JP2013103655A - Control device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a hybrid vehicle can generating electricity more efficiently than conventional devices.SOLUTION: A control device is applied to the hybrid vehicle 1 that includes a gear box 10 having an input shaft 11 connected to an internal combustion engine 2, and an output shaft 12 connected to a drive wheel 7 in a power transmissible manner, and can change a gear ratio between the input shaft 11 and the output shaft 12; a second clutch 25 that can switch between an input shaft connection state in which a motor generator 3 and the input shaft 11 are connected in the power transmissible manner and an output shaft connection state in which the motor generator 3 and the output shaft 12 are connected in the power transmissible manner; and a battery 4 electrically connected to the motor generator 3. The control device switches the state of the second clutch 25 from the output shaft connection state to the input shaft connection state when a speed of the vehicle 1 is not less than a predetermined determining speed. The determining speed when the electricity accumulation rate of the battery 4 is less than a predetermined determining electricity accumulation rate is made smaller than that when the electricity accumulation rate of the battery 4 is not less than the predetermined determining electricity accumulation rate.

Description

  In the present invention, an internal combustion engine and a motor / generator are mounted, a transmission is provided in a power transmission path between the internal combustion engine and a drive wheel, and the connection destination of the motor / generator is connected to an input shaft or an output of the transmission. The present invention relates to a control device for a hybrid vehicle that can be selectively switched to a shaft.

  There is known a hybrid vehicle that includes an internal combustion engine and a motor / generator as a power source, and in which a transmission is provided in a power transmission path between the internal combustion engine and drive wheels. Further, in such a hybrid vehicle, the connection state of the output shaft of the motor / generator by the switching mechanism, the IN connection state connected to the input shaft of the transmission, the OUT connection state connected to the output shaft of the transmission, and the input shaft Vehicles that can be switched to a neutral state that is disconnected from both the output shaft and the output shaft are known. As a control device for controlling the switching mechanism, the device switches the connection state to the IN connection state when the vehicle starts, and switches the connection state in the order of the OUT connection state, the IN connection state, and the neutral state as the vehicle speed increases after the vehicle starts. Is known (see Patent Document 1). In addition, Patent Documents 2 and 3 exist as prior art documents related to the present invention.

JP 2010-208518 A JP 2010-247689 JP 2010-208520 A

  In general, a motor / generator has a rotation speed range in which power generation can be performed efficiently. If the rotation speed of the motor / generator is higher than the rotation speed range, the efficiency of power generation decreases. When the output shaft of the motor / generator is connected to the output shaft of the transmission, the rotational speed of the motor / generator tends to be higher than the rotational speed range. As a result, the power generation efficiency of the motor / generator may be reduced. Therefore, in this case, it is more likely that power generation can be performed more efficiently if the output shaft of the motor / generator is connected to the input shaft of the transmission. In the apparatus of Patent Document 1, the connection destination of the output shaft of the motor / generator is not switched in consideration of such power generation efficiency.

  Accordingly, an object of the present invention is to provide a control device for a hybrid vehicle that can generate power more efficiently than before.

  The control device of the present invention includes an internal combustion engine, a motor / generator functioning as an electric motor and a generator, an input shaft connected to the internal combustion engine, and an output shaft connected to drive wheels so as to be able to transmit power. A transmission capable of changing a transmission gear ratio between the input shaft and the output shaft, an input shaft connection state in which the motor generator and the input shaft are connected so as to transmit power, and the motor generator And a connection destination switching means that can be switched to an output shaft connection state in which the output shaft is connected so that power can be transmitted, and a battery that is electrically connected to the motor / generator. A control device comprising control means for switching the connection destination switching means from the output shaft connected state to the input shaft connected state when the vehicle speed is equal to or higher than a predetermined determination speed; When the battery storage rate of the battery is less than a predetermined determination storage rate, there is provided determination speed changing means for making the determination speed smaller than when the battery storage rate is equal to or higher than the determination storage rate (Claim 1). .

  According to the control device of the present invention, since the determination speed is reduced when the battery storage rate is less than the determination storage rate, the speed range of the vehicle in which the motor / generator is connected to the input shaft can be expanded. Therefore, power generation can be performed with the motor / generator connected to the input shaft. In this case, since it is highly possible that the rotation speed of the motor / generator is within the rotation speed range where the power generation efficiency is good, the motor / generator can efficiently generate power. Therefore, fuel consumption can be improved.

  In one form of the control device of the present invention, the determination speed changing means may decrease the determination speed as the storage rate of the battery decreases. According to this aspect, the determination speed can be appropriately changed according to the storage rate. Therefore, it is possible to increase the frequency with which the motor / generator is connected to the input shaft when the motor / generator starts power generation. Therefore, power generation can be performed efficiently.

  In one aspect of the control device of the present invention, the determination speed changing means reduces the determination speed when power is generated by the motor / generator than when power generation is not performed by the motor / generator. (Claim 3). The motor / generator can generate power more efficiently when the motor / generator is connected to the output shaft than to the output shaft. Therefore, power generation can be performed efficiently by reducing the determination speed in this way.

  In one form of the control device of the present invention, the determination speed changing means drives the driving wheel by the motor / generator when the motor / generator cannot assist in driving the driving wheel at the time of shifting the transmission. The determination speed may be made lower than that in the case where the above can be assisted (Claim 4). By reducing the determination speed in this manner, efficient power generation can be performed quickly when it is necessary to generate power with the motor / generator.

  As described above, according to the control device of the present invention, when the battery storage rate is less than the determination storage rate, the determination speed is reduced, so that power can be generated efficiently. Therefore, fuel consumption can be improved.

The figure which shows typically the vehicle incorporating the control apparatus which concerns on one form of this invention. The figure for demonstrating the determination speed at the time of normal time, and the determination speed at the time of low SOC. The flowchart which shows the determination speed change routine which a control apparatus performs. The figure which shows the relationship between the electrical storage rate of a battery, 1st determination speed, and 2nd determination speed.

  FIG. 1 schematically shows a vehicle in which a control device according to one embodiment of the present invention is incorporated. The vehicle 1 includes an internal combustion engine (hereinafter sometimes referred to as an engine) 2 and a motor / generator (hereinafter sometimes abbreviated as MG) 3 as power sources. That is, the vehicle 1 is configured as a hybrid vehicle. The engine 2 is a known spark ignition internal combustion engine having a plurality of cylinders. The MG 3 is a well-known device that is mounted on a hybrid vehicle and functions as an electric motor and a generator. The MG 3 includes a rotor 3b that rotates integrally with the rotor shaft 3a, and a stator 3c that is coaxially disposed on the outer periphery of the rotor 3b and fixed to a case (not shown). The MG 3 is electrically connected to the battery 4. The battery 4 is configured to be able to supply electricity to the MG 3 when the MG 3 functions as an electric motor, and to be charged with electricity generated by the MG 3 when the MG 3 functions as a generator.

  The vehicle 1 is equipped with a forward four-speed transmission 10, and the engine 2 and MG 3 are connected to the transmission 10. The transmission 10 is also connected to an output unit 5 for outputting power to the drive wheels 5 of the vehicle 1. The output unit 5 includes an output gear 6 and a differential mechanism 8 connected to the drive wheel 7. The output gear 6 is attached to the output shaft 12 of the transmission 10 so as to rotate integrally. Further, the output gear 6 meshes with a ring gear 8 a provided in the case of the differential mechanism 8. The differential mechanism 8 is a known mechanism that distributes the transmitted power to the left and right drive wheels 7.

  The transmission 10 includes an input shaft 11 and an output shaft 12. Between the input shaft 11 and the output shaft 12, first to fourth transmission gear pairs G1 to G4 are provided. The first transmission gear pair G1 is composed of a first drive gear 13 and a first driven gear 14 that mesh with each other, and the second transmission gear pair G2 is composed of a second drive gear 15 and a second driven gear 16 that mesh with each other. Yes. The third transmission gear pair G3 is composed of a third drive gear 17 and a third driven gear 18 that mesh with each other, and the fourth transmission gear pair G4 is composed of a fourth drive gear 19 and a fourth driven gear 20 that mesh with each other. Yes. The first to fourth transmission gear pairs G1 to G4 are provided so that the drive gear and the driven gear always mesh with each other. Different transmission gear ratios are set for the respective transmission gear pairs G1 to G4. The transmission gear ratio is set to decrease in the order of the first transmission gear pair G1, the second transmission gear pair G2, the third transmission gear pair G3, and the fourth transmission gear pair G4. Therefore, the first transmission gear pair G1 corresponds to the first speed, and the second transmission gear pair corresponds to the second speed. The third transmission gear pair G3 corresponds to the third speed, and the fourth transmission gear pair G4 corresponds to the fourth speed.

  The first to fourth drive gears 13, 15, 17, 19 are supported on the input shaft 11 so as to be rotatable relative to the input shaft 11. As shown in this figure, these gears are arranged in the order of the first drive gear 13, the second drive gear 15, the third drive gear 17, and the fourth drive gear 19 in the axial direction. On the other hand, the first to fourth driven gears 14, 16, 18, and 20 are fixed to the output shaft 12 so as to rotate integrally with the output shaft 12.

  A first sleeve 21 and a second sleeve 22 are provided on the input shaft 11. The sleeves 21 and 22 are supported by the input shaft 11 so as to rotate integrally with the input shaft 11 and be movable in the axial direction. As shown in this figure, the first sleeve 21 is provided between the first drive gear 13 and the second drive gear 15. The second sleeve 22 is provided between the third drive gear 17 and the fourth drive gear 19.

  The first sleeve 21 has a first speed position that meshes with the first drive gear 13 so that the input shaft 11 and the first drive gear 13 rotate integrally, and the input shaft 11 and the second drive gear 15 rotate integrally. Thus, the second speed gear position that meshes with the second drive gear 15 and the release position that does not mesh with either the first drive gear 13 or the second drive gear 15 can be switched. The second sleeve 22 has a third speed position that meshes with the third drive gear 17 so that the input shaft 11 and the third drive gear 17 rotate integrally, and the input shaft 11 and the fourth drive gear 19 rotate integrally. Thus, it is provided to be switchable between a fourth speed position that meshes with the fourth drive gear 19 and a release position that does not mesh with either the third drive gear 17 or the fourth drive gear 19. In the transmission 10, power transmission between the input shaft 11 and the output shaft 12 is interrupted when both the first sleeve 21 and the second sleeve 22 are switched to the release position. Hereinafter, this state may be referred to as a neutral state. When switching the gear position, the state of the transmission 10 is first switched from the state before the shift to the neutral state. Thereafter, the state is switched from the neutral state to the state after the shift. Although not shown, the input shaft 11 has a plurality of rotations synchronized with each other when the first and second sleeves 21 and 22 are engaged with the first to fourth drive gears 13, 15, 17 and 19. The synchro mechanism is provided. For these synchro mechanisms, a synchro mechanism that synchronizes rotation by friction engagement, for example, a known key-type synchromesh mechanism may be used. Therefore, detailed description of the synchro mechanism is omitted.

  The transmission 10 is provided with an actuator 23 for driving the first sleeve 21 and the second sleeve 22. The actuator 23 drives the shift forks 23a engaged with the sleeves 21 and 22, and thereby drives the sleeves 21 and 22, respectively.

  As shown in this figure, the output shaft 2 a of the engine 2 is connected to the input shaft 11 via the first clutch 24. The first clutch 24 is a known clutch that can be switched between an engaged state in which power is transmitted between the engine 2 and the input shaft 11 and a released state in which the power transmission is interrupted.

  The rotor shaft 3a of the MG 3 is provided with a second clutch 25 as connection destination switching means. A constant meshing gear pair 26 is provided between the rotor shaft 3 a and the output shaft 12. The gear pair 26 includes a first gear 27 fixed to the output shaft 12 and a second gear 28 that is provided on the rotor shaft 3 a and meshes with the first gear 27. In the second clutch 25, the rotor shaft 3a and the input shaft 11 are connected to each other so that power can be transmitted, and the rotor shaft 3a and the output shaft 12 are connected to each other via a gear pair 26 so that power can be transmitted. It is configured to be switchable between an output shaft connection state and a neutral state in which the rotor shaft 3a is disconnected from both the input shaft 11 and the output shaft 12. For the second clutch 25, for example, a well-known dog clutch capable of switching the connection destination by changing the position of the sleeve may be used.

  Operations of the engine 2, the MG 3, the transmission 10, the first clutch 24, and the second clutch 25 are controlled by the control device 30. The control device 30 is configured as a computer unit including a microprocessor and peripheral devices such as RAM and ROM necessary for its operation. The control device 30 holds various control programs for causing the vehicle 1 to travel appropriately. The control device 30 executes control of the control objects such as the engine 2 and the MG 3 by executing these programs. Various sensors for acquiring information related to the vehicle 1 are connected to the control device 30. For example, a vehicle speed sensor 31 that outputs a signal corresponding to the speed (vehicle speed) of the vehicle 1, an SOC sensor 32 that outputs a signal corresponding to the state of charge (storage rate) of the battery 4, and the like are connected to the control device 30. . Various other sensors are also connected, but their illustration is omitted. The control device 30 is also connected to various levers and switches such as a shift lever operated by the driver, but these are not shown.

  Next, control executed by the control device 30 will be described. As described above, the transmission 10 once enters the neutral state when the gear position is switched. Further, the first clutch 24 is switched to the temporarily released state when the gear position is switched. In these cases, the power of the engine 2 cannot be transmitted to the output shaft 12. Therefore, when the second clutch 25 is in the output shaft connected state, the control device 30 drives the output shaft 12 with the MG 3 so that the torque transmitted to the drive wheels 7 does not fluctuate in such a state. Hereinafter, assisting the driving of the driving wheels 7 with the MG 3 at the time of shifting the gears in this way may be referred to as shift assist.

  The control device 30 changes the connection destination of the rotor shaft 3a of the MG 3 according to the vehicle speed. As is well known, an upper limit value of the number of rotations that can rotate the rotor 3b is set in the MG3. Therefore, the control device 30 changes the connection destination of the rotor shaft 3a so that the rotation speed of the rotor 3b does not exceed the upper limit value. Specifically, the control device 30 switches the second clutch 25 to the input shaft connected state when the vehicle speed becomes equal to or higher than a predetermined first determination speed when the second clutch 25 is in the output shaft connected state. Further, the control device 30 switches the second clutch 25 to the output shaft connected state when the vehicle speed becomes lower than a predetermined second determination speed when the second clutch 25 is in the input shaft connected state. As described above, the shift assist described above can be executed by switching the second clutch 25 to the output shaft connected state. Note that a speed lower than the first determination speed is set as the second determination speed. By executing this control, the control device 30 functions as the control means of the present invention. Further, by switching the state of the second clutch 25 in this way, the first determination speed corresponds to the determination speed of the present invention.

  Control device 30 changes the values of the first determination speed and the second determination speed in accordance with the storage rate of battery 4. Generally, MG3 has a rotation speed range in which power generation can be performed efficiently. When the rotor shaft 3a of the MG 3 is connected to the output shaft 12, the rotation speed of the rotor shaft 3a tends to be high, and therefore the frequency at which the rotation speed of the rotor shaft 3a is higher than the rotation speed range where the power generation efficiency is good increases. Therefore, control device 30 reduces the value of each determination speed when the storage rate of battery 4 is less than the preset determination storage rate, compared to when the storage rate is greater than or equal to the determination storage rate. This increases the frequency with which the rotor shaft 3 a is connected to the input shaft 11. The determination power storage rate is a value set as a reference for determining whether or not it is necessary to charge the battery 4 by generating power with the MG 3. Therefore, what is necessary is just to set suitably according to the capacity | capacitance of the battery 4, etc. FIG.

  FIG. 2 shows determination speeds V1 and V2 when the storage rate is equal to or higher than the determination storage rate, and determination speeds V1 'and V2' when the storage rate is less than the determination storage rate. Hereinafter, the respective determination speeds when the power storage rate is equal to or higher than the determination power storage rate are referred to as a normal first determination speed V1 and a normal second determination speed V2. Further, the respective determination speeds when the power storage rate is lower than the determination power storage rate are referred to as a low SOC first determination speed V1 'and a low SOC second determination speed V2'. As shown in this figure, the low SOC determination speeds V1 'and V2' are both lower than the normal determination speeds V1 and V2. Further, the first determination speed V1 'at the time of low SOC is smaller than the second determination speed V2 at the normal time. For example, when the rotor shaft 3 a is connected to the input shaft 11, power can be generated more efficiently than when the rotor shaft 3 a is connected to the output shaft 12, for example, in a speed range equal to or higher than the first determination speed V 1 ′ at low SOC. Speed range is set.

  Control device 30 also changes the value of each determination speed in accordance with conditions other than the storage rate of battery 4. For example, the control device 30 changes the value of each determination speed depending on whether the MG 3 is generating power. As described above, when the rotor shaft 3a is connected to the input shaft 11, the rotational speed of the rotor shaft 3a is likely to be within the rotational speed range where the power generation efficiency is good. Therefore, when power is generated by MG3, the value of the determination speed is changed to low SOC determination speeds V1 'and V2'. The control device 30 also changes the value of each determination speed depending on whether or not the shift assist can be executed. As described above, the upper limit value of the number of rotations that can rotate the rotor 3b is set in the MG3. For this reason, if the vehicle speed is high and the shift assist is performed, the shift assist cannot be executed if the rotational speed of the rotor 3b exceeds the upper limit. Further, the shift assist cannot be executed even when the driving wheel 7 cannot be driven sufficiently by the MG 3 when the battery 4 has a low power storage rate and the gears are switched. Therefore, the control device 30 changes the value of the determination speed to the low SOC determination speeds V1 'and V2' when the shift assist cannot be executed.

  FIG. 3 shows a determination speed change routine executed by the control device 30 to change each determination speed in this way. This routine is repeatedly executed at a predetermined cycle while the vehicle 1 is traveling. By executing this routine, the control device 30 functions as the determination speed changing means of the present invention.

  In this routine, the control device 30 first acquires the traveling state of the vehicle in step S11. As the running state, for example, the vehicle speed, the storage rate of the battery 4, and the like are acquired. In this process, it is also acquired whether or not the MG 3 is currently functioning as a generator to generate power. In next step S12, control device 30 determines whether or not the storage rate of battery 4 is greater than or equal to the determined storage rate. When it determines with an electrical storage rate being more than a determination electrical storage rate, it progresses to step S13 and the control apparatus 30 determines whether it is generating electric power in MG3. If it is determined that power generation is not being performed, the process proceeds to step S14, and the control device 30 determines whether or not shift assist can be executed. When it is determined that the shift assist can be executed, the process proceeds to step S15, and the control device 30 changes the first determination speed and the second determination speed to the normal determination speeds V1 and V2. Thereafter, the current routine is terminated.

  On the other hand, when it is determined that the power storage rate is less than the determined power storage rate, when it is determined that power is being generated in MG3, or when it is determined that the shift assist cannot be performed, the process proceeds to step S16, and the control device 30 performs the first operation. The determination speed and the second determination speed are changed to low SOC determination speeds V1 ′ and V2 ′. Thereafter, the current routine is terminated.

  As described above, according to the present invention, when the storage rate of the battery 4 is less than the determination storage rate, the first determination speed and the second determination speed are changed to the low SOC determination speeds V1 ′ and V2 ′. Make it smaller. As a result, the vehicle speed range in which the second clutch 25 is in the input shaft connected state can be expanded, so that the MG 3 can efficiently generate power. Therefore, fuel consumption can be improved. In addition, when the storage rate of the battery 4 is equal to or higher than the determination storage rate, the first determination speed and the second determination speed are changed to normal determination speeds V1 and V2. In this case, since the vehicle speed region where the shift assist is performed is expanded, drivability can be improved.

  Further, in the present invention, each determination speed is changed to a low SOC determination speed even when power is generated by MG3, so that power can be efficiently generated by MG3. Therefore, fuel consumption can be further improved. Furthermore, in the present invention, each determination speed is changed to a low SOC determination speed even when shift assist cannot be executed. By changing in this way, efficient power generation can be performed quickly when it is necessary to generate power in MG3.

  In the above-described embodiment, each determination speed is changed depending on whether or not the storage rate is equal to or higher than the determination storage rate, but the method of changing each determination speed is not limited to this method. For example, as shown in FIG. 4, the value of each determination speed may be changed so that each determination speed decreases as the power storage rate of the battery 4 decreases. In this figure, line L1 indicates the first determination speed, and line L2 indicates the second determination speed. In this case, each determination speed can be changed more appropriately according to the storage rate. Therefore, it is possible to increase the frequency with which the rotor shaft 3a is connected to the input shaft 11 when the MG 3 starts power generation. Therefore, power generation can be performed more efficiently.

  The present invention is not limited to the above-described form and can be implemented in various forms. For example, the transmission of a vehicle to which the present invention is applied is not limited to a transmission having a maximum forward speed of four speeds. For example, the highest forward speed may be a transmission of 3rd speed or 5th speed or more. Further, all of the plurality of sleeves may not be provided on the input shaft. For example, all of the plurality of sleeves may be provided on the output shaft, or some of the plurality of sleeves may be provided on the input shaft and the remaining sleeves may be provided on the output shaft.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Internal combustion engine 3 Motor generator 4 Battery 7 Drive wheel 10 Transmission 11 Input shaft 12 Output shaft 25 2nd clutch (connection destination switching means)
30 Control device (control means, determination speed changing means)

Claims (4)

An internal combustion engine;
A motor / generator functioning as an electric motor and a generator;
A transmission having an input shaft connected to the internal combustion engine and an output shaft connected to drive wheels so as to be capable of transmitting power, and capable of changing a gear ratio between the input shaft and the output shaft;
Connection that can be switched between an input shaft connection state in which the motor / generator and the input shaft are connected so that power can be transmitted and an output shaft connection state in which the motor / generator and the output shaft are connected so that power can be transmitted Destination switching means,
Applied to a hybrid vehicle comprising a battery electrically connected to the motor generator,
In a control device comprising control means for switching the connection destination switching means from the output shaft connected state to the input shaft connected state when the vehicle speed is equal to or higher than a predetermined determination speed,
A control device comprising determination speed changing means for reducing the determination speed when the battery storage rate of the battery is less than a predetermined determination storage rate than when the battery storage rate is equal to or higher than the determination storage rate.   The control device according to claim 1, wherein the determination speed changing unit decreases the determination speed as the storage rate of the battery decreases.   3. The control device according to claim 1, wherein the determination speed changing unit makes the determination speed smaller when power is generated by the motor / generator than when power generation is not performed by the motor / generator. 4. .   If the motor / generator cannot assist in driving the drive wheels during the shifting of the transmission, the determination speed changing means may increase the determination speed more than in the case where the motor / generator can assist in driving the drive wheels. The control device according to claim 1, wherein the control device is made small.

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