JP2011251615A - Control device of vehicle driving system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promptly change engine speed of an internal combustion engine to the engine speed at which the system efficiency expressed by multiplication value of thermal efficiency of the internal combustion engine and transmission efficiency of a power transmission mechanism becomes maximum, in a vehicle driving system which can change the engine speed, while fixing output of the internal combustion engine.SOLUTION: The allowable maximum variation of the engine speed is associated with output and is stored in a storage device. The allowable maximum variation according to the requested output is read from the storage device, and the engine speed is changed by the allowance maximum variation by making the engine speed on line of operation set beforehand into an initial value. Then whenever the engine speed is changed, the system efficiency expressed by a multiplication value of the thermal efficiency of the internal combustion engine and the transmission efficiency of the power transmission mechanism is computed, and the engine speed at which the system efficiency becomes the maximum is specified, and the engine speed at which the system efficiency becomes the maximum is decided as the optimal engine speed.

Description

  The present invention relates to a control device for a vehicle drive system capable of changing the rotation speed while keeping the output of an internal combustion engine constant, and more particularly to a control device for a vehicle drive system suitable for use in a hybrid system in which power circulation can occur. .

  Conventionally, a vehicle drive system using a continuously variable transmission as a power transmission mechanism that transmits power generated by an internal combustion engine to drive wheels is known. Japanese Unexamined Patent Application Publication No. 2009-154724 discloses an example of such a vehicle drive system. The system disclosed in this publication includes an electric differential mechanism between the internal combustion engine and the continuously variable transmission, and controls the gear ratio of the continuously variable transmission so that the combustion efficiency of the internal combustion engine is optimized. However, transmission efficiency can be increased by controlling the differential state.

JP 2009-154724 A Japanese Patent Laid-Open No. 11-257112 JP 2003-161185 A JP 2004-232487 A

  By the way, in order to improve the fuel efficiency of the vehicle, it is important to increase the efficiency of the entire system of the vehicle drive system (hereinafter referred to as system efficiency). The system efficiency can be expressed by a multiplication value of each efficiency until power is generated from fuel in the internal combustion engine and the power is transmitted to the drive wheels. More specifically, it can be expressed by a multiplication value of the thermal efficiency of the internal combustion engine and the transmission efficiency of the power transmission mechanism. For this reason, in order to improve system efficiency, it is ideal to maximize both thermal efficiency and transmission efficiency, but this is not always possible. In general, the thermal efficiency of the internal combustion engine and the transmission efficiency of the power transmission mechanism depend on the number of revolutions, but depending on the configuration of the power transmission mechanism, increasing the thermal efficiency and increasing the transmission efficiency may be contradictory. In this case, it is necessary to find a rotation speed at which the system efficiency is maximized while changing the rotation speed. From the viewpoint of improving fuel efficiency, it is desirable to reduce the time spent for the work as much as possible. On the other hand, if the rotational speed is changed too rapidly, there is a risk that the passenger will feel uncomfortable due to the torque fluctuation of the internal combustion engine caused thereby.

  The present invention has been made in view of the above-described problems. In a vehicle drive system capable of changing the rotation speed while keeping the output of the internal combustion engine constant, the thermal efficiency of the internal combustion engine and the transmission efficiency of the power transmission mechanism are An object of the present invention is to quickly change the rotational speed of the internal combustion engine to the rotational speed at which the system efficiency represented by the multiplication value is maximized.

In order to achieve the above object, a control device for a vehicle drive system according to a first invention comprises:
In a control device for a vehicle drive system having an internal combustion engine and a power transmission mechanism for transmitting power generated by the internal combustion engine to drive wheels, and capable of changing the rotational speed while keeping the output of the internal combustion engine constant,
Storage means for storing the maximum allowable change in the rotational speed in association with the output;
A rotation speed changing means for reading the allowable maximum change amount corresponding to the requested output from the storage means, and setting a rotation speed on a preset operation line as an initial value, and changing the rotation speed with the allowable maximum change amount;
System efficiency calculation means for calculating a system efficiency represented by a product of the thermal efficiency of the internal combustion engine and the transmission efficiency of the power transmission mechanism each time the rotation speed is changed by the rotation speed change means;
An optimum rotational speed determining means for identifying the rotational speed at which the system efficiency is maximized and determining the rotational speed as the optimal rotational speed;
It is characterized by having.

A control device for a vehicle drive system according to a second invention is the control device for a vehicle drive system according to the first invention,
In changing the engine speed while keeping the output of the internal combustion engine constant,
Learning means for learning the maximum change amount of the engine speed at which the torque fluctuation amount of the internal combustion engine does not exceed the allowable value as the allowable maximum change amount in the output,
Is further provided.

A control device for a vehicle drive system according to a third aspect of the invention is the control device for a vehicle drive system according to the first or second aspect of the invention,
The internal combustion engine is a turbocharged internal combustion engine,
The controller is
Exhaust energy increase amount calculation means for calculating an increase amount of exhaust energy every time the rotation speed is changed by the rotation speed change means;
When the amount of increase in exhaust energy exceeds a reference value, a rotational speed change amount correcting means for reducing the rotational speed change amount by the rotational speed changing means;
Is further provided.

  According to the control device for a vehicle drive system of the first aspect of the present invention, the rotational speed of the internal combustion engine is quickly increased to the rotational speed at which the system efficiency is maximized by changing the rotational speed with the allowable maximum change amount according to the required output. Can be changed.

  According to the control device for a vehicle drive system of the second invention, the rotational speed of the internal combustion engine can be quickly changed to the rotational speed at which the system efficiency is maximized while suppressing the torque fluctuation amount to a reference value or less.

  According to the control device for a vehicle drive system of the third aspect of the invention, the engine speed is rapidly changed to the engine speed at which the system efficiency is maximized while preventing the turbocharger from being supercharged as the exhaust energy increases. Can be made.

It is a figure which shows the structure of the hybrid system to which the control apparatus of Embodiment 1 of this invention is applied. It is a figure which shows the flow of the motive power in the hybrid system of FIG. (A) shows the flow of power during normal travel, and (B) shows the flow of power during power circulation. It is a figure which shows the image of the map used for determination of the operating point of an engine. It is a figure which shows the relationship between a power circulation rate and transmission efficiency. It is a collinear diagram of the hybrid system shown in FIG. It is a figure which shows each relationship between a rotation speed, engine thermal efficiency, transmission efficiency, and system efficiency. It is a flowchart which shows the routine of rotation speed control by the control apparatus of Embodiment 1 of this invention. It is a figure which shows the image of the map which links | relates an allowable maximum rotation speed variation | change_quantity with an output. It is a figure for demonstrating the effect of the rotation speed control by the control apparatus of Embodiment 1 of this invention. It is a flowchart which shows the routine for rotation speed control performed by the control apparatus of Embodiment 1 of this invention.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 9.

  In Embodiment 1 of the present invention, the present invention is applied to a control device of a hybrid system. FIG. 1 is a diagram illustrating a configuration of a hybrid system according to the present embodiment. The hybrid system according to the present embodiment includes an internal combustion engine 2, a first motor generator (MG1) 4, a second motor generator (MG2) 6, a power split mechanism 8, an inverter 10, a speed reducer 12, and an electronic control unit (ECU). 20 is provided. The first motor generator 4, the second motor generator 6, the power split mechanism 8, the inverter 10 and the speed reducer 12 constitute a power transmission mechanism 18 that transmits the power generated by the internal combustion engine 2 to the drive wheels 14L and 14R. . Further, the control device of the present embodiment is realized by a program executed by the electronic control unit 20. The electronic control unit 20 controls the operation of the engine 2 and also controls each operation of the first motor generator 4 and the second motor generator 6 via the inverter 10.

  There is no limitation on the type of the internal combustion engine (hereinafter referred to as the engine) 2 according to the present embodiment. Various types of engines can be used, such as spark ignition engines, compression ignition engines, 4-stroke engines, 2-stroke engines, reciprocating engines, rotary engines, single-cylinder engines, multi-cylinder engines, naturally aspirated engines, and turbo engines. . An in-cylinder pressure sensor is provided in at least one cylinder of the engine 2.

  The power generated by the engine 2 is divided into two paths by the power split mechanism 8 constituting the power transmission mechanism 18. The power split mechanism 8 is constituted by a planetary gear. The engine 2 is connected to the carrier shaft, the first motor generator 4 is connected to the sun gear, and the speed reducer 12 and the second motor generator 6 are connected to the internal gear. One path divided by the power split mechanism 8 is a path for supplying power to the drive wheels 14L and 14R via the speed reducer 12, and the other path is a path for supplying power to the first motor generator 4. It is.

  The first motor generator 4 and the second motor generator 6 are both three-phase AC synchronous motor generators. The first motor generator 4 functions as a generator by the driving force of the engine 2 supplied via the power split mechanism 8. The electric power generated by the first motor generator 4 is supplied to the second motor generator 6 via the inverter 10. Receiving the electric power, the second motor generator 6 functions as a motor and generates power. The power generated by the second motor generator 6 is transmitted to the drive wheels 14L and 14R through the speed reducer 12 together with the power of the engine 2 divided by the power split mechanism 8.

  The power flow in the power transmission mechanism 18 described above is represented by a diagram as shown in FIG. This shows the flow of power during normal driving of the vehicle. In this case, the transmission efficiency of the power transmission mechanism 18 can be regarded as almost constant regardless of the rotational speed of the engine 2. Therefore, in order to increase the system efficiency in the case shown in FIG. 2A, the engine 2 may be operated at an operating point where the thermal efficiency of the engine 2 becomes high.

  FIG. 3 is a diagram showing an image of a map used for determining the operating point of the engine. The operating point of the engine is specified by the torque and the rotational speed. In FIG. 3, an iso-output line and an isothermal efficiency line are drawn. The operating lines shown in FIG. 3 are obtained by continuously connecting the operating points at the respective outputs. The operation line is set so as to pass near the point where the thermal efficiency of the engine 2 is high on each equal output line. During normal running as shown in FIG. 2A, the rotational speed corresponding to the required output is determined according to this operation line.

  However, depending on the driving situation of the vehicle and the situation of the system, as shown in (B) of FIG. 2, power circulation may occur inside the power transmission mechanism 18. In this case, the second motor generator 6 functions as a generator, and the first motor generator 4 functions as an electric motor. Such power circulation increases loss and reduces transmission efficiency. Here, the ratio of the power consumed by the first motor generator 4 to the power generated by the engine 2 is defined as the power circulation rate. Then, the relationship between the power circulation rate and the transmission efficiency of the power transmission mechanism 18 is as shown in FIG. From FIG. 4, it can be confirmed that if it is desired to increase the transmission efficiency of the power transmission mechanism 18, it is necessary to keep the power circulation rate low.

  FIG. 5 is a collinear diagram of the hybrid system shown in FIG. This nomogram shows the relationship between the rotational speed of the engine (E / G) 2, the rotational speed of the first motor generator (MG1) 4, and the rotational speed of the speed reducer 12 that is the output unit (OUT PUT). Has been. If attention is paid only to the thermal efficiency of the engine 1, it is preferable to keep the rotational speed of the engine 2 low as shown by the broken line in FIG. However, in that case, the rotation speed of the first motor generator 4 increases in the reverse direction. For this reason, the power generated by the first motor generator 4 increases, and the loss due to power circulation increases accordingly.

  If it is desired to reduce the loss due to power circulation, the rotational speed of the engine 2 may be increased as shown by the solid line in FIG. This is because the reverse rotation speed of the first motor generator 4 can be kept low by doing so. However, regarding the thermal efficiency of the engine 2, increasing the rotational speed of the engine 2 reduces the thermal efficiency. That is, increasing the thermal efficiency of the engine 2 and increasing the transmission efficiency of the power transmission mechanism 18 are in a trade-off relationship with respect to the rotational speed.

  FIG. 6 is a diagram showing each relationship between the rotational speed and the thermal efficiency, transmission efficiency, and system efficiency during power circulation. As shown in FIG. 6, the system efficiency, which is a product of the thermal efficiency of the engine 2 and the transmission efficiency of the power transmission mechanism 18, becomes maximum at a certain rotational speed. Such a rotational speed can be searched by changing the rotational speed while calculating the system efficiency. At that time, as the amount of change in the rotational speed is increased, the time required for the search can be shortened and the system efficiency can be quickly increased to the maximum. However, if the amount of change in the rotational speed is too large, the occupant may feel uncomfortable due to an increase in the torque fluctuation amount of the engine 2.

  Therefore, in the present embodiment, the following rotation speed control is performed by the electronic control unit 20. FIG. 7 is a flowchart showing a routine of the rotational speed control executed by the electronic control unit 20 in the present embodiment.

  In the first step S2, it is determined whether the running state of the vehicle is steady running. The determination is made, for example, whether or not the equal accelerator opening has continued for a predetermined period, whether or not the variation rate between cycles of the maximum in-cylinder pressure is within a predetermined value, or the variation rate between cycles of the maximum in-cylinder pressure crank angle. It is performed from the viewpoint of whether or not it is within a predetermined value.

When the traveling state of the vehicle is steady traveling, the process of step S4 is performed. In step S4, the memory is searched using the current requested output as a key, and the allowable maximum change amount ΔNe _max corresponding to the requested output is read. As the amount of change in the rotational speed increases, the torque fluctuation amount of the engine 2 also increases. The allowable maximum change amount ΔNe _max is the maximum rotational speed change amount at which the torque fluctuation amount of the engine 2 does not exceed the allowable value. The electronic control unit 20 learns the allowable maximum change amount ΔNe _max in association with the output of the engine 2 and stores the learned value in the memory. FIG. 8 is a diagram showing an image of a map that associates the allowable maximum rotational speed change amount ΔNe _max with the output of the engine 2. The reason why the allowable maximum rotational speed change amount ΔNe _max is smaller as the output is higher (higher rotation) because the fluctuation of the internal EGR becomes larger as the rotational speed is higher, and the torque fluctuation amount is increased accordingly.

In step S4, it is next determined whether or not the read allowable maximum change amount ΔNe _max is zero. When learning of the allowable maximum change amount ΔNe _max is not completed, the value read from the memory is zero.

If the allowable maximum change amount ΔNe _max is not zero, the process of step S8 is performed next. On the other hand, when the allowable maximum change amount ΔNe _max is zero, the process of step S6 is performed after the process of step S6. In step S6, a predetermined value ΔNe1 is input as the allowable maximum change amount ΔNe _max . The predetermined value ΔNe1 is a provisional allowable maximum change amount, and is set to a value larger than an expected allowable maximum change amount.

  In step S8, system state quantities such as the rotation speed, load, fuel injection quantity, power circulation quantity and the like are referred to. Specifically, the power consumed by the first motor generator 4 is referred to as the power circulation amount.

In the next step S10, the illustrated efficiency of the engine 2 and the transmission efficiency of the power transmission mechanism 18 are acquired. Then, a multiplication value of the indicated efficiency and the transmission efficiency is calculated as the system efficiency η _sys .

  For obtaining the transmission efficiency, a map that defines the relationship between the transmission efficiency and the power circulation rate as shown in FIG. 4 is used. The power circulation rate is calculated from the power circulation amount referred to in step S8, and the transmission efficiency corresponding to the power circulation rate is read from the map.

On the other hand, the illustrated efficiency of the engine 2 is calculated by the following equation 1. In Equation 1, _Qf is the heat generation amount of all the supplied fuel, and is calculated from the fuel injection amount. Q is a theoretical cycle work and can be calculated by the following equation (2). L _p is the pump loss, and can be calculated from the PV diagram of the previous cycle. _Lex is an exhaust loss, which is proportional to the product of the exhaust temperature, the specific heat of the burned gas, and the exhaust manifold volume. The exhaust temperature can be calculated by using the output value of the in-cylinder pressure sensor when the exhaust valve is opened.

In step S12, the value of the system efficiency η _sys calculated in step S10 is substituted for the parameter η _base . In step S14, the value of the system efficiency η _sys calculated in step S10 is also substituted for the parameter η _para .

In the next step S16, the value of the parameter eta _para it is determined whether or the value of the parameter eta _base. Since the values of the two parameters η _para and η _base are the same at the first execution of this step, the determination result of this step is affirmative. In that case, the process after step S18 is performed.

In step S18, the rotational speed Ne of the engine 2 is increased by an amount obtained by multiplying the allowable maximum change amount ΔNe _max by the correction coefficient T. The initial value of the rotational speed Ne is the rotational speed on the operation line shown in FIG. 3, and is determined corresponding to the required output. The initial value of the correction coefficient T is 1, and at that time, the allowable maximum change amount ΔNe _max is added to the rotational speed Ne as it is. At this time, torque control by an actuator such as a throttle is performed so that the output of the engine 2 does not change, that is, the operating point of the engine 2 changes along the iso-output line.

In the next step S20, the system efficiency η _sys is recalculated based on the system state quantity after the operation change. In step S22, the value of the system efficiency η _sys after the operation change calculated in step S20 is substituted for the parameter η _para . The value of the system efficiency η _sys before the operation change is substituted for another parameter η _base .

In the next step S24, the torque fluctuation amount T is calculated from the engine state amount such as the in-cylinder pressure. Then, it is determined whether or not the torque fluctuation amount T is smaller than a predetermined reference value. If the torque fluctuation amount T is smaller than the predetermined value, it is determined that the current rotational speed change amount, that is, the amount obtained by multiplying the allowable maximum change amount ΔNe _max by the correction coefficient T is an appropriate value in terms of torque fluctuation. be able to. In this case, the current rotational speed change amount (ΔNe _max × T) is stored in the memory as a learned value of the allowable maximum change amount ΔNe _max . On the other hand, if the torque fluctuation amount T is equal to or greater than a predetermined value, it can be determined that the current rotational speed change amount is an inappropriate value in terms of torque fluctuation. In that case, the process of step S26 is performed, and the value of the correction coefficient T is subtracted by a predetermined value a.

After step S24 or S26, it returns to step S16 again and determination is performed. In the second and subsequent determinations in step S16, the value of the system efficiency η _sys after the operation change assigned to the parameter η _para and the value of the system efficiency η _sys before the operation change assigned to the parameter η _base are obtained. Will be compared. If the parameter η _para is larger than the parameter η _base , it can be determined that there is room for further increasing the system efficiency η _sys .

Until the parameter η _para becomes smaller than the parameter η _base , the process proceeds again to step S18, where the rotation speed Ne of the engine 2 is further increased by an amount obtained by multiplying the allowable maximum change amount ΔNe _max by the correction coefficient T. If the correction coefficient T is subtracted in step S26, the rotation speed change amount (ΔNe _max × T) is calculated using the subtracted correction coefficient T. In step S20, the system efficiency η _sys is recalculated based on the system state quantity after the operation change. Thereafter, the processes of steps S22, S24, and S26 are performed as in the previous case, and the determination of step S16 is performed again using the new parameters η _para and η _base .

If the determination result in step S16 is negative, that is, if the value of the system efficiency η _sys after the operation change is smaller than the value of the system efficiency η _sys before the operation change, the rotation at that time The number Ne is determined as the optimum rotational speed that maximizes the system efficiency η _sys . Then, after the process of step S28, this routine is terminated. In step S28, the value of the correction coefficient T is initialized and returned to 1. Note that, as a result of the determination in step S2, the routine is ended after the processing in step S28 even when the traveling state of the vehicle is not steady traveling.

FIG. 9 shows the engine speed Ne and the speed change amount ΔNe when the speed control of the present embodiment is performed (shown by a solid line) and when the speed change amount is kept low (shown by a broken line). It is a chart which compares and shows each time change. As can be seen from this figure, according to the rotation speed control executed in the present embodiment, the torque fluctuation amount is set to the reference value by changing the rotation speed Ne with the allowable maximum change amount ΔNe _max according to the required output. While suppressing to the following, the rotation speed of the engine 2 can be rapidly changed to the rotation speed at which the system efficiency is maximized.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG.

  The configuration of the hybrid system to which the control device of the second embodiment of the present invention is applied is shown in FIG. 1 as in the first embodiment. However, unlike the first embodiment, the hybrid system according to the present embodiment is limited in the configuration of the engine 2. The engine 2 according to the present embodiment is a turbo engine equipped with a turbocharger. In a turbo engine, the exhaust energy changes when the rotational speed or load changes. Since the increase / decrease in the exhaust energy affects the rotational speed of the turbine, the controllability of the engine 2 may be impaired by supercharging when the exhaust energy increases rapidly.

  Therefore, in the present embodiment, the following rotation speed control is performed by the electronic control unit 20. FIG. 10 is a flowchart showing a rotation speed control routine executed by the electronic control unit 20 in the present embodiment. In FIG. 10, the same step numbers are assigned to the processes common to the rotational speed control executed in the first embodiment. In the following, processing unique to the rotational speed control executed in the present embodiment will be described mainly.

In the present embodiment, the process of step S30 is performed after the processes of step S12 and step S14 or in parallel with these processes. In step S30, the value of the exhaust loss at the present time is substituted for the parameter L _ex1 . The exhaust loss is proportional to the exhaust temperature, and the exhaust temperature can be obtained by calculation using the output value of the in-cylinder pressure sensor when the exhaust valve is opened.

In the present embodiment, the determination in step S16 is performed after the process in step S30. Result of the determination in step S16, if the value of the parameter eta _para or more values of the parameters eta _base, followed by processing in step S18 is performed. In step S18, the rotational speed Ne of the engine 2 is increased by an amount obtained by multiplying the allowable maximum change amount ΔNe _max by the correction coefficient T, and at the same time, the operating point of the engine 2 changes along the iso-output line. In addition, torque control is performed by an actuator such as a throttle.

In the next step S20, the system efficiency η _sys is recalculated based on the system state quantity after the operation change. In the subsequent step S22, the value of the system efficiency η _sys after the operation change is substituted for the parameter η _para, and the value of the system efficiency η _sys before the operation change is substituted for the parameter η _base .

In the present embodiment, next, the process of step S32 is performed. In step S32, the value of the exhaust loss at the current time, that is, the value of the exhaust loss after the operation change is substituted for the parameter L _ex2 . By increasing the engine speed in step S18, the exhaust loss value is larger than the value before the operation change.

In the next step S34, the absolute value of the difference between the parameter L _ex2 and the parameter L _ex1 is calculated, and the value is compared with a predetermined reference value ΔL _ex . The absolute value of the difference between the parameter L _ex2 and the parameter L _ex1 corresponds to the amount of increase in exhaust energy accompanying the increase in the rotational speed. On the other hand, the reference value ΔL _ex is set in correspondence with the limit amount of exhaust energy increase at which supercharging can occur. Therefore, if the absolute value of the difference between the parameter L _ex2 and the parameter L _ex1 exceeds the reference value ΔL _ex , it can be determined that there is a high possibility that supercharging will occur due to an excessive increase in exhaust energy.

As a result of the determination in step S34, if the absolute value of the difference between the parameter L _ex2 and the parameter L _ex1 exceeds the reference value ΔL _ex , the process of step S36 is performed. In step S36, the rotational speed Ne of the engine 2 is reduced by an amount obtained by multiplying the maximum allowable change amount ΔNe _max by the correction coefficient b. This is because an excessive increase in exhaust energy is suppressed by suppressing an increase in the rotational speed Ne of the engine 2 and the occurrence of supercharging is prevented. Note that the correction coefficient b is a value smaller than the correction coefficient T, and may be a multiplication value of the correction coefficient T and a predetermined value less than 1, for example. After the process of step S36, the determination of step S24 is performed. On the other hand, if the absolute value of the difference is less than or equal to the reference value ΔL _ex , the determination in step S24 is performed without reducing the rotational speed Ne.

After step S24 or S26, it returns to step S16 again and determination is performed. In the second and subsequent determinations in step S16, the value of the system efficiency η _sys after the operation change assigned to the parameter η _para and the value of the system efficiency η _sys before the operation change assigned to the parameter η _base are obtained. Will be compared.

The process proceeds to step S18 again until the parameter η _para becomes smaller than the parameter η _base , and then the processes of steps S20, S22, S32, S34, S36, S24, and S26 are performed. During the second and subsequent executions of the process of step S32, the value of the exhaust loss before the operation change is substituted for the parameter L _ex1 and the value of the exhaust loss at the present time, that is, the value of the exhaust loss after the operation change is the parameter L _Assigned to _ex2 . When the absolute value of the difference between the parameter L _ex2 and the parameter L _ex1 exceeds the reference value ΔL _ex , the engine speed in step S36 is slightly suppressed so as to slightly suppress the engine speed Ne increased in step S18. Ne is corrected. Thereafter, the rotational speed is increased toward the rotational speed at which the system efficiency η _sys is maximized while suppressing the increase in the rotational speed Ne of the engine 2 to the extent that the exhaust energy does not increase rapidly.

  As described above, according to the rotation speed control executed in the present embodiment, a rapid increase in the rotation speed that causes a rapid increase in exhaust energy is prevented. Thereby, the rotation speed of the engine 2 can be rapidly changed to the rotation speed at which the system efficiency is maximized while preventing the turbocharger from being supercharged due to the increase in exhaust energy.

Others.
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the present invention is applied to a hybrid system. However, if the vehicle drive system is capable of changing the rotational speed while keeping the output of the engine constant, such as a continuously variable transmission, the present invention is applied. It is possible to apply the invention. Even when the present invention is applied to a hybrid system, the configuration of the hybrid system to which the present invention is applicable is not limited to FIG. However, from the viewpoint of the effect of the present invention, application to a system in which power circulation can occur is most effective.

2 Engine 4 First motor generator 6 Second motor generator 8 Power split mechanism 10 Inverter 12 Reducer 14L, 14R Drive wheel 18 Power transmission mechanism 20 Electronic control unit

Claims (3)

In a control device for a vehicle drive system having an internal combustion engine and a power transmission mechanism for transmitting power generated by the internal combustion engine to drive wheels, and capable of changing the rotational speed while keeping the output of the internal combustion engine constant,
Storage means for storing the maximum allowable change in the rotational speed in association with the output;
A rotation speed changing means for reading the allowable maximum change amount corresponding to the requested output from the storage means, and setting a rotation speed on a preset operation line as an initial value, and changing the rotation speed with the allowable maximum change amount;
System efficiency calculation means for calculating a system efficiency represented by a product of the thermal efficiency of the internal combustion engine and the transmission efficiency of the power transmission mechanism each time the rotation speed is changed by the rotation speed change means;
An optimum rotational speed determining means for identifying the rotational speed at which the system efficiency is maximized and determining the rotational speed as the optimal rotational speed;
A control device for a vehicle drive system comprising: Learning to learn the maximum change amount of the engine speed at which the torque fluctuation amount of the internal combustion engine does not exceed the allowable value as the allowable maximum change amount in the output when changing the engine speed while keeping the output of the internal combustion engine constant means,
The vehicle drive system control device according to claim 1, further comprising: The internal combustion engine is a turbocharged internal combustion engine,
The controller is
Exhaust energy increase amount calculation means for calculating an increase amount of exhaust energy every time the rotation speed is changed by the rotation speed change means;
When the amount of increase in exhaust energy exceeds a reference value, a rotational speed change amount correcting means for reducing the rotational speed change amount by the rotational speed changing means;
The vehicle drive system control device according to claim 1, further comprising:

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