JP4576748B2 - Output control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an output control device for an internal combustion engine that integrally controls an air conditioner such as an air conditioner and an engine.
[0002]
[Prior art]
In a vehicle having an air conditioner such as an air conditioner, when the operation switch is operated and there is an air conditioner operation command, the compressor clutch that interrupts the rotation from the engine that is the internal combustion engine to the compressor for the air conditioner is turned on, The air conditioner is operated by rotating the compressor. For this reason, since the load applied to the engine varies greatly when the air conditioner is operating and when the air conditioner is not operating, correction is generally made so that the output torque of the engine increases when the air conditioner is operating. For example, there is a technique that obtains a load torque using a refrigerant pressure discharged from a compressor correlated with a load torque of the compressor, and corrects an output torque according to the load torque. When the engine output is controlled in accordance with the refrigerant pressure from the compressor as described above, the correction may be delayed due to a response delay of the detecting means for detecting the refrigerant pressure, and the engine output torque may be insufficient.
[0003]
In recent years, lean combustion internal combustion engines in which an internal combustion engine is operated at an air-fuel ratio that is significantly leaner than the stoichiometric air-fuel ratio to improve fuel efficiency have been put into practical use. Such a lean-burn internal combustion engine is operated with a lean air-fuel ratio while suppressing the output torque of the engine in a low-load operation region including idle operation. However, when the operation switch of the air conditioner is turned on during lean operation with a lean air-fuel ratio in a lean combustion internal combustion engine, the engine needs torque to operate the compressor for the air conditioner, and increases the engine speed, The lean operation is prohibited and the stoichiometric operation with the stoichiometric air-fuel ratio is forcibly changed, resulting in a reduction in fuel consumption. In particular, in the case of a vehicle with a small displacement or a vehicle with a low engine output, the lean operation period is shortened.
[0004]
Therefore, in Japanese Patent Laid-Open No. 11-82092, when the air conditioner is turned on from off, the load torque of the compressor when on is predicted (estimated) from the discharge pressure (refrigerant pressure) of the compressor when off, and this predicted value (estimated value) ), An idle rotation control device for correcting engine idle rotation has been proposed.
[0005]
[Problems to be solved by the invention]
In the invention proposed in Japanese Patent Laid-Open No. 11-82092, it is assumed that the engine is idling, and when applied to other operating areas as it is, the engine output may be insufficient when the air conditioner is turned on / off. .
The present invention provides an output control device for an internal combustion engine capable of accurately estimating a load torque of a compressor in a wide range of an operation region and appropriately controlling an engine output accordingly to improve fuel consumption and drivability. With the goal.
[0006]
[Means for Solving the Problems]
To achieve the above object, an output control device for an internal combustion engine according to the present invention controls the output of the internal combustion engine in accordance with the load torque of a compressor for an air conditioner to which the rotational torque of the internal combustion engine is transmitted via a clutch. Yes, the load torque is estimated based on the rotational speed of the internal combustion engine within a predetermined time after the clutch is turned on.
According to the present invention, since the compressor load torque is estimated based on the rotational speed of the internal combustion engine within a predetermined time period such as immediately after the clutch is turned on and the air conditioner is activated, the load torque of the compressor is estimated from the refrigerant pressure. It is possible to estimate the load torque of the compressor more accurately than when estimating the torque, and to estimate the load torque with high accuracy regardless of the operation region.
[0007]
The output control device for an internal combustion engine according to the present invention, the clutch is in the ON predetermined time, to estimate the load torque have use a predetermined amount higher estimated torque than the maximum load torque of the compressor, the load torque estimate Never fall below the actual load torque. The output control device for an internal combustion engine according to the present invention estimates the load torque based on the refrigerant pressure discharged from the compressor after a predetermined time has elapsed since the clutch was turned on. For this reason, when a predetermined time elapses when the refrigerant pressure becomes stable, a load torque close to the actual load torque can be estimated from the refrigerant pressure, so that a useless increase in output can be suppressed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In FIG. 1, a vehicle denoted by reference numeral 1 includes an engine 2 that is an internal combustion engine, a compressor 3 for an air conditioner 10 that is rotationally driven by transmitting rotational torque of the engine 2 by a belt 30 and pulleys 31 and 32, and an engine 2. A rotation sensor 4 for detecting the rotation speed of the engine (hereinafter referred to as "engine rotation speed Ne"), a refrigerant pressure sensor 5 for detecting the refrigerant pressure discharged from the compressor 3, and an output control device 8 for controlling the engine output. Yes.
[0009]
The pulley 31 is provided so as to rotate integrally with a rotation shaft (not shown) of the compressor 3, and the pulley 32 is provided so as to rotate integrally with a crank shaft (not shown) of the engine 2. The pulley 31 is provided with an electromagnetic compressor clutch 33 that interrupts rotation from the engine 2 to the compressor 3. The compressor clutch 33 transmits the rotation from the engine 2 to the compressor 3 in the on state to drive the compressor 3 to rotate, and the compressor clutch 33 cuts off the rotation from the engine 2 to the compressor 3 in the off state. Set to the stopped state.
[0010]
The air conditioner 10 has a cooler (cooling / dehumidification function), a heater (heating function), and a well-known ventilation function. A cooler is performed by heat exchange by vaporization and liquefaction of a refrigerant. The other end of the medium pipe 16 connected at one end to the evaporator 14 is connected to the discharge side of the compressor 3. A condenser 11, a receiver 12, an expansion valve 13, and an evaporator 14 are arranged in this order from the compressor 3 side in the refrigerant pipe 16. The expansion valve 13 and the evaporator 14 constitute a cooling unit 15. In this embodiment, the refrigerant pressure sensor 5 is disposed in the receiver 12 and is configured to detect the refrigerant pressure passing through the condenser 11, that is, the high-pressure refrigerant pressure P discharged from the compressor 3. The arrangement location of the refrigerant pressure sensor 5 is not limited to the receiver 12 as long as it is on the refrigerant pipe 16 from the compressor 3 to the expansion valve 13. Outside the refrigerant pipe 16, a refrigerant pipe 17 for returning the refrigerant introduced into the evaporator 15 to the compressor 3 is arranged with both ends thereof connected to the evaporator 15 and the suction side of the compressor 3.
[0011]
Therefore, the low-pressure gaseous refrigerant is compressed by the compressor 3 to become high-temperature and high-pressure gas, cooled by the condenser 11 by the traveling wind or the radiator fan 19 and liquefied, and the high-pressure liquid refrigerant is rapidly expanded by the expansion valve 13. It becomes easy to atomize, and the evaporator 14 generates heat from the surrounding fins to become a gaseous refrigerant. The refrigerant cools by taking a large amount of heat during the vaporization, and becomes a low-pressure gaseous refrigerant again through the refrigerant passage 17 and is returned to the compressor 3.
[0012]
A radiator 18 and a heater core 20 of an air conditioner are connected to a water jacket (not shown) of the engine 2 through a cooling water circulation path. A radiator fan 19 and a blower fan 21 are disposed in the vicinity of the radiator 18 and the heater core 20, respectively. For this reason, the heater generates warm air by taking heat from the heater core 20 heated by the cooling water from the engine 2 by the wind of the blower fan 21 and uses it as heating in the vehicle interior. Switching between the heater and the cooler is performed by operating an air conditioner switch 9 as an operation switch installed on an instrument panel or the like in the passenger compartment.
[0013]
The output control device 8 includes first compressor torque estimating means M1 for estimating the first load torque (S-CPT1) of the compressor 3 based on the pressure information P from the refrigerant pressure sensor 5, and the engine speed Ne from the rotation sensor 4. And an air conditioner ECU 6 as a controller for air conditioner control having a second compressor torque estimating means M2 for estimating a load torque (S-CPT2) higher than at least the first load torque (S-CPT1), An engine ECU 7 is provided as an engine controller for controlling each operation.
[0014]
The engine ECU 7 constituting the output control device 8 is connected to a rotation sensor 4, a compressor clutch 33, a fuel injection system of an engine (not shown), an accelerator opening sensor, an air flow sensor, and the like, and detection information from these sensors. An appropriate amount of fuel is injected into each cylinder of the engine 2 at an appropriate timing by an optimal value such as a fuel injection amount and an ignition timing calculated based on the above, and ignition is performed at an appropriate timing by an ignition plug.
An air conditioner ECU 6 is connected to the engine ECU 7. Along with the compressor 3, the refrigerant pressure sensor 5, and the air conditioner switch 9, the air conditioner ECU 6 is connected with a monitor 22 as a display unit that displays the operating state of the air conditioner and the like.
[0015]
As shown in FIG. 2, an A / C operation signal such as on / off information of the air conditioner switch 9 and the refrigerant pressure P from the refrigerant pressure sensor 5 are sent to the air conditioner ECU 6, and the rotation sensor 4 is sent to the engine ECU 7. The engine speed Ne from is sent. The compressor clutch signal and the engine speed Ne are sent from the engine ECU 7 to the air conditioner ECU 6, and an A / C signal that informs the air conditioner ECU 6 that the cooler is on is estimated from the air conditioner ECU 6 to the air conditioner ECU 6. Each estimated compressor torque (S-CPT1, S-CPT2) is sent.
[0016]
The air conditioner ECU 6 calculates the rotational speed (C-rpm) of the compressor when the A / C is on by multiplying the engine rotational speed Ne by the pulley ratio of the pulleys 31 and 32. As shown in FIG. 3, the first compressor torque estimating means M1 included in the air conditioner ECU 6 is a map in which the vertical axis indicates the estimated compressor torque and the horizontal axis indicates the refrigerant pressure, and the first estimated torque corresponding to the refrigerant pressure P ( S-CPT1) is selected. This map is stored in advance in a memory (not shown) of the air conditioner ECU 6.
[0017]
As shown in FIG. 5, the second compressor torque estimating means M2 included in the air conditioner ECU 6 is a map in which the vertical axis indicates the estimated compressor torque and the horizontal axis indicates the rotation speed (C-rpm) of the compressor 3 at the time of startup. Is stored in advance in a memory (not shown) of the air conditioner ECU 6.
In this map, a second estimated torque (5% to 10%) higher than the first estimated torque (S-CPT1) and a predetermined amount X (5% to 10%) higher than the maximum load torque (T-max) of the compressor 3 indicated by a broken line. S-CPT2) is stored. In FIG. 5, the predetermined amount Y indicates the amount of change in the engine speed Ne that is estimated to increase during the delay time from when the air conditioner ECU 6 reads the engine speed Ne until the compressor clutch 33 is activated. By appropriately setting the predetermined amount Y, the predetermined amount X is uniquely determined. In this way, even if the engine speed Ne fluctuates within the delay time, it can be estimated without falling below the maximum load torque (T-max) of the compressor 3 when the compressor clutch 33 is turned on. A sufficient output of 2 can be secured. The second estimated torque (S-CPT2) becomes substantially constant when the compressor rotation speed (C-rpm) exceeds a certain value because it exceeds the transmission torque performance of the compressor clutch 33.
[0018]
An example of control by the output control device 8 having such a configuration will be described with reference to a flowchart shown in FIG.
When the driver operates the air conditioner switch 9 to turn on in step S1, the engine rotational speed Ne and the refrigerant pressure P are read in step S2, and the process proceeds to step S3. If the A / C signal is turned on in step S3, the process proceeds to step S4, where the compressor clutch signal is determined. If it is turned on, the process proceeds to step S5, and whether a predetermined time t1 has elapsed after the clutch is turned on. It is determined whether or not. In this determination, if the predetermined time t1 has elapsed after the clutch is turned on, the process proceeds to step S6, and the stable torque that becomes the first estimated torque (S-CPT1) is estimated from the refrigerant pressure P by the map shown in FIG. The process proceeds to step S8.
[0019]
If the A / C signal is not turned on in step S3, the compressor clutch signal is not turned on in step S4, or if the predetermined time t1 has not passed since the clutch is turned on in step S5, the process goes to step S7. Then, the starting torque that is the second estimated torque (S-CPT2) is estimated from the engine speed Ne from the map shown in FIG. 5, and the process proceeds to step S8.
[0020]
In step S1, if the air conditioner switch 9 is not turned on, the process proceeds to step S10 to determine whether the A / C signal is off. If it is determined that the air conditioner switch 9 is not turned off, the A / C signal is turned off in step S11 and the process proceeds to step S8. In step S8, the engine ECU 7 controls the output of the engine 2 in accordance with each estimated compressor torque (S-CPT1, S-CPT2) estimated on the air conditioner ECU 6 side, and proceeds to step S9 to control the operation of the compressor clutch 33. To do.
[0021]
FIG. 6 is a map in which the vertical axis represents the actual load torque (CP torque) of the compressor 3 and the horizontal axis represents time (t), and is a characteristic diagram showing the torque fluctuation of the compressor 3 over time. As shown in FIG. 6, immediately after the compressor clutch 33 is turned on (clutch on), the actual load torque (CP torque) of the compressor 3 may suddenly increase to near the maximum load torque (T-max). . This sudden rise occurs because there is a time difference from when the compressor clutch 33 is turned on until the expansion valve 13 responds, and the internal pressure in the refrigerant pipe 16 increases in proportion to the rotational speed of the compressor 3. It seems to be because. Therefore, in the present invention, the output of the engine 2 is controlled using the second estimated torque (S-CPT2) estimated from the engine speed Ne for a predetermined time t1 even when the compressor clutch 33 is on. Then, after the elapse of the predetermined time t1, that is, when the load torque is stabilized after the excessive increase of the load torque that occurs at the time of startup shown in FIG. 6, the first estimated torque (S-CPT1) based on the stable refrigerant pressure P is reached. ) And the output of the engine 2 is controlled using this estimated torque. The first estimated torque (S-CPT1) is substantially the same value as the actual load torque (CP torque) of the compressor 3 when stable.
[0022]
As described above, during the predetermined time t1 when the compressor clutch 33 is turned on and the refrigerant pressure P is not stabilized immediately after the air conditioner is operated, the load torque is not estimated using the unstable refrigerant pressure, and the reliable engine rotation is performed. Since the second load torque (S-CPT2) is estimated based on the number Ne, the load torque of the compressor 3 can be accurately estimated, and the load torque can be accurately estimated regardless of the operation region. Further, in the present embodiment, the second load torque (S-CPT2) is higher than the maximum load torque (T-max) generated in the compressor 3, so that the estimated load torque is the actual load torque within the predetermined time t1. Never fall below.
[0023]
After the predetermined time t1 has elapsed after the compressor clutch 33 is turned on, the first estimated torque (S-CPT1) is estimated based on the refrigerant pressure P whose fluctuation has been stabilized. It can be estimated from the pressure P. That is, the engine output is corrected and controlled using the second estimated torque (S-CPT2) at the time when the refrigerant pressure P is unstable (within the predetermined period t1) immediately after the air conditioner is operated, so that the engine output is too low. Disappears. When the refrigerant pressure P becomes stable after the lapse of the predetermined time t1, the control value is switched to the first estimated torque (S-CPT1) corresponding to the actual load torque (CP torque) of the compressor 3 obtained from the refrigerant pressure P. Since the engine output is corrected and controlled, it is possible to suppress the engine output from becoming higher than necessary and to improve fuel efficiency. For this reason, it is possible to accurately estimate the load torque of the compressor 3 in a wide range of the operation region, and appropriately control the engine output accordingly, thereby improving fuel consumption and drivability.
[0024]
In the present embodiment, the second estimated torque (S-CPT2) is higher than the maximum load torque (T-max), but it is sufficient that it is at least higher than the first estimated torque (S-CPT1). Of course, a torque substantially equal to (T-max) may be used. The first compressor torque estimating means M1 and the second compressor torque estimating means M2 are provided in the air conditioner ECU 6, but may be provided in the engine ECU 7.
[0025]
【The invention's effect】
According to the present invention, the load torque of the compressor is estimated based on the rotational speed of the internal combustion engine within a predetermined time period in which the refrigerant pressure is not stable, such as immediately after the clutch is turned on and the air conditioner is operated. The load torque of the compressor can be estimated more accurately than when estimating the load torque, and the load torque can be estimated accurately regardless of the operating region, the engine output can be controlled appropriately, and fuel efficiency and drivability can be improved. Can be improved.
According to the present invention, since the load torque is estimated using the maximum load torque of the compressor within a predetermined time after the clutch is turned on, the estimated load torque does not fall below the actual load torque, and more appropriately. Engine output can be controlled, and fuel economy and drivability can be improved.
According to the present invention, after a predetermined time has elapsed after the clutch is turned on, the load torque is estimated to be close to the actual load torque based on the refrigerant pressure discharged from the compressor. Therefore, the engine output can be controlled more appropriately, and fuel consumption and drivability can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an output control device for an internal combustion engine and a vehicle having the same according to the present invention.
FIG. 2 is a block diagram showing a configuration of an output control device and a signal flow.
FIG. 3 is a diagram showing characteristics of first estimated torque estimated by first compressor torque estimating means.
FIG. 4 is a flowchart showing an example of output control according to the present invention.
FIG. 5 is a diagram showing characteristics of second estimated torque estimated by second compressor torque estimating means.
FIG. 6 is a diagram illustrating an example of torque fluctuation of a compressor.
[Explanation of symbols]
2 Internal combustion engine 3 Compressor 8 for air conditioner Output control device 33 Clutch Ne Speed P of internal combustion engine Refrigerant pressure S-CPT1 Load torque S-CPT2 estimated from refrigerant pressure Load torque t1 estimated from speed of internal combustion engine Predetermined time T -Max Maximum load torque

Claims (2)

In an output control device for an internal combustion engine that controls an output in accordance with a load torque of a compressor for an air conditioner to which the rotational torque of the internal combustion engine is transmitted via a clutch,
In a predetermined time after the clutch is turned on, the load torque is estimated using a rotational speed of the internal combustion engine and an estimated torque that is higher than the maximum load torque of the compressor by a predetermined amount . Output control device.   2. The output control apparatus for an internal combustion engine according to claim 1, wherein the load torque is estimated based on a refrigerant pressure discharged from the compressor after a predetermined time has elapsed since the clutch was turned on.

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