Idling stop control method for engine and idling stop control device for engine

Abstract

An idling stop control method for an engine (1) provides a method for controlling idling stop for a vehicle (100) having an air conditioner (3) that performs air conditioning by using the engine (1) in operation. When a count value (CV) of a counter (71) reaches a prescribed threshold value (Th) during execution of the idling stop and conditions are satisfied, the idling stop is prohibited. In the case where the air conditioner (3) is in cooling operation, the count value (CV) of the counter (71) is increased at a first increment rate (Inc1) during execution of the idling stop, and when the conditions are satisfied, the idling stop is prohibited. In the case where the air conditioner (3) is in heating operation, the count value (CV) is increased at a second increment rate (Inc2) different from the first increment rate (Inc1) during execution of the idling stop, and when the conditions are satisfied, the idling stop is prohibited.

Description

Engine idling stop control method and engine idling stop control device

[0001] The present invention relates to an engine idling stop control method and an engine idling stop control device.

[0002] Patent Document 1 describes a method for controlling idling in a vehicle in which the refrigerant in the refrigeration cycle of the air conditioner is circulated by the driving force transmitted from the engine to the compressor via a magnetic clutch. In this control method, if the air conditioner is in cooling operation when the vehicle is stopped and the magnetic clutch is disengaged for a predetermined period of time before the vehicle is stopped, the engine is maintained in an idling state even after the vehicle is stopped.

[0003] Japanese Patent Application Laid-Open No. 2006-37860

[0004] In a vehicle in which the cooling operation of the air conditioner is stopped during an engine idling stop, the heating operation of the air conditioner may also be stopped during the engine idling stop. Patent Document 1 only mentions the control content during cooling operation, and does not mention heating operation. If the heating operation of the air conditioner is also stopped during an engine idling stop, and the change in comfort experienced by the vehicle occupants during the idling stop differs between when the cooling operation is stopped and when the heating operation is stopped, the control in Patent Document 1 cannot address this.

[0005] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to enable appropriate idling stop control to be performed in accordance with both cooling operation and heating operation when the air conditioning system is stopped due to engine idling stop.

[0006] In order to solve the above-mentioned problems, an engine idling stop control method according to one aspect of the present invention prohibits idling stop in a vehicle having an air conditioner that performs air conditioning using an operating engine when a condition is met. The condition is deemed to be met when a count value of a counter reaches a predetermined threshold value during idling stop. During cooling operation of the air conditioner, the count value of the counter is increased at a first increase rate during idling stop, and idling stop is prohibited when the condition is met. During heating operation of the air conditioner, the count value is increased at a second increase rate different from the first increase rate during idling stop, and idling stop is prohibited when the condition is met.

[0007] According to the present invention, when the operation of the air conditioner is stopped due to engine idling stop, appropriate idling stop control can be performed corresponding to both cooling operation and heating operation.

[0008] Fig. 1 is a diagram showing an example of the configuration of a vehicle equipped with an idling stop control device that executes a control method according to an embodiment of the present invention. Fig. 2 is a flowchart showing an example of a processing procedure performed by the idling stop control device of Fig. 1. Fig. 3 is a timing chart showing an example of the relationship between the count value of a counter and the idling state of an engine during cooling operation of the air conditioner of Fig. 1. Fig. 4 is a timing chart showing an example of the relationship between the count value of a counter and the idling state of an engine during heating operation of the air conditioner of Fig. 1.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, identical parts are designated by the same reference numerals, and description thereof will be omitted. As shown in the example of FIG. 1 , a vehicle 100 of this embodiment includes an engine 1, an air conditioning device 3, an interior temperature sensor 5, and an idling stop control device 7. An idling stop control method according to an embodiment of the present invention can be executed by, for example, the idling stop control device 7.

[0010] The engine 1 is an internal combustion engine that idles when the vehicle 100 stops traveling. The air conditioner 3 performs air conditioning using the operating engine 1. The air conditioner 3 has a refrigeration cycle 31 for cooling operation and a heater core 33 for heating operation. The refrigeration cycle 31 circulates a refrigerant using a compressor (not shown) that operates using the power of the engine 1. The refrigeration cycle 31 has an evaporator 311 that cools the air inside the vehicle 100 through heat exchange using the heat of vaporization of the refrigerant. The heater core 33 performs heat exchange using heat generated by the engine 1. The heater core 33 can, for example, release heat from the coolant (not shown) that has cooled the engine 1 into the interior of the vehicle 100 to warm the air inside the interior. The interior temperature sensor 5 detects the temperature inside the vehicle 100.

[0011] The idling stop control device 7 controls idling stop of the engine 1 in the vehicle 100 while the air conditioning device 3 is operating. In the following description, idling stop may be abbreviated as IS. The IS control device 7 can obtain information indicating whether the engine 1 is operating or not from an engine ECU (Electronic Control Unit) that controls the operation of the engine 1.

[0012] For example, the IS control device 7 executes the IS of the engine 1 after a certain time has elapsed since the vehicle 100 has stopped running. When the IS is executed, the engine 1 is stopped and idling of the engine 1 ends. The IS control device 7 terminates the IS of the engine 1 when the vehicle 100 that has stopped running starts running again. If a condition is met while the IS is being executed, the IS control device 7 prohibits the IS of the engine 1. If the IS is prohibited during the IS of the engine 1, the engine 1 is restarted. The conditions under which the IS control device 7 prohibits the IS of the engine 1 will be described later.

[0013] The IS control device 7 includes, for example, a general-purpose microcontroller as a computer. The microcontroller has an arithmetic unit and an input / output unit. The arithmetic unit includes a central processing unit (CPU) and a memory. The memory includes a read-only memory (ROM) and a random access memory (RAM). The arithmetic unit can virtually configure multiple information processing circuits by having the CPU execute programs stored in the memory. The memory may include a data storage that accumulates data and configures a database. The data storage may be configured, for example, by a storage device such as an SSD (solid state drive) or an HDD (hard disk drive). The multiple information processing circuits configured in the arithmetic unit may configure a counter 71, a first increment unit 72, a second increment unit 73, a first decrement unit 74, a second decrement unit 75, a prohibition unit 76, and an estimation unit 77 of the IS control device 7, which will be described later. The IS control device 7 may be configured, for example, by an ECU mounted on the vehicle 100. The IS control device 7 may be configured by a single ECU, or multiple ECUs may cooperate to configure the IS control device 7. The IS control device 7 configured by an ECU may also function as an engine ECU, in which case the IS control device 7 may directly obtain information from the engine 1 indicating whether the engine 1 is operating or not.

[0014] In this embodiment, an example is shown in which multiple information processing circuits built in a microcontroller are realized by software. Of course, it is also possible to configure the information processing circuits by providing dedicated hardware for executing the information processing of the counter 71 and each of the units 72 to 77 of the IS control device 7, as described below. Alternatively, the multiple information processing circuits may be configured by individual hardware. Dedicated hardware includes devices such as an application specific integrated circuit (ASIC) or conventional circuit components arranged to perform the functions of the counter 71 and each of the units 72 to 77.

[0015] The counter 71 counts a count value that increases or decreases while the air conditioner 3 is operating. The count value increases while the engine 1 is executing an IS and decreases while the engine 1 is running. The count value counted by the counter 71 can be used as an indication of the time required for the operation of the air conditioner 3 to restore cabin comfort in the vehicle 100 after the engine 1 has finished IS. Since the air conditioner 3 performs air conditioning using the operating engine 1, operation of the air conditioner 3 is stopped during the engine 1 IS. While operation of the air conditioner 3 is stopped, the cabin comfort of the vehicle 100 decreases. The longer the engine 1 IS, the greater the decrease in cabin comfort. The engine 1 IS may occur intermittently, for example, due to traffic congestion, switching of traffic lights, etc.

[0016] When the engine 1 repeats an IS multiple times, the air conditioner 3 stops operation after each IS of the engine 1. If the air conditioner 3 repeatedly stops operation, for example, if the engine 1 operates for a short time between ISs, the air conditioner 3 operating while the engine 1 is running may not be able to fully restore the interior comfort that was reduced by the air conditioner 3 stopping operation. If the reduced interior comfort is not restored during the operation of the air conditioner 3 between ISs, the reduction in interior comfort will accumulate and increase with the repetition of ISs, even if the time of each IS is short. When the air conditioner 3 resumes operation after the end of an IS, the extent to which the interior comfort has decreased due to the air conditioner 3 stopping operation cannot be appropriately evaluated based solely on the duration of the IS that ended when the air conditioner 3 resumes operation. The counter 71 provides a numerical value that serves as an indicator of the interior comfort of the vehicle 100, which is reduced due to the air conditioner 3 stopping operation and then restored by operation, by using a count value that decreases while the engine 1 is running and increases while the IS is being executed.

[0017] The count value of counter 71 increases as the comfort level in the interior of vehicle 100 decreases. When the count value of counter 71 increases and reaches a predetermined threshold, it is determined that a condition for prohibiting IS of engine 1 is met. When the condition is met, prohibition unit 76 prohibits IS of engine 1.

[0018] The counter 71 may have an upper limit or a lower limit for the count value. The upper limit of the count value may be any value equal to or greater than a predetermined threshold, and may be, for example, the same as the predetermined threshold. When the counter 71 has an upper limit for the count value, once the count value reaches the upper limit, the counter value is maintained at the upper limit without increasing, even if the IS of the engine 1 continues to be executed thereafter. The lower limit of the count value may be, for example, a value determined based on the magnitude of the difference between the upper limit and the count value. The lower limit of the count value may be any value lower than the predetermined threshold, and may be, for example, zero, or a positive or negative value other than zero. When the counter 71 has a lower limit for the count value, once the count value reaches the lower limit, the counter value is maintained at the lower limit without decreasing, even if the operation of the engine 1 continues thereafter. In this embodiment, as will be described later, when the count value increases and reaches the predetermined threshold, the idling state of the engine 1 switches from IS to idling, and the count value is decreased. The upper limit of the count value counted by the counter 71 is the predetermined threshold.

[0019] The first increment unit 72 increments the count value of the counter 71 at a first increment rate while the IS of the engine 1 is being executed when the air conditioner 3 is in cooling operation. The second increment unit 73 increments the count value of the counter 71 at a second increment rate different from the first increment rate while the IS of the engine 1 is being executed when the air conditioner 3 is in heating operation. The first increment rate and the second increment rate can be set individually. Either the first increment rate or the second increment rate may be set to a higher value, or they may be set to the same value.

[0020] For example, in the case of the air conditioner 3 of this embodiment, when the air conditioner 3 is stopped during cooling operation, the circulation of the refrigerant stops in the refrigeration cycle 31. When the circulation of the refrigerant stops, the refrigerant is no longer decompressed by the expansion valve (not shown) upstream of the evaporator 311, and low-temperature refrigerant is no longer supplied to the evaporator 311. The cooling capacity of the interior of the vehicle 1 by the air conditioner 3 is reduced in a short period of time when the air conditioner 3 is stopped due to the engine 1 stoppage. When the air conditioner 3 is stopped during heating operation, the circulation of the engine 1 coolant stops, but the supply of coolant to the heater core 33 continues for a while due to inertial force. The heating capacity of the interior of the vehicle 1 by the air conditioner 3 is reduced gradually rather than in a short period of time when the air conditioner 3 is stopped due to the engine 1 stoppage. When the air conditioner 3 is stopped, the change in the thermal load in the interior of the vehicle 100 is faster during cooling operation than during heating operation. In the present embodiment, for example, the first increase rate is set to a value higher than the second increase rate, taking into consideration differences in changes in the thermal load inside the vehicle 100 while the air conditioner 3 is not operating.

[0021] The first decrement unit 74 decrements the count value of the counter 71 at a first decrement rate while the engine 1 is running when the air conditioner 3 is in cooling operation. The second decrement unit 75 decrements the count value of the counter 71 at a second decrement rate different from the first decrement rate while the engine 1 is running when the air conditioner 3 is in heating operation. The first decrement rate and the second decrement rate can be set individually. Either the first decrement rate or the second decrement rate may be set to a higher value, or they may be set to the same value.

[0022] For example, in the case of the air conditioner 3 of this embodiment, when the air conditioner 3 starts operating in cooling mode, the expansion valve (not shown) begins to decompress the refrigerant, and low-temperature refrigerant is immediately supplied to the evaporator 311. The cooling capacity of the interior of the vehicle by the air conditioner 3 increases in a short time when the air conditioner 3 starts operating due to the start of the engine 1. When the air conditioner 3 starts operating in heating mode, circulation of engine 1 coolant begins and coolant is supplied to the heater core 33, but the temperature of the supplied coolant only increases gradually until the engine 1 warms up after startup. The change in the thermal load in the interior of the vehicle 100 during operation of the air conditioner 3 is faster during heating operation than during cooling operation of the air conditioner 3. In this embodiment, for example, the second reduction rate is set to a value higher than the first reduction rate, taking into account the difference in the change in the thermal load in the interior of the vehicle 100 during operation of the air conditioner 3.

[0023] During cooling operation of the air conditioner 3, a change in the thermal load in the interior of the vehicle 100 occurs due to heat exchange by the evaporator 311. The first decrease rate may be set to a value corresponding to the heat exchange capacity of the evaporator 311. During heating operation of the air conditioner 3, a change in the thermal load in the interior of the vehicle 100 occurs due to heat exchange by the heater core 33. The second decrease rate may be set to a value corresponding to the heat exchange capacity of the heater core 33.

[0024] The estimation unit 77 estimates whether the operation of the air conditioner 3 is cooling operation or heating operation based on the change in the indoor temperature detected by the indoor temperature sensor 5. The IS control device 7 may store and accumulate the history of the indoor temperature detected by the indoor temperature sensor 5, for example, in data storage. In this case, the estimation unit 77 can determine the change in the indoor temperature from the temperature history in the data storage. For example, the estimation unit 77 may estimate that the operation of the air conditioner 3 is cooling operation when the determined change in the indoor temperature is a decrease exceeding a predetermined range per unit time. For example, the estimation unit 77 may estimate that the operation of the air conditioner 3 is heating operation when the determined change in the indoor temperature is an increase exceeding a predetermined range per unit time. For example, the estimation unit 77 may estimate that the operation state of the air conditioner 3 is stopped when the determined change in the indoor temperature is an increase and decrease within a predetermined range per unit time.

[0025] The flowchart in Figure 2 shows an example of a processing procedure repeatedly performed by the calculation unit of the microcontroller of the IS control device 7 when executing the IS control method for the engine 1 according to this embodiment. The estimation unit 77 of the calculation unit acquires a history of the indoor temperature (step S101). The estimation unit 77 determines the change in the indoor temperature from the acquired history and estimates the operating state of the air conditioner 3 from the determined change. If the estimation unit 77 estimates that the operating state of the air conditioner 3 is operating, it further estimates the operating details of the air conditioner 3 (step S103). The calculation unit checks whether the operating state of the air conditioner 3 estimated by the estimation unit 77 is operating (step S105). If the estimated operating state is stopped (NO in step S105), the series of processes ends.

[0026] If the estimated operating state is operating (YES in step S105), the calculation unit checks whether the operation of the air conditioner 3 estimated by the estimation unit 77 is cooling operation (step S107). If the estimated operation is heating operation (NO in step S107), the processing proceeds to step S115, which will be described later. If the estimated operation is cooling operation (YES in step S107), the calculation unit checks whether the engine 1 is executing IS (step S109). The calculation unit can check whether the engine 1 is executing IS based on whether the engine 1 is operating. Information on whether the engine 1 is operating can be obtained from an engine ECU (not shown) or can be obtained directly from the engine 1.

[0027] If the engine 1 is executing the IS (YES in step S109), the first increment unit 72 increments the count value of the counter 71 at a first increment rate, and the process proceeds to step S121, which will be described later. If the engine 1 is operating (NO in step S109), the first decrement unit 74 decrements the count value of the counter 71 at a first decrement rate, and the process proceeds to step S121.

[0028] In step S115, the calculation unit checks whether the engine 1 is executing the IS, as in step S109. If the engine 1 is executing the IS (YES in step S115), the second increment unit 73 increments the count value of the counter 71 at the second increment rate, and the process proceeds to step S121. If the engine 1 is running (NO in step S115), the second decrement unit 75 decrements the count value of the counter 71 at the second decrement rate, and the process proceeds to step S121.

[0029] In step S121, the prohibition unit 76 checks whether the count value CV of the counter 71 has increased and reached a predetermined threshold value Th. If the increased count value CV has reached the predetermined threshold value Th (YES in step S121), the prohibition unit 76 prohibits IS of the engine 1 (step S123) and then ends the series of processes. If the increased count value CV is lower than the predetermined threshold value Th (NO in step S121), the series of processes ends.

[0030] The timing charts in Figures 3 and 4 show an example of the relationship between the count value CV of the counter 71 while the air conditioner 3 is operating and the idling state of the engine 1. Figure 3 shows an example of the air conditioner 3 operating in cooling mode, and Figure 4 shows an example of the air conditioner 3 operating in heating mode. The upper graphs in Figures 3 and 4 show the progress of the count value CV of the counter 71, and the lower graphs show the idling state of the engine 1. In the lower graphs, a high level indicates that the engine 1 is in idle mode, and a low level indicates that the engine 1 is idling.

[0031] In FIG. 3 , times t11 to t16 in the lower graph indicate, in chronological order, the timing at which the engine 1 switches from idling to idle during cooling operation of the air conditioner 3. At times t11, t13, and t15, the engine 1 performs an idle stop (IS). The engine 1 is stopped, for example, when the vehicle 100 is stopped while waiting at a traffic light. During the engine 1 IS after times t11, t13, and t15, the count value CV of the counter 71 increases each time the process of FIG. 2 is performed. FIG. 3 illustrates a case where the count value CV before time t11 is the lower limit. During the engine 1 IS during cooling operation of the air conditioner 3, the thermal load inside the vehicle 100 changes more quickly than during heating operation. During the engine 1 IS, the count value CV of the counter 71 increases at a first increase rate Inc1, which is higher than the second increase rate Inc2 during heating operation of the air conditioner 3.

[0032] In the example of FIG. 3 , at time t12, the engine 1's idle state, which started at time t11, ends, and the engine 1 switches from the idle state to idle. At this point, the count value CV of the counter 71 has not yet reached its upper limit. The end of the IS at time t12 is not a forced end caused by the count value CV reaching its upper limit and prohibiting the IS. At time t12, for example, the idle state of the engine 1 switches to idle because the vehicle 100 is no longer waiting at a traffic light and the stop operation is canceled. While the engine 1 is idling after time t12, the count value CV of the counter 71 decreases each time the process of FIG. 2 is executed. While the engine 1 is idling during cooling operation of the air conditioner 3, the thermal load inside the vehicle 100 changes more slowly than during heating operation. During the engine IS, the count value CV of the counter 71 decreases at a first decrease rate Dec1 that is lower than the second decrease rate Dec2 during the heating operation of the air conditioner 3.

[0033] The idling state of the engine 1 switches to idling at time t12, and then switches to IS at time t13. At time t13, the count value CV of the counter 71 has not yet reached its lower limit. After time t13, the count value CV of the counter 71 increases again from the count value CV at time t13 at the first increase rate Inc1 each time the process of FIG. 2 is executed.

[0034] In the example of Fig. 3, at time t14, the count value CV of the counter 71 reaches its upper limit, the IS of the engine 1 is prohibited, the IS is forcibly terminated, and the idling state of the engine 1 is switched from IS to idling. After time t14, the count value CV of the counter 71 decreases again at the first decrease rate Dec1 each time the process of Fig. 2 is executed.

[0035] The idling state of the engine 1 switches to idling at time t14, and then switches to IS at time t15. At time t15, the count value CV of the counter 71 has not yet reached its lower limit. After time t15, the count value CV of the counter 71 increases again from the count value CV at time t15 at the first increase rate Inc1 each time the process of FIG. 2 is executed.

[0036] In the example of Fig. 3, at time t16, the count value CV of the counter 71 reaches its upper limit, prohibiting the IS of the engine 1, forcibly ending the IS of the engine 1 that started at time t15, and switching the idling state of the engine 1 from IS to idling. After time t16, the count value CV of the counter 71 decreases again at the first decrease rate Dec1 each time the process of Fig. 2 is executed.

[0037] When the air conditioner 3 is operating in cooling mode, the change in the thermal load inside the vehicle 100 is greater when the air conditioner 3 is stopped than when the air conditioner 3 is operating. When the air conditioner 3 is operating in cooling mode, the count value CV of the counter 71 increases during the engine idling period when the air conditioner 3 is stopped, at a rate faster than the rate of decrease during the engine idling period when the air conditioner 3 is operating.

[0038] 4, times t21 to t26 in the lower graph indicate, in chronological order, the timing at which the idling state of the engine 1 switches during heating operation of the air conditioner 3. At times t21, t23, and t26, the engine 1 is idled when the vehicle 100 stops, for example, while waiting at a traffic light. During the engine 1 idle period after each of times t21, t23, and t26, the count value CV increases at a second increase rate Inc2 that is lower than the first increase rate Inc1 during cooling operation of the air conditioner 3.

[0039] In the example of FIG. 4 , at time t22, the engine 1 idle state (IS) that started at time t21 ends, and the engine 1 switches from IS to idling. At this point, the count value CV of the counter 71 has not yet reached its upper limit. The end of IS at time t22 is not a forced end caused by the count value CV reaching its upper limit and prohibiting IS. At time t22, for example, the idle state of the engine 1 switches to idling because the vehicle 100 is no longer waiting at a traffic light and the stop operation for the vehicle 100 is canceled. While the engine 1 is idling after time t22, each time the process of FIG. 2 is executed, the count value CV of the counter 71 decreases at a second decrease rate Dec2 that is higher than the first decrease rate Dec1 during the cooling operation of the air conditioner 3.

[0040] The idling state of the engine 1 switches to idling at time t22, and then switches to IS at time t23. At time t23, the count value CV of the counter 71 has not yet reached its lower limit. After time t23, each time the process of FIG. 2 is executed, the count value CV of the counter 71 increases again from the count value CV at time t23 at the second increase rate Inc2.

[0041] In the example of Fig. 4, at time t24, the count value CV of the counter 71 reaches its upper limit, prohibiting the IS of the engine 1, forcibly ending the IS of the engine 1 that started at time t23, and switching the idling state of the engine 1 from IS to idling. After time t24, the count value CV of the counter 71 decreases again at the second decrease rate Dec2 each time the process of Fig. 2 is executed.

[0042] After the engine 1 switches from idling to idle at time t24, the count value CV of the counter 71 reaches its lower limit at time t25 and stops decreasing. After time t25, the engine 1 switches from idling to idle at time t26. At time t26, the count value CV of the counter 71 is maintained at the lower limit. After time t26, each time the process of FIG. 2 is executed, the count value CV of the counter 71 increases again from the lower limit at the second increase rate Inc2.

[0043] In this embodiment, the count value CV of the counter 71, which increases while the engine 1 is in IS mode, provides a numerical value that indicates the degree of comfort within the vehicle 100 that will decrease when the air conditioner 3 is stopped. The count value CV increases as the degree of comfort within the vehicle 100 decreases. When the count value CV reaches a predetermined threshold, the engine 1 is prohibited from IS, and the engine 1 is forcibly switched to idling. The rate at which the count value CV is increased differs depending on whether the air conditioner 3 is in cooling operation or heating operation. Therefore, while the air conditioner 3 is stopped due to the engine 1 IS mode, appropriate IS control can be performed that corresponds to whether the air conditioner 3 is in cooling operation or heating operation.

[0044] When the air conditioner 3 is stopped, the change in the thermal load inside the vehicle 100 is faster during cooling operation than during heating operation of the air conditioner 3. In this embodiment, the first increase rate of the count value CV during cooling operation of the air conditioner 3 is set to be higher than the second increase rate of the count value CV during heating operation of the air conditioner 3. Therefore, when the air conditioner 3 is stopped and the comfort inside the vehicle 100 decreases, the count value CV of the counter 71 is increased at a rate during cooling operation and at a rate during heating operation, respectively, so that a numerical value that serves as an indicator of the comfort inside the vehicle 100 can be obtained that is appropriate for each operating state.

[0045] In this embodiment, when the count value CV of the counter 71 increases and reaches a predetermined threshold value, and IS of the engine 1 is prohibited, the count value CV at that time is maintained and not reset. If the engine 1 operates and the air conditioner 3 is operated after IS is prohibited, and the interior comfort of the vehicle 100 changes, a numerical value that can be used as a guide to interior comfort by reflecting this change can continue to be obtained from the count value CV even after IS is prohibited.

[0046] In this embodiment, the count value CV of the counter 71, which decreases while the engine 1 is running, provides a numerical value that indicates the level of comfort within the vehicle 100 that will be restored by operating the air conditioner 3. The rate at which the count value CV is decreased differs depending on whether the air conditioner 3 is in cooling operation or heating operation. Therefore, while the air conditioner 3 is operating due to the operation of the engine 1, appropriate IS control can be performed that corresponds to whether the air conditioner 3 is in cooling operation or heating operation.

[0047] The change in the thermal load inside the vehicle 100 while the air conditioner 3 is operating is faster during heating operation than during cooling operation of the air conditioner 3. In this embodiment, the second decrease rate of the count value CV during heating operation of the air conditioner 3 is set to be higher than the first decrease rate of the count value CV during cooling operation of the air conditioner 3. Therefore, during operation of the air conditioner 3 to restore reduced comfort inside the vehicle 100, the count value CV of the counter 71 is decreased at a different pace during cooling operation and heating operation, thereby making it possible to obtain a numerical value that serves as an indicator of indoor comfort that is appropriate for each operating mode.

[0048] By setting the first decrease rate of the count value CV during cooling operation of the air conditioner 3 to a value corresponding to the heat exchange capacity of the evaporator 311, the first decrease rate can be set to a highly accurate value based on the heat exchange capacity of the evaporator 311 that causes a change in the thermal load inside the room during cooling operation. By setting the second decrease rate of the count value CV during heating operation of the air conditioner 3 to a value corresponding to the heat exchange capacity of the heater core 33, the second decrease rate can be set to a highly accurate value based on the heat exchange capacity of the heater core 33 that causes a change in the thermal load inside the room during heating operation.

[0049] In this embodiment, the estimation unit 77 estimates whether the operation of the air conditioner 3 is cooling operation or heating operation based on the change in the indoor temperature of the vehicle 100 detected by the indoor temperature sensor 5. Therefore, the operation of the air conditioner 3 can be identified without using a dedicated sensor or the like.

[0050] In this embodiment, the comfort of the interior of the vehicle 100 conditioned by the air conditioner 3 is evaluated without using any sensors other than the interior temperature sensor 5, and the IS control device 7 can appropriately control the IS of the engine 1 in accordance with whether it is cooling operation or heating operation. In particular, when the installation of an on-board diagnostics (OBD) is required for the configuration related to the evaluation of interior comfort, the estimation unit 77 can estimate the operating conditions of the air conditioner 3, thereby minimizing the number of elements to be diagnosed.

[0051] The above-described embodiment and its modifications are merely examples of the present invention. Therefore, the present invention is not limited to the above-described embodiment, and various modifications can be made to the design and other aspects of the present invention without departing from the technical concept of the present invention.

[0052] REFERENCE SIGNS LIST 1 Engine 3 Air conditioning device 5 Interior temperature sensor 7 Idling stop control device 31 Refrigeration cycle 311 Evaporator 33 Heater core 71 Counter 72 First increment section 73 Second increment section 74 First decrement section 75 Second decrement section 76 Prohibition section 77 Estimation section 100 Vehicle CV Count value Dec1 First decrement rate Dec2 Second decrement rate Inc1 First increase rate Inc2 Second increase rate Th Predetermined threshold

Claims

1. An idling stop control method for a vehicle having an air conditioner that performs air conditioning using an operating engine, which prohibits an idling stop of the vehicle when it is considered that a condition is satisfied because a count value of a counter reaches a predetermined threshold value during execution of the idling stop, wherein during a cooling operation of the air conditioner, the count value of the counter is increased at a first increase rate during execution of the idling stop, and when the condition is satisfied, the idling stop is prohibited; during a heating operation of the air conditioner, the count value is increased at a second increase rate different from the first increase rate during execution of the idling stop, and when the condition is satisfied, the idling stop is prohibited. An idling stop control method for an engine.

2. The idling stop control method for an engine according to claim 1, wherein a change in the heat load inside the vehicle during a stop of the operation of the air conditioner is faster during the cooling operation than during the heating operation, and the first increase rate is higher than the second increase rate.

3. The idling stop control method for an engine according to claim 1 or 2, wherein the count value is not reset by prohibiting the idling stop.

4. The idling stop control method for an engine according to any one of claims 1 to 3, wherein during the cooling operation, the count value is decreased at a first decrease rate during operation of the engine; during the heating operation, the count value is decreased at a second decrease rate during operation of the engine.

5. The idling stop control method for an engine according to claim 4, wherein a change in the heat load inside the vehicle during operation of the air conditioner is faster during the heating operation than during the cooling operation, and the second decrease rate is higher than the first decrease rate.

6. The air conditioner has a refrigeration cycle that circulates a refrigerant using the power of the engine, and a heater core that performs heat exchange using heat generated by the engine, wherein the first decrease rate is set to a value corresponding to the heat exchange capacity of the evaporator of the refrigeration cycle, and the second decrease rate is set to a value corresponding to the heat exchange capacity of the heater core. The idling stop control method for an engine according to claim 4 or 5.

7. The engine idling stop control method according to any one of claims 1 to 6, which detects the temperature inside the vehicle and estimates whether the operation content of the air conditioner is either a cooling operation or a heating operation from the transition of the detected temperature.

8. An engine idling stop control device that prohibits the idling stop of a vehicle having an air conditioner that performs air conditioning using an operating engine when a count value of a counter reaches a predetermined threshold value and a condition is satisfied during the execution of the idling stop, the engine idling stop control device comprising: a counter whose count value increases or decreases during operation of the air conditioner; a first increasing unit that increases the count value at a first increasing rate during execution of the idling stop when the air conditioner is in a cooling operation; and a second increasing unit that increases the count value at a second increasing rate different from the first increasing rate during execution of the idling stop when the air conditioner is in a heating operation.

Images