Cooling device for vehicle batteries

Abstract

To accurately determine normality / abnormality of an expansion valve against a change of an environmental factor in a device in which the expansion valve is disposed upstream of an on-vehicle battery of piping through which a refrigerant for air-conditioning inside of a cabin passes and that cools the on-vehicle battery by using the refrigerant cooled when passing through the expansion valve.SOLUTION: A monitoring device is added. The monitoring device executes processing for: controlling an opening of an expansion valve to a predetermined opening; specifying a threshold value stored in a map associated with an environmental factor value detected by an environmental factor value detector; and comparing a change amount of a refrigerant temperature detected by a refrigerant temperature detector from start of the processing for controlling the opening of the expansion valve to the predetermined opening until elapse of a predetermined time with the threshold value specified in the processing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a cooling device for an on-board battery, and to a cooling device having a function of monitoring the normality / abnormality of an expansion valve that adjusts the degree of expansion of a refrigerant used by the cooling device. [Background technology]

[0002] Patent Document 1 discloses a technology that adds a function to cool an on-board battery to an on-board air conditioning unit that conditions the interior of a vehicle. In this technology, the refrigerant for the air conditioning of the vehicle interior is used to cool the on-board battery. Specifically, the refrigerant is made to flow through a pipe that passes around the on-board battery, and an expansion valve is placed upstream of the on-board battery. The refrigerant is expanded and cooled as it passes through the expansion valve, and is made to flow around the on-board battery to cool it.

[0003] In a technology for cooling an on-board battery with a refrigerant cooled using an expansion valve, a technology for monitoring whether an abnormality occurs in the expansion valve is required. In Patent Document 1, the amount of temperature change of the refrigerant from the start of the cooling action by the expansion valve until a predetermined time has elapsed is detected, and the amount of temperature change is compared with a threshold value. In Patent Document 1, a command to close is given to the expansion valve and the amount of temperature change is detected. If the expansion valve operates normally and closes as commanded, the refrigerant cannot pass through the expansion valve, and therefore does not expand and is not cooled, and the amount of temperature change is small. If an abnormality occurs in the expansion valve and it does not close as commanded, the refrigerant expands and is cooled, and a previously assumed amount of temperature change is obtained. By giving a command to close the expansion valve and comparing the amount of temperature change of the refrigerant detected with a threshold value, it is possible to monitor whether an abnormality occurs in the expansion valve that does not close. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-14972 Summary of the Invention [Problem to be solved by the invention]

[0005] Since the amount of change in refrigerant temperature detected when the expansion valve is closed is significantly different from the amount of change in refrigerant temperature detected when the expansion valve is not closed, it is relatively easy to determine the threshold value to be compared with the amount of change in refrigerant temperature.

[0006] In Patent Document 1, two sets of piping are used in parallel to cool an on-board battery group, so even if one expansion valve arranged in one piping is closed, the refrigerant can flow through the other piping, and no problems will occur even if the expansion valve is closed when performing the diagnosis.

[0007] On the other hand, if there is only one pipe cooling the on-board batteries, closing the expansion valve installed in that pipe will eliminate the passage for the refrigerant to flow, and the compressor and other components will become abnormally high pressure, which may cause damage. In this case, a technology is required to monitor the expansion valve for normality and abnormality without giving a command to close it. When monitoring the expansion valve for normality and abnormality without giving a command to close it, the expansion valve is left open to a certain extent.

[0008] When monitoring the normal / abnormal state of an expansion valve without giving a close command to the expansion valve, it is necessary to distinguish between the amount of temperature change of the refrigerant under normal conditions when it is adjusted to a specified degree of expansion and the amount of temperature change of the refrigerant under abnormal conditions when it is not adjusted to a specified degree of expansion, and it is not easy to determine a threshold value for making this distinction.

[0009] The amount of change in refrigerant temperature from the start of the cooling action by the expansion valve until a predetermined time has elapsed not only varies depending on the degree of expansion by the expansion valve, but also varies depending on environmental factors such as the outside air temperature. In an air conditioner, the refrigerant compressed and heated by a compressor is cooled by outside air, and the refrigerant cooled by the outside air is caused to flow around the vehicle battery. The amount of change in refrigerant temperature varies depending on the outside air temperature. The amount of change in refrigerant temperature also varies depending on the battery temperature, the vehicle speed, the engine output, the amount of solar radiation, the amount of radiation, and the like. Due to these environmental factors, a threshold value that can distinguish between normal and abnormal conditions of the expansion valve in one environment may not be a threshold value that can distinguish between normal and abnormal conditions of the expansion valve in another environment. In this case, a misidentification will occur in the other environment.

[0010] This specification discloses a technique that can maintain high accuracy in determining whether an expansion valve is normal or abnormal despite changes in environmental factors. [Means for solving the problem]

[0011] The cooling device for an on-board battery disclosed in this specification comprises piping that extends around the on-board battery and through which a refrigerant that air-conditions the vehicle compartment passes, an expansion valve that is arranged on the piping upstream of the on-board battery, a refrigerant temperature detector that is arranged downstream of the expansion valve and detects the temperature of the refrigerant passing through, an environmental factor value detector that detects values ​​of environmental factors that affect the refrigerant temperature, a map that stores thresholds corresponding to the environmental factor values, and a monitoring device that monitors the normal state of the expansion valve. The monitoring device executes a process of adjusting the opening of the expansion valve to a predetermined opening, a process of identifying a threshold value stored in the map in correspondence with the environmental factor value detected by the environmental factor value detector, and a process of comparing the amount of change in refrigerant temperature detected by the refrigerant temperature detector between the start of the process of adjusting the expansion valve to the predetermined opening and the elapse of a predetermined time with the threshold value identified in the process.

[0012] According to this device, it is possible to maintain high accuracy in determining whether the expansion valve is normal or abnormal, despite changes in environmental factors.

[0013] Details and further improvements of the technology disclosed in this specification are described in the following "Forms for Carrying Out the Invention". [Brief description of the drawings]

[0014] [Figure 1] The diagram shows the configuration of a vehicle cabin air conditioner that adds an on-board battery cooling function. [Diagram 2] 4 shows a processing procedure performed by a device for monitoring the normality and abnormality of an expansion valve. [Diagram 3] The temperature change pattern of the refrigerant is shown. [Figure 4] 1 illustrates an example of the contents of a map that stores environmental factor values ​​and corresponding threshold values. [Diagram 5] A list of environmental factors is shown below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The features of the following embodiments are listed below. (Feature 1) The entire amount of refrigerant that cools the onboard battery passes through a single expansion valve. When that expansion valve closes, the refrigerant cannot circulate. (Feature 2) If an expansion valve and solenoid valve are placed in the circulation path of the refrigerant that cools the on-board battery, the refrigerant will expand and change temperature even when passing through the solenoid valve. If a solenoid valve is not placed in the circulation path, the refrigerant will only expand and change temperature when passing through the expansion valve. This temperature change is used to distinguish between normal and abnormal conditions. (Feature 3) The amount of temperature change in the coolant upstream (inlet) of the vehicle battery is compared with a threshold value. (Feature 4) The amount of temperature change in the refrigerant downstream (outlet) of the vehicle battery is compared with a threshold value. (Feature 5) The amount of change in the inlet temperature of the refrigerant is compared with an inlet threshold value, and the amount of change in the outlet temperature is compared with an outlet threshold value. (Feature 6) The AND of the two discrimination results obtained by Feature 5 is used. (Feature 7) Use the OR of the two discrimination results obtained by Feature 5. EXAMPLES

[0016] FIG. 1 shows the configuration of an air conditioner in which a function of cooling vehicle-mounted batteries 28a, 28b, and 28c is added to a vehicle interior air conditioner 2. The vehicle cabin air conditioner 2 has a known configuration and is described in detail in Patent Document 1, etc. The refrigerant stored in the accumulator 10 is compressed by the compressor 6, and the refrigerant heated by the compression is guided to a heat exchanger in the vehicle cabin to heat the vehicle cabin, the compressed refrigerant is cooled by outside air in the heat exchanger 4, and the cooled refrigerant is guided to the heat exchanger in the vehicle cabin via a check valve 8 and a vehicle cabin air conditioning expansion valve to cool the vehicle cabin.

[0017] The refrigerant that has passed through the heat exchanger 4 is also guided to the vehicle-mounted battery cooling unit 20 by the piping 22 via the check valve 8. The refrigerant that has passed through the piping 22 expands and is cooled when passing through the expansion valve 24, and the cooled refrigerant passes through the piping 30. The piping 30 passes around the vehicle-mounted batteries 28a, 28b, and 28c, and the cooled refrigerant cools the vehicle-mounted batteries 28a, 28b, and 28c. The vehicle-mounted battery cooling unit 20 is provided with a refrigerant inlet temperature sensor 26 that detects the refrigerant temperature upstream (inlet) of the vehicle-mounted battery, and a refrigerant outlet temperature sensor 32 that detects the refrigerant temperature downstream (outlet) of the vehicle-mounted battery. The refrigerant that has passed through the vehicle-mounted battery cooling unit 20 returns to the accumulator 10.

[0018] The accumulator 10, compressor 6, heat exchanger 4, and check valve 8 are used both for the vehicle cabin air conditioner 2 and the vehicle-mounted battery cooling device, and constitute a circulation path for the refrigerant passing through the vehicle-mounted battery cooling unit 20. A path that bypasses the circulation path and a solenoid valve that opens and closes the bypass path are connected to the circulation path, but no solenoid valve is provided in the circulation path itself. The entire amount of refrigerant passing through the vehicle-mounted battery cooling unit 20 passes through the expansion valve 24, and expands only when passing through the expansion valve 24, and does not expand and be cooled anywhere else.

[0019] The expansion valve 24 changes its opening according to an opening command issued by the monitoring device 34, and adjusts the degree of expansion and cooling of the refrigerant. The expansion valve 24 may operate abnormally, and it is necessary to monitor whether an abnormality occurs in which the valve is fixed in a fully open state even when a specified opening is commanded (in this case, the refrigerant passes through the expansion valve without changing its volume, and the refrigerant is not cooled), in which the valve is fixed in a fully closed state even when a specified opening is commanded (in this case, the refrigerant does not flow, and the refrigerant does not expand or cool), or in which the valve is opened less than the specified opening (in this case, the refrigerant expands excessively and is cooled excessively). The detection values ​​of the refrigerant inlet temperature sensor 26 and the refrigerant outlet temperature sensor 32 are input to the monitoring device 34. In addition, the detection values ​​of the environmental factor value detector 36 described later are input, and a map 38 described later can be referenced.

[0020] 2 shows the processing procedure executed by the monitoring device 34, which is executed every time the vehicle ignition key is turned on and the vehicle is switched to a running state. In step 202, the vehicle battery temperature is compared with a threshold value to determine whether the battery needs to be cooled. If the battery needs to be cooled, normal / abnormal monitoring processing from step 204 onwards is executed.

[0021] In step 204, the opening of the expansion valve 24 is adjusted to a predetermined opening. The predetermined opening here is an opening suitable for the monitoring process, and is called the initial value. The initial value is neither fully closed nor fully open, but is set to an intermediate opening. The expansion valve is not closed during the monitoring process, and the refrigerant circulation circuit is not closed.

[0022] In step 206, the value of the environmental factor, in this embodiment the outside air temperature, is detected. In step 208, a threshold value stored in association with the detected outside air temperature is read from map 38. Figure 4 shows an example of the contents stored in map 38, in which three types of threshold values ​​are stored in association with the outside air temperatures.

[0023] In step 210 of Fig. 2, the amount of temperature change in a predetermined period detected by the refrigerant inlet temperature sensor 26 is compared with a first comparison value. Fig. 3 shows the change pattern of the refrigerant temperature. The refrigerant expands and is cooled as it passes through the expansion valve 24. If the expansion valve 24 is normal, the detection value of the refrigerant inlet temperature sensor 26 decreases according to the central curve J2. In contrast, if the above-mentioned fully open or fully closed abnormality occurs, the refrigerant is not cooled, as described above. The detection value of the refrigerant inlet temperature sensor 26 does not decrease easily, as shown by the upper curve J1. Conversely, if an abnormality occurs in the expansion valve 24 that does not open to the commanded opening degree, the refrigerant will be excessively cooled, as described above. The detection values ​​of the refrigerant inlet temperature sensor 26 and the refrigerant outlet temperature sensor 32 decrease rapidly, as shown by the lower curve J3.

[0024] The first threshold value is selected to determine whether the refrigerant temperature change pattern is a normal event as shown by curve J2, or an abnormal event as shown by curve J1. The first threshold value is selected to determine whether the refrigerant temperature change pattern is normal or abnormal based on the detection value of refrigerant inlet temperature sensor 26. The second and third thresholds are selected to be values ​​that enable discrimination between a normal event as shown by curve J2 and an abnormal event as shown by curve J3. The second threshold is selected to be a value that enables discrimination between normal and abnormal from the detection value of refrigerant inlet temperature sensor 26, and the third threshold is selected to be a value that enables discrimination between normal and abnormal from the detection value of refrigerant outlet temperature sensor 32.

[0025] The temperature change patterns shown by the curves J1, J2, and J3 not only change depending on the normal / abnormal state of the expansion valve 24, but also change depending on the outside air temperature. For example, the temperature of the refrigerant cooled by the outside air in the heat exchanger 4 is affected by the outside air temperature. If a common value is used as the threshold value for determining normal / abnormal state regardless of the outside air temperature, normal / abnormal state may be erroneously determined depending on the outside air temperature.

[0026] In this embodiment, as shown in Fig. 4, a threshold value selected by taking into account the influence of the outside temperature is used, so that erroneous determination due to the outside temperature can be prevented. Regardless of the high or low outside temperature, the normality or abnormality of the expansion valve can be accurately determined.

[0027] If an abnormality shown by curve J1 in Fig. 3 occurs, step 210 in Fig. 2 will be NO. In this case, a temporary abnormality is determined in step 216. If an abnormality shown by curve J3 in Fig. 3 occurs, step 212 in Fig. 2 will be NO. In this case as well, a temporary abnormality is determined in step 216. In the case of a provisional abnormality, it is determined whether the battery temperature is equal to or higher than a predetermined value (step 218), and if the battery temperature is high, it is deemed abnormal (step 220), and an abnormality processing procedure (not shown) is started.

[0028] 2, step 210 is YES, and step 212 is also YES. In this case, it is determined to be normal (step 214), and the monitoring process is terminated.

[0029] In this embodiment, in step 212 of Fig. 2, if both the inlet temperature change amount and the outlet temperature change amount are normal, it is determined to be normal, and if at least one of them is abnormal, it is determined to be abnormal. A determination process is adopted that makes it difficult to overlook abnormalities. In contrast, it is also possible to determine that at least one of the inlet temperature change amount and outlet temperature change amount is normal. This reduces the chance of erroneously determining that something is abnormal.

[0030] The environmental factors to be taken into consideration when selecting the threshold value are not limited to the outside temperature. As shown in Fig. 5, the refrigerant temperature also changes depending on the battery temperature, vehicle speed, engine output, amount of solar radiation, and amount of radiation. Threshold values ​​corresponding to one or a combination of multiple environmental factors in Fig. 5 can be stored in a map.

[0031] In this embodiment, the piping 30 extends around the vehicle battery and is a piping through which a refrigerant for air conditioning the vehicle interior passes, the expansion valve 24 is an expansion valve arranged upstream of the vehicle battery 28 on the piping 30, the refrigerant inlet temperature sensor 26 and the refrigerant outlet temperature sensor 32 are arranged downstream of the expansion valve 24 and are refrigerant temperature detectors for detecting the temperature of the refrigerant, the outside air temperature sensor 36 is an environmental factor value detector for detecting the value of an environmental factor that affects the refrigerant temperature, and the map 38 stores threshold values ​​corresponding to the environmental factor values. The monitoring device 34 executes a process of adjusting the opening of the expansion valve 24 to a predetermined opening, a process of identifying a threshold value stored in the map 38 in association with the environmental factor value detected by the environmental factor value detector 36, and a process of comparing the amount of change in the refrigerant temperature detected by the refrigerant temperature detectors 26, 32 during the period from the start of the process of adjusting the expansion valve 24 to the predetermined opening until a predetermined time has elapsed with the threshold value identified by the process, thereby monitoring the normality or abnormality of the expansion valve 24. The embodiment described above is one example and can be modified in various ways. For example, either the refrigerant inlet temperature sensor 26 or the refrigerant outlet temperature sensor 32 can be omitted. When both the refrigerant inlet temperature sensor 26 and the refrigerant outlet temperature sensor 32 are used, the respective detection values ​​may be compared with the respective threshold values ​​in step 210 of Fig. 2. When two determination results are obtained, the normal / abnormal determination may be performed by ANDing them, or by ORing them. [Explanation of symbols]

[0032] 2: Cabin air conditioner 4: Heat exchanger 6: Compressor 8: Check valve 10: Accumulator 20: Vehicle battery cooling unit 22: Piping 24: Expansion valve 26: Refrigerant inlet temperature sensor 28a, 28b, 28c: Vehicle battery 30:Plumbing 32: Refrigerant outlet temperature sensor 34: Monitoring device 36: Environmental factor value detector (outside air temperature sensor) 38: Map

Claims

1. a pipe extending around the vehicle-mounted battery and through which a refrigerant for conditioning an interior of the vehicle passes; an expansion valve disposed on the piping upstream of the vehicle-mounted battery; a refrigerant temperature detector disposed downstream of the expansion valve and detecting a temperature of the refrigerant; an environmental factor value detector for detecting a value of an environmental factor that affects the temperature of the refrigerant; A map storing threshold values ​​corresponding to the environmental factor values; A monitoring device is provided for monitoring the normality or abnormality of the expansion valve, The monitoring device executes a process of adjusting the opening of the expansion valve to a predetermined opening, a process of identifying a threshold value stored in the map in association with the environmental factor value detected by the environmental factor value detector, and a process of comparing an amount of change in refrigerant temperature detected by the refrigerant temperature detector during a predetermined time period from the start of the process of adjusting the expansion valve to the predetermined opening with the threshold value identified in the process, The environmental factors include vehicle speed.

2. The vehicle battery cooling device according to claim 1 , wherein the environmental factors further include one or more of an outside air temperature, a battery temperature, an engine output, an amount of solar radiation, and an amount of radiation.

3. The refrigerant temperature detectors are disposed upstream and downstream of the vehicle battery, 3. The cooling device for an automotive battery as described in claim 1 or 2, wherein the monitoring device performs a process of comparing the amount of change in refrigerant temperature upstream of the automotive battery with an upstream threshold value, and a process of comparing the amount of change in refrigerant temperature downstream of the automotive battery with a downstream threshold value.

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