JP2012154433A - Controlling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve of fuel consumption performance of a vehicle provided with an internal combustion engine and a continuously variable transmission.SOLUTION: The speed change ratio of the continuously variable transmission is changed according to the temperature of the internal combustion engine, the speed change ratio is corrected such that as the temperature of the internal combustion engine falls, the number of rotations decreases and the torque increases, and the speed change ratio is corrected such that as the temperature of the internal combustion engine rises, the number of rotations increases and the torque decreases. That is, by focusing attention on that an equi-fuel consumption curve fluctuates in accordance with the temperature of the internal combustion engine, the speed change rate curve is changed corresponding to the fluctuation.

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, in a control device for a vehicle including an internal combustion engine and a continuously variable transmission, the transmission ratio of the continuously variable transmission is changed in accordance with the temperature of the internal combustion engine. The gear ratio is corrected so as to be torque, and the gear ratio is corrected so that the higher the temperature of the internal combustion engine, the higher the rotation speed and the lower the torque. That is, focusing on the fact that the equal fuel consumption rate line fluctuates due to the increase or decrease of the mechanical loss depending on the temperature of the internal combustion engine, the gear ratio line is changed in response to the fluctuation.

  However, if the gear ratio is changed according to the temperature of the internal combustion engine, the effectiveness of the engine brake during deceleration changes depending on the temperature of the internal combustion engine, which may give the driver a sense of incongruity and lead to a decrease in drivability. Therefore, it is preferable to reduce the gear ratio correction amount during fuel cut during deceleration to make the engine braking effect uniform.

  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 when engine temperature rose. The figure which shows the shift line which changed when the engine temperature fell.

  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. In particular, as shown in FIG. 4, when the temperature of the internal combustion engine 0, that is, the coolant temperature rises, the desired shift line (indicated by a thick solid line in the figure) is displaced to the high rotation and low torque side. Alternatively, as shown in FIG. 5, when the cooling water temperature decreases, the shift line that should be shifted to the low rotation and high torque side.

  In view of the above-described phenomenon, in the present embodiment, a shift determined along a reference shift line (a thick solid line in FIG. 3 and a chain line in FIGS. 4 and 5) under a predetermined operation state including a certain coolant temperature. The gear ratio to be given to the CVT 9 (thick solid line in FIGS. 4 and 5) is determined by adding a correction amount corresponding to the level of the cooling water temperature to the ratio (multiplication or addition). Specifically, the gear ratio is corrected such that the lower the rotation speed and the higher torque the lower the measured water temperature of the internal combustion engine 0 with respect to the reference cooling water temperature, and the higher the rotation speed and the lower torque the lower the gear temperature ratio. Correct. The ECU 4 stores in advance in the storage device 42 map data defining the relationship between the actually measured water temperature of the internal combustion engine 0 (or the difference between the actually measured temperature and the reference water temperature) and the gear ratio correction amount. The map data is searched using as a key to know the correction amount of the gear 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 the correction amount.

  However, changing the gear ratio according to the temperature of the internal combustion engine 0 means that the effectiveness of engine braking during deceleration changes depending on the temperature of the internal combustion engine 0. 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 temperature of the internal combustion engine 0 is high, the gear ratio that is normally close to the high gear is corrected to close to the low gear when the engine is braked, and when the temperature of the internal combustion engine 0 is low, the gear ratio that is normally close to the low gear is changed. When the engine is braked, correct it closer to the high gear.

  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 the fuel cut, the transmission ratio of the CVT 9 is determined along a transmission line that does not depend on the water temperature.

  According to the present embodiment, in the vehicle control device including the internal combustion engine 0 and the continuously variable transmission 9, the transmission ratio of the continuously variable transmission 9 is changed according to the temperature of the internal combustion engine 0. The gear ratio is corrected so that the lower the temperature is, the lower the rotation speed and the higher torque is. The higher the temperature of the internal combustion engine 0 is, the higher the rotation speed is, and the lower the torque is, so the gear ratio is corrected. Accordingly, the gear ratio line can be changed to improve the fuel efficiency over various driving conditions.

  In addition, since the gear ratio correction amount is reduced during fuel cut during deceleration, the effect of engine braking during deceleration changes depending on the temperature of the internal combustion engine 0, which alleviates the problem that leads to lower drivability. Can be resolved.

  The present invention is not limited to the embodiment described in detail above. For example, in the above-described embodiment, the control device stores and holds map data of a single shift line at the reference water temperature and map data of the correction amount of the gear ratio corresponding to the actually measured water temperature, and the shift line at the reference water temperature. 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 the plurality of actually measured water temperatures, and effectively changes the map data to be referred to according to the actually measured water temperatures. It is good also as correcting the gear ratio given to.

  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 (2)

A control device for a vehicle including an internal combustion engine and a continuously variable transmission,
The transmission ratio of the continuously variable transmission is changed according to the temperature of the internal combustion engine. The lower the temperature of the internal combustion engine, the lower the rotation ratio and the higher the torque, so that the speed ratio is corrected. A control device that corrects a gear ratio so as to achieve high rotation and low torque. The control device according to claim 1, wherein the correction amount of the transmission ratio is reduced during fuel cut during deceleration.

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