JP2010143295A - Controller for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a hybrid vehicle, preventing an overspeed of a power generator. <P>SOLUTION: The controller for the hybrid vehicle includes: the power generator 304 receiving engine rotation; a motor 303 driving drive wheels with power generated at the power generator 304 as a drive source; and a CPU 101 restricting engine torque such that a rotation speed of the power generator 304 falls within a limit line or below. The CPU 101 restricts the engine torque in consideration of temporal change in friction of a drive transmission path from an engine 305 to the drive wheels. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to the technical field of hybrid vehicle control devices.

In the conventional hybrid vehicle control device, in order to prevent over-rotation of the generator, the engine torque is limited based on the driving state of the electric motor with respect to the engine torque obtained based on the driver's operation. As an example related to the above description, a technique described in Patent Document 1 is known.
JP 2005-313865 A

  However, the above-described prior art has a problem in that over-rotation of the generator cannot be prevented depending on the state of the engine driving the generator and the transmission to which the driving force of the engine is transmitted.

  The objective of this invention is providing the control apparatus of the hybrid vehicle which can prevent the overspeed of a generator.

  In order to achieve the above object, in the present invention, the rotational speed of the generator is limited in consideration of changes over time in the friction of the engine and the drive transmission path from the engine to the drive wheels.

  Therefore, in the present invention, since the rotational speed of the generator is limited in consideration of the friction of the drive transmission path that changes with time, it is possible to prevent the generator from over-rotating.

  Hereinafter, the best mode for carrying out the present invention will be described based on examples.

FIG. 1 is a system configuration diagram of a drive system of a hybrid vehicle according to a first embodiment.
The CPU (generator rotation speed limiting means) 101 monitors the state (SOC, temperature, deterioration state, etc.) of the high-power battery 301, calculates the input / output possible electric energy according to the SOC, temperature, deterioration state, Based on the control of the inverter 302, the drive motor (hereinafter referred to as motor) 303 and the generator 304 are operated, and the engine 305 is controlled.

Further, the CPU 101 considers the regenerative braking force by the motor 303, and transmits, for example, a braking force calculation command value (including front and rear braking distribution) generated by the mechanical brake 202 such as a hydraulic brake to the brake actuator 201.
Further, the engine 305 and a transaxle (a transmission incorporating a differential gear, hereinafter referred to as T / A) 306 have a function of detecting and recording the cumulative number of revolutions. The vehicle speed (vehicle speed) is basically ascertained from the number of rotations of the motor 303.
The auxiliary battery 102 has a role of providing operating power for the CPU 101. In this system, power is supplied by a DC / DC converter 402 that uses a high-power battery 301 as a power source.

The brake actuator 201 receives a braking force calculation command value to be generated by the mechanical brake 202 calculated by the CPU 101, and applies a necessary hydraulic pressure to the mechanical brake 202 according to the braking force calculation command value.
The mechanical brake 202 generates a braking force according to the hydraulic pressure generated by the brake actuator 201.

  The high-power battery 301 assists vehicle travel by supplying electric power to the motor 303 via the inverter 302, and has a role of collecting electric power generated by the generator 304 via the inverter 302.

  The inverter 302 is directly controlled by the CPU 101. The electric energy of the high-power battery 301 is supplied to the motor 303 according to the generated torque and the rotational speed of the engine 305, and the electric energy generated by operating the generator 304 is returned to the high-power battery 301. The motor 303, the generator 304, and the engine 305 are directly connected to a planetary gear mechanism built in the T / A 306, and are controlled so as to maintain a balance between torque and rotational speed.

  The motor 303 alone generates drive torque when the vehicle speed is low. Further, when the vehicle speed is high, the driving torque of the engine 305 is assisted. Further, during deceleration, it has a function of generating electric energy by generating power (regenerative braking) and returning it to the high-power battery 301 via the inverter 302.

  The generator 304 supports the start of the engine 305 by supplying electric power from the high-power battery 301 when the vehicle is started and operating as a motor. This is because a hybrid electric vehicle basically has no starter. During normal travel, electric energy is generated (power generation) by balancing the motor 303 and the engine 305 and returned to the high-power battery 301. Sometimes it is possible to cope with rapid acceleration by supplying the motor 303 directly.

  The engine 305 is directly controlled by the CPU 101. Specifically, when the vehicle speed is high, torque is generated to drive the vehicle. Note that the engine 305 does not need to be controlled because the motor travels when the vehicle speed is low. In other words, control that does not start the engine 305 is applied in the low vehicle speed range.

The T / A 306 has a planetary gear mechanism, and an engine 305 is directly connected to the carrier, a motor 303 is connected to the ring gear, and a generator 304 is directly connected to the sun gear. In the T / A 306, a transmission equivalent to the conventional system is also configured inside.
The engine water temperature sensor 401 measures the temperature outside the vehicle, and the CPU 101 detects it. Specifically, it is set to measure the intake air temperature of the engine 305.
DC / DC converter 402 converts the electric power of high-power battery 301 to about 12 V and supplies it to auxiliary battery 102 (having the same function as an alternator in a conventional engine vehicle).

  The CPU 101 monitors the increase in the rotational speed of the generator 304 and controls the engine torque so that the rotational speed is equal to or lower than a predetermined rotational speed (limit line), thereby limiting the rotational speed of the generator 304. Here, the CPU 101 sets a plurality of determination thresholds for limiting the number of rotations with respect to the inclination of the increase in the number of rotations, and determines whether the engine is over-rotated (the number of rotations of the generator 304 is equal to or higher than the predetermined number). By limiting the upper limit value of the torque, the engine torque is limited step by step.

That is, the limit is not ON / OFF, and the inclination of the increase in the rotational speed is gradually reduced so that the rotational speed of the generator 304 draws an asymptotic line with respect to the limit line (predetermined rotational speed).
Here, the upper limit value of the engine torque is set to a predetermined value obtained in advance through experiments or the like. Hereinafter, this upper limit value is referred to as a reference upper limit value.

In the first embodiment, the engine torque limit rate K [%] corresponding to the change over time in the friction of the drive transmission path from the engine 305 to the drive wheels is set, and the upper limit value of the engine torque is set by multiplying the reference upper limit value. . That is, the engine torque limit rate K decreases from the value when the friction of the drive transmission path is in a new state (a state where the cumulative use time is short) as the use time increases, whereas the generator This is for correcting the upper limit value of the engine torque to be small so that the rotation speed of 304 is always below the limit line.
Hereinafter, a method for setting the engine torque limit rate K will be described.

[Engine torque limit rate setting process]
FIG. 2 is a flowchart showing the flow of the engine torque limit rate setting process of the CPU 101, and each step will be described below.

  In step S11, the accumulated number of revolutions of the engine 305 is confirmed and collated with the map of FIG. 3, the engine torque limit rate K1 is set, and the process proceeds to step S12. FIG. 3 is an example of an engine torque limit rate map according to the engine cumulative speed, and the engine torque limit rate K1 is increased as the cumulative speed is higher.

  In step S12, the engine coolant temperature is confirmed by the engine coolant temperature sensor 401 and collated with the map of FIG. 4, the engine torque limit rate K2 is set, and the process proceeds to step S13. FIG. 4 is an example of an engine torque limit rate map according to the engine water temperature. The engine torque limit rate K2 is increased as the engine water temperature increases until the engine water temperature reaches a predetermined temperature, and the engine water temperature exceeds the predetermined temperature. If so, set a constant value.

  In step S13, the accumulated rotational speed of T / A 306 is confirmed and collated with the map of FIG. 5, an engine torque limit rate K3 is set, and the process proceeds to step S14. FIG. 5 is an example of an engine torque limit rate map according to the T / A accumulated rotational speed, and the engine torque limit rate K3 is increased as the T / A accumulated rotational speed is higher.

In step S14, the engine torque limit rate K is set based on the engine torque limit rates K1, K2, and K3 set in step S11 to step S13, and the process proceeds to return. The engine torque limit rate K is calculated based on the following formula, for example.
K = K1 × K2 × K3

  By multiplying the engine torque limit rate K obtained by the above method by a preset reference upper limit value, the final engine torque corresponding to the change over time in the friction of the drive transmission path from the engine 305 to the drive wheel is obtained. Set the upper limit.

[When engine torque limit is released]
In the first embodiment, when the engine torque is limited, when the rotation speed of the generator 304 reaches a certain rotation speed sufficiently lower than the limit line (determination threshold value for releasing the rotation speed limit), the engine torque limit is released. At this time, the CPU 101 corrects the determination threshold value for canceling the rotation speed limit in accordance with the change over time in the friction of the drive transmission path from the engine 305 to the drive wheel. Specifically, the determination threshold is decreased as the amount of decrease in friction due to changes with time is larger. The amount of reduction in friction due to changes over time is determined from the engine cumulative speed, engine water temperature, and T / A cumulative speed, as in the case of the engine torque limit rate setting process described above.

Next, the operation will be described.
[Engine torque limiting action]
In the first embodiment, when the engine torque is limited in order to prevent the generator 304 from over-rotating, the time-dependent change in mechanical friction of the engine 305, T / A 306, and the like is taken into account. As a result, even if the usage time has elapsed and the friction of the engine 305, T / A 306, or motor 303 has changed from the new state, the generator 304 rotates to correct the upper limit of the engine torque accordingly. The number can be set without excess and deficiency, and overspeed can be prevented appropriately.

  Specifically, when the engine 305 and the T / A 306 are used to some extent, the friction decreases due to wear, and therefore, the rotational speed of each element on the drive transmission path is likely to increase. At this time, the rotational speed of the generator 304 is affected by the temporal change of the friction of the engine 305 directly connected to the generator 304 and the T / A 306 interposed between the engine 305 and the drive wheels.

  FIG. 6 is a time chart of the generator operation when the reduction of the engine and T / A friction is not taken into account. When the engine torque is limited without taking into account the temporal change of the engine friction and T / A friction, The operating state (rotation speed) of the machine is approaching a potential line where sufficient potential can be obtained over time.

  This means that the potential of the generator is not fully exhibited in the new state. When engine friction and T / A friction are not taken into account, the potential of the generator is fully exhibited in the new state, but it is also assumed that the potential gradually decreases with time. In other words, if the friction change of the drive transmission path from the engine connected to the generator to the driving wheel, such as engine friction and T / A friction, is not taken into consideration, the state where the potential of the generator is sufficiently exhibited cannot be maintained.

  On the other hand, in the first embodiment, even if the rotational speed of the generator 304 is likely to increase by increasing the limit of the engine torque in accordance with the decrease in the mechanical friction of the drive transmission path, the generator 304 It is possible to prevent the number of rotations from exceeding the limit line. That is, it is possible to always prevent over-rotation of the generator 304 regardless of the cumulative usage time of the engine 305 and the T / A 306.

  FIG. 7 is a time chart of the generator operation showing the engine torque limiting action of the first embodiment. In the first embodiment, the engine torque is limited in consideration of changes in engine friction and T / A friction. The generator potential can always be set on the potential line. That is, it is possible to always maintain a state in which the generator potential is sufficiently exerted.

In the first embodiment, the engine torque is limited as the accumulated engine speed is higher.
The engine friction has a characteristic that it is greatly reduced for a while from a new state and then finely reduced. By setting the engine torque limit rate K1 in consideration of this characteristic, it is possible to effectively utilize the potential of the generator 304 while suppressing excessive rotation of the generator 304.

  That is, the rotational speed of the generator 304 driven by the engine 305 can be appropriately set by taking into account the mechanical friction of the engine 305 that changes with time. This limitation of engine torque in accordance with the accumulated engine speed is particularly effective when performing idle stop control in a hybrid vehicle (HEV) in which driving wheels are driven by an engine and a motor. This is because, in an idle stop vehicle, it is impossible to collate friction changes with travel distance. Therefore, by using the cumulative number of revolutions of the engine 305, a change in friction can be detected with high accuracy.

In the first embodiment, when the engine water temperature is equal to or lower than a predetermined value, the engine torque is limited as the engine water temperature is higher.
The engine friction has a characteristic that when the engine water temperature is low, the engine friction increases as the engine water temperature decreases. By setting the engine torque limit rate K2 in consideration of this characteristic, it is possible to effectively utilize the potential of the generator 304 while suppressing the overspeed of the generator 304.
That is, the rotational speed of the generator 304 can be appropriately set by taking into account the mechanical friction of the engine 305 having temperature dependency.

In the first embodiment, the engine torque is limited as the T / A accumulated rotational speed increases.
Transmission friction has the property of gradually decreasing due to oil viscosity and bearing wear. By setting the engine torque limit rate K3 in consideration of this characteristic, it is possible to effectively utilize the potential of the generator 304 while suppressing excessive rotation of the generator 304.
That is, the rotational speed of the generator 304 can be appropriately set by taking into account the mechanical friction of the T / A 306 that changes with time.

  Further, in the first embodiment, the determination threshold value for canceling the engine torque limit is corrected according to the decrease in mechanical friction, so that the system performance of the drive system can be utilized more efficiently as in the case of engine torque limit. In addition, the torque step at the time of release can be suppressed and smooth behavior can be realized.

Next, the effect will be described.
In the hybrid vehicle control device of the first embodiment, the following effects can be obtained.

  (1) The generator torque to which engine rotation is input, the motor 303 that drives the drive wheels using the power generated by the generator 304 as a drive source, and the engine torque so that the rotation speed of the generator 304 is below the limit line. The CPU 101 limits the engine torque in consideration of the change over time in the friction of the drive transmission path from the engine 305 to the drive wheels. Thereby, over-rotation of the generator 304 can be prevented regardless of the change of friction with time.

  (2) The CPU 101 increases the limit amount of the engine torque as the reduction in friction due to changes over time increases, so that it is possible to prevent over-rotation of the generator 304 that tends to increase due to the reduction in friction.

  (3) When the engine cumulative speed is high, the CPU 101 increases the engine torque limit amount more than when the engine cumulative speed is low. Can be set.

  (4) When the engine water temperature is high, the CPU 101 increases the engine torque limit amount more than when the engine water temperature is low, so the rotation speed of the generator 304 driven by the temperature-dependent engine 305 is appropriate. Can be set.

  (5) When the T / A cumulative rotational speed is high, the CPU 101 increases the engine torque limit amount when the T / A cumulative rotational speed is low, so the time-dependent T / A306 mechanical friction is taken into account. By doing so, the rotation speed of the generator 304 can be set appropriately.

  (6) The CPU 101 sets multiple determination thresholds for limiting the number of rotations with respect to the slope of the increase in the number of rotations of the generator 304. Restrict to. Thereby, the system performance of the drive system can be utilized more efficiently. In addition, the torque step can be kept small and smooth behavior can be realized.

  (7) Since the CPU 101 sets the determination threshold value for releasing the rotation speed limit of the generator 304 in consideration of the change with time of the friction, the system performance of the drive system can be utilized more efficiently. In addition, the torque step can be kept small and smooth behavior can be realized.

FIG. 8 is a system configuration diagram of the drive system of the hybrid vehicle of the second embodiment.
In addition, the same code | symbol is attached | subjected to the structure same as FIG. 1, and only a different part from Example 1 is demonstrated.

  The CPU 101 monitors the state of the high-power battery 301, calculates the input / output possible electric energy according to the SOC, temperature, and deterioration state, and controls the inverter 302 based on this to generate a motor generator (electric motor, generator). The engine 305 is operated and the engine 305 is controlled (including driving force distribution).

  Further, the CPU 101 considers the regenerative braking force by the motor 303 and transmits a braking force calculation command value (including front / rear braking distribution) generated by the mechanical brake 202 to the brake actuator 201. Further, it has a function of detecting and recording the accumulated rotational speed of the engine 305 and the T / M 306. The vehicle speed is basically determined from the motor generator 308 rotational speed.

  The high-power battery 301 assists vehicle travel by supplying electric power to the motor generator 308 via the inverter 302, and has a role of collecting electric power generated by the motor generator 308 via the inverter 302.

  The inverter 302 is directly controlled by the CPU 101. The electric energy of the high-power battery 301 is supplied to the motor generator 308 according to the generated torque and the rotational speed of the engine 305, and the electric energy generated by operating the motor generator 308 is returned to the high-power battery 301.

  An automatic transmission (hereinafter referred to as T / M) 307 has a function of transmitting kinetic energy of an engine 305 and a motor generator 308, which are driving sources of a vehicle, to driving wheels. Intended for configurations other than THS systems, such as AT and CVT.

The motor generator 308 generates drive torque independently when the vehicle speed is low. Further, when the vehicle speed is high, the driving torque of the engine 305 is assisted. Further, during deceleration, it has a function of generating electric energy by generating power (regenerative braking) and returning it to the high-power battery 301 via the inverter 302. In addition, it is possible to perform a power generation operation with the power of the engine 305 during traveling.
The motor generator 308 supports the start of the engine 305 by supplying electric power from the high-power battery 301 and operating as a motor when the vehicle is started.

[Engine torque limit rate setting process]
In the engine torque limiting rate setting process of the second embodiment, in the flowchart of the first embodiment shown in FIG. 2, “cumulative rotational speed of T / A 306” in step S13 is changed to “cumulative rotational speed of T / M307”. The horizontal axis in FIG. 5 is changed from “T / A cumulative rotational speed” to “T / M cumulative rotational speed”.

That is, in the second embodiment, the engine torque limit rate K3 is increased as the T / M cumulative rotational speed is higher.
Therefore, the hybrid vehicle control apparatus according to the second embodiment achieves the same effects as those of the first embodiment, and can obtain the same effects as the effects (1) to (7) of the first embodiment.

(Other examples)
The best mode for carrying out the present invention has been described with reference to the embodiments based on the drawings. However, the specific configuration of the present invention is not limited to that shown in the embodiments, and the gist of the present invention. Even if there is a design change that does not change the value, it is included in the present invention.

  In the first embodiment, an example in which the number of revolutions of the generator is limited by limiting the torque of the engine has been described. However, not only the engine torque but also elements of a drive transmission path from the engine to the drive wheels, for example, the output of an electric motor or a transmission You may restrict | limit the rotation speed of a generator by the restrictions (restriction number of rotations of an electric motor, upshift of a transmission).

  The configuration of the hybrid vehicle to which the present invention can be applied is not limited to the embodiment, and the present invention drives an engine-driven generator and driving wheels using the power generated by the generator as a drive source. A hybrid vehicle having an electric motor can be applied regardless of the series hybrid method, the parallel hybrid method, or the series / parallel hybrid method, and has the same effects as the embodiment.

  The configurations of hybrid vehicles to which the present invention can be applied are listed below. In addition, the friction generation site to be considered when limiting the rotational speed of the generator is shown. In the following drawings, a solid line indicates a driving force transmission path, and a broken line indicates a power supply path. In addition, illustration is abbreviate | omitted about the storage battery which stores the electric power generated by a generator.

(a) A hybrid vehicle in which the engine only generates electric power and the drive wheels are rotated only by the electric motor, and a transmission is interposed between the electric motor and the drive wheels (FIG. 9).
In this type, since the engine and the driving wheel are not connected, the rotational speed of the generator is determined by the engine. Therefore, the rotational speed of the generator is limited in consideration of the temporal change of engine friction.

(b) A hybrid vehicle in which the engine only generates electric power and the drive wheels are rotated only by the electric motor, and the electric motor and the drive wheels are directly connected (FIG. 10).
In this type, similarly to the above (a), the rotational speed of the generator is limited in consideration of the temporal change of engine friction.

(c) A series-parallel hybrid hybrid vehicle in which an engine, an electric motor, and a driving wheel are connected to a transmission connected to a driving wheel, respectively, and the driving wheel is rotated by the engine and the electric motor. In addition, since Example 1 shown in FIG. 1 is this type, illustration is abbreviate | omitted.
In this type, since the transmission is provided in the drive transmission path between the engine and the drive wheels, the rotational speed of the generator is affected by the engine and the transmission. Therefore, the rotational speed of the generator is limited in consideration of changes with time of the friction of the engine and the transmission.

(d) A hybrid vehicle (FIG. 11), which is a parallel hybrid system in which an engine and an electric motor are connected to drive wheels via different paths, and a transmission is interposed between the engine and the drive wheels.
In this type, similarly to the above (c), the rotational speed of the generator is limited in consideration of changes with time of the friction of the engine and the transmission.

(e) A hybrid vehicle having a parallel hybrid system in which an engine, an electric motor (generator), and driving wheels are connected in series, and a transmission is interposed between the electric motor and the driving wheels. In addition, since Example 2 shown in FIG. 8 is this type, illustration is abbreviate | omitted.
In this type, since the electric motor and the transmission are provided in the drive transmission path between the engine and the driving wheel, the rotational speed of the generator is affected by the engine, the electric motor, and the transmission. Therefore, the rotational speed of the generator is limited in consideration of changes with time in the friction of the engine, the electric motor, and the transmission.

(f) A hybrid vehicle in which an engine, an electric motor, and driving wheels are connected in series, and the electric motor and driving wheels are directly connected (FIG. 12).
In this type, since the electric motor is provided in the drive transmission path between the engine and the drive wheels, the rotational speed of the generator is affected by the engine and the electric motor. Therefore, the rotational speed of the generator is limited in consideration of changes with time of the friction of the engine and the electric motor.

1 is a system configuration diagram of a drive system of a hybrid vehicle of Example 1. FIG. It is a flowchart which shows the flow of the engine torque limiting rate setting process of CPU101. It is an example of the engine torque limiting rate map according to an engine accumulated rotation speed. It is an example of the engine torque limiting rate map according to engine water temperature. It is an example of an engine torque limiting rate map according to the T / A accumulated rotation speed. It is a time chart of generator operation in the case of not considering the decrease in engine and T / A friction. 2 is a time chart of generator operation showing an engine torque limiting action of the first embodiment. FIG. 4 is a system configuration diagram of a drive system of a hybrid vehicle according to a second embodiment. It is a system block diagram of the drive system of the hybrid vehicle of another Example. It is a system block diagram of the drive system of the hybrid vehicle of another Example. It is a system block diagram of the drive system of the hybrid vehicle of another Example. It is a system block diagram of the drive system of the hybrid vehicle of another Example.

Explanation of symbols

101 CPU (generator speed limiter)
102 Auxiliary battery
201 Brake actuator
202 Mechanical brake
301 Heavy battery
302 inverter
303 Motor (electric motor)
304 generator
305 engine
306 T / A (transmission)
307 T / M (transmission)
308 Motor generator (electric motor, generator)
401 Engine water temperature sensor
402 DC / DC converter

Claims (7)

A generator to which engine rotation is input,
An electric motor that drives the drive wheels using the power generated by the generator as a drive source;
Generator rotational speed limiting means for limiting the rotational speed of the generator to a predetermined rotational speed or less;
With
The control device for a hybrid vehicle, wherein the generator rotation speed limiting means limits the rotation speed of the generator in consideration of a change with time of friction of the engine and a drive transmission path from the engine to a drive wheel. In the hybrid vehicle control device according to claim 1,
The control device for a hybrid vehicle, characterized in that the generator rotation speed limiting means increases a limit amount of the rotation speed of the generator as the reduction of the friction due to change with time is larger. In the hybrid vehicle control device according to claim 1 or 2,
The control device for a hybrid vehicle, wherein the generator rotation speed limiting means increases the limit amount of the generator rotation speed when the cumulative rotation speed of the engine is high than when the cumulative rotation speed is low. . The hybrid vehicle control device according to any one of claims 1 to 3,
The control device for a hybrid vehicle, characterized in that the generator rotation speed limiting means increases the limit amount of the generator rotation speed when the engine water temperature is high than when the engine water temperature is low. In the hybrid vehicle control device according to any one of claims 1 to 4,
A transmission is interposed between the engine and the drive wheel,
The generator rotation speed limiting means increases the limit amount of the generator rotation speed when the cumulative rotation speed of the transmission is high compared to when the cumulative rotation speed is low. apparatus. In the hybrid vehicle control device according to any one of claims 1 to 5,
The generator rotation speed limiting means sets a plurality of rotation speed limit determination thresholds with respect to the increase in the rotation speed of the generator, and the generator rotation speed is determined according to the possibility that the rotation speed is equal to or higher than the predetermined rotation speed. A control apparatus for a hybrid vehicle, wherein the number is limited in stages. The hybrid vehicle control device according to any one of claims 1 to 6,
The control device for a hybrid vehicle, wherein the generator rotation speed limiting means sets a determination threshold value for releasing the rotation speed limitation of the generator in consideration of a change with time of the friction.

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