Vehicle air conditioner

Abstract

To provide a vehicular cooler which can be used for a long time.SOLUTION: A vehicle 10 has an internal combustion engine 11, an engine drive type first compressor 14, a capacitor 15, and a motor driven capacitor fan 16. A vehicular cooler includes a motor driven second compressor 31, a second storage battery 32, a power conversion part 33 for boosting and outputting a DC voltage, and a cooler control device 35. The cooler control device 35 executes basic operation processing and rotation reduction processing. The basic operation processing controls the operation of the capacitor fan 16 and controls the operation of the second compressor 31, in a mode of setting the temperature in a cabin at a set temperature set by a user. The rotation reduction processing controls the operation of the second compressor 31 so that when power consumption of the second compressor 31 becomes an upper limit value or more, rotation speed of the second compressor 31 becomes low compared to a case where the power consumption is not the upper limit value or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle cooler.

Background Art

[0002] Vehicles such as automobiles have a cooling device (so-called cooler). Usually, a vehicle powered by an internal combustion engine has, as components of the vehicle cooler, an engine-driven compressor, a condenser which is a heat exchanger for cooling the refrigerant, an electric condenser fan for blowing air to the condenser, etc. (see Patent Document 1).

[0003] Patent Document 1 discloses a configuration for enabling the use of a vehicle cooler even when the internal combustion engine is stopped. Such a configuration includes an electric compressor, a storage battery used as a power source when the internal combustion engine is stopped, a power conversion unit that boosts and outputs the DC voltage of the storage battery, and a control unit that executes various operation controls.

[0004] In the vehicle cooler described in Patent Document 1, when the internal combustion engine is stopped, the operations of the electric compressor and the condenser fan are controlled by the control unit based on the DC power supplied from the storage battery and the power conversion unit. Thereby, the vehicle cooler can be used.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Vehicle air conditioners that can be used even when the internal combustion engine is stopped have a variety of potential uses, such as when sleeping in the vehicle or when eating lunch inside the vehicle while out and about. Depending on the usage scenario, it may be necessary to limit the rotation speed of the condenser fan to reduce noise to the surrounding area.

[0007] In this case, if the condenser fan's airflow capacity is insufficient, the refrigerant inside the condenser will remain at a high temperature and pressure. This may lead to an increased load (power consumption) on the electric compressor. In this case, not only will the usable time of the vehicle's air conditioner be shortened, but in the worst case, the power consumption of the vehicle's air conditioner may exceed the capacity limit of the power conversion unit, causing the power conversion unit to shut down and the vehicle's air conditioner to stop working. [Means for solving the problem]

[0008] The following describes various embodiments of the apparatus for solving the above problems. [Aspect 1] A vehicle air conditioner applicable to a vehicle having an internal combustion engine as a vehicle power source, an engine-driven first compressor for pressurizing a refrigerant, a condenser used for cooling the refrigerant, and an electric condenser fan for blowing air to the condenser, wherein when the internal combustion engine is stopped, the vehicle air conditioner comprises an electric second compressor for pressurizing the refrigerant, a storage battery that serves as a power source for the condenser fan and the second compressor, a power conversion unit that boosts and outputs the DC voltage of the storage battery, and a control unit that controls the operation of the condenser fan and the second compressor, wherein the control unit performs basic operation processing and rotation reduction processing, the basic operation processing is a process that controls the operation of the condenser fan and the operation of the second compressor in such a manner that the temperature inside the vehicle reaches a set temperature set by the user, and the rotation reduction processing is a process that controls the operation of the second compressor so that the rotation speed of the second compressor is lower than when it is not when the power consumption of the second compressor exceeds an upper limit.

[0009] In the above configuration, when operating the vehicle's air conditioner while the internal combustion engine is stopped, the condenser fan and the second compressor operate based on power supplied from the battery and the power conversion unit. With this configuration, in this case, the second compressor can be operated within a range where its power consumption does not exceed the upper limit. This makes it possible to operate the second compressor so that the power consumed by the condenser fan and the second compressor, in other words, the output (power) of the power conversion unit, does not exceed the capacity limit of the power conversion unit. Therefore, it is possible to avoid a situation where the power conversion unit stops and the vehicle's air conditioner stops due to exceeding the capacity limit, even though there is still power remaining in the battery. Consequently, the vehicle's air conditioner can be used for extended periods.

[0010] [Aspect 2] The vehicle cooler according to [Aspect 1], comprising a temperature detection unit for detecting the actual temperature which is the temperature inside the vehicle, and a temperature setting unit for setting the set temperature, wherein the basic operation process includes a process for calculating a first control target value for the rotation speed of the condenser fan and a second control target value for the rotation speed of the second compressor based on the difference between the actual temperature and the set temperature, and a process for controlling the operation of the condenser fan based on the first control target value and controlling the operation of the second compressor based on the second control target value, and the rotation reduction process includes a process for changing the second control target value to a value corresponding to a lower speed compared to when the power consumption of the second compressor exceeds the upper limit value.

[0011] According to the above configuration, when the power consumption of the second compressor exceeds the upper limit, the rotational speed of the second compressor can be reduced compared to when it is not. This reduces the power consumption of the second compressor.

[0012] [Aspect 3] The vehicle cooler according to [Aspect 1] or [Aspect 2], wherein the rotational speed reduction process includes a reduction process that gradually lowers the rotational speed of the second compressor during the period from when the power consumption of the second compressor exceeds the upper limit to when it falls below the lower limit, and an increase process that gradually increases the rotational speed of the second compressor during the period from when the power consumption of the second compressor falls below the lower limit to when it exceeds the upper limit.

[0013] In the above configuration, when the rotational speed of the second compressor is changed, there is a delay between the timing of the change in rotational speed and the timing of changes in the refrigerant temperature and the temperature inside the vehicle. Therefore, simply changing the rotational speed of the second compressor may not allow for proper control of the power consumption of the second compressor due to this delay in timing.

[0014] In this regard, the above configuration allows the power consumption of the second compressor to be gradually changed in a manner that alternately increases and decreases between an upper limit and a lower limit. This suppresses the occurrence of the so-called overshoot phenomenon, where the power consumption of the second compressor significantly exceeds the upper limit. Therefore, it is possible to prevent the power consumption of the electrical equipment constituting the vehicle air conditioner (including the second compressor) from exceeding the capacity limit of the power conversion unit. Consequently, it is possible to prevent the power conversion unit from shutting down due to exceeding the capacity limit, thus enabling the vehicle air conditioner to be used for extended periods. Moreover, it is possible to suppress the occurrence of the so-called undershoot phenomenon, where the power consumption of the second compressor significantly falls below the lower limit. This prevents an unnecessary decrease in the refrigerant pumping function of the second compressor, thus preventing a decrease in the cooling function of the vehicle air conditioner.

[0015] [Aspect 4] A vehicle cooler according to any one of [Aspect 1] to [Aspect 3], comprising a day / night detection unit that detects whether it is day or night, wherein the control unit performs an upper limit setting process, and the upper limit setting process includes a process of setting the upper limit of the rotation speed of the condenser fan to a value corresponding to a lower speed when it is detected as night than when it is detected as day by the day / night detection unit, and a process of controlling the operation of the condenser fan in a manner that limits the rotation speed of the condenser fan by the upper limit.

[0016] During the day, the outside temperature tends to be higher than at night, which increases the load (power consumption) on the second compressor. On the other hand, noise is less of a problem during the day compared to night, making it possible to increase the rotation speed of the condenser fan. And when the rotation speed of the condenser fan is increased, it becomes less likely that the cooling capacity of the refrigerant by the condenser fan will be insufficient, and therefore less likely that the power consumption of the second compressor will increase due to insufficient cooling capacity.

[0017] With the above configuration, the condenser fan can be set to a relatively high rotation speed during the day. Therefore, even though the load on the second compressor tends to increase due to high ambient temperatures, the high cooling effect of the condenser fan can be obtained, thus suppressing the increase in power consumption of the second compressor caused by insufficient cooling capacity. Moreover, at night, the rotation speed of the condenser fan can be reduced. This makes it possible to use the vehicle's air conditioner for extended periods while keeping noise levels down. [Effects of the Invention]

[0018] According to the present invention, it becomes possible to use a vehicle air conditioner for extended periods. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic diagram of a vehicle air conditioner according to one embodiment. [Figure 2]It is a flowchart showing the execution procedure of the cooler operation process. [Figure 3] (a) to (c) are timing charts showing an example of the execution mode of the cooler operation process when it is detected as night. [Figure 4] (a) to (c) are timing charts showing an example of the execution mode of the cooler operation process when it is detected as day. [Figure 5] It is a flowchart showing the execution procedure of the first setting process. [Figure 6] It is a flowchart showing the execution procedure of the second setting process.

Mode for Carrying Out the Invention

[0020] Hereinafter, a vehicle cooler according to an embodiment will be described with reference to FIGS. 1 to 4. <Vehicle> As shown in FIG. 1, the vehicle 10 includes an internal combustion engine 11, a generator 12, and a first storage battery 13. The internal combustion engine 11 functions as a vehicle power source. The generator 12 is of an engine-driven type driven by the output shaft of the internal combustion engine 11. The first storage battery 13 is charged by the generated power of the generator 12 and functions as a power source for the vehicle 10.

[0021] <Vehicle Cooler> The vehicle 10 has, as components of the vehicle cooler, a first compressor 14, a condenser 15, a condenser fan 16, and a cooling unit 17.

[0022] The first compressor 14 is for pumping the refrigerant RE. As the first compressor 14, an engine-driven type driven by the output shaft of the internal combustion engine 11 is adopted.

[0023] The condenser 15 is a heat exchanger for cooling the refrigerant RE. In the present embodiment, the refrigerant RE pumped by the first compressor 14 flows into the condenser 15.

[0024] The condenser fan 16 is for blowing air to the condenser 15. The air blown from the condenser fan 16 cools the refrigerant RE passing through the condenser 15. An electrically powered condenser fan 16 is used.

[0025] The cooling unit 17 is for supplying cooled air to the vehicle interior. The cooling unit 17 includes an expansion valve 171 for reducing pressure and expanding the refrigerant RE, an evaporator 172 which is a heat exchanger, and a blower fan 173 for supplying air to the evaporator 172. The refrigerant RE that has passed through the condenser 15 flows into the cooling unit 17.

[0026] The refrigerant RE that flows into the cooling unit 17 first passes through the expansion valve 171. At this time, the refrigerant RE is depressurized and expanded, causing its temperature to decrease. After passing through the expansion valve 171, the refrigerant RE flows into the evaporator 172 in a low-temperature state. In the cooling unit 17, air is blown to the evaporator 172 by the blower fan 173. As a result, cool air is generated through heat exchange between the air blown to the evaporator 172 and the refrigerant RE passing through the inside of the evaporator 172, and this cool air is sent into the vehicle cabin. The refrigerant RE that has passed through the cooling unit 17 is then pumped under pressure by the first compressor 14. In this embodiment of the vehicle cooler, when the internal combustion engine 11 is in operation, the vehicle cabin is cooled in this manner.

[0027] Vehicle 10 is equipped with various sensors. These sensors include a temperature sensor 21, which acts as a temperature detection unit to detect the temperature inside the vehicle (hereinafter referred to as the actual temperature TR), and an illuminance sensor 22, which detects the illuminance outside the vehicle. Other sensors include a setting switch 23, which acts as a temperature setting unit to set a target temperature inside the vehicle (hereinafter referred to as the set temperature TT), and an operation switch 24, which switches between operating and stopping the internal combustion engine 11. The setting switch 23 and the operation switch 24 are operation switches operated by the occupants.

[0028] The vehicle 10 is equipped with a vehicle control device 18 consisting of a microcomputer and the like. The vehicle control device 18 receives output signals from various sensors and output signals from the condenser fan 16 (specifically, signals indicating the actual rotational speed of the condenser fan 16 [hereinafter referred to as the actual fan rotational speed RNF]). Based on these signals, the vehicle control device 18 performs various calculations and, based on the results of these calculations, executes various controls related to the operation of the vehicle 10, such as operation control of the internal combustion engine 11 and operation control of the generator 12.

[0029] Furthermore, the vehicle control device 18 performs various controls related to the operation of the vehicle cooler, such as controlling the operation of the first compressor 14, the condenser fan 16, and the cooling unit 17 (specifically, the blower fan 173), when the internal combustion engine 11 is in operation. Specifically, the vehicle control device 18 performs control of the operation of the first compressor 14, the condenser fan 16, and the cooling unit 17 so as to match the actual temperature TR with the set temperature TT.

[0030] In this embodiment, when the internal combustion engine 11 is operated by turning on the operation switch 24, the circulation path of the refrigerant RE in the vehicle cooler is composed of an engine-driven first compressor 14, a condenser 15, and a cooling unit 17.

[0031] The vehicle air conditioner of this embodiment can be used even when the operation of the internal combustion engine 11 is stopped by turning off the operation switch 24, that is, when the engine-driven first compressor 14 is not operating. To achieve this configuration, the vehicle 10 is provided with a second compressor 31, a second battery 32, a power conversion unit 33, an air conditioner switch 34, and an air conditioner control device 35 as a control unit. In this embodiment, by assembling the second compressor 31, the second battery 32, the power conversion unit 33, the air conditioner switch 34, and the air conditioner control device 35 into an existing vehicle, it is possible to realize a vehicle air conditioner that can be used even when the internal combustion engine 11 is stopped.

[0032] The second compressor 31 is for pumping the refrigerant RE. An electric type is used for the second compressor 31. In this embodiment, when the internal combustion engine 11 is stopped, the second compressor 31 is activated to pump the refrigerant RE.

[0033] The second battery 32 functions as a power source for the vehicle's air conditioner when the internal combustion engine 11 is stopped. The second battery 32 is charged by the electricity generated by the generator 12 when the internal combustion engine 11 is running.

[0034] The power conversion unit 33 is a boost converter that increases the input DC voltage and outputs it. More specifically, the power conversion unit 33 increases the DC voltage input from the second battery 32 and outputs it to the electrical equipment that constitutes the vehicle air conditioner. This electrical equipment includes the second compressor 31, condenser fan 16, cooling unit 17, various sensors, and air conditioner control device 35.

[0035] The air conditioner switch 34 is a switch used to switch the vehicle's air conditioner on and off. The air conditioner switch 34 is an operating switch that is operated by the user. The air conditioner control device 35 is configured with a microcomputer and the like. The air conditioner control device 35 receives output signals from various sensors and the output signal from the condenser fan 16. The air conditioner control device 35 also receives the output signal from the second compressor 31 (specifically, the signal indicating the actual rotational speed of the second compressor 31 [hereinafter referred to as the actual compressor rotational speed RNC] and the power consumption WC) and the output signal from the air conditioner switch 34. Based on these signals, the air conditioner control device 35 performs various calculations and, based on the calculation results, executes various controls related to the operation of the vehicle air conditioner, such as operation control of the second compressor 31, operation control of the condenser fan 16, and operation control of the cooling unit 17.

[0036] In this embodiment, when the internal combustion engine 11 is stopped by turning off the operation switch 24, the circulation path of the refrigerant RE in the vehicle cooler is composed of an electrically operated second compressor 31, a condenser 15, and a cooling unit 17. At this time, power is supplied to the second compressor 31 and the condenser fan 16 from the second storage battery 32 and the power conversion unit 33.

[0037] Then, with the internal combustion engine 11 stopped by turning the operation switch 24 to the OFF position, the vehicle air conditioner of this embodiment will start operating when the air conditioner switch 34 is turned to the ON position. Specifically, the air conditioner control device 35 performs basic operation processing, upper limit setting processing, and rotation reduction processing.

[0038] <Basic Operation Procedures> The basic operation process involves controlling the operation of the condenser fan 16 and the second compressor 31 in such a manner that the temperature inside the vehicle (actual temperature TR) is set to a set temperature TT set by the user.

[0039] In the basic operation process, first, the difference ΔT (=TT-TR) between the actual temperature TR detected by the temperature sensor 21 and the set temperature TT set by the setting switch 23 is calculated. Then, based on this difference ΔT, a first control target value (hereinafter referred to as the target fan rotation speed TNF) for the rotation speed of the condenser fan 16 is calculated. In this embodiment, the relationship between the above difference ΔT and the rotation speed of the condenser fan 16 appropriate for matching the actual temperature TR with the set temperature TT has been determined in advance from the results of various experiments and simulations conducted by the inventors. This relationship is stored in the cooler control device 35 as a calculation map A for calculating the target fan rotation speed TNF based on the above difference ΔT. Specifically, the calculation map A defines a relationship in which a higher speed is calculated as the target fan rotation speed TNF when the above difference ΔT is large.

[0040] In the basic operation process, the operation of the condenser fan 16 is feedback-controlled so that the target fan rotation speed TNF, which is the control target value, matches the actual fan rotation speed RNF, which is the actual rotation speed.

[0041] In addition, during basic operation, a second control target value (hereinafter referred to as the target compressor rotation speed TNC) for the rotation speed of the second compressor 31 is calculated based on the difference ΔT. In this embodiment, the relationship between the difference ΔT and the rotation speed of the second compressor 31 appropriate for matching the actual temperature TR with the set temperature TT has been determined in advance from the results of various experiments and simulations conducted by the inventors. This relationship is stored in the cooler control device 35 as a calculation map B for calculating the target compressor rotation speed TNC based on the difference ΔT. Specifically, the calculation map B defines a relationship in which a higher speed is calculated as the target compressor rotation speed TNC when the difference ΔT is large.

[0042] In the basic operation process, the operation of the second compressor 31 is feedback-controlled so that the target compressor rotation speed TNC, which is the control target value, matches the actual compressor rotation speed RNC, which is the actual rotation speed.

[0043] <Upper limit setting process> The upper limit setting process is executed as follows: In the upper limit setting process, first, an upper limit value LNF for the rotation speed of the condenser fan 16 is set based on the output signal of the illuminance sensor 22. In this embodiment, if the illuminance outside the vehicle detected by the illuminance sensor 22 is above a predetermined value, it is detected as "daytime" because it is relatively bright outside the vehicle. On the other hand, if the illuminance outside the vehicle detected by the illuminance sensor 22 is below a predetermined value, it is detected as "nighttime" because it is dark outside the vehicle. In this embodiment, the illuminance sensor 22 corresponds to a day / night detection unit that detects whether it is daytime or nighttime.

[0044] In the upper limit setting process, the upper limit value LNF for the rotational speed of the condenser fan 16 is set so that it corresponds to a lower speed when it is detected as "night" than when it is detected as "day". Specifically, when it is detected as "day", the upper limit value LNF is set to a value L1 that corresponds to a relatively high speed (in this embodiment, 70% of the maximum rotational speed of the condenser fan 16). When it is detected as "night", the upper limit value LNF is set to a value L2 that corresponds to a relatively low speed (in this embodiment, 30% of the maximum rotational speed of the condenser fan 16).

[0045] In the upper limit setting process, the operation of the condenser fan 16 is controlled in such a manner that the rotation speed of the condenser fan 16 is limited by the upper limit value LNF. Specifically, if the target fan rotation speed TNF calculated based on the difference ΔT is greater than the upper limit value LNF, the upper limit value LNF is set as the target fan rotation speed TNF. On the other hand, if the target fan rotation speed TNF calculated based on the difference ΔT is less than or equal to the upper limit value LNF, the target fan rotation speed TNF is not changed to the upper limit value LNF. Through this upper limit setting process, the rotation speed of the condenser fan 16 can be limited to a relatively high speed during the day when noise is less of a problem, while the rotation speed of the condenser fan 16 can be limited to a relatively low speed at night when noise is more of a problem.

[0046] <Rotation speed reduction process> The rotation reduction process is performed as follows: In the rotation reduction process, when the power consumption WC of the second compressor 31 exceeds the upper limit value LU, the operation of the second compressor 31 is controlled so that the rotation speed of the second compressor 31 is lower than when it is not.

[0047] In this embodiment, the upper limit LU and lower limit LB for the power consumption WC of the second compressor 31 are predetermined and stored in the cooler control device 35. The upper limit LU and lower limit LB are set to values ​​that prevent the power consumption of the electrical equipment constituting the vehicle cooler (including the second compressor 31) from exceeding the capacity limit of the power conversion unit 33. In this embodiment, the upper limit LU is set to a value equivalent to 90% of the rated power of the power conversion unit 33 (for example, 900 watts). The lower limit LB is set to a value equivalent to 70% of the rated power of the power conversion unit 33 (for example, 700 watts).

[0048] In the rotational speed reduction process, specifically, during the period T1 from when the power consumption WC of the second compressor 31 exceeds the upper limit LU until it reaches the lower limit LB, a reduction process is performed to gradually lower the rotational speed of the second compressor 31. In this embodiment, a reduction correction amount KC is set to change the target compressor rotational speed TNC to a value corresponding to a lower speed. During the reduction process, this reduction correction amount KC is gradually increased over time.

[0049] In the rotational speed reduction process, once the power consumption WC of the second compressor 31 falls below the lower limit LB through the execution of the reduction process, an increase process is then executed to gradually increase the rotational speed of the second compressor 31. In the increase process, the deceleration correction amount KC is gradually reduced over time. This increase process is executed during the period T2 from when the power consumption WC of the second compressor 31 falls below the lower limit LB until it rises above the upper limit LU.

[0050] <Air conditioner operation process> The following describes in detail the process related to the operation control of the vehicle's air conditioner when the internal combustion engine 11 is stopped, including the basic operation process, the upper limit setting process, and the rotation reduction process.

[0051] Figure 2 shows the execution procedure for the cooler operation process described above. The series of processes shown in the flowchart in the figure are executed by the cooler control device 35 as processes at predetermined intervals. This cooler operation process is executed under the condition that the cooler switch 34 is turned ON while the operation switch 24 is turned OFF.

[0052] As shown in Figure 2, this process first sets an upper limit LNF for the rotational speed of the condenser fan 16 (specifically, the target fan rotational speed TNF) (steps S1 to S3). Specifically, if "daytime" is detected (step S1: YES), a value L1 corresponding to a relatively high speed is set as the upper limit LNF (step S2). On the other hand, if "nighttime" is detected (step S1: NO), a value L2 corresponding to a relatively low speed is set as the upper limit LNF (step S3).

[0053] Subsequently, the target fan rotation speed TNF is calculated from calculation map A based on the difference ΔT between the actual temperature TR and the set temperature TT (step S4). Also, the target compressor rotation speed TNC is calculated from calculation map B based on the difference ΔT between the actual temperature TR and the set temperature TT (step S4).

[0054] Then, the operation of the condenser fan 16 is controlled based on the target fan rotation speed TNF and the upper limit LNF (step S5). Specifically, the operation of the condenser fan 16 is feedback controlled to match the target fan rotation speed TNF, which is limited by the upper limit LNF, with the actual fan rotation speed RNF.

[0055] Subsequently, it is determined whether there is a history of the power consumption WC of the second compressor 31 exceeding the upper limit value LU during the current operating period (step S6). The operating period refers to the period from when the vehicle air conditioner is started to when the internal combustion engine 11 is stopped until it is stopped.

[0056] If there is no history as described above (step S6: NO), the deceleration correction amount KC is set to "0" (step S7). In this case, since the power consumption WC of the second compressor 31 is not greater than or equal to the upper limit value LU, the target compressor rotation speed TNC is not changed.

[0057] On the other hand, if the above history exists (step S6: YES), it is determined whether the period T1 is the time from when the power consumption WC of the second compressor 31 exceeds the upper limit value LU until it falls below the lower limit value LB (step S8).

[0058] Then, if it is period T1 (step S8: YES), the value obtained by adding a predetermined amount K to the deceleration correction amount KC (= KC + K) is set as the new deceleration correction amount KC (step S9). On the other hand, if it is not period T1 (step S8: NO), that is, if it is period T2, from when the power consumption WC of the second compressor 31 falls below the lower limit LB until it rises above the upper limit LU, the deceleration correction amount KC is set as follows (step S10). That is, the value obtained by subtracting a predetermined amount K from the deceleration correction amount KC (= KC - K) is set as the new deceleration correction amount KC.

[0059] After the deceleration correction amount KC is set in this manner, the target compressor rotational speed TNC is changed to a value corresponding to a lower speed by this deceleration correction amount KC (step S11). Specifically, the value obtained by subtracting the deceleration correction amount KC from the target compressor rotational speed TNC (=TNC-KC) is set as the new target compressor rotational speed TNC.

[0060] Subsequently, the operation of the second compressor 31 is controlled based on the target compressor rotational speed TNC (step S12). More specifically, the operation of the second compressor 31 is feedback controlled to match the target compressor rotational speed TNC with the actual compressor rotational speed RNC.

[0061] <Effects and Effects> The following explains the effects and benefits of performing the cooler operation process. Here, we will first explain the effects and behaviors when "night" is detected, referring to Figure 3.

[0062] In the example shown in Figure 3, the difference ΔT between the actual temperature TR and the set temperature TT gradually increases over time from time t11 to t13. Furthermore, throughout the entire period (times t11 to t18), the rotational speed of the condenser fan 16 (specifically, the target fan rotational speed TNF) is always limited by the upper limit LNF (specifically, the value L2). As a result, the actual fan rotational speed RNF (Figure 3(a)) remains approximately constant at the upper limit LNF.

[0063] Furthermore, between times t11 and t13, the rotational speed of the second compressor 31 (specifically, the actual compressor rotational speed RNC shown in Figure 3(b)) gradually increases as the above-mentioned difference ΔT increases.

[0064] Furthermore, between times t11 and t13, the power consumption WC of the second compressor 31 (Figure 3(c)) increases as the above difference ΔT increases. In this example, before time t12, the cooling capacity of the refrigerant RE by the condenser fan 16 is sufficient. Therefore, at this time, the power consumption WC of the second compressor 31 gradually increases in line with the increase in the actual compressor rotation speed RNC (Figure 3(b)).

[0065] In this example, at time t12, the cooling capacity of the refrigerant RE by the airflow from the condenser fan 16 becomes insufficient. As a result, the power consumption WC of the second compressor 31 increases rapidly after time t12. When this happens, the rapid increase in power consumption WC of the second compressor 31 may cause the power consumption of the electrical equipment constituting the vehicle air conditioner (including the second compressor 31) to exceed the capacity limit of the power conversion unit 33. In this case, the vehicle air conditioner will shut down.

[0066] In this example, at time t13, the power consumption WC of the second compressor 31 reaches its upper limit value LU. As a result, from time t13 onward, the operation of the second compressor 31 is controlled in a manner that lowers the actual compressor rotation speed RNC through a rotation reduction process.

[0067] According to this embodiment, the second compressor 31 can be operated within a range where its power consumption WC does not exceed the upper limit LU after time t13. Therefore, the second compressor 31 can be operated while suppressing its power consumption WC to such an extent that the power consumption of the electrical equipment constituting the vehicle air conditioner does not exceed the capacity limit of the power conversion unit 33. Moreover, it is possible to avoid a situation where the power conversion unit 33 stops and the vehicle air conditioner stops due to exceeding the capacity limit of the power conversion unit 33, even though there is still power remaining in the second battery 32. In this way, this embodiment makes it possible to use the vehicle air conditioner for a long period of time.

[0068] In this case, when the target compressor rotation speed TNC is changed, there is a delay between the timing of the change and the timing of changes in the temperature of the refrigerant RE and the temperature inside the vehicle. Therefore, simply changing the target compressor rotation speed TNC may not allow for proper control of the power consumption WC of the second compressor 31 due to this delay in the timing of changes.

[0069] In this embodiment, during the rotational speed reduction process from time t13 onward, the reduction process is executed during the period T1 (times t13-t14, t15-t16, t17-t18) from when the power consumption WC of the second compressor 31 exceeds the upper limit LU until it reaches the lower limit LB. During this reduction process, the operation of the second compressor 31 is controlled so that the actual compressor rotational speed RNC (Figure 3(b)) gradually decreases. Therefore, during period T1, the power consumption WC of the second compressor 31 (Figure 3(c)) gradually decreases.

[0070] On the other hand, during the rotational speed reduction process from time t13 onward, a speed increase process is executed during the period T2 (times t14-t15, t16-t17) from when the power consumption WC of the second compressor 31 falls below the lower limit LB until it rises above the upper limit LU. In this speed increase process, the operation of the second compressor 31 is controlled so that the actual compressor rotational speed RNC gradually increases. Therefore, during period T2, the power consumption WC of the second compressor 31 gradually increases.

[0071] According to this embodiment, during the rotational speed reduction process after time t13, the power consumption WC of the second compressor 31 can be gradually changed in a manner that alternately increases and decreases between an upper limit LU and a lower limit LB. This suppresses the occurrence of the phenomenon where the power consumption WC of the second compressor 31 exceeds the upper limit LU, known as the overshoot phenomenon. Therefore, it is possible to prevent the power consumption of the electrical equipment, including the second compressor 31, from exceeding the capacity limit of the power conversion unit 33. Consequently, it is possible to prevent the power conversion unit 33 from stopping due to exceeding the capacity limit, thus enabling the vehicle air conditioner to be used for a long period of time. Furthermore, it is possible to suppress the occurrence of the phenomenon where the power consumption WC of the second compressor 31 falls below the lower limit LB, known as the undershoot phenomenon. This prevents the refrigerant pumping function of the second compressor 31 from unnecessarily decreasing, thus preventing a decrease in the cooling function of the vehicle air conditioner.

[0072] Next, we will explain the effects of executing the air conditioner activation process when "daytime" is detected, referring to Figure 4. In the example shown in Figure 4, the difference ΔT between the actual temperature TR and the set temperature TT gradually increases over time from time t21 to t24.

[0073] Furthermore, between times t21 and t22, the rotational speed of the condenser fan 16 (specifically, the actual fan rotational speed RNF shown in Figure 4(a)) gradually increases as the difference ΔT increases. In this example, at time t22, the rotational speed of the condenser fan 16 (specifically, the target fan rotational speed TNF) is limited by the upper limit value LNF (specifically, value L1). Therefore, from time t22 onward, the actual fan rotational speed RNF remains constant at the upper limit value LNF.

[0074] Furthermore, between times t21 and t24, the rotational speed of the second compressor 31 (specifically, the actual compressor rotational speed RNC shown in Figure 4(b)) gradually increases as the above-mentioned difference ΔT increases.

[0075] Furthermore, between times t21 and t24, the power consumption WC of the second compressor 31 (Figure 4(c)) increases as the above difference ΔT increases. In this example, before time t23, the cooling capacity of the refrigerant RE by the condenser fan 16 is sufficient. Therefore, at this time, the power consumption WC of the second compressor 31 gradually increases in line with the increase in the actual compressor rotation speed RNC.

[0076] In this example, at time t23, the cooling capacity of the refrigerant RE by the airflow from the condenser fan 16 becomes insufficient. As a result, the power consumption WC of the second compressor 31 increases rapidly from time t23 onward. Then, in this example, at time t24, the power consumption WC of the second compressor 31 reaches its upper limit value LU. Consequently, from time t24 onward, the operation of the second compressor 31 is controlled in a manner that lowers the actual compressor rotation speed RNC through a rotation speed reduction process.

[0077] According to this embodiment, the second compressor 31 can be operated from time t24 onward within a range where the power consumption WC of the second compressor 31 does not exceed the upper limit LU. Therefore, the second compressor 31 can be operated while suppressing its power consumption WC to such an extent that the power consumption of the electrical equipment constituting the vehicle air conditioner does not exceed the capacity limit of the power conversion unit 33. Moreover, it is possible to avoid a situation where the power conversion unit 33 stops and the vehicle air conditioner stops due to exceeding the capacity limit of the power conversion unit 33, even though there is still power remaining in the second battery 32. Consequently, the vehicle air conditioner can be used for extended periods.

[0078] In this embodiment, during the rotational speed reduction process from time t24 onward, the reduction process is executed during the period T1 (times t24-t25, t26-t27, t28-t29). During this reduction process, the actual compressor rotational speed RNC (Figure 4(b)) gradually decreases, so the power consumption WC (Figure 4(c)) of the second compressor 31 gradually decreases.

[0079] On the other hand, during the rotational speed reduction process from time t24 onward, an increase process is performed during the period T2 (times t25-t26, t27-t28). During this increase process, the actual compressor rotational speed RNC gradually increases, so the power consumption WC of the second compressor 31 gradually increases.

[0080] According to this embodiment, in the rotation reduction process after time t24, the power consumption WC of the second compressor 31 can be gradually changed in a manner that alternately increases and decreases between an upper limit LU and a lower limit LB. This prevents the power conversion unit 33 from stopping due to the power consumption of the electrical equipment, including the second compressor 31, exceeding the capacity limit of the power conversion unit 33, thereby enabling the vehicle air conditioner to be used for a longer period of time. Moreover, since the refrigerant pumping function of the second compressor 31 is prevented from being unnecessarily reduced, the cooling function of the vehicle air conditioner can be prevented from deteriorating.

[0081] <Effects and Effects> The effects and benefits of the vehicle cooler of this embodiment will be explained. (1) The cooler control device 35 performs basic operation processing and rotation reduction processing. In basic operation processing, it controls the operation of the condenser fan 16 and the operation of the second compressor 31 in such a manner that the actual temperature TR becomes the set temperature TT. In rotation reduction processing, when the power consumption WC of the second compressor 31 exceeds the upper limit value LU, it controls the operation of the second compressor 31 so that the rotation speed of the second compressor 31 is lower than when it is not.

[0082] According to this embodiment, the second compressor 31 can be operated so that the power consumed by the electrical equipment constituting the vehicle air conditioner does not exceed the capacity limit of the power conversion unit 33. This makes it possible to use the vehicle air conditioner for extended periods.

[0083] (2) In the basic operation process, the target fan rotation speed TNF and the target compressor rotation speed TNC are calculated based on the difference ΔT between the actual temperature TR and the set temperature TT. The operation of the condenser fan 16 is controlled based on the target fan rotation speed TNF, and the operation of the second compressor 31 is controlled based on the target compressor rotation speed TNC. In the rotation reduction process, when the power consumption WC of the second compressor 31 exceeds the upper limit value LU, the target compressor rotation speed TNC is changed to a value corresponding to a lower speed compared to when it is not.

[0084] According to this embodiment, when the power consumption WC of the second compressor 31 exceeds the upper limit value LU, the rotational speed of the second compressor 31 can be reduced compared to when it is not. This makes it possible to reduce the power consumption WC of the second compressor 31.

[0085] (3) The rotational speed reduction process includes a reduction process that gradually lowers the rotational speed of the second compressor 31 during the period T1 from when the power consumption WC of the second compressor 31 is above the upper limit LU until it falls below the lower limit LB. The rotational speed reduction process also includes an increase process that gradually raises the rotational speed of the second compressor 31 during the period T2 from when the power consumption WC of the second compressor 31 is below the lower limit LB until it is above the upper limit LU.

[0086] According to this embodiment, the power consumption WC of the second compressor 31 can be gradually changed in a manner that alternately increases and decreases between an upper limit LU and a lower limit LB. This prevents the shutdown of the power conversion unit 33 due to exceeding the capacity limit, thus enabling the vehicle air conditioner to be used for extended periods. Moreover, since the refrigerant pumping function of the second compressor 31 is prevented from being unnecessarily reduced, the cooling function of the vehicle air conditioner can be prevented from deteriorating.

[0087] (4) The cooler control device 35 performs an upper limit setting process. In the upper limit setting process, the upper limit value LNF for the target fan rotation speed TNF is set to a value that corresponds to a lower speed when it is detected as "night" than when it is detected as "day". In the upper limit setting process, the operation of the condenser fan 16 is controlled in such a manner that the target fan rotation speed TNF is limited by the upper limit value LNF.

[0088] During the day, the outside temperature tends to be higher than at night, which increases the load on the second compressor 31 (specifically, its power consumption WC). On the other hand, noise is less of a problem during the day compared to at night, allowing the rotation speed of the condenser fan 16 to be increased. A higher rotation speed of the condenser fan 16 makes it less likely for the condenser fan 16 to have insufficient cooling capacity for the refrigerant RE. Therefore, it also makes it less likely for the power consumption WC of the second compressor 31 to increase due to the aforementioned insufficient cooling capacity.

[0089] According to this embodiment, during the day, the rotation speed of the condenser fan 16 can be set to a relatively high speed. This allows for a high cooling effect from the condenser fan 16, even though the load on the second compressor 31 tends to increase due to the high ambient temperature. Therefore, it is possible to suppress the increase in power consumption WC of the second compressor 31 caused by insufficient cooling capacity of the refrigerant RE by the condenser fan 16. Moreover, at night, the rotation speed of the condenser fan 16 can be set to a low speed. This makes it possible to use the vehicle air conditioner for extended periods while suppressing noise.

[0090] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0091] When the voltage RV of the second battery 32 falls below the judgment value JV, a first setting process may be executed to set an upper limit LNC for the rotational speed of the second compressor 31 (specifically, the target compressor rotational speed TNC). In this configuration, for example, the second battery 32 may have a rated voltage of "12 volts," and the judgment value JV may be set to "10 volts."

[0092] Figure 5 shows an example of the first setting process described above. As shown in Figure 5, in this process, when the voltage RV of the second battery 32 becomes less than or equal to the determination value JV (step S20: YES), the upper limit LNC for the target compressor rotation speed TNC is set (step S21). On the other hand, when the voltage RV of the second battery 32 is higher than the determination value JV (step S20: NO), the upper limit LNC is not set (the process in step S21 is skipped).

[0093] In this case, if the voltage RV of the second battery 32 becomes very low, the output voltage of the power conversion unit 33 may decrease as a result. In this case, it is easy for the power conversion unit 33 to stop due to exceeding its capacity limit. In this regard, with the above configuration, an upper limit LNC is set in such a case, and this upper limit LNC can limit the rotation speed of the second compressor 31 to a low speed. Therefore, even if the voltage RV of the second battery 32 is very low at this time, it is possible to continue the operation of the vehicle air conditioner by keeping the power consumption WC of the second compressor 31 to a small amount.

[0094] • A second setting process may be implemented to variably set the upper limit value LU for the power consumption WC of the second compressor 31 according to the number of times the power consumption WC exceeded the upper limit value LU during the current operating period.

[0095] Figure 6 shows an example of the second setting process described above. As shown in Figure 6, in this process, the more times the above process is performed, the lower the value corresponding to the power is set as the upper limit value LU (step S30). Specifically, if the above number of times is "0", the upper limit value LU is set to a predetermined value LU0 (for example, 90% of the rated power of the power conversion unit 33). If the above number of times is "1", the upper limit value LU is set to a predetermined value LU1 (for example, 85% of the rated power of the power conversion unit 33). If the above number of times is "2", the upper limit value LU is set to a predetermined value LU2 (for example, 80% of the rated power of the power conversion unit 33). If the above number of times is "3 or more", the upper limit value LU is set to a predetermined value LU3 (for example, 75% of the rated power of the power conversion unit 33). The above number of times is counted by the cooler control device 35 and stored in the cooler control device 35.

[0096] With the above configuration, the more frequent the above cycles are, that is, the more likely it is to cause a sharp increase in the power consumption WC of the second compressor 31 due to insufficient cooling capacity of the condenser fan 16, the more the upper limit value LU can be set to a value corresponding to low power. As a result, when the power consumption WC of the second compressor 31 tends to be high, the power consumption WC can be kept low. Therefore, it becomes possible to use the vehicle's air conditioner for extended periods.

[0097] • In the cooler control process, a reset process may be performed. The reset process erases the history if the power consumption WC of the second compressor 31 does not exceed the upper limit value LU for a predetermined period of time. The predetermined period can be set to a predetermined time (for example, 30 minutes), or to the period from when the power consumption WC of the second compressor 31 exceeds the upper limit value LNC until it decreases to a predetermined value (for example, 60% of the rated power of the power conversion unit 33).

[0098] By performing the above reset process, when the power consumption WC of the second compressor 31 is reduced to a low level (for example, at night), the restrictions on the rotational speed and power consumption WC of the second compressor 31 caused by the rotational speed reduction process can be released. As a result, the cooling function of the vehicle air conditioner will be optimally performed thereafter.

[0099] Instead of providing an illuminance sensor 22 as a day / night detection unit to detect whether it is day or night, an outside temperature sensor for detecting the temperature outside the vehicle may be provided. Alternatively, the air conditioner control device 35 may detect whether it is day or night based on time information and date information it possesses. In this case, the air conditioner control device 35 corresponds to the day / night detection unit.

[0100] Regardless of whether it is day or night, a predetermined constant value may be set as the upper limit LNF for the rotational speed of the condenser fan 16. In this case, the day / night detection unit can be omitted.

[0101] The vehicle cooler according to the above embodiment can also be applied to vehicle coolers of a type in which no upper limit value LNF is set for the rotation speed of the condenser fan 16 when "daytime" is detected.

[0102] In the rotation reduction process, instead of performing both reduction and increase processes, a process may be implemented in which the deceleration correction amount KC is increased by a predetermined amount K each time the power consumption WC exceeds the upper limit value LU.

[0103] The second storage battery 32 is not limited to being charged by the power generated by the generator 12, but may also be charged by an external power source such as a household power supply. [Explanation of Symbols]

[0104] 10 vehicles 11 Internal Combustion Engine 12 Generators 13. First Battery 14. First Compressor 15 Capacitors 16 condenser fan 17 Cooling section 171 Expansion valve 172 Evaporator 173 Blower Fan 18. Vehicle control system 21 Temperature sensor 22 Illuminance Sensor 23 Setting Switch 24. Operation switch 31. Second Compressor 32 Second Battery 33 Power Conversion Unit 34 Cooler switch 35. Cooler control device

Claims

1. This is applied to a vehicle having an internal combustion engine as a vehicle power source, an engine-driven first compressor for pressurizing and pumping a refrigerant, a condenser used for cooling the refrigerant, and an electric condenser fan for blowing air to the condenser. A vehicle air conditioner comprising: an electrically operated second compressor for pressurizing the refrigerant when the internal combustion engine is stopped; a storage battery that serves as a power source for the condenser fan and the second compressor; a power conversion unit that boosts and outputs the DC voltage of the storage battery; and a control unit that controls the operation of the condenser fan and the second compressor, A temperature detection unit that detects the actual temperature, which is the temperature inside the vehicle, The system includes a temperature setting unit for setting the aforementioned set temperature, The control unit performs basic operation processing and rotation reduction processing. The basic operation process includes a process for calculating a first control target value for the rotational speed of the condenser fan and a second control target value for the rotational speed of the second compressor based on the difference between the actual temperature and the set temperature, and a process for controlling the operation of the condenser fan based on the first control target value and controlling the operation of the second compressor based on the second control target value. The aforementioned rotation reduction process includes a process that changes the second control target value to a value corresponding to a lower speed compared to when the power consumption of the second compressor exceeds an upper limit, in a vehicle air conditioner.

2. Applicable to a vehicle having an internal combustion engine as a vehicle power source, an engine-driven first compressor for pressurizing and pumping a refrigerant, a condenser used for cooling the refrigerant, and an electric condenser fan for blowing air to the condenser, A vehicle air conditioner comprising: an electrically operated second compressor for pressurizing the refrigerant when the internal combustion engine is stopped; a storage battery that serves as a power source for the condenser fan and the second compressor; a power conversion unit that boosts and outputs the DC voltage of the storage battery; and a control unit that controls the operation of the condenser fan and the second compressor, The control unit performs basic operation processing and rotation reduction processing. The basic operation process is a process that controls the operation of the condenser fan and the operation of the second compressor in such a manner that the temperature inside the vehicle reaches a set temperature set by the user. The aforementioned rotation reduction process is, This process controls the operation of the second compressor such that, when the power consumption of the second compressor exceeds an upper limit, the rotational speed of the second compressor is lower than when it is not, and The process includes a reduction process that gradually lowers the rotational speed of the second compressor during the period from when the power consumption of the second compressor exceeds the upper limit until it falls below the lower limit, and an increase process that gradually raises the rotational speed of the second compressor during the period from when the power consumption of the second compressor falls below the lower limit until it exceeds the upper limit. Vehicle air conditioner.

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