JP3518588B2 - Hybrid electric vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a hybrid electric vehicle, and more particularly to an output control technique for a parallel hybrid electric vehicle. 2. Description of the Related Art In recent years, a parallel hybrid electric vehicle has been developed in which an internal combustion engine is mounted together with an electric motor (motor) as a driving force source of a vehicle, and the vehicle can travel in accordance with the output of the electric motor and the output of the internal combustion engine. And have become publicly known. In such a parallel-type hybrid electric vehicle, usually, since the acceleration response of the motor is good, the motor is preferentially operated, and the shortage of the required output by the output of the motor is compared with the output of the internal combustion engine. To make up for it. When the remaining capacity of the battery for supplying electric power to the electric motor is insufficient, the electric motor (or generator) is operated to generate electric power mainly by the output of the internal combustion engine to charge the battery. However, in the above-mentioned parallel hybrid electric vehicle, when the driver requests an output larger than the maximum output of the internal combustion engine alone, the remaining capacity of the battery is not sufficient. In this case, an output corresponding to the required output can be secured.However, when the remaining capacity of the battery is small and the output of the electric motor is small, the shortage of the electric motor cannot be compensated for by the output of the internal combustion engine. There is a problem that the source cannot secure an output that meets the required output. In other words, when the driver requests an output larger than the maximum output of the internal combustion engine alone, the generated output of the driving power source varies depending on the remaining capacity of the battery even though the output is the same. There is a problem. [0004] Even if the remaining capacity of the battery is sufficient when the driver requests an output larger than the maximum output of the internal combustion engine alone, the output request continues for a long period of time and the remaining capacity of the battery remains unchanged. When the output of the electric motor decreases due to the decrease of the electric power, the same problem occurs again, and the output of the entire driving force source may suddenly decrease while the vehicle is accelerating. Further, at this time, when the electric motor is used as a generator because the remaining capacity of the battery is small, the output of the internal combustion engine is taken away by the power generation, and the output for traveling further decreases. There is also a risk. As described above, it is not possible for the driver to vary the generated output of the driving power source in accordance with the remaining capacity of the battery irrespective of the same output request, or to suddenly decrease the output of the entire driving power source irrespective of acceleration traveling. This is unpleasant because it gives a sense of discomfort. The present invention has been made to solve such a problem, and an object of the present invention is to provide a hybrid electric system which can always generate the same output in response to an output request regardless of the remaining capacity of a battery. To provide a car. [0007] In order to achieve the above object, according to the first aspect of the present invention, the hybrid electric vehicle is configured such that the target output of the internal combustion engine is controlled by the driving force source control means.
When the output exceeds the maximum output, the motor is given priority at the effective maximum output.
Manner within the output range limits the maximum output of the internal combustion engine of limiting the maximum output value of the effective maximum output amount corresponding internal combustion engine as well as operation, the output of the entire driving force source the maximum output value of the internal combustion engine
The operation of the internal combustion engine is controlled so as not to exceed . That is, the maximum output of the driving force source is always made equal to the maximum output of the internal combustion engine regardless of the remaining capacity of the battery. Thus, even if the required output from the driver is large, Regardless of the remaining capacity of the battery, the same output can always be generated from the driving force source in response to the output request, and the driver is preferably prevented from feeling uncomfortable. When the internal combustion engine is operated within the output range in which the maximum output of the internal combustion engine is suppressed by the effective maximum output of the motor when the remaining capacity of the battery is sufficient, the target output power is particularly increased. Therefore, the degree of enrichment of the air-fuel ratio, which tends to be greatly enriched during acceleration running, can be suppressed to be small. For example, if the internal combustion engine is capable of stoichiometric (stoichiometric air-fuel ratio) operation or lean air-fuel ratio operation, Lean air-fuel ratio operation can be continuously performed, and fuel efficiency is improved. Embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, there is shown a schematic configuration diagram of a parallel hybrid electric vehicle. Hereinafter, the configuration of the hybrid electric vehicle of the present invention will be described with reference to FIG. As shown in FIG. 1, a parallel-type hybrid electric vehicle has an engine (internal combustion engine) 1 and a motor generator (electric motor) 1 as driving power sources (power plants).
0, the output shaft 2 of the engine 1 is connected to the rotation shaft 12 of the motor generator 10 via the clutch device 4 in the parallel hybrid electric vehicle of the present invention. Reference numeral 12 is connected to a drive shaft 22 via an automatic transmission 20. Further, an axle 26 is connected to the drive shaft 22 via a differential gear 24. A pair of wheels 28, 28 are connected to both ends of the axle 26 as drive wheels. The engine 1 is, for example, a water-cooled gasoline engine, and has a sufficient maximum output capable of driving the wheels 28 and 28 to run the vehicle. The clutch device 4 is a clutch device in which the clutch plate 4a on the engine 1 side moves and disconnects from the clutch plate 4b on the motor generator 10 side. The clutch plate 4a is disengaged by the electric actuator 6 via the rod 7. It is configured to be touched. The motor generator 10 is an electric motor that functions as both a motor and a generator, that is, a generator, and is configured such that a stator coil (excitation coil) 16 surrounds a rotor coil 14 integrated with a rotating shaft 12. Have been. That is, the motor generator 10
Functions as a motor that rotates the rotating shaft 12 by energizing the stator coil 16 to generate a magnetic field and also energizing the rotor coil 14 to generate a magnetic field. On the other hand, a generator that generates an exciting current in the rotor coil 14 by generating a magnetic field by rotating the rotor coil 14 integrated with the rotating shaft 12 by an external force from the wheels 28, 28 transmitted via the drive shaft 22. Function as Then, the motor generator 10
When functioning as a motor, the output can be changed by changing the amount of power to the rotor coil 14, while when functioning as a generator, the amount of power can be adjusted by changing the amount of power to the stator coil 16. It has been. The rotating shaft 12 has a motor generator 1
A rotation speed sensor 13 for detecting a rotation speed of 0, that is, a driving force source rotation speed N is provided. The automatic transmission 20 reduces or increases the rotation speed of the rotating shaft 12, changes the output torque generated on the motor generator 10 side, and transmits the output torque to the wheels 28, 28. For example, a continuously variable automatic transmission is used. In addition, the continuously variable automatic transmission is well-known, and the description thereof is omitted here. Electronic control unit (ECU)
Reference numeral 50 denotes a main control unit which comprises a central processing unit (CPU) and controls various operations of the electric vehicle. The input side of the main control unit 50 is connected to an accelerator pedal 52 in addition to the above-described rotation speed sensor 13 and the like. The operation amount of the accelerator pedal 52,
That is, an accelerator position sensor (APS) 54 for detecting an accelerator opening θacc which is a driver's required output is connected, and a battery (secondary battery) for operating not only the ECU 50 but also various drive units. )
70 are connected. Note that the battery 70 is connected so that when the motor generator 10 functions as a generator, the generated power according to the amount of electricity supplied to the stator coil 16 is charged and stored. On the other hand, the output side of the ECU 50 is connected to the electric actuator 6, the rotor coil 14 and the stator coil 16 of the motor generator 10, and the like.
Hereinafter, the operation of the hybrid electric vehicle configured as described above, that is, the output control content of the hybrid electric vehicle according to the present invention will be described. Referring to FIG.
A flow chart of a control routine of the output control according to the present invention, which is executed by the control unit 50, is shown (driving force source control means). Referring to FIG. 3, the driving force source rotation speed N and the driving force in the output control are shown. The motor torque Tpm and the engine torque Tpe together with the relationship with the total torque Tp of the source
2 is visually shown, and will be described below with reference to FIG. 3 along the flowchart of FIG. By the way, in the hybrid electric vehicle, the driving force source rotation speed N is changed from the start to the predetermined rotation speed N1.
Until the speed reaches, for example, 1000 rpm, the motor travel is performed only by the motor generator 10, and the motor travel and the engine travel are performed by adding the output of the engine 1 to the output of the motor generator 10 within a range of a predetermined rotation speed N1 or more. Hereinafter, a case where the driving force source rotation speed N is equal to or higher than the predetermined rotation speed N1 will be described. First, in step S10, a required torque (target output) Td required for the driving force source is calculated based on information from the APS 54 (target output detecting means). In step S12, the required torque Td is equal to the rated maximum torque of motor generator 10 (effective maximum output).
It is determined whether the difference is equal to or less than Tmmax. That is, it is determined whether or not the range is such that the motor can be driven only by the motor generator 10. If the determination result is true (Yes) and it is determined that the required torque Td is equal to or less than the rated maximum torque Tmmax, the process proceeds to step S14. In step S14, it is determined whether or not the state of charge of the battery 70, that is, the state of charge (SOC) is equal to or greater than a predetermined capacity SOCmin capable of securing the rated maximum torque (effective maximum output) Tmmax. Judge (motor maximum output deriving means). The SOC can be easily detected by a voltmeter connected to the battery 70 (battery remaining capacity detecting means). If the determination result is true (Ye
If it is determined in s) that the SOC is equal to or greater than the predetermined capacity SOCmin, that is, the charge amount of the battery 70 is sufficient, the process proceeds to step S16. In step S16, a torque generated by the motor generator 10, that is, a motor torque Tpm is calculated based on the required torque Td. Here, the motor torque Tp
m is made equal to the required torque Td (Tpm = Td).
Then, in step S18, the motor running is performed with the total torque Tp of the driving force source as the motor torque Tpm (Tp = Tpm). That is, when the required torque Td is equal to or less than the rated maximum torque Tmmax and the charged amount of the battery 70 is sufficient, the clutch device 4 of the engine 1 is disconnected, and the vehicle travels only with the output of the motor generator 10. I do. On the other hand, if the determination result of step S14 is false (N
If it is determined in o) that the SOC is less than the predetermined capacity SOCmin, that is, if it is determined that the charge amount of the battery 70 is small enough to ensure the rated maximum torque Tmmax, the process proceeds to step S20. In step S20, in order to charge the battery 70, the motor generator 10 is driven to generate electric power by the driving force of the engine 1, so that the negative torque generated in the power generating operation of the motor generator 10, that is, the generated torque Tge (negative value). Is calculated. Further, based on the required torque Td and the generated torque Tge,
The generated torque of the engine 1, that is, the engine torque Tpe is calculated. Then, in step S22, the total torque Tp of the driving force source is set to the sum of the engine torque Tpe and the power generation torque Tge (Tp = Tpe + Tge), and the engine travels and the engine power travel is performed (engine travel + engine power travel). . In other words, even if the required torque Td is equal to or less than the rated maximum torque Tmmax, the SOC remains at the predetermined capacity SO.
If the charge amount of the battery 70 is smaller than Cmin, the clutch device 4 of the engine 1 is connected, and the vehicle runs with the output of the engine 1. If the result of the determination in step S12 is false (N
If it is determined in o) that the required torque Td is greater than the rated maximum torque Tmmax, the process proceeds to step S24, where the required torque Td is greater than the rated maximum torque Tmmax, ie, the maximum torque of the engine 1 alone, that is, the engine It is determined whether the torque is equal to or less than the maximum torque Temax. The determination result is true (Yes), and the required torque Td is the rated maximum torque T
If it is determined that it is within the range between mmax and the engine maximum torque Temax, the process proceeds to step S26. In step S26, the above-mentioned step S14
As in the case of, it is determined whether or not the SOC is equal to or more than the predetermined capacity SOCmin. If the determination result is true (Yes) and SO
If C is equal to or larger than the predetermined capacity SOCmin, the process proceeds to step S28. In step S28, the engine torque Tp is set together with the motor torque Tpm based on the required torque Td.
e is calculated. Specifically, here, since the charge amount of the battery 70 is sufficient, the motor torque Tpm is set to the rated maximum torque Tmmax (Tpm = Tmmax), and the shortage of the rated maximum torque Tmmax is set to the engine torque Tpe. . Then, in step S30, the total torque Tp of the driving force source is set to the sum of the rated maximum torque Tmmax and the engine torque Tpe (Tp = Tmmax + Tp
e) Motor running and engine running are performed (motor running + engine running). That is, the required torque Td is larger than the rated maximum torque Tmmax and the engine maximum torque Tem
ax or less and when the charge amount of the battery 70 is sufficient, the clutch device 4 of the engine 1 is connected, the motor is driven with the output of the motor generator 10 at the maximum, and the shortage of the motor output is detected by the engine. The engine is run so as to compensate with the output of 1. On the other hand, if the determination result of step S26 is false (N
If it is determined in step o) that the SOC is less than the predetermined capacity SOCmin, the process proceeds to step S22 through step S20.
To perform the engine running and the engine power generation running as described above. If the result of the determination in step S24 is false (No), that is, if it is determined that the required torque Td is not within the range between the rated maximum torque Tmmax and the engine maximum torque Temax and is larger than the engine maximum torque Temax, then step S32 is performed. To step S14, step S2
As in the case of No. 6, it is determined whether or not the SOC is equal to or more than the predetermined capacity SOCmin. If the determination result is true (Yes) and S
If OC is equal to or greater than the predetermined capacity SOCmin, the process proceeds to step S34. In step S34, the above-mentioned step S28
As in the case of (1), the engine torque Tpe is calculated together with the motor torque Tpm based on the required torque Td. That is, since the charge amount of the battery 70 is sufficient, the motor torque Tpm is set to the rated maximum torque Tmmax (T
pm = Tmmax), and the shortage of the rated maximum torque Tmmax is calculated as the engine torque Tpe. However, in this case, regarding the engine torque Tpe, the rated maximum torque Tmmax and the engine torque Tpe
The sum with pe is the maximum engine torque T of the engine 1 alone.
Set it so that it does not exceed emax. That is, FIG.
As shown in the figure, the maximum total torque Tpmax is defined as the engine maximum torque Temax, and the value obtained by subtracting the rated maximum torque Tmmax (shaded area in the figure) from the engine maximum torque Temax, that is, the limited engine maximum torque (limited maximum output)
Temmax is set to the engine torque Tpe (Tpe = Temmax). In step S36, the total torque Tp of the driving force source is set to the sum of the rated maximum torque Tmmax and the limited engine maximum torque Temmax (Tp = Tmmax).
+ Temmax), the motor running and the engine running are performed such that the total torque Tp does not exceed the engine maximum torque Temax of the engine 1 alone (motor running + engine running). That is, when the required torque Td is larger than the engine maximum torque Temax and the charge amount of the battery 70 is sufficient, the motor is driven with the output of the motor generator 10 at the maximum, and the total torque Tp is increased regardless of the required torque Td. The engine is driven so as to be equal to the engine maximum torque Temax of the engine 1 alone. On the other hand, if the determination result of step S32 is false (N
In the case of o), if the SOC is less than the predetermined capacity SOCmin, the process proceeds to step S38, where the generated torque of the engine 1 based on the required torque Td, that is, the engine torque Tpe
Is calculated. That is, similarly to the above, the SOC becomes the predetermined capacity SO.
In the case where it is less than Cmin, the motor running is stopped, and the required torque Td is covered by the output of the engine 1. However, in this case, the required torque Td is larger than the engine maximum torque Temax, but the engine 1 cannot output any more torque.
Is the engine maximum torque Temax. In this case, the power generation torque Tg
e is not calculated, this is due to the engine torque Tpe
Is no longer the engine maximum torque T according to the required torque Td.
This is because emax has been reached and there is no room to supplement the power generation torque Tge. Then, in step S40, the total running torque Tp of the driving force source is set to the engine maximum torque Temax (Tp = Temax), and the engine runs. As described above, in the output control of the hybrid electric vehicle according to the present invention, the required torque Td is larger than the engine maximum torque Temax of the engine 1 alone, the SOC is equal to or more than the predetermined capacity SOCmin, and the charge amount of the battery 70 is reduced. Even if it is sufficient, the maximum total torque Tpmax is set to the maximum engine torque Tem of the engine 1 alone as in the case where the charge amount of the battery 70 is not sufficient and the engine runs only with the engine 1 (step S40).
ax (see FIG. 3), and the required torque Td
Regardless of the total torque Tp is the maximum total torque Tpmax,
That is, the vehicle travels so as to be equal to the engine maximum torque Temax (step S36). Therefore, when the required torque Td is larger than the engine maximum torque Temax of the engine 1 alone, the total torque Tp is always the maximum total torque Tpmax, that is, the engine maximum torque Temax regardless of the magnitude of the SOC.
As a result, the variation in the output of the driving force source during acceleration running, that is, the required torque Td
The variation of the total torque Tp with respect to the occupant is eliminated, and the occupant is preferably prevented from feeling uncomfortable. Further, the result of the determination in step S32 is determined to be true (Yes), and step S36 is executed, and the total torque Tp of the driving force source is set to the maximum based on the sum of the rated maximum torque Tmmax and the limited engine maximum torque Temmax. In the case where the total torque Tpmax is set, if the state where the required torque Td is larger than the engine maximum torque Temax is continued for a long period of time, the charge amount of the battery 70 gradually decreases and the SOC becomes less than the predetermined capacity SOCmin. In this case, the result of the determination in step S32 is false (No), the motor travel is stopped, and only the engine travel is performed. The torque Tp is satisfactorily maintained at the maximum total torque Tpmax, that is, the engine maximum torque Temax. As a result, the output does not suddenly decrease due to the decrease in the SOC while the vehicle is accelerating, and the occupant is also preferably prevented from feeling uncomfortable. As described above, when the required torque Td is larger than the engine maximum torque Temax of the engine 1 alone and the SOC is equal to or more than the predetermined capacity SOCmin,
Distribute the torque of Engine 1 to the maximum engine torque Temax
Than the rated maximum torque Tmma of the motor generator 10.
Assuming that the limited engine maximum torque Temmax is smaller by x, the degree of enrichment of the air-fuel ratio, which tends to be greatly enriched particularly during acceleration running with a large required torque Td, can be suppressed to a small value. If the operation or the engine 1 is an engine capable of operating at a lean air-fuel ratio, the lean air-fuel ratio operation can be continuously performed, and there is an advantage that the fuel consumption can be prevented from increasing unnecessarily. As a result, it is possible to prevent the fuel efficiency from deteriorating and to reduce the amount of harmful substances contained in the exhaust gas and discharged into the atmosphere. In the above embodiment, for example, the maximum torque of the rich air-fuel ratio operation is set to the engine maximum torque Temax, that is, the maximum total torque Tpmax.
It is not always necessary to match the engine maximum torque Temax with the maximum total torque Tpmax.
pmax may be appropriately changed and set according to the use or specification of the vehicle. That is, the maximum torque of the stoichiometric air-fuel ratio operation is defined as the maximum total torque Tpmax, the maximum torque of the rich air-fuel ratio operation is defined as the engine maximum torque Temax, and the motor generator 1 is calculated from the maximum torque of the stoichiometric air-fuel ratio operation.
A value obtained by subtracting the rated maximum torque Tmmax of 0 may be defined as the limited engine maximum torque Temmax. In this manner, the maximum total torque Tpma
Even when the vehicle is traveling at x, the power generation operation of the motor generator 10 becomes possible. That is, the power generation torque Tge generated by the power generation operation of the motor generator 10 can be compensated for by the increase in torque due to the rich air-fuel ratio operation, and the maximum total torque Tpmax can be kept from changing even when the power generation operation is performed. . Further, when the maximum torque of the stoichiometric air-fuel ratio operation is set to the maximum total torque Tpmax, the fuel consumption is reduced as a whole as compared with the case where the maximum torque of the rich air-fuel ratio operation is set to the maximum total torque Tpmax. ,
The case where the maximum torque of the stoichiometric air-fuel ratio operation is set to the maximum total torque Tpmax is set as the economy mode,
A configuration may be adopted in which the driver can freely select the economy mode during traveling. This makes it possible to improve the fuel efficiency by reducing the frequency of performing the rich air-fuel ratio operation. In this case, it is preferable to display by a lamp or the like that the current traveling is traveling in the economy mode. In the above embodiment, the required torque Td
Is larger than the rated maximum torque Tmmax,
It is determined whether or not OC is equal to or more than a predetermined capacity SOCmin,
When the SOC is less than the predetermined capacity SOCmin, the motor travel is completely stopped and only the engine is run. However, even when the SOC becomes less than the predetermined capacity SOCmin, the motor torque Tpm corresponding to the SOC is reduced. , And while maintaining the total torque Tp (including the maximum total torque Tpmax) of the driving force source, the engine torque Tpe according to the maximum value (effective maximum output) of the motor torque Tpm that changes with the SOC. May be variably set. By doing so, the SOC becomes equal to the predetermined capacity SO.
When it is less than Cmin, the running state can be gradually shifted to the engine running in accordance with the decrease of the SOC, and smooth running can be realized. As described above in detail, according to the hybrid electric vehicle of the first aspect of the present invention, the maximum output of the driving power source is always the maximum output of the internal combustion engine regardless of the remaining capacity of the battery. Therefore, even when the required output from the driver is large, the same output is always output from the driving power source in response to the output request regardless of whether the remaining battery capacity is sufficient. This makes it possible to prevent the driver from feeling uncomfortable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a hybrid electric vehicle according to the present invention. FIG. 2 is a flowchart showing a control routine of output control according to the present invention. FIG. 3 is a graph showing the relationship between the driving force source rotation speed N and the total torque Tp of the driving force source in the output control according to the present invention, wherein the torque distribution between the motor torque Tpm and the engine torque Tpe in the output control is shown. FIG. [Description of Signs] 1 engine (internal combustion engine) 4 clutch device 10 motor generator (electric motor) 13 rotation speed sensor 50 electronic control unit (ECU) 54 accelerator position sensor (APS) 70 battery

Continuation of the front page (51) Int.Cl. ⁷ identification code FI B60K 6/04 530 B60K 6/04 530 730 730 B60L 11/14 B60L 11/14 (58) Investigation field (Int.Cl. ⁷ , DB name) ) F02D 29/02 F02D 29/06 B60K 6/02-6/04

Claims (1)

(57) [Claim 1] A driving power source for a vehicle comprising an internal combustion engine and an electric motor, target output detecting means for detecting a target output required for the driving power source, and the electric motor Battery remaining capacity detecting means for detecting a remaining capacity of a battery that supplies power to the motor; motor maximum output deriving means for deriving an effective maximum output of the motor according to a detection value of the battery remaining capacity detecting means; the target output is detected by the detection means
When the maximum output of the internal combustion engine is exceeded , the motor is
The internal combustion engine is operated preferentially at the effective maximum output derived by the motor maximum output deriving means , and the maximum output value of the internal combustion engine is limited by the effective maximum output.
Within the output range of the output, the output of the entire driving force
A hybrid electric vehicle comprising: driving force source control means for controlling the operation of the internal combustion engine so as not to exceed the maximum output value of the fuel engine .