JP7632344B2 - Cooling device for vehicle batteries - Google Patents

Description

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

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 the vehicle. In this technology, the refrigerant for the air conditioning in the vehicle cabin is used to cool the on-board battery. Specifically, the refrigerant is made to flow through piping 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 then made to flow around the on-board battery to cool it.

In the technology for cooling an on-board battery with a refrigerant cooled using an expansion valve, a technology is required to monitor whether an abnormality has occurred in the expansion valve. 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 passed 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 the amount of temperature change expected in advance is obtained. By giving a command to close the expansion valve and comparing the detected amount of temperature change of the refrigerant with a threshold value, it is possible to monitor whether an abnormality has occurred in the expansion valve that does not close.

JP 2021-14972 A

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, so the threshold value to be compared with the amount of change in refrigerant temperature can be determined relatively easily. With conventional technology, no special technology is required to determine the threshold value.

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 installed in one of the piping is closed, the refrigerant can still flow through the other piping. No problems arise even if the expansion valve is closed when performing the diagnosis.

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, which could cause the compressor and other components to become abnormally high pressure and be damaged. In this case, technology is required to monitor the expansion valve for normality and abnormalities without giving the expansion valve a command to close. When monitoring the expansion valve for normality and abnormalities without giving the expansion valve a command to close, the expansion valve will be left open to a certain extent.

When monitoring the normal/abnormal state of the expansion valve without issuing a command to close it, it is necessary to distinguish between the amount of change in refrigerant temperature during normal operation when the expansion is adjusted to a specified degree and the amount of change in refrigerant temperature during abnormal operation when the expansion is not adjusted to a specified degree, and it is not easy to determine a threshold value for making this distinction.

The amount of change in refrigerant temperature from the start of the cooling action by the expansion valve until a specified time has passed not only depends on the degree of expansion by the expansion valve, but also 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 circulated around the vehicle battery. The amount of change in refrigerant temperature changes depending on the outside air temperature. The amount of change in refrigerant temperature also changes depending on the battery temperature, vehicle speed, engine output, amount of solar radiation, amount of radiation, etc. 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 the 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.

This specification discloses a technology that can maintain high accuracy in determining whether an expansion valve is normal or abnormal despite changes in environmental factors.

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.

This device can maintain high accuracy in determining whether an expansion valve is normal or abnormal, even when environmental factors change.

Details and further improvements of the technology disclosed in this specification are explained in the "Description of Embodiments" below.

The diagram shows the configuration of a vehicle cabin air conditioner that adds an on-board battery cooling function. 4 shows a processing procedure performed by a device for monitoring the normality and abnormality of an expansion valve. The temperature change pattern of the refrigerant is shown. 1 illustrates an example of the contents of a map that stores environmental factor values and corresponding threshold values. A list of environmental factors is shown below.

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 the 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 vehicle battery, the refrigerant expands and changes temperature even when passing through the solenoid valve. If a solenoid valve is not placed in the circulation path, the refrigerant expands and changes temperature only when passing through the expansion valve. This temperature change is used to distinguish between normal and abnormal conditions.
(Feature 3) The amount of change in temperature of the coolant upstream (at the inlet) of the vehicle battery is compared with a threshold value.
(Feature 4) The amount of change in temperature of the coolant 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 in Feature 5 is used.
(Feature 7) The OR of the two discrimination results obtained in Feature 5 is used.

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.

The refrigerant that has passed through the heat exchanger 4 is also guided to the vehicle-mounted battery cooling unit 20 by the pipe 22 via the check valve 8. The refrigerant that has passed through the pipe 22 expands and is cooled when passing through the expansion valve 24, and the cooled refrigerant passes through the pipe 30. The pipe 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.

The accumulator 10, compressor 6, heat exchanger 4, and check valve 8 are used for both the vehicle cabin air conditioner 2 and the vehicle battery cooling device, and form a circulation path for the refrigerant passing through the vehicle 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 disposed in the circulation path itself. The entire amount of refrigerant passing through the vehicle 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.

The expansion valve 24 changes its opening according to the opening command issued by the monitoring device 34 to adjust 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 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.

Figure 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 requires cooling. If the battery requires cooling, normal/abnormal monitoring processing from step 204 onwards is executed.

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.

In step 206, the value of the environmental factor, in this embodiment the outside air temperature, is detected. In step 208, the 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 value are stored in association with the outside air temperature.

2, the amount of temperature change in a predetermined period detected by the coolant inlet temperature sensor 26 is compared with a first comparison value. FIG 3 shows a change pattern of the coolant 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.

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 the 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 the 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 the refrigerant outlet temperature sensor 32.

The temperature change patterns shown by curves J1, J2, and J3 not only change depending on whether the expansion valve 24 is normal or abnormal, 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 whether the temperature is normal or abnormal, regardless of the outside air temperature, the temperature may be erroneously determined to be normal or abnormal depending on the outside air temperature.

In this embodiment, as shown in FIG. 4, a threshold value is used that is selected taking into account the influence of the outside temperature, so misjudgment due to the outside temperature can be prevented. Regardless of the high or low outside temperature, it is possible to accurately judge whether the expansion valve is normal or abnormal.

If an abnormality shown by curve J1 in Fig. 3 occurs, step 210 in Fig. 2 becomes 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 becomes NO. In this case, a temporary abnormality is also 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 to be abnormal (step 220), and an abnormality processing procedure (not shown) is started.

If it is a normal event as shown by curve J2 in FIG. 2, step 210 will be YES and step 212 will also be YES. In this case, it is considered normal (step 214) and the monitoring process ends.

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, if at least one of the inlet temperature change amount and outlet temperature change amount is normal, it may be determined to be normal. This reduces the chance of erroneously determining that something is abnormal.

The environmental factors taken into account when selecting the threshold value are not limited to the outside temperature. As shown in Figure 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 more combinations of the environmental factors in Figure 5 can be stored in a map.

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 degree of the expansion valve 24 to a predetermined opening degree, a process of specifying a threshold value stored in the map 38 in correspondence 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 degree until a predetermined time has elapsed with the threshold value specified in the process, thereby monitoring the normality or abnormality of the expansion valve 24.
The embodiment described above is merely an 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 discrimination results are obtained, the normal/abnormal discrimination may be performed by ANDing them, or by ORing them.

2: Vehicle interior air conditioning device 4: Heat exchanger 6: Compressor 8: Check valve 10: Accumulator 20: Vehicle-mounted battery cooling unit 22: Pipe 24: Expansion valve 26: Refrigerant inlet temperature sensor 28a, 28b, 28c: Vehicle-mounted battery 30: Pipe 32: Refrigerant outlet temperature sensor 34: Monitoring device
36: Environmental factor value detector (outside air temperature sensor)
38: Map

Claims (3)

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 . 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. 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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