JP2000217201A - Regenerative braking controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regenerative braking controller which can keep the energy regeneration efficiency high and can always ensure sufficient braking force. SOLUTION: Generally, when there is a demand on a vehicle to brake, a clutch between an internal combustion engine and members of a drive system is disconnected and a generator connected to the members of a drive system is actuated to generate power by external force transmitted from wheels via the members of a drive system, by which regenerative braking is accomplished. Meanwhile, a service brake is actuated according to a demanded quantity of braking to compensate for the shortage of braking force caused by a regenerative braking (S16-S22). However, if the braking load of the serving brake detected or estimated by a brake load detector becomes a proscribed value or higher (S26), when regenerative braking is limited according to a quantity of stored energy of a battery by a regenerative braking limiting means (S24), the clutch is connected by an engine brake controller so as to operate an engine brake (S28-S36).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerative braking control device, and more particularly, to a braking control technique for regenerating braking energy as electric energy.

[0002]

2. Description of the Related Art A generator is connected to a drive shaft (drive system member) of an internal combustion engine mounted on a vehicle, and an external force transmitted from the wheels through the drive shaft when the vehicle is in a braking state is used. 2. Description of the Related Art An energy regenerating device that operates a generator and thereby applies a braking force to wheels via a drive shaft and generates power is disclosed in Japanese Patent Application Laid-Open No. Hei 9-135502 and the like.

[0003] In such an energy regenerating apparatus, electric energy regenerated by power generation is charged into a battery and accumulated, and in the technology disclosed in the above-mentioned publication, power is generated by a generator during energy regenerating. amount,
That is, an attempt is made to maximize the amount of energy regeneration.

[0004]

In the technique disclosed in the above publication, the internal combustion engine is always connected to the drive shaft. Therefore, in this technology, even if an attempt is made to regenerate energy by the generator, the engine brake always operates, and it is difficult to realize highly efficient energy regeneration.

[0005] Therefore, it has been considered that the internal combustion engine is separated from the drive shaft at the time of energy regeneration, whereby the external force from the wheels can be efficiently transmitted to the generator. Then, in this case, as for the braking force that is insufficient due to the braking force generated by the power generation of the generator, the service brake (drum brake, Friction brakes such as disc brakes) are used to compensate.

However, when the charged amount of the battery has reached or is close to the charged capacity, the power generation by the generator is usually prohibited or largely restricted in order to prevent overcharging. In this case, there is a problem that the load on the service brake becomes extremely large. In particular,
When the vehicle is driven for a long time while braking on a downhill road or the like, the service brake may cause a fade phenomenon and the braking force may be attenuated, which is not preferable.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a regenerative braking control device capable of maintaining high energy regeneration efficiency and always ensuring a sufficient braking force. To provide.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, the clutch between the internal combustion engine and the drive system member is normally disconnected by the regenerative braking means.
A generator connected to the drive system member is operated by an external force transmitted from wheels via the drive system member to generate power, thereby performing regenerative braking, and a service brake is operated according to a required braking amount. This compensates for the lack of the braking force due to the regenerative braking. However, the service detected or estimated by the brake load detecting means when the regenerative braking is limited by the regenerative braking limiting means according to the state of charge of the battery. When the braking load of the brake becomes larger than a predetermined amount, the clutch is connected by the engine brake control means and the engine brake operates.

Therefore, at the time of energy regeneration, the generator can be operated very efficiently by the external force from the wheels, and reliable braking can be realized with good response by the service brake. In this case, the use of the engine brake prevents the occurrence of a fade phenomenon due to an excessive load on the service brake.

[0010] Thus, during braking of the vehicle, high-efficiency energy regeneration can be realized and a sufficient braking force can always be ensured.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, a schematic configuration diagram of a hybrid electric vehicle is shown. Hereinafter, a configuration of a regenerative braking control device according to the present invention will be described with reference to FIG. The hybrid electric vehicle shown in FIG. 1 is of a so-called parallel type, in which an output shaft 2 of an engine (internal combustion engine) 1 is connected to a rotating shaft (drive system member) of a motor generator 10 via a clutch device (clutch) 4. The rotation shaft 12 of the motor generator (generator) 10 is connected to a drive shaft (drive system member) 2 through an automatic transmission 20.
2 are connected. 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 engine 1 is provided with a coolant temperature sensor 3 for detecting a coolant temperature, that is, a coolant temperature Tw.
Further, near the output shaft 2, the rotation speed of the output shaft 2,
That is, an engine rotation sensor 5 for detecting the engine rotation speed Ne is provided.

The clutch device 4 includes a motor generator 1
A clutch device in which the clutch plate 4a on the engine 1 side moves and disconnects from the clutch plate 4b on the 0 side,
The clutch plate 4a is configured to be connected and disconnected by the electric actuator 6 via the rod 7. 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 the rotating shaft 12. .
That is, the motor generator 10 includes the stator coil 1
6 to form a magnetic field, and the rotor coil 14
The motor also functions as a motor that rotates the rotating shaft 12 by generating a magnetic field by energizing the rotating shaft 12, and forms a magnetic field by energizing the stator coil 16. Wheels 28 transmitted through
The rotor coil 14 functions as a generator that generates an exciting current in the rotor coil 14 by generating a magnetic field by rotating the rotor coil 14 by an external force.

Then, the motor generator 10
When functioning as a motor, the output can be changed by changing the amount of current supplied to the rotor coil 14. On the other hand, when functioning as a generator, the amount of generated power can be changed by changing the amount of power supplied to the stator coil 16. It has been. By the way, when the motor generator 10 functions as a generator, the rotational energy of the rotor coil 14 is converted into electric energy, so that the rotational speed of the rotor coil 14 is reduced by an amount corresponding to the power generation amount. become. That is, the motor generator 1
When it is set to 0, it functions as a braking device at the same time as generating electricity when functioning as a generator. That is, if the motor generator 10 is caused to function as a generator when the vehicle is to be braked, vehicle braking (regenerative braking) can be performed while satisfactorily changing the braking energy into electric energy (regenerative braking means).

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 known, and the description thereof is omitted here. As shown in the figure, the axle 26 is provided with a pair of hydraulic disc brake devices (service brakes) 30, 30 near the wheels 28, 28.
The hydraulic disc brake devices 30, 30 sandwich the discs 32, 32 which rotate together with the axle 26, with brake pads 34, 34 operated by hydraulic pressure to generate frictional force, and attenuate the rotation of the wheels 28, 28 by the frictional force. This is a hydraulic brake for braking the vehicle.

Accordingly, one end of a high-pressure oil passage 36 is connected to each of the brake pads 34, 34, and the other end of the high-pressure oil passage 36 is connected to a high-pressure pump 40 via an electromagnetic pressure regulating valve 38. I have. Further, the high-pressure pump 40 is connected to an oil tank 42. That is, the hydraulic oil in the oil tank 42 is made high pressure by the high pressure pump 40,
Thereafter, the pressure is adjusted by the electromagnetic pressure adjusting valve 38 and supplied to the brake pads 34, 34. As a result, the electromagnetic pressure adjusting valve 38 is appropriately adjusted to change the hydraulic pressure,
The braking force of the hydraulic disc brake devices 30, 30 is made variable.

Electronic control unit (ECU) 50
Is a main control device which comprises a central processing unit (CPU) and controls various operations of the electric vehicle. The input side of the main control device includes an accelerator pedal 52 in addition to the water temperature sensor 3 and the engine rotation sensor 5 described above. Connected to the accelerator pedal 5
2, an accelerator position sensor (APS) 54 for detecting the accelerator opening θacc, and a brake pedal 56,
That is, the brake pedal pressure sensor 58 for detecting the degree of braking request is connected, and a battery (secondary battery) 70 for operating not only the ECU 50 but also various drive units is connected. The battery 70
Are connected such 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, on the output side of the ECU 50, the electric actuator 6, the rotor coil 14 and the stator coil 16 of the motor generator 10, the electromagnetic pressure regulating valve 38
Etc. are connected. Hereinafter, the operation of the regenerative braking control device according to the present invention of the hybrid electric vehicle configured as described above will be described.

Referring to FIG. 2, there is shown a flowchart of a braking control routine executed by the ECU 50, and will be described below with reference to the flowchart.
First, in step S10, it is determined whether or not the accelerator is off. That is, the driver's foot separates from the accelerator pedal 52, and the accelerator opening θac based on the output value of the APS 54.
It is determined whether or not c has become the value 0 (or a predetermined value near the value 0), and the vehicle has shifted to the braking state.

If the result of the determination in step S10 is false (No)
In this case, it can be considered that the vehicle has not shifted to the braking state. In this case, the routine exits without performing anything. On the other hand, if the determination result is true (Yes) and it is determined that the vehicle has shifted to the braking state, then step S1 is performed.
Proceed to 2. In step S12, the state of charge (SOC) of the battery 70 is calculated. Actually, the relationship between the charge voltage of the battery 70 and the SOC is mapped in advance, and the SOC is read from the map (charge state detection means).

In step S14, the SOC becomes a predetermined value X1
It is determined whether or not the above is true, that is, whether or not the charge amount of the battery 70 is saturated. Usually, when the motor generator 10 functions as a motor and the vehicle is running immediately before the accelerator is turned off, it is considered that the electric power charged in the battery 70 was being consumed by the motor generator 10. Therefore, in this case, the determination result of step S14 is false (No), and the SOC can be determined to be less than the predetermined value X1, and the process proceeds to step S16.

When the vehicle has shifted to the braking state and S
When the OC is less than the predetermined value X1 and the battery 70 has room for charging, the regenerative braking of the motor generator 10 is preferentially performed, and the braking energy is effectively recovered. Is compensated by a hydraulic brake having a good braking response. At this time, if the braking force can be covered only by the regenerative braking, the hydraulic braking force is set to zero.

In step S16, the distribution of the regenerative braking force and the hydraulic braking force is calculated. For more information,
First, the amount of power to the stator coil 16 is set based on the braking request degree information from the brake pedal pressure sensor 58,
The regenerative braking force by motor generator 10 is set. Actually, the amount of current supplied to the stator coil 16 and the regenerative braking force are mapped in advance, and a regenerative braking force that satisfies the degree of braking request is read from the map. Then, when the regenerative braking force is less than the required braking degree, the difference is compensated for by the hydraulic braking force.

After the distribution of the regenerative braking force and the hydraulic braking force is determined as described above, the clutch is disconnected in step S18. That is, the clutch device 4 is set in the disconnected state, and the rotating shaft 12 of the motor generator 10 and the engine 1
Is disconnected from the output shaft 2. After the clutch is disengaged, the engine 1 is brought into an idle state or a stopped state, and is brought into a non-drive state.

As described above, when the clutch is released during braking, the engine braking effect of the engine 1 can be completely eliminated, whereby the external force transmitted from the wheels 28, 28 transmitted through the drive shaft 22 is substantially 100%. Coil 1
4 so that the amount of power generated by the motor generator 10 can be maximized and the braking energy can be efficiently converted to electric energy.

Then, in step S20, regenerative braking control is performed based on the regenerative braking force obtained in step S16. That is, the amount of power supply to the stator coil 16 of the motor generator 10 is controlled. Note that the regenerative braking control is performed by a subroutine (not shown).
Further, in step S22, the above-described step S16
The hydraulic brake is performed based on the hydraulic brake force obtained in step. That is, the valve opening degree of the electromagnetic pressure adjusting valve 38 is controlled. The hydraulic brake control is also performed in a subroutine (not shown).

As described above, when the SOC is determined to be less than the predetermined value X1 at the time of braking, braking is performed by the regenerative braking force and the hydraulic braking force. This routine is repeatedly executed, and is continued as long as the determination result of step S14 is false (No) and the SOC is determined to be less than the predetermined value X1. When the regenerative braking is performed, the degree of the braking request is reduced. Therefore, the distribution of the regenerative braking force and the hydraulic braking force is always updated to an appropriate one by repeatedly performing step S16 while giving priority to the regenerative braking. Is done.

When the regenerative braking is performed as described above, the SOC increases. In particular, when the regenerative braking time is long, the SOC increases.
Reaches the predetermined value X1, and in this case, the determination result of step S14 is determined to be true (Yes). As described above, when the SOC reaches the predetermined value X1 and the charge amount is saturated, the battery 70 is charged when the battery 70 is further charged.
0 or the motor generator 10 itself may be damaged. Therefore, in this case, the regenerative braking is stopped in step S24. That is, the amount of electricity supplied to the stator coil 16 of the motor generator 10 is set to a value of 0 (zero) so as not to generate power, and the rotor coil 14 is caused to idle without resistance due to a magnetic field (regenerative braking limiting means).

In the next step S26, it is determined whether or not the vehicle is currently traveling on a long downhill on a mountain road or the like and the braking load applied to the hydraulic brake is large. Specifically, for example, the duration of time since the braking request degree signal is output from the brake tread pressure sensor 58 is measured, and when the duration is continued without interruption, the vehicle may go down for a long time. It is determined that the vehicle is traveling on a slope and the braking load is large (brake load detecting means).

If the result of the determination in step S26 is true (Ye
If it is determined in s) that the vehicle is currently traveling on a long downhill, the process proceeds to step S28. Step S
At 28, the clutch is engaged this time. That is, the clutch device 4 is connected to rotate the rotating shaft 12 of the motor generator 10 and the output shaft 2 of the engine 1 synchronously. Accordingly, the engine brake is applied to the wheels 28 by the non-driven engine 1 (engine brake control means).

That is, when the regenerative braking is stopped, the hydraulic braking force must be increased accordingly.
At this time, especially when the vehicle is traveling on a long downhill and the braking load is large, the discs 32, 32 of the hydraulic disc brake devices 30, 30 and the brake pads 34, 34 may be overheated by frictional heat. However, by applying the engine brake in this way, overheating of the hydraulic disc brake devices 30, 30 is suppressed. As a result, a reduction in the braking force due to the so-called fade phenomenon of the hydraulic brake is suitably prevented.

In step S30, the engine rotation speed information Ne is detected from the engine rotation sensor 5, and the cooling water temperature information Tw is detected from the water temperature sensor 3.
In step S32, an engine braking force is calculated from the engine speed information Ne and the coolant temperature information Tw. Actually, the engine braking force is set in advance as a map according to the engine rotation speed information Ne and the cooling water temperature information Tw, and the engine braking force is read from the map.

In step S34, a hydraulic braking force is calculated. Specifically, based on the braking request information from the brake pedal pressure sensor 58, the difference between the braking request and the engine braking force is used as the hydraulic braking force. Then, in step S36, hydraulic brake control is performed based on the hydraulic brake force in the same manner as in step S22.

On the other hand, if the determination result of step S26 is false (N
In o), if it is determined that the vehicle is not currently traveling on a long downhill, but is traveling on a flat road, the process proceeds to step S38. In step S38, the clutch is disconnected. In general, when the vehicle is traveling on a flat road or the like, the degree of braking request is small, and even if regenerative braking is stopped, the hydraulic braking force increases as the hydraulic disk brake devices 30, 30 overheat, that is, the hydraulic brake fades. It is not large enough to cause the phenomenon. Therefore, when the vehicle is not traveling on a long downhill but traveling on a flat road or the like,
This prevents the engine brake from acting when the clutch is disconnected, and preferentially uses a hydraulic brake with better response.

Therefore, in this case, in step S40, only the hydraulic brake control is performed according to the degree of braking request without engine braking. By the way, in the above embodiment, the engine brake is applied when the vehicle is traveling on a long downhill. For example, as another embodiment, as shown in FIG. Instead of determining whether or not there is, the hydraulic brake temperature Tb is directly estimated (step S26a), and it is determined whether or not the hydraulic brake temperature Tb is equal to or higher than a predetermined value T1 (step S26b). If the result is true (Yes), it may be determined that the braking load is large, and the engine brake may be activated by engaging the clutch.

In this case, since the amount of generated frictional heat is correlated with the stepping pressure output from the brake stepping pressure sensor 58, the hydraulic brake temperature Tb is, for example, the stepping pressure when the brake pedal 56 is continuously depressed. The pressure is integrated and estimated according to the integrated value (brake load detecting means). In the above embodiment, the engine brake is used after the SOC of the battery 70 reaches the predetermined value X1 and the regenerative braking is stopped. For example, even if the SOC does not reach the predetermined value X1, the engine brake is used.
The regenerative braking may be limited according to the value (regenerative braking limiting means). At this time, when the distribution of the hydraulic braking force becomes extremely large, the engine brake may be used together.

In the above-described embodiment, the hybrid electric vehicle has been described as an example. However, the present invention is not limited to this, and is an energy regenerating vehicle provided with a generator (generator) having only a power generation function instead of the motor generator 10. However, the present invention can be favorably applied.

[0038]

As described above in detail, according to the regenerative braking control device of the first aspect of the present invention, at the time of energy regeneration, the generator can be operated very efficiently by the external force from the wheels and the service can be performed. With the brake, reliable braking with good response can be realized, and when regenerative braking is limited, the occurrence of a fade phenomenon due to an excessive load on the service brake can be suitably prevented by using the engine brake together.

Therefore, during braking of the vehicle, high-efficiency energy regeneration can be realized, and a sufficient braking force can always be secured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a hybrid electric vehicle, showing a configuration of a regenerative braking control device according to the present invention.

FIG. 2 is a flowchart showing a braking control routine of the regenerative braking control device according to the present invention.

FIG. 3 is a part of a flowchart showing a braking control routine according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 engine (internal combustion engine) 3 water temperature sensor 4 clutch device 5 engine rotation sensor 10 motor generator (generator) 12 rotation shaft (drive system member) 14 rotor coil 16 stator coil 22 drive shaft (drive system member) 26 axle 28 wheels 30 Hydraulic disc brake device (service brake) 50 Electronic control unit (ECU) 54 Accelerator position sensor (APS) 58 Brake pressure sensor 70 Battery

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 13/04 F02D 13/04 Z // B60K 6/00 B60K 9/00 Z 8/00 F term (reference ) 3D041 AA21 AA33 AA34 AA65 AB01 AC01 AC06 AC26 AD02 AD10 AD41 AD50 AE00 AE02 AE03 AE14 AE41 AF00 3G092 AA01 AC02 DF05 FA24 FA34 HE01Z HE08Z HF01X HF02Z HF08Z HF15X Q16 PU02 PU08 PU08 PI08 PU08 PI08 QI09 QI13 QI14 QN03 RB08 SE04 TE02 TE08 TI02 TI05 TO21 TO23 TU16

Claims (1)

[Claims] 1. An internal combustion engine connected to a drive system member of a vehicle via a clutch, and a generator connected to the drive system member of the vehicle when the vehicle has a braking request when the vehicle has a braking request. Regenerative braking means for applying a braking force to the drive system member to generate regenerative braking by actuating power generated by an external force transmitted therefrom; and braking for supplementing the braking force by the regenerative braking means when a vehicle has a braking request. A service brake for applying a braking force by friction to a drive system member of the vehicle in accordance with a required amount; a battery for storing power from the generator; a charge state detection unit for detecting a charge state of the battery; Regenerative braking limiting means for limiting regenerative braking by the regenerative braking means in accordance with charging state information from state detecting means; and detecting or estimating a magnitude of a braking load of the service brake. Brake load detecting means, and when the regenerative braking is not restricted by the regenerative braking restricting means, the clutch is disengaged, the regenerative braking is restricted, and the braking load detected or estimated by the brake load detecting means is smaller than a predetermined amount. Regenerative braking control, characterized by comprising: an engine brake control means for connecting the clutch to apply a braking force by an engine brake to the drive system member when the motor is large.