Vehicle air conditioning control system

Abstract

Appropriately determine the timing of air conditioning control. [Solution] A vehicle air conditioning control system 1 comprises an internal combustion engine 2 of the vehicle, an AC compressor 3 that can be driven by the torque of the internal combustion engine 2, and an ECU 11 that controls the torque transmission from the internal combustion engine 2 to the AC compressor 3. The ECU 11 sets a limit refrigerant pressure Plim in the AC compressor 3 based on the difference between the upper limit torque Tlim that can be output by the internal combustion engine 2 and the idle torque Ti for maintaining the internal combustion engine 2 in an idle state, and stops the AC compressor 3 when the refrigerant pressure P of the AC compressor 3 exceeds the limit refrigerant pressure Plim.

Description

[Technical Field]

[0001] The present invention relates to a vehicle air conditioning control system. [Background technology]

[0002] Air conditioners used in vehicles equipped with internal combustion engines use the driving force of the internal combustion engine to operate a compressor, compressing, radiating heat, and expanding a refrigerant, and then cooling the air using the refrigerant, whose temperature drops as it expands. In other words, vehicle air conditioners can lower the temperature inside the vehicle cabin by repeating the above cycle. Vehicle air conditioners can also be used to control the humidity inside the vehicle cabin. For example, Patent Document 1 discloses a technology that cuts off the air conditioning when torque is insufficient to provide an anti-fogging function when switching from automatic to manual driving while an autonomous vehicle is traveling.

[0003] More specifically, in the above-mentioned conventional technology, when the sum of the drive torque required for driving and the air conditioning torque required for the compressor exceeds the maximum output torque of the internal combustion engine, the air conditioning control is executed to prioritize the comfort of the occupants during automatic driving, and the air conditioning cut-off control is prohibited during manual driving to prevent fogging of the windshield. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-70331 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, the air conditioning is stopped when the sum of the drive torque and the air conditioning torque exceeds the maximum output torque. Therefore, if the drive torque increases without changing the maximum output torque, the limit value of the air conditioning torque decreases, and the air conditioning output tends to be suppressed. This causes the temperature inside the vehicle to easily change, which may reduce the comfort of the occupants.

[0006] The present invention has been made in view of the above problems, and its object is to provide a vehicle air conditioning control system that can appropriately determine the timing of air conditioning control. [Means for solving the problem]

[0007] In order to achieve the above object, the vehicle air conditioning control system of the present invention comprises an internal combustion engine of a vehicle, an air conditioning compressor that can be driven by the torque of the internal combustion engine, and a control device that controls the torque transmission from the internal combustion engine to the air conditioning compressor, wherein the control device sets a limit refrigerant pressure in the air conditioning compressor based on the difference between the upper limit torque that can be output by the internal combustion engine and the idle torque for maintaining an idle state, and stops the air conditioning compressor when the refrigerant pressure of the air conditioning compressor exceeds the limit refrigerant pressure. [Effects of the Invention]

[0008] The automotive air conditioning control system calculates the maximum torque that the internal combustion engine can output for the interior air conditioning compressor, which is driven by the engine's output torque, as an upper limit torque that can be output, and calculates the idle torque required for idling. Based on the difference between these values, the system determines the limit value of the refrigerant pressure in the air conditioning compressor, i.e., the limit refrigerant pressure, from the torque that can be allocated to the air conditioning compressor. The control device then controls the air conditioning compressor to stop if the refrigerant pressure in the air conditioning compressor exceeds the limit refrigerant pressure. Because the limit refrigerant pressure is calculated from the difference between the upper limit torque that can be output and the idle torque, an increase in drive torque does not decrease the limit refrigerant pressure. This prevents a decrease in air conditioning output due to an increase in drive torque, ensuring a comfortable interior temperature environment.

[0009] Furthermore, even when the air density around the vehicle decreases, for example, in a high-altitude environment, and the maximum torque that can be output decreases, the vehicle air conditioning control system can stop the air conditioning compressor at the appropriate time by lowering the limit refrigerant pressure, thereby maintaining engine output.

[0010] Therefore, the vehicle air conditioning control system of the present invention can appropriately determine the timing of air conditioning control. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram showing the main configuration of a vehicle air conditioning control system; [Figure 2] 3 is a timing chart showing the operating states of each part of the vehicle air conditioning control system. [Figure 3] 4 is a timing chart showing changes in the output torque and ignition timing of the internal combustion engine, as well as changes in the refrigerant pressure during an intermittent air conditioning control period. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the embodiments will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the contents described below, and can be implemented with any modifications within the scope that does not change the gist of the disclosure. Furthermore, all drawings used to explain the embodiments are schematic representations of components, and may be partially emphasized, enlarged, reduced, or omitted to facilitate understanding, and may not accurately represent the scale, shape, etc. of the components.

[0013] 1 is a configuration diagram showing the main components of a vehicle air conditioning control system 1. The vehicle air conditioning control system 1 is a system that controls air conditioning in an engine-driven vehicle, and in this embodiment includes an internal combustion engine 2, an AC compressor (air conditioner compressor) 3, an accessory belt 4, an AC clutch 5, a capacitor 6, a refrigerant circuit 7, a refrigerant pressure sensor 8, an AC switch 9, a shift lever 10, and an ECU 11. Note that the vehicle is also equipped with other components that are included in a typical engine vehicle, but illustrations and descriptions of these components will be omitted here.

[0014] The internal combustion engine 2 is an engine that outputs power using fuel such as gasoline, and mainly outputs a torque for driving the vehicle. However, in the vehicle air-conditioning control system 1 of this embodiment, the internal combustion engine 2 is a component of the vehicle air-conditioning control system 1 in which a part of the torque it outputs is used as air-conditioning torque for air-conditioning the interior of the vehicle.

[0015] The AC compressor 3 is a compressor that can be driven by the torque output by the internal combustion engine 2, and compresses the air conditioning refrigerant. The accessory belt 4 connects the rotating shafts of the internal combustion engine 2 and the AC compressor 3, thereby transmitting the torque of the internal combustion engine 2 to the AC compressor 3. The AC clutch 5 is provided between the accessory belt 4 and the AC compressor 3, and controls the connection and disconnection of the torque transmitted from the internal combustion engine 2 to the AC compressor 3 via the accessory belt 4.

[0016] The condenser 6 is a heat exchanger that cools the refrigerant supplied from the AC compressor 3 using the wind generated by the vehicle's movement or a fan (not shown). The refrigerant circuit 7 is a pipe that circulates the refrigerant between the AC compressor 3 and the condenser 6, and absorbs heat from the air blown into the vehicle interior by vaporizing the refrigerant in an evaporator (not shown) provided on the flow path. The refrigerant pressure sensor 8 is a pressure sensor provided on the flow path of the refrigerant circuit 7, and monitors the refrigerant pressure related to the adjustment of the vehicle interior temperature.

[0017] The AC switch 9 is provided, for example, on the instrument panel of the vehicle and is an operating part for turning the air conditioner on and off by the occupant's operation. The shift lever 10 is provided in the driver's seat of the vehicle and is an operating part for switching the vehicle's shift range between N range, D range, etc. by the occupant's operation.

[0018] The ECU 11 is a known electronic control unit that acquires information related to the operating state from each component of the vehicle air conditioning control system 1, including the internal combustion engine 2, and controls the vehicle's running and the air conditioning inside the vehicle by controlling each of the components. More specifically, the ECU 11 acquires information from each sensor from the refrigerant pressure sensor 8, the AC switch 9, and the shift lever 10. The ECU 11 also issues instructions for connecting and disconnecting the AC clutch 5, and adjusts the throttle opening and ignition timing of the internal combustion engine 2 to control the torque and rotation speed.

[0019] Next, the operation of the vehicle air conditioning control system 1 will be described. FIG. 2 is a timing chart showing the operating states of each part of the vehicle air conditioning control system 1. After the vehicle ignition is turned on and the vehicle starts idling, the ECU 11 controls the AC clutch 5 to turn on when the occupant operates the AC switch 9 at timing T1. The ECU 11 may also be configured to automatically control the ON / OFF of the AC clutch 5 based on the temperature inside and outside the vehicle. The ECU 11 also increases the throttle opening of the internal combustion engine 2 to increase the intake volume and improve charging efficiency, while delaying the ignition timing to maintain a constant torque. This allows the ECU 11 to respond to instantaneous increases in torque and prepares the AC compressor 3 for operation.

[0020] Furthermore, at timing T2, the ECU 11 controls the AC compressor 3 to be ON and advances the ignition timing of the internal combustion engine 2 while maintaining the charging efficiency, i.e., the intake air volume. As a result, the air conditioning torque Tac is added to the idle torque Ti of the internal combustion engine 2, increasing the total output torque. When the AC compressor 3 starts to drive, the refrigerant pressure P of the internal combustion engine 2 also increases with the air conditioning torque Tac, and air conditioning in the vehicle interior begins. Furthermore, when the refrigerant pressure P of the AC compressor 3 is maintained at a constant value at timing T3, the output torque of the internal combustion engine 2 is also maintained constant.

[0021] Here, since the output torque of the internal combustion engine 2 has an upper limit torque Tlim that can be output, if the sum of the idle torque Ti and the air conditioning torque Tac exceeds the upper limit torque Tlim that can be output, the idle torque Ti is given priority and the operation of the air conditioning is restricted. More specifically, the ECU 11 calculates the upper limit torque Tlim that can be output of the internal combustion engine 2 and the idle torque Ti required to maintain the internal combustion engine 2 in an idle state, and sets a limit refrigerant pressure Plim that corresponds to the torque value that can be allocated to the AC compressor 3 based on the difference between the two.

[0022] The limit refrigerant pressure Plim is calculated based on a torque value obtained by subtracting the idle torque Ti for maintaining an idle state from the maximum possible output torque Tlim. The ECU 11 takes atmospheric pressure into consideration when calculating the maximum possible output torque Tlim of the internal combustion engine 2. Therefore, in an environment such as high altitude where the air density is low, the maximum possible output torque Tlim decreases.

[0023] Next, at timing T4, when the driver shifts the shift lever 10 from N (Neutral) to D (Drive), the clutch of the automatic transmission (not shown) is engaged, increasing the required idle torque Ti. To meet this demand, the ECU 11 increases the charging efficiency and advances the ignition timing. This increases the total output torque of the internal combustion engine 2. Furthermore, although the upper limit torque Tlim that can be output remains unchanged, the limit refrigerant pressure Plim also decreases as the idle torque Ti increases, and the torque that can be output as the air conditioning torque Tac also decreases.

[0024] Then, at timing T5, the refrigerant pressure P of the AC compressor 3 remains unchanged, but the limit refrigerant pressure Plim decreases, causing the refrigerant pressure P to exceed the limit refrigerant pressure Plim. At this time, the ECU 11 determines that the output torque of the internal combustion engine 2 is insufficient, and disengages the AC clutch 5 to switch off the AC compressor 3. This allows the vehicle air conditioning control system 1 to prevent the vehicle engine from stalling even when the output torque is insufficient.

[0025] Furthermore, because the air conditioning torque Tac is no longer needed due to the stopping of the AC compressor 3, the output torque of the internal combustion engine 2 decreases, and after a slight delay, the refrigerant pressure P also begins to decrease until it again falls below the limit refrigerant pressure Plim. The ECU 11 presets a lower limit refrigerant pressure Pu that is lower than the limit refrigerant pressure Plim by a predetermined pressure, and restarts the AC compressor 3 when the refrigerant pressure P of the AC compressor 3 falls below the lower limit refrigerant pressure Pu, as shown at timing T6.

[0026] Then, because the refrigerant pressure P increases again when the AC compressor 3 is driven again, the ECU 11 intermittently drives the AC compressor 3 based on a comparison between the refrigerant pressure P and the limit refrigerant pressure Plim and the lower limit refrigerant pressure Pu. This allows the vehicle air-conditioning control system 1 to secure the driving period of the AC compressor 3 as long as possible and suppress an increase in the temperature inside the vehicle.

[0027] Alternatively, the ECU 11 may reduce the lower limit refrigerant pressure Pu in response to a decrease in the interior temperature. That is, the ECU 11 presets the lower limit refrigerant pressure Pu to a predetermined value lower than the limit refrigerant pressure Plim, and controls the lower limit refrigerant pressure Pu to be reduced as the interior temperature decreases. If the interior temperature is low, even if the interior cooling capacity of the air conditioning decreases slightly, the interior temperature will not become too high, and a slight decrease in the refrigerant pressure P can be tolerated. Therefore, by reducing the lower limit refrigerant pressure Pu, frequent ON / OFF switching of the AC compressor 3 is suppressed.

[0028] 2, the engine speed of the internal combustion engine 2 is substantially constant. When the vehicle starts moving after timing T6, the throttle opening of the internal combustion engine 2 increases, and the limit refrigerant pressure Plim also increases. This makes it difficult for the refrigerant pressure P to exceed the limit refrigerant pressure Plim, allowing the AC compressor 3 to be driven continuously without any restrictions.

[0029] Next, the behavior of the internal combustion engine 2 and the AC compressor 3 during intermittent air conditioning control will be described in more detail. Fig. 3 is an enlarged view of a portion of Fig. 2 from timing T6 onwards, and is a timing chart showing the changes in the output torque and ignition timing of the internal combustion engine 2, as well as the refrigerant pressure P during intermittent air conditioning control.

[0030] When the refrigerant pressure P falls below the lower limit refrigerant pressure Pu at timing T6, the ECU 11 switches ON the AC compressor 3. At this time, the refrigerant pressure P does not immediately begin to increase, but continues to decrease for a certain period together with the air conditioning torque Tac of the ECU 11. During this period, the ignition timing of the internal combustion engine 2, which had been set to the advanced angle, is gradually returned to the retarded angle side in accordance with the decrease in the air conditioning torque Tac.

[0031] Then, at timing T7, when the air conditioning torque Tac begins to increase as the refrigerant pressure P increases, control is performed to again advance the ignition timing while maintaining the intake air amount of the internal combustion engine 2 in order to immediately respond to the increase in the required output torque.

[0032] Furthermore, at timing T8 when the refrigerant pressure P exceeds the limit refrigerant pressure Plim again, the ECU 11 switches the AC compressor 3 OFF and retards the ignition timing while maintaining the intake amount of the internal combustion engine 2, thereby preparing for the next restart of the AC compressor 3. As a result, the ECU 11 continues the intermittent air conditioner control and keeps the air conditioner ON as long as possible by repeating the same control as that performed at timings T6 to T8 even during the drive period of the AC compressor 3 from timings T9 to T11.

[0033] As described above, the vehicle air-conditioning control system 1 according to the present invention calculates the maximum torque that the internal combustion engine 2 can output, i.e., the upper limit torque Tlim, for the AC compressor 3 for vehicle air conditioning, which is driven by the output torque of the internal combustion engine 2, and also calculates the idle torque Ti required for idle operation.Based on the difference between these values, the system determines the limit value of the refrigerant pressure P in the AC compressor 3, i.e., the limit refrigerant pressure Plim, from the torque that can be allocated to the AC compressor 3.The ECU 11 then performs control to stop the AC compressor 3 when the refrigerant pressure P in the AC compressor 3 exceeds the limit refrigerant pressure Plim.

[0034] Therefore, even when the air density around the vehicle decreases due to a high altitude environment, for example, and the maximum output torque Tlim decreases, the vehicle air conditioning control system 1 can stop the AC compressor 3 at the appropriate time by lowering the limit refrigerant pressure Plim to maintain engine output, and can control air conditioning without incorporating special control specifically for idle states.In this case, because the maximum output torque Tlim depends on atmospheric pressure, air conditioning can be improved without incorporating special control for when the atmospheric pressure is low.

[0035] Furthermore, the vehicle air conditioning control system 1 does not stop the air conditioning when the output torque of the internal combustion engine 2 reaches its limit, but rather uses refrigerant pressure-based control that stops the air conditioning when the refrigerant pressure P of the AC compressor 3 exceeds the limit refrigerant pressure Plim, thereby preventing a reduction in air conditioning output due to an increase in drive torque as in conventional technology.

[0036] Furthermore, according to the vehicle air conditioning control system 1 of the present invention, the vehicle air conditioning is intermittently driven based on a comparison of the refrigerant pressure P with the limit refrigerant pressure Plim and the lower limit refrigerant pressure Pu, thereby ensuring the driving period of the AC compressor 3 as long as possible and ensuring a comfortable temperature environment inside the vehicle. [Explanation of symbols]

[0037] 1. Vehicle air conditioning control system 2. Internal combustion engine 3 AC compressor (air conditioner compressor) 4 Auxiliary belt 5 AC clutch 6 capacitors 7 Refrigerant circuit 8 Refrigerant pressure sensor 9 AC switch 10 Shift lever 11 ECU P refrigerant pressure Plim limit refrigerant pressure Pu lower limit refrigerant pressure Ti idle torque Tac Air Conditioning Torque Tlim Maximum torque that can be output

Claims

1. an internal combustion engine of a vehicle; an air conditioner compressor that can be driven by the torque of the internal combustion engine; a control device that controls torque transmission from the internal combustion engine to the air conditioner compressor, The control device sets a limit refrigerant pressure in the air conditioning compressor according to the difference between an upper limit torque that can be output by the internal combustion engine and an idle torque for maintaining an idle state, and stops the air conditioning compressor when the refrigerant pressure in the air conditioning compressor exceeds the limit refrigerant pressure.

2. 2. The vehicle air conditioning control system according to claim 1, wherein the control device restarts the air conditioning compressor when the refrigerant pressure of the air conditioning compressor falls below a lower limit refrigerant pressure that is lower than the limit refrigerant pressure.

3. The vehicle air conditioning control system according to claim 2 , wherein the control device reduces the lower limit refrigerant pressure in response to a decrease in the temperature inside the vehicle.

4. 3. The vehicle air conditioning control system according to claim 1, wherein the control device retards ignition timing while maintaining an intake air amount of the internal combustion engine when the air conditioning compressor is stopped based on the limit refrigerant pressure.

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