JP3783663B2 - Vehicle engine start control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine start control device suitable for a vehicle, in particular, an idle stop vehicle that automatically stops and restarts an engine.
[0002]
[Prior art]
In order to improve the fuel consumption and exhaust emission of a vehicle, an idle stop vehicle equipped with an engine automatic stop / automatic restart device is conventionally known. This engine automatic stop / automatic restart device automatically stops the engine when the vehicle temporarily stops due to a signal, etc., and automatically restarts the engine when the vehicle starts again. It is. However, the engine is automatically restarted in a state in which the driving force in the forward direction of the engine can be transmitted to the axle, for example, when the vehicle is automatically stopped with the automatic transmission select lever in the D position. Since the negative pressure in the engine intake passage is small (close to atmospheric pressure), when the engine actually starts up, the engine speed rapidly increases, that is, overshoots, so-called overshoot torque vehicle There is a problem that the acceleration increases rapidly and gives an unpleasant torque shock to the vehicle occupant.
[0003]
Japanese Patent Laid-Open No. 2000-274273 discloses a motor generator (motor generator) that rotates in synchronism with the engine when the engine is automatically restarted in order to reduce such torque shock during engine restart. Discloses a technique for performing regenerative power generation by controlling the rotational speed to a predetermined target rotational speed to suppress overshoot torque when the engine is started.
[0004]
[Problems to be solved by the invention]
However, in order to absorb and cancel the overshoot torque only by the motor generator, it is necessary to perform power running / regenerative control of the motor generator with high accuracy, and there are problems listed below. First, it complicates the control of the power head and the control unit that drive and control the motor generator. Second, a high-power motor having a rated output that can reliably cancel overshoot must be employed, which may increase the size and cost of the motor. Third, when the regenerative operation of the motor is suppressed / prohibited due to a full charge of the battery, overshoot cannot be absorbed / cancelled.
[0005]
The present invention has been made in view of such problems, and effectively absorbs overshoot torque by effectively using a refrigerant compressor such as an air compressor of an air conditioner used in most automobiles.・ It will be offset.
[0006]
[Means for Solving the Problems]
An engine start control device according to the present invention is applied to a vehicle including an engine and a refrigerant compressor of an air conditioner, and overshoot torque absorbing means for absorbing engine overshoot torque at the time of predetermined engine start , engine And a motor generator connected to the battery, capable of both power running and regenerative operation, and performing power running when the engine is started to crank the engine, and the overshoot torque absorbing means includes the battery based on the state of charge is characterized by comprising a motor switching means for switching the motor generator from the power running operation to a regenerative operation or stop state, the refrigerant compressor drive means for temporarily driving the refrigerant compressor, the .
[0007]
【The invention's effect】
According to the present invention, it is possible to reliably absorb and cancel overshoot torque by effectively using a refrigerant compressor employed in most automobiles. Therefore, for example, control can be simplified as compared with the case where the overshoot torque is absorbed only by the motor generator as described above. In addition, even when a motor generator is used in combination and the regenerative operation of the motor generator cannot be performed due to restrictions on the battery side, etc., overshoot torque can be satisfactorily absorbed and offset by the load of the refrigerant compressor, and the refrigerant compressor Since the regenerative torque of the motor generator can be suppressed by the load, the motor generator can be reduced in size and output.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a system configuration diagram schematically showing a hybrid vehicle to which an engine start control device according to an embodiment of the present invention is applied. This vehicle includes an engine 1, a motor generator (motor generator) 2 that rotates in synchronization with the engine 1, a torque converter 4 provided in a power transmission path that connects the motor generator 2 and the drive wheels of the vehicle, and a A step transmission 3.
[0009]
As is well known, the engine 1 is a gasoline engine or a diesel engine that generates driving force by burning fuel such as gasoline or light oil.
[0010]
The motor generator 2 is a three-phase AC motor generator that is connected to the battery 5 via the inverter 6 and is capable of both power running and regenerative operation. For example, when starting the engine 1, it functions as a starting motor by performing a power running operation, and when charging the battery 5, it functions as a generator by performing a regenerative operation. In this embodiment, the rotor of the motor generator 2 is directly connected to the rear end of the output shaft (crankshaft) of the engine 1, but both may be connected via pulleys, belts, sprockets, chains, and the like.
[0011]
In this embodiment, the torque converter 4 and the continuously variable transmission 3 constitute a power transmission mechanism. As the power transmission mechanism, a torque converter and a stepped automatic transmission, or a stepped automatic transmission with an electromagnetic clutch can be adopted. The continuously variable transmission 3 is a belt-type continuously variable transmission in which the speed ratio transmitted via the metal belt 3c is changed by changing the pulley ratio of the two variable pulleys 3a and 3b. A well-known toroidal continuously variable transmission can be used instead of the belt-type continuously variable transmission.
[0012]
The air conditioner of this vehicle is a cooling device, a refrigerant compressor 11 that compresses the refrigerant gas, a capacitor 12 that radiates and liquefies the high-temperature and high-pressure refrigerant gas sent from the refrigerant compressor 11, and sends from this capacitor 12. A liquid tank 13 that temporarily stores the liquefied refrigerant to be stored, and an evaporator 14 that uses the latent heat of evaporation when the liquefied refrigerant is vaporized as a low heat source for cooling, and has a heater core 15 as a heating device. is doing. The blower unit 16 provided with the evaporator 14 and the heater core 15 is provided with an intake door 17, a blower fan motor 18, an air mix door 19, and the like.
[0013]
The refrigerant compressor 11 is connected to the crankshaft of the engine 1 via pulleys 1a and 11a and an auxiliary machine driving belt 7, and is driven to rotate by the engine 1. The refrigerant compressor 11 is capable of adjusting the load continuously or stepwise. It is a variable capacity compressor such as a plate type. The refrigerant compressor 11 includes an electromagnetic clutch 11 b that intermittently transmits power to the engine 1.
[0014]
The vehicle includes an oil temperature sensor 21 that detects the oil temperature of the continuously variable transmission 3, a motor temperature sensor 22 that detects the temperature of the motor generator 2, and a cooling water temperature of the engine 1 as various sensors that detect the vehicle state. A water temperature sensor 23 for detecting the opening, a brake stroke sensor 24 for detecting the opening degree (stroke amount) and ON / OFF of the brake pedal, a slope sensor 25 for detecting a vehicle gradient, and an acceleration sensor 26 for detecting vehicle acceleration. A vehicle speed sensor 27 for detecting the vehicle speed is provided.
[0015]
The vehicle includes a CPU, a ROM, a RAM, and the like, and as a control device (microcomputer system) that stores and executes various control processes, an engine control module 32 that controls the fuel injection amount, ignition timing, and the like of the engine 1; An A / C control module 33 for adjusting / controlling the load of the refrigerant compressor 11 and switching control of ON / OFF of the electromagnetic clutch 11b, a battery controller 34 for calculating / detecting the charged amount (SOC) of the battery 5, and a vehicle And a vehicle control unit 31 for controlling the entire operation. The vehicle control unit 31 outputs a command signal to the engine control module 32 and the A / C control module 33 based on the vehicle state detected and calculated by the various sensors and the like, and sends a command signal to the inverter 6. It outputs and performs the rotation speed control or torque control of the motor generator 2.
[0016]
The vehicle control unit 31 automatically stops the engine 1 when the vehicle temporarily stops at an intersection or the like, that is, performs idle stop, and automatically restarts the engine 1 when the vehicle starts from the idle stop. The engine is automatically stopped and restarted. In other words, when a predetermined engine automatic stop condition is satisfied, including the vehicle speed being zero and the SOC of the battery 5 being equal to or higher than the reference value, fuel injection of the engine 1 (and spark ignition in the case of a gasoline engine) via the engine control module 7. When the predetermined engine automatic restart condition is satisfied, the motor generator 2 is operated in power to crank the engine 1 and fuel injection (and spark ignition in the case of a gasoline engine) is performed. To restart the engine automatically.
[0017]
With reference to FIG.2 and FIG.3, the flow of control which absorbs an engine overshoot torque at the time of an engine automatic restart is demonstrated in detail (overshoot torque absorption means). FIG. 2 is a flowchart executed by the vehicle control unit 31, and FIG. 3 is a time chart when the engine is automatically restarted.
[0018]
In step S1, it is first determined whether or not an idle stop is being performed. Specifically, the shift position of the continuously variable transmission 3 is in the drive (D) range, that is, the state where the driving force can be transmitted from the engine 1 and the motor generator 2 to the drive wheels via the torque converter 4 and the continuously variable transmission 3. When the brake pedal is depressed (brake SW is ON), the vehicle speed is almost 0 (zero), the vehicle door is closed, and the hood is closed. Then, it is determined that the idle stop is being performed, and the process proceeds to S2.
[0019]
In S2, it is determined whether or not there is a drive request for the motor generator 2 for cranking the engine 1. Specifically, when the accelerator pedal depression (accelerator pedal ON) or brake pedal OFF (or looseness) is detected, the battery voltage, brake booster negative pressure, engine water temperature, When either the transmission oil temperature or the transmission oil pressure falls below the specified value, it is determined that there is a cranking request for the engine 1, and the process proceeds to S3. The first time T1 in FIG. 3 corresponds to the time when the determination of S2 is affirmed.
[0020]
In S <b> 3, the power running operation of the motor generator 2 is started, and the motor generator 2 starts the rotational drive of the engine 1, i.e., cranking. As a result, as shown in FIG. 3A, the engine speed increases toward the idle target speed. For example, as shown in FIG. 3 (e), the motor generator 2 is subjected to constant torque control (straight line E1) until the engine speed reaches a predetermined speed lower than the idle target speed, and from this predetermined speed. The constant output control is performed until the idle target rotational speed is reached (curve E2).
[0021]
In S4, it is determined whether or not a first engine start condition is satisfied. The first engine start condition is a condition corresponding to a request for starting fuel injection and spark ignition of the engine 1 and a request for driving the refrigerant compressor 11, and the engine speed is set to a predetermined idle target speed. Affirmed before reaching. In this embodiment, when the input of the cylinder discrimination signal is detected, the determination in S4 is affirmed. Note that the determination in S4 may be affirmed when the engine speed or the motor activation time reaches a predetermined threshold value. The second time T2 in FIG. 3 corresponds to the time when the determination of S4 is affirmed.
[0022]
If the determination in S4 is affirmative, the process proceeds to S5, and engine combustion injection and spark ignition are resumed. In subsequent S6 to S9, in order to reduce and absorb the overshoot torque of the engine, the electromagnetic clutch 11b is turned on and the driving of the refrigerant compressor 11 is started (refrigerant compressor driving means). At this time, the load of the refrigerant compressor 11 acting on the engine 1 side is set in consideration of the overshoot torque and the regenerative torque of the motor generator 2 so as to cancel and absorb the overshoot torque with high accuracy. .
[0023]
Specifically, in S6, the engine overshoot torque is estimated based on the engine cranking elapsed time (T1 to T2), the engine water temperature, the intake negative pressure, and the like. In order to simplify the control, the engine overshoot torque may be a fixed value. In S7, in addition to the overshoot torque, the regenerative torque is estimated based on the SOC of the battery, the battery temperature, and the like. For example, in a situation where the SOC is large and the amount of charge, that is, regenerative power is limited or prohibited, the regenerative torque is limited or zero. In S8, the load of the refrigerant compressor 11 is set based on these overshoot torque and regenerative torque. Specifically, the load of the refrigerant compressor 11 is set so as to absorb the surplus torque obtained by subtracting the regenerative torque from the overshoot torque, and in the subsequent S9, the electromagnetic clutch 11b is turned on to actually drive the refrigerant compressor 11. To start. As an example, a load of about 2 to 3 kW is required to absorb the overshoot torque at the time of releasing the D range idle stop of the 4-cylinder 1.8L engine.
[0024]
Referring to FIG. 3, if the SOC of battery 5 is large and regeneration / charging by motor generator 2 is prohibited, no regenerative torque can be obtained as shown by solid line E3, so only by the load of the refrigerant compressor. It is necessary to absorb overshoot torque. Therefore, as indicated by the solid line F1, the load of the refrigerant compressor 11 is set relatively large. On the other hand, in a situation where the SOC is small and the regenerative torque of the motor generator 2 can be applied (broken line E4), the remaining output obtained by subtracting the output of the motor generator 2 becomes the load of the refrigerant compressor, and as shown by the broken line F2, the refrigerant compressor 11 The load of is set relatively small.
[0025]
Since the energy absorbed by the refrigerant compressor 11 is used to store the evaporator 14, the overshoot torque is generated by the load of the refrigerant compressor 11 even in a situation where the battery is not fully charged and cannot provide regenerative torque. It can be absorbed and offset effectively.
[0026]
In S10, it is determined whether the second engine start condition is satisfied. Specifically, it is determined whether the engine speed has reached the target idle speed, in other words, whether the engine has reached a state where it can operate independently. The third time T3 in FIG. 3 corresponds to the time when the determination of S10 is affirmed.
[0027]
If this S10 is affirmed, the routine proceeds to S11, where the motor generator 2 is switched from the power running operation to the regenerative operation or stopped state (motor switching means). In a situation where the SOC is large and the regenerative operation is prohibited, the motor generator 2 is stopped, that is, in a no-load rotation state as shown by a solid line E3 in FIG. 3, and in other situations, as shown by a broken line E4 in FIG. The motor generator 2 is switched to the regenerative operation. The regenerative torque at this time is used to absorb the overshoot torque as described above.
[0028]
In S12, it is determined whether the engine restart is completed. For example, if the state where the engine speed has reached the idle target speed continues for a predetermined period, it is determined that the engine restart has been completed, that is, complete explosion has occurred, the determination in S12 is affirmed, and the process proceeds to S13 and thereafter. The fourth time T4 in FIG. 3 corresponds to the time when the determination of S12 is affirmed.
[0029]
In S13-15, the refrigerant compressor 11 is returned to a normal operation state. Specifically, if the air conditioner switch provided near the driver's seat or the like is ON, the process proceeds to S14, and the load of the refrigerant compressor 11 is reset based on the current air conditioning request (see the solid line F3 in FIG. 3). When the air conditioner switch is OFF, the process proceeds to S15, the electromagnetic clutch 11b is returned to OFF, and the operation of the refrigerant compressor 11 is stopped (see F4 in FIG. 3).
[0030]
As described above, in this embodiment, in addition to the regenerative torque by the motor generator 2, the load of the refrigerant compressor 11 is used together to absorb and cancel the overshoot torque. Compared with the case where the shoot torque is absorbed and offset, the motor generator 2 can be reduced in size and output, which is advantageous in terms of cost.
[0031]
In addition, the overshoot torque is regenerated with the regenerative torque as much as possible to improve the energy efficiency, and the overshoot torque can be reliably ensured by the load of the refrigerant compressor 11 even in a situation where the regenerative torque cannot be applied due to SOC restrictions or the like. Can be reduced or eliminated.
[0032]
Further, in anticipation of a response delay of the refrigerant compressor 11, the driving start timing T2 of the refrigerant compressor is set before the operation switching timing T3 of the motor generator, that is, the overshoot torque generation timing T3. For this reason, the response delay of the refrigerant compressor 11 can be offset and the overshoot torque can be absorbed with high accuracy.
[0033]
In addition, this invention is not limited to the said Example, A various deformation | transformation and change are included. For example, in the above embodiment, the restart of fuel injection of the engine and the start of driving of the refrigerant compressor 11 are performed at the same timing T2 mainly for the purpose of simplifying the control, but they may be performed at different timings.
[0034]
In the above embodiment, the routine of FIG. 2 for absorbing the overshoot torque is executed only in a state where the driving force of the engine can be transmitted to the axle, that is, in a situation where the overshoot torque affects the propulsive force of the vehicle. However, the above-described routine of FIG. 2 may be executed even when the engine driving force is not transmitted to the axle, for example, when the shift position of the transmission is in the N range or the P range.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a vehicle engine start control device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a control flow at the time of automatic engine restart according to the embodiment.
FIG. 3 is a time chart when the engine is automatically restarted according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Motor generator 11 ... Refrigerant compressor 11b ... Electromagnetic clutch

Claims (5)

In a vehicle including an engine and a refrigerant compressor of an air conditioner,
Overshoot torque absorbing means for absorbing engine overshoot torque at a predetermined engine start ;
A motor generator connected to the engine and the battery, capable of both power running and regenerative operation, and performing power running when the engine is started to crank the engine; and
The overshoot torque absorbing means , based on the state of charge of the battery, motor switching means for switching the motor generator from a power running operation to a regenerative operation or a stopped state; and a refrigerant compressor drive for temporarily driving the refrigerant compressor engine start control device for a vehicle, characterized in that it comprises a means. The vehicle is an idle stop vehicle that automatically stops and restarts the engine,
2. The engine start control device for a vehicle according to claim 1, wherein the predetermined engine start time is an automatic engine restart time. The refrigerant compressor is a variable capacity type,
The refrigerant compressor driving means adjusts a load of the refrigerant compressor based on a vehicle state ;
And the refrigerant compressor drive means,
Means for estimating the regenerative torque of the motor generator;
The vehicle engine start control device according to claim 1 , further comprising: a unit that calculates a load of the refrigerant compressor based on the overshoot torque and the regenerative torque . The said overshoot torque absorption means operates the said refrigerant | coolant compressor drive means so that the surplus torque which deducted the regenerative torque by the said motor switching means from the overshoot torque may be absorbed . An engine starter for a vehicle according to any one of the above. The vehicle engine start control according to any one of claims 1 to 4, wherein driving of the refrigerant compressor by the refrigerant compressor driving means is started before switching the operation of the motor generator by the motor switching means. apparatus.

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