though it can operate normally.

  On the other hand, in the cooling system according to the present embodiment, it is possible to detect a partial abnormality of the flow path by determining whether or not an imbalance in the flow rate between the plurality of branch paths has occurred. it can. Therefore, it is possible to avoid problems such as the load factor of motor generator MG being limited or unnecessary replacement of water pump 104 being performed.

  Further, since the cause of the partial abnormality can be determined based on the rotation speed of the water pump 104 and the cooling water temperature TW when the partial abnormality is detected, by executing control for removing the cause Partial abnormalities can be resolved.

(Example of change)
Although the cooling system according to the present embodiment is configured to detect the flow rates Fa, Fb, Fc in the plurality of branch paths B1 to B3 by the flow sensor provided for each branch path, the flow rates Fa, Fb, Fc. It is good also as a structure which estimates. As a method for estimating the flow rate, for example, in the cooling system shown in FIG. 2, the control device 30 uses the power in the inverter 14 for the flow rate estimation under the condition that other drive commands for the PCU 40 are not issued. The flow rate can be estimated based on the degree to which the control element is temporarily heated and then the power control element is cooled. According to this, it becomes possible to detect the flow rate with high accuracy without providing a flow rate sensor for each branch path.

  Hereinafter, with reference to the drawings, a diagnosis process of the cooling system according to the modification of the embodiment of the present invention will be described.

FIG. 6 is a waveform diagram for explaining the diagnosis time of the cooling system according to this modification.
Referring to FIG. 1 and FIG. 6, when an activation instruction is given from the driver by a start button or the like of the vehicle, the vehicle completes a self-check of the ECU and enters a ReadyON state. Thereafter, in a state where the vehicle is set to the parking range and stopped at times t1 to t2, control device 30 outputs a torque command to inverter 14 for a short time. This torque command is smaller than the torque command during running after time t3. Therefore, if the parking range is set and the accelerator pedal is not depressed, the torque enough to start the vehicle is not generated.

  Since the short-time torque command is for generating heat in the power control element of the inverter, it does not have to generate torque. For example, the inverter 14 may be controlled so that only the d-axis current of the inverter flows and the q-axis current does not flow so as not to generate torque.

  When the diagnosis of the operation status of the water pump 104 is completed by time t3 and it is confirmed that the operation status is normal, an acceleration / deceleration instruction such as from the accelerator pedal is given as shown at times t3 to t4. In response, a torque command is generated and the vehicle shifts to a state where it can travel. The time point t3 may be defined as the ReadyON state.

  FIG. 7 is a flowchart for explaining control of the diagnosis time of the cooling system shown in FIG. The processing of this flowchart is called from the main routine and executed when the start switch for starting the vehicle system is set to the ON state.

  With reference to FIGS. 6 and 7, in step S <b> 10, it is determined whether or not a charging / discharging operation using inverter 14 is performed from battery B. If there is no charge / discharge operation, the process proceeds to step S20, and the cooling system is diagnosed. Thereby, an environment with less noise suitable for the diagnosis of the cooling system 104 is ensured. If there is a charge / discharge operation in step S10, for example, if the accelerator is stepped on immediately, the cooling system is not diagnosed and the next opportunity is waited, and control is returned to the main routine in step S60.

  Prioritizing the diagnosis of the cooling system, the shift position after the start switch is prohibited from moving from the parking position or the input of the accelerator pedal is not accepted until the diagnosis of the cooling system is completed. good.

In step S20, the flow rate Ft of the flow path 116 and the flow rates Fa, Fb, and Fc of the branch paths B1 to B3 are detected based on the degree to which the power control element of the inverter 14 is heated for a short time and then cooled. . Based on the detected flow rates Fa, F b , Fc, it is possible to diagnose whether flow rate imbalance has occurred.

  In step S30, it is determined whether or not the cooling system is normal. The process in step S30 is executed according to the flowcharts of FIGS. When it is determined that the cooling system is normal, the process proceeds to step S40, and charging / discharging operation using the inverter 14 from the battery B is permitted. As a result, the vehicle can travel. The detected cooling water amount may be fed back and used for pump control. On the other hand, when it is determined in step S30 that the cooling system is not normal, that is, when an abnormality of the cooling system is determined, a warning is displayed on a display device, a warning lamp, or the like.

  When the process of step S40 or step S50 ends, control is transferred to the main routine in step S60.

  FIG. 8 is a flowchart for explaining the flow rate detection process used in the diagnosis of the cooling system in step S20 of FIG. The process of this flowchart is called and executed from the process of the flowchart of FIG. 7 which is the main routine. Moreover, the process of this flowchart is performed in parallel for the flow path 116 and the branch paths B1 to B3.

  Referring to FIG. 8, the process of this flowchart is started based on an operation for instructing vehicle system activation or vehicle system termination. First, in step S21, the control device 30 determines whether or not the condition that the shift range is set to the P (parking) range and the accelerator pedal is not operated (OFF state) is satisfied. While this condition is not satisfied, the process proceeds to step S37, and control is transferred to the main routine. In the case of a hybrid vehicle, there is a case where the motor inverter is energized in order to start the engine when the battery storage amount is low, so the condition that the battery storage amount does not decrease is added. May be.

  If the condition of step S21 is satisfied, the process proceeds to step S22, where the water temperature Tw at that time is stored as a value Tw0, and the inverter element temperature Ti is stored as a value Ti0.

  Subsequently, in step S23, the command torque is determined from the water temperature-command torque map.

  FIG. 9 is a diagram showing an example of a water temperature-command torque map referred to in step S23 of FIG. In the example of the map shown in FIG. 9, the command torque is set so as to decrease as the water temperature rises.

  Referring to FIG. 8 again, following step S23, in step S24, control device 30 provides command torque determined based on the water temperature to inverter 14 (torque ON). In step S25, the command torque is set to zero again (torque OFF). As described above, the power control element in the inverter generates heat for a short time as shown at times t1 to t2 in FIG.

  In step S25, control device 30 returns the command torque to zero, and simultaneously stores the temperature of the power control element in the inverter at that time as peak temperature Ti1, and stores the time at that time as t1.

FIG. 10 is a diagram for explaining the measurement of the rate of temperature decrease.
Referring to FIGS. 8 and 10, the temperature of the power control element of the inverter starts to rise at time t <b> 0 in response to the inverter torque command being set to the ON state. The element temperature continues to rise until the inverter torque command is set to the OFF state. At time t1 corresponding to setting the inverter torque command to the OFF state, the element temperature takes the peak value Ti1. This peak value Ti1 and the time t1 at that time are recorded in the internal memory or the like of the control device 30 during the process of step S25.

Subsequently, in step S26, a difference value ΔTi01 between the peak temperature Ti1 and the current inverter element temperature Ti0 is calculated based on the following equation (1).
ΔTi01 = Ti1-Ti0 (1)
In step S27, the specified number m is set, and the counter is further initialized. The counter value n is set to “2”.

The processing from step S28 to step S34 is repeated based on the counter value n.
First, in step S28, control device 30 determines a calculated temperature for the rate of temperature decrease of the power control element of the inverter. When the difference of the calculated temperature for calculating the rate of temperature decrease of the power control element of the inverter corresponding to the counter value n is ΔTi1n, the following equation (2) is obtained.
ΔTi1n = ΔTi01 * (n−1) / n (2)
For example, when n = 2, ΔTi12 = ΔTi01 * 1/2, and when the temperature difference is reduced to half, the first measurement is performed. When n = 3, the temperature difference decreases to 1/3.

Subsequently, in step S29, it is determined whether or not the current temperature has dropped to a temperature Tin represented by the following equation (3).
Tin = Ti1-ΔTi1n (3)
In step S29, times t2, t3, and t4 are measured when the temperature differences ΔTi12, ΔTi13, and ΔTi14 calculated in step S28 decrease from the peak value Ti1, respectively. For example, the times t2 and t3 can be times when the temperature difference becomes 1/2 and 1/3 of ΔTi01, respectively. Although not shown in the flowchart of FIG. 8, a time when the temperature is slightly higher than the initial temperature Ti0 (for example, + 2 ° C.) can be set as a measurement point, as at time t4 in FIG.

  Based on the measured time tn and the stored time t1, a time difference Δt1n from time t1 is calculated in step S30. As shown in FIG. 10, time differences Δt12, Δt13, Δt14 corresponding to the temperature differences ΔTi12, ΔTi13, ΔTi14, respectively, are calculated. The calculated value is recorded in an internal memory of the control device 30 or the like.

  Subsequently, in step S31, the flow rate is calculated from the temperature difference ΔTin and time difference Δtin and the descending rate flow rate map.

  FIG. 11 is a diagram illustrating an example of a descending rate flow map. Since the descending rate flow rate map of FIG. 11 is different for each cooling system of the vehicle, a value obtained experimentally in advance is used. Note that the vehicle itself may acquire data when the water pump is normal immediately after factory shipment or inspection, and this may be used as a reference value. In step S31, the obtained flow rate Qn is stored.

  Subsequently, in step S32, it is determined again whether or not the condition of step S21 is continued. This condition is a condition that the shift range is set to the P (parking) range and the accelerator pedal is not operated (OFF state).

  If this condition is not satisfied, the process proceeds to step S35, and the flow rate is calculated based on the measurement results so far. On the other hand, if this condition is still satisfied, the process proceeds to step S33, and measurement data is acquired to further increase the accuracy of the detected flow rate.

  In step S33, the counter value n of the counter set in step S27 is increased by 1. In step S24, it is determined whether or not the counter value is smaller than the number of measurements m set in step S27. When n <m, the processing from step S28 is repeated again, and the acquisition of the data set of the time difference Δt1n and the temperature difference ΔTin is continued.

  If n is equal to m in step S34 and the predetermined number of measurements m has been completed, the process proceeds to step S35.

  In step S35, an average value Qout of the flow rate Qj (j = 2,... M) for the measured number of times is calculated. And in step S36, based on the flow volume detected about each of the flow path 116 and the branch paths B1-B3, the process by the flowchart of FIG. 4 and FIG. To be judged. In step S37 following step S36, control is transferred to the flowchart of FIG. 7 which is the main routine.

  According to this modified example, an accurate flow rate of the coolant medium can be detected, so that an accurate abnormality determination of the cooling system can be performed. More specifically, by detecting the descending rate of the inverter element temperature, the amount of cooling water can be determined from a map showing the relationship between the “decreasing rate and the flow rate” without adding a new flow rate sensor.

  In addition, in the case of a hybrid vehicle before or after the start of traveling, a pump diagnosis is performed when the engine is stopped and when the vehicle is stopped, thereby removing disturbances that cause an increase in inverter element temperature and enabling accurate flow rate detection.

  Furthermore, by changing the magnitude of the inverter command torque based on the coolant temperature, the inverter element can be raised as a heat source while avoiding destruction of the inverter element.

  In addition, by measuring the descent rate a plurality of times, the coolant flow rate can be calculated with high accuracy from a map showing the relationship between the “descent rate and the flow rate”. In this case, the amount of cooling water is calculated from the descent rate measured before that even if the vehicle starts running or the engine starts before measuring the specified number of times (some hybrid vehicles use an inverter for the motor to start the engine). be able to.

  In the present embodiment, an electric vehicle is illustrated as an example of a vehicle equipped with a cooling system. However, the application of the present invention is not limited to such an example. That is, as long as the vehicle is equipped with a cooling system, the present invention is also applicable to a hybrid vehicle and a fuel cell vehicle that use an internal combustion engine together.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a vehicle equipped with a cooling system.

  DESCRIPTION OF SYMBOLS 10 Voltage sensor, 12 Voltage converter, 13 Voltage sensor, 14 Inverter, 15 U-phase arm, 16 V-phase arm, 17 W-phase arm, 24 Current sensor, 30 Control apparatus, 100 Vehicle, 102 Radiator, 104 Water pump, 106 Reservoir Tank, 108, 110, 112 Temperature sensor, 111 Accelerator sensor, 113 Shift position sensor, 114 Rotational speed sensor, 116, 122 Flow path, 120 Cooling water inlet, 124 Cooling water outlet, 131-133 Flow rate sensor, 400 Power element substrate , B battery, B1-B3 branch path, C0, C1 smoothing capacitor, D1-D8 diode, L1 reactor, MG motor generator, Q1-Q8 IGBT element, SMRB, SMRG System main relay.

Claims (11)

A cooling system for cooling a heat source,
A flow path for circulating a liquid medium for cooling the heat source;
A pump for circulating the liquid medium provided on the flow path,
The flow path includes a plurality of branch paths arranged in parallel with respect to the flow direction of the liquid medium between the upstream side and the downstream side of the heat generation source,
By detecting an imbalance in the flow rate of the liquid medium flowing through each of the plurality of branch paths, an abnormality occurring in any of the plurality of branch paths is detected, and an imbalance in the flow rate of the liquid medium is detected. A cooling system further comprising a control device for diagnosing the cause of occurrence of the abnormality based on the state of the cooling system at the time.   2. The cooling system according to claim 1, wherein the controller diagnoses the cause of occurrence of the abnormality based at least on the number of rotations of the pump when an imbalance in the flow rate of the liquid medium is detected. A rotation speed sensor for detecting the rotation speed of the pump;
In the control device, when an imbalance in the flow rate of the liquid medium is detected, a first condition is established that a detection value of the rotation speed sensor when the pump is driven rises higher than a control target value. The cooling system according to claim 2, which diagnoses that air is sometimes mixed in the flow path. A temperature sensor for detecting the temperature of the liquid medium;
When the first condition is not satisfied, the control device determines whether or not a second condition that the detected value of the temperature sensor is lower than a predetermined threshold is satisfied, and the second condition The cooling system according to claim 3, wherein when the condition is established, it is diagnosed that the flow path is frozen.   When the second condition is satisfied, the control device determines whether or not the flow rate of the flow path is within a control range, and a third state that the flow rate of the flow path is within the control range. The cooling system according to claim 4, wherein when one of the conditions is satisfied, it is diagnosed that one of the plurality of branch paths is frozen.   The control device according to claim 3, wherein when the first condition is not satisfied and the second condition is not satisfied, the control device diagnoses that a foreign substance is mixed in any of the plurality of branch paths. Cooling system.   7. The control device according to claim 3, wherein the control device temporarily increases the rotational speed of the pump when it is diagnosed that air or a foreign substance is mixed in any of the plurality of branch paths. Cooling system.   The control device, when it is diagnosed that any of the plurality of branch paths is frozen, temporarily increases the heat generation amount of a heat source corresponding to the branch path where freezing is diagnosed. 5. The cooling system according to 5. The heat source is a drive device having an electric motor and an inverter for driving the electric motor,
An element temperature sensor for detecting the temperature of the power control element in the inverter;
The control device reduces heat generation of the power control element after temporarily generating heat in the power control element in the inverter under a condition that satisfies other drive commands for the inverter. The flow rate of each of the plurality of branch paths is estimated according to the degree of decrease in the detected value of the temperature sensor, and the flow medium unbalance is detected based on the estimated value of the flow rate of each of the plurality of branch paths. The cooling system according to claim 1.   The cooling system according to claim 1, wherein the plurality of branch paths are configured to have an equal flow rate. A drive device using an electric motor as a drive source;
A cooling system for cooling the drive device,
The cooling system includes:
A flow path for circulating a liquid medium for cooling the drive device;
A pump for circulating the liquid medium provided on the flow path,
The flow path is arranged in parallel to the flow direction of the fluid medium between the upstream side and the downstream side of the outgoing heat source, and a plurality of branch passages configured to have equal flow area from each other Including
By detecting an imbalance in the flow rate of the liquid medium flowing through each of the plurality of branch paths, an abnormality occurring in any of the plurality of branch paths is detected, and an imbalance in the flow rate of the liquid medium is detected. A vehicle further comprising a control device for diagnosing the cause of occurrence of the abnormality based on the state of the cooling system at the time.

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