JP5679186B2 - Control device - Google Patents

Description

  The present invention relates to a control device for a vehicle including an internal combustion engine and a continuously variable transmission.

  Recent automobiles are often AT cars equipped with automatic transmissions. As an automatic transmission for a vehicle, a continuously variable transmission including a torque converter and a belt-type continuously variable transmission mechanism is known (for example, refer to the following patent document).

  The transmission ratio of the continuously variable transmission is controlled so as to realize the optimum fuel consumption in accordance with the fuel consumption rate (fuel consumption rate) characteristics of the internal combustion engine. As shown in FIG. 3, when the engine speed is set on the horizontal axis and the engine torque is set on the vertical axis, the engine output that is the product of the engine speed and the engine torque becomes constant. Is shown in the form of a hyperbola. Further, a set of the engine speed and the engine torque at which the fuel consumption rate is constant is represented as an equal fuel consumption rate line (indicated by a thin solid line in the figure). By combining the two, the gear ratio that provides the best fuel efficiency when achieving a certain engine output can be plotted for various engine outputs. This is the shift line shown in FIG. 3 (indicated by a thick solid line in the figure). An on-vehicle electronic control unit (Electronic Control Unit) operates the speed ratio of the continuously variable transmission along the shift line in accordance with the increase or decrease in the required load (output) commanded by the driver.

  However, the fuel consumption rate characteristic of the internal combustion engine is not always constant. If the equal fuel consumption rate line fluctuates, the shift line should naturally change, but conventionally, the transmission ratio of the continuously variable transmission is controlled based on a unique shift line determined by conformance. May not be able to maximize fuel efficiency.

JP 2010-071427 A

  An object of the present invention is to further improve the fuel efficiency of a vehicle including an internal combustion engine and a continuously variable transmission.

In the present invention, there is provided a control apparatus for a vehicle having an internal combustion engine and the continuously variable transmission, the value of the parameters affecting the fuel consumption rate of the internal combustion engine, stores in advance the relationship between the fuel consumption rate, and stores With reference to the relationship between the parameter and the fuel consumption rate, the fuel consumption rate under the parameter value in a predetermined driving state including the value of a certain predetermined parameter and the value of the parameter in the current driving state The rate of change between the fuel consumption rate in the engine is obtained, and based on this, the torque change rate of the internal combustion engine between the predetermined operating state and the current operating state is obtained, and the engine required in the predetermined operating state The relationship between the output and the target engine speed that defines the gear ratio of the continuously variable transmission when achieving the engine output is stored in advance, and the relationship between the stored engine output and the target engine speed Referring to the continuously variable transmission gear ratio, the target engine speed corresponding to the currently requested engine output is obtained and the target engine speed obtained by multiplying the target engine speed by the torque change rate is realized. The control device is configured to use the ignition timing and the air-fuel ratio of the gas charged in the cylinder as the parameters . That is, pay attention to the fact that the equal fuel consumption rate line fluctuates when the ignition timing is retarded or the fuel injection amount is increased to prevent knocking, and the gear ratio line is changed in response to the fluctuation. I did it.

In addition, according to the present invention, there is provided a control apparatus for a vehicle including an internal combustion engine and a continuously variable transmission, which is required for each parameter value that affects the fuel efficiency of the internal combustion engine in an operating state including the parameter value. Map data indicating the relationship between the engine output and the target engine speed that defines the speed ratio of the continuously variable transmission when achieving the engine output is stored in advance, and the value of the parameter in the current operating state is stored. With reference to the corresponding map data, the target engine speed corresponding to the currently requested engine output is obtained, and the speed ratio of the continuously variable transmission is operated so as to embody the target engine speed. A control device using ignition timing and air-fuel ratio as the parameters was configured.

  According to the present invention, it is possible to further improve the fuel consumption performance of a vehicle including an internal combustion engine and a continuously variable transmission.

The figure which shows the structure of the internal combustion engine in one Embodiment of this invention. The figure which shows the structure of the automatic transmission in the embodiment. The figure which shows the shift line of the gear ratio control which the control apparatus of the embodiment implements. The figure which shows the shift line which changed in the case of torque-down. The figure which shows the relationship between ignition timing and a fuel consumption rate. The figure which shows the relationship between an air fuel ratio and a fuel consumption rate.

  An embodiment of the present invention will be described with reference to the drawings. The internal combustion engine 0 schematically showing the configuration of one cylinder in FIG. 1 is mounted on, for example, an automobile. The intake system 1 of the internal combustion engine 0 is provided with a throttle valve (in particular, an electronic throttle valve) 11 that opens and closes according to the amount of depression of the accelerator pedal, and an intake air that integrally has a surge tank 13 downstream of the throttle valve 11. A manifold 12 is attached. The surge tank 13 is provided with a pressure sensor for detecting the intake pipe pressure (or intake negative pressure).

An exhaust manifold 51 is attached to the exhaust system 5 and a three-way catalyst 52 for exhaust gas purification is attached. A front O ₂ sensor is disposed upstream of the catalyst 52 and a rear O ₂ sensor is disposed downstream. The O ₂ sensor 54 outputs a voltage signal corresponding to the oxygen concentration in the exhaust gas by reacting in contact with the exhaust gas.

  An EGR device 6 is interposed between the intake system 1 and the exhaust system 5. The EGR device 6 includes an external EGR passage 61 having a start end communicating with the exhaust manifold 51 and a terminal end communicating with the surge tank 13, and an external EGR valve 62 provided on the EGR passage 61. If the EGR valve 62 is opened, an external EGR that recirculates the exhaust gas from the exhaust system 5 to the intake system 1 and mixes it with the intake air can be realized.

  An intake valve 21, an exhaust valve 22, an injector 3, and a spark plug 23 are provided on the ceiling portion (cylinder head) of the combustion chamber formed in the upper part of the cylinder 2.

  FIG. 2 shows an example of an automatic transmission. This automatic transmission is a continuously variable transmission including a torque converter 7 and a belt type CVT 9. The driving force output from the internal combustion engine 0 is input to the pump impeller 71 on the input side of the torque converter 7 and transmitted to the turbine runner 72 on the output side. The rotation of the turbine runner 72 is transmitted to the drive shaft 94 of the CVT 9 via the forward / reverse switching device 8 using a planetary gear mechanism, and rotates the driven shaft 95 through a shift in the CVT 9. An output gear 101 is fixed to the driven shaft 95, and this output gear 101 meshes with the ring gear 102 of the differential device to rotate the axle 103 and thus the drive wheel (not shown).

  The torque converter 7 includes a lockup mechanism (not shown). The lockup mechanism is known in this field, and includes a lockup clutch that locks up the input side and the output side of the torque converter 7, and a lockup solenoid that controls the hydraulic pressure for driving the lockup clutch to connect and disconnect. A valve is an element. The lockup mechanism connects the lockup clutch and fastens the input side and the output side in a situation that does not involve a change in the gear ratio by the automatic transmission.

In the forward / reverse switching device 8, the sun gear 81 communicates with the turbine runner 72 via the input shaft 73, and the ring gear 82 communicates with the drive shaft 94. Between the planetary carrier 83 that supports the planetary gear 831 and the transmission case, a forward brake 84 that is a hydraulic clutch that can be connected and disconnected is interposed. Further, a reverse clutch 85 that is a hydraulic clutch that can be connected and disconnected is also provided between the planetary carrier 83 and the sun gear 81 (or the input shaft 73). And the reverse clutch 85 is disconnected. As a result, the rotation of the input shaft 73 is reversed and decelerated and transmitted to the drive shaft 94 for forward travel. In turn, in the R range, the reverse clutch 85 is engaged and the forward brake 84 is disconnected. As a result, the sun gear 81 and the planetary carrier 83 rotate integrally, and the input shaft 73 and the drive shaft 94 are directly connected to perform reverse travel. In the N range and P range, which are non-traveling ranges, both the reverse clutch 84 and the forward brake 85 are disconnected.

  The CVT 9 includes a driving pulley 91 and a driven pulley 92, and a belt 93 wound around the pulleys 91 and 92 as elements. The drive pulley 91 is disposed behind the movable sheave 912, a fixed sheave 911 fixed to the drive shaft 94, a movable sheave 912 supported on the drive shaft 91 via a roller spline so as to be displaceable in the axial direction. A hydraulic servo 913 is provided, and the gear ratio can be changed steplessly by operating the hydraulic servo 913 and displacing the movable sheave 912. The driven pulley 92 is disposed on the back of the movable sheave 922, a fixed sheave 921 fixed to the driven shaft 95, a movable sheave 922 supported on the driven shaft 95 via a roller spline so as to be axially displaceable. A hydraulic servo 923 is provided, and a belt thrust necessary for torque transmission is applied by operating the hydraulic servo 923 and displacing the movable sheave 922.

  The ECU 4 that controls operation of the internal combustion engine 0 and the CVT 9 is a microcomputer system having a central processing unit 41, a storage device 42, an input interface 43, an output interface 44, and the like.

The input interface 43 outputs an intake pressure signal a output from a pressure sensor that detects the pressure in the intake pipe, a rotation speed signal b output from the rotation speed sensor that detects the engine speed, and a vehicle speed sensor 73 that detects the vehicle speed. Vehicle speed signal c, accelerator pedal position signal d output from an accelerator pedal position sensor that detects the amount of accelerator pedal depression (or throttle valve 11), and shift lever position (shift range). Shift position signal e output from the position switch, water temperature signal f output from the water temperature sensor for detecting the coolant temperature, crank angle signal output from the timing sensor at the end of the intake camshaft 91, and cylinder discrimination signal g , 240 ° CA (crank angle) from the timing sensor at the end of the exhaust camshaft 92 Exhaust cam signal h which is output every rotation, the front O ₂ upstream air-fuel ratio signal i output from the sensor, downstream air-fuel ratio signal j outputted from the rear O ₂ sensor, a knock sensor for detecting the occurrence of knocking The knocking signal k etc. output from is input. The amount of depression of the accelerator pedal indicates a required load commanded by the driver. The coolant temperature indicates the temperature of the internal combustion engine 0.

  From the output interface 44, a fuel injection signal n is output to the injector 3, an ignition signal m is output to the spark plug 8, an EGR valve opening signal o is output to the EGR valve 62, and a gear ratio signal p is output to the CVT 9. To do.

  The central processing unit 41 interprets and executes a program stored in the storage device 42 in advance, such as the fuel injection amount and ignition timing of the internal combustion engine 0, the EGR gas recirculation amount (intake EGR rate), the gear ratio, and the like. Carry out control.

  In the operation control of the internal combustion engine 0, the ECU 4 sends various information a, b, c, d, e, f, g, h, i, j, k necessary for the operation control of the internal combustion engine 0 via the input interface 43. Obtain the current intake air amount and the EGR rate of the intake air, and control the fuel injection amount, the fuel injection timing, the ignition timing, the opening degree of the EGR valve 62 (the number of EGR steps), the CVT 9 Calculate the gear ratio and the like. Then, control signals m, n, o, and p corresponding to the calculated control input are applied via the output interface 44. Since the calculation method of the control input can be the same as the known operation control of the internal combustion engine 0, the description is omitted here.

  The ECU 4 as the control device in the present embodiment sets the gear ratio of the CVT 9 so that the fuel efficiency is optimized while achieving the required load, that is, the output commanded by the driver. As already mentioned, there are an infinite number of engine speed and torque groups that achieve a certain output, but the most fuel efficient group is uniquely determined by the iso-fuel line that is the output characteristic of the internal combustion engine 0. Determined. A shift line is a plot of a set of engine speed and torque with the highest fuel efficiency for various outputs. The ECU 4 stores in advance the map data of the shift line under a predetermined operating state in the storage device 42, searches the map data using the required load as a key, knows the gear ratio on the shift line, and is movable. The sheaves 912 and 922 are operated to control the CVT 9 to the gear ratio.

  On the other hand, the equal fuel consumption line is not always constant, and changes according to the operating state of the internal combustion engine 0. That is, the shift line also changes according to the operating state of the internal combustion engine 0.

  For example, in a knock control system, the occurrence of knocking is sensed via a knock sensor, and a process of retarding the ignition timing until knocking does not occur is executed. The retard / advance angle of the ignition timing is a factor that changes the fuel consumption rate characteristic of the internal combustion engine 0. If the ignition timing is retarded, not only the fuel consumption rate deteriorates but also the engine torque decreases, and the equal fuel consumption rate line changes from a two-dot chain line to a thin solid line as shown in FIG. . And the shift line which should be displaced from the position shown with a dashed-dotted line to the high rotation and low torque side, as shown with a thick solid line.

  Control of the air-fuel ratio of the intake air that fills the cylinder 2 is also a factor that changes the fuel consumption rate characteristic of the internal combustion engine 0. The air / fuel ratio lean / rich itself is not directly linked to fluctuations in the fuel efficiency ratio line. However, since leaning is generally performed by reducing the fuel injection amount and enriching is performed by increasing the fuel injection amount, lean / rich correction of the air-fuel ratio causes an increase / decrease in engine torque and changes the fuel efficiency ratio line.

  In view of the above-described phenomenon, in the present embodiment, it is determined along a reference shift line (a thick solid line in FIG. 3, a one-dot chain line in FIG. 4) under a predetermined operation state including an ignition timing and an air-fuel ratio. A gear ratio given to the CVT 9 by adding (multiplying or adding) a correction amount according to the retard / advance amount of the ignition timing and a correction amount according to the air-fuel ratio to the gear ratio (the bold solid line in FIG. 4) ). The reference shift line is the shift line in the reference operation state of the internal combustion engine 0.

  The ECU 4 stores in advance in the storage device 42 map data that defines the relationship between the ignition timing and the amount of change in the fuel consumption rate resulting therefrom. FIG. 5 illustrates map data. The fuel consumption rate (weight of fuel consumed to obtain unit output, g / kW · h) is minimum (fuel consumption is highest) at the MBT point in the figure, and is retarded from the ignition timing corresponding to the MBT point. Or it increases (fuel consumption worsens) as it advances. The ECU 4 searches the map using the retard / advance amount of the current ignition timing as a key, the reference fuel efficiency corresponding to the ignition timing corresponding to the reference operation state, and the retard / advance amount of the current ignition timing. The ratio of the fuel efficiency corresponding to is replaced with the torque reduction at the time of equal fuel consumption, and the torque reduction ratio resulting from the correction of the ignition timing retardation is calculated. This torque reduction rate (= reference fuel consumption rate / fuel consumption rate corresponding to the current ignition timing) becomes a positive number smaller than 1 when the ignition timing is corrected or moved away from the MBT, and the current ignition timing is the reference. Set to 1 when the ignition timing does not change in the operating state.

  In addition, the ECU 4 stores in advance the map data defining the relationship between the air-fuel ratio and the amount of change in the fuel consumption rate in the storage device 42 in advance. FIG. 6 illustrates map data. The fuel consumption rate becomes the minimum at the fuel efficiency best air-fuel ratio (existing between the output air-fuel ratio and the theoretical air-fuel ratio) in the figure, and becomes leaner or richer than the air-fuel ratio corresponding to the fuel efficiency best air-fuel ratio point. Increase. The ECU 4 searches the map using the current air-fuel ratio as a key, and calculates the lean ratio of the air-fuel ratio as the ratio of the reference fuel efficiency corresponding to the air-fuel ratio corresponding to the reference operation state and the fuel efficiency corresponding to the current air-fuel ratio. / Calculate the torque down rate due to rich correction. This torque-down rate (= reference fuel efficiency / fuel efficiency corresponding to the current air-fuel ratio) is a positive number smaller than 1 when the current air-fuel ratio is away from the fuel efficiency best air-fuel ratio. Becomes a positive number of 1 or more when the fuel efficiency best air-fuel ratio approaches, and becomes 1 when the current air-fuel ratio does not change from the air-fuel ratio in the reference operation state.

  When the fuel economy rate deteriorates due to ignition timing delay correction or fuel increase correction to prevent knocking, the degree of torque reduction can be estimated from these deterioration factors, and the same output can be maintained with the reduced torque The gear ratio of the CVT 9 is controlled in accordance with the shift line shifted to the low gear side. This makes it possible to perform a shift with the highest fuel efficiency on the deteriorated equal fuel efficiency rate line (thick solid line in FIG. 4).

  As an example, it is assumed that the engine speed at the time of controlling the CVT 9 along the reference shift line as the engine output for a certain required load is 1500 rpm. At this time, assuming that the torque down rate by correcting the ignition timing is 0.93 and the torque down rate by air-fuel ratio control is 0.96, the engine speed required to achieve the same output is 1500 / (0. 93 × 0.96) = 1680 rpm. The ECU 4 controls the CVT 9 with 1680 rpm as a target rotational speed.

  The ignition timing in the reference operation state that defines the above-described reference fuel consumption rate may be MBT. The air-fuel ratio in the reference operation state may be the fuel efficiency best air-fuel ratio.

  It is also preferable that the shift line is not changed immediately, but is gradually changed by a smoothing process such as by taking a moving average of a correction amount (torque down rate).

  However, changing the gear ratio in accordance with the operating state of the internal combustion engine 0, that is, the ignition timing retardation correction amount, the target air-fuel ratio, etc. means that the effectiveness of engine braking during deceleration changes depending on the operating state. means. Changes in the effectiveness of the engine brake may cause the driver to feel uncomfortable and lead to a decrease in drivability. Therefore, during the fuel cut at the time of deceleration, the correction amount of the gear ratio is reduced so that the effectiveness of the engine brake approaches a constant value. Specifically, when the ignition timing is retarded or when the fuel is increased, the gear ratio that is normally close to the low gear is corrected to the high gear when the engine is braked.

  In general, a fuel cut is started when a predetermined fuel cut condition (accelerator pedal depression amount is 0 or below a threshold value close to 0 and the engine speed is equal to or higher than a certain value) is satisfied. The process ends when a cut end condition (such as when the accelerator pedal depression amount exceeds a threshold value or the engine speed has decreased to a predetermined return speed) is satisfied. The ECU 4 discounts the gear ratio correction amount or sets the correction amount to zero during the fuel cut period. In other words, during fuel cut, the transmission ratio of the CVT 9 is determined along a shift line that does not depend on parameters such as ignition timing and air-fuel ratio.

  According to the present embodiment, in a vehicle control apparatus including the internal combustion engine 0 and the continuously variable transmission 9, the relationship between parameters (ignition timing, air-fuel ratio, etc.) that affect the fuel efficiency of the internal combustion engine 0 and the fuel efficiency is obtained. The torque change amount (torque down rate) of the internal combustion engine 0 due to the difference between the value of the parameter in the reference operating state and the value of the parameter in the current operating state is estimated in advance, and the torque change Since the gear ratio of the continuously variable transmission 9 is corrected so as to change the target rotational speed in accordance with the amount, the gear ratio line can be changed according to the increase / decrease of various losses, etc. Can be improved. In particular, it is possible to easily calculate an appropriate target rotational speed.

  In addition, since the air-fuel ratio of the gas charged in the cylinder of the internal combustion engine is used as the parameter, it is possible to cope with various fuel increase corrections such as during warm-up and during high rotation and high load.

  The present invention is not limited to the embodiment described in detail above. In the above embodiment, the ignition timing and the air-fuel ratio are adopted as the parameters of the operating state, but the parameters are not limited to this. For example, the temperature of the internal combustion engine (cooling water temperature) is used as a parameter, the gear ratio is corrected so that the lower the internal combustion engine temperature, the lower the rotation speed and the higher torque, and the higher the internal combustion engine temperature, the higher the rotation speed and the lower torque. It is also conceivable to correct the gear ratio so that

  Further, in the above embodiment, the control device stores and holds map data of a single shift line in the reference operation state and map data of the correction amount of the gear ratio corresponding to the parameter, and the shift line in the reference operation state. The correction amount was taken into account. Instead, the control device stores and holds map data of a plurality of shift lines corresponding to each of a plurality of ignition timings and a plurality of air-fuel ratios, and changes map data to be referred to according to the ignition timing and the air-fuel ratio. Thus, the gear ratio effectively applied to the continuously variable transmission may be corrected.

  Further, in the above embodiment, the target rotational speed of the internal combustion engine is determined by obtaining the torque reduction rate from the amount of change in the parameter that affects the fuel efficiency. Instead, the relationship between the fuel efficiency of the internal combustion engine and the torque in various operating conditions is stored in advance in a storage device, and the amount of change in the fuel efficiency is obtained from the amount of change in the parameter that affects the fuel efficiency. The target rotational speed of the internal combustion engine may be set according to the torque change amount corresponding to the rate change amount.

  The automatic transmission in the above embodiment is a continuously variable transmission having a belt type CVT, but the present invention can naturally be applied even if a transmission mechanism other than the CVT is adopted.

  In addition, the specific configuration of each unit, the processing procedure, and the like can be variously modified without departing from the spirit of the present invention.

  The present invention can be used to control an internal combustion engine and an automatic transmission mounted on a vehicle.

0 ... Internal combustion engine 4 ... ECU (control device)
9 ... CVT (continuously variable transmission)

Claims (4)

A control device for a vehicle including an internal combustion engine and a continuously variable transmission,
The relationship between the value of the parameter that affects the fuel consumption rate of the internal combustion engine and the fuel consumption rate is stored in advance,
With reference to the relationship between the stored parameter and the fuel consumption rate, the fuel consumption rate under the value of the parameter in a predetermined operation state including the value of a certain predetermined parameter, and the parameter in the current operation state Obtaining the rate of change between the fuel efficiency rate under the value and obtaining the torque change rate of the internal combustion engine between the predetermined operating state and the current operating state based on this,
Storing in advance a relationship between an engine output required in the predetermined operating state and a target engine speed that defines a transmission ratio of the continuously variable transmission when the engine output is achieved;
A target engine speed corresponding to the currently requested engine output is obtained by referring to the relationship between the stored engine output and the target engine speed, and the target engine speed is multiplied by the torque change rate. The gear ratio of the continuously variable transmission is manipulated to realize the engine speed,
A control device using ignition timing as the parameter . A control device for a vehicle including an internal combustion engine and a continuously variable transmission,
For each parameter value that affects the fuel efficiency of the internal combustion engine, a target that defines the engine output required in the driving state including the parameter value and the speed ratio of the continuously variable transmission when the engine output is achieved. Map data indicating the relationship with the engine speed is stored in advance,
The continuously variable transmission is configured to obtain the target engine speed corresponding to the currently requested engine output by referring to the map data corresponding to the parameter value in the current operating state, and to realize the target engine speed. To control the gear ratio of
A control device using ignition timing as the parameter . A control device for a vehicle including an internal combustion engine and a continuously variable transmission,
The relationship between the value of the parameter that affects the fuel consumption rate of the internal combustion engine and the fuel consumption rate is stored in advance,
With reference to the relationship between the stored parameter and the fuel consumption rate, the fuel consumption rate under the value of the parameter in a predetermined operation state including the value of a certain predetermined parameter, and the parameter in the current operation state Obtaining the rate of change between the fuel efficiency rate under the value and obtaining the torque change rate of the internal combustion engine between the predetermined operating state and the current operating state based on this,
Storing in advance a relationship between an engine output required in the predetermined operating state and a target engine speed that defines a transmission ratio of the continuously variable transmission when the engine output is achieved;
A target engine speed corresponding to the currently requested engine output is obtained by referring to the relationship between the stored engine output and the target engine speed, and the target engine speed is multiplied by the torque change rate. The gear ratio of the continuously variable transmission is manipulated to realize the engine speed,
A control device using an air-fuel ratio as the parameter. A control device for a vehicle including an internal combustion engine and a continuously variable transmission,
For each parameter value that affects the fuel efficiency of the internal combustion engine, a target that defines the engine output required in the driving state including the parameter value and the speed ratio of the continuously variable transmission when the engine output is achieved. Map data indicating the relationship with the engine speed is stored in advance,
The continuously variable transmission is configured to obtain the target engine speed corresponding to the currently requested engine output by referring to the map data corresponding to the parameter value in the current operating state, and to realize the target engine speed. To control the gear ratio of
A control device using an air-fuel ratio as the parameter.

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