JP4600291B2 - Vehicle driving force control device - Google Patents

Description

  The present invention relates to a driving force control device for a vehicle equipped with a power train having an engine and an automatic transmission equipped with a torque converter, and in particular, outputs a torque corresponding to a driver's acceleration request from the engine. The present invention relates to a driving force control device that can realize an excellent acceleration characteristic.

  In a vehicle equipped with an engine and an automatic transmission that can control engine output torque independently of the driver's accelerator pedal operation, it is calculated based on the driver's accelerator pedal operation amount, vehicle driving conditions, etc. Furthermore, there is a concept of “driving force control” that realizes a positive and negative target driving torque by an engine torque and a transmission gear ratio of an automatic transmission. Also, control methods called “driving force request type” and “driving force demand type” are similar to this.

  Furthermore, the torque converter provided in the automatic transmission has a lock-up clutch to improve transmission efficiency, and engages the lock-up clutch (lock-up clutch state) and releases (torque converter) according to the state of the vehicle. Technology) and slip control.

  A control device for a vehicle equipped with such an automatic transmission and an engine is disclosed in Japanese Patent Laid-Open No. 8-74611 (Patent Document 1). The control device disclosed in this publication is a device for controlling an engine and an automatic transmission having a lock-up mechanism for preventing a torque converter from slipping, and is a driving state detection means for detecting a driving state. The engine torque adjustment means for adjusting the engine torque when a shift from the lockup state during the deceleration operation to the acceleration state is detected by means of, and the actual lockup release start or the actual shift by the lockup release / shift detection means Engine torque adjustment stopping means for immediately stopping the adjustment of the engine torque when the start of the engine is detected.

According to this control apparatus, when the transition from the lock-up state during the deceleration operation to the acceleration state is detected by the driving state detection unit, the engine torque adjustment unit adjusts the engine torque, but the lock-up release / shift detection unit When the actual start of unlocking or the start of actual shifting is detected, the engine torque adjustment stopping means immediately stops the engine torque adjustment. Therefore, the adjustment of the engine torque is continued until the time of the cancellation, so that the rise of the output shaft torque becomes gentle and the pull-in torque due to the lockup release or the downshift is prevented, and the drivability is good. become.
JP-A-8-74611

  In the control device disclosed in Patent Document 1, when the start of lockup release or the start of downshift is detected during the torque down control, the torque down control is stopped and the rise characteristic of the output shaft torque is detected. Deterioration is suppressed.

  By the way, in an automatic transmission including a torque converter with a lock-up clutch, when the lock-up clutch is in a released state, the torque amplification function of the torque converter is manifested (torque converter state), and the lock-up clutch is in an engaged state. The torque amplification function of the torque converter does not appear (lock-up state). For this reason, the torque output from the engine is amplified in the torque converter state, but is not amplified in the lockup state. The torque output from the engine is transmitted to the automatic transmission. When a downshift is performed, the output shaft torque increases after the completion of the downshift. However, during the shift, the torque is transmitted by changing the friction engagement element. It is hard to be done (including the state where torque is not transmitted).

  However, in the control device disclosed in Patent Document 1, when the lock-up release is started (when the transition from the lock-up state to the torque converter state is started), the engine torque-down control is stopped. Along with this, the engine torque is increased in the torque converter state, so that an excessive initial acceleration may occur. In addition, when the downshift is started, the engine torque-down control is stopped, but even if the torque-down control is executed at that time, it takes time until the engine torque actually increases. There may be a case where no engine torque is generated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a driving force control device capable of obtaining good acceleration characteristics during stepping-up acceleration.

  A driving force control apparatus according to a first aspect of the present invention controls driving force of a vehicle on which an engine and an automatic transmission having a torque converter having a lockup mechanism are mounted. The automatic transmission determines a downshift according to a previously prepared downshift line. The driving force control device includes a means for detecting the state of the lockup mechanism, a determination means for determining whether the downshift is close based on the state of the vehicle and the downshift line, Control means for increasing the engine torque toward the torque required for the engine when the vehicle is accelerated. The control means includes means for increasing the engine torque by changing the rising characteristic of the engine torque based on at least one of the state of the lockup mechanism and the determination regarding the downshift.

  According to the first invention, when the lockup mechanism is on (lockup clutch is engaged), the torque amplification function of the torque converter does not appear, and when the downshift is started, the automatic shift is performed until the shift is completed. Torque is less likely to be transmitted by changing the friction engagement element of the machine. When the acceleration request is issued and the downshift is determined, the fact that the accelerator pedal is stepped on indicates that the driver is not satisfied with the acceleration feeling. In this case, if the engine torque is increased without considering the state of the lockup mechanism and the downshift, the output shaft torque becomes insufficient, and the driver's request cannot be met. Therefore, the calculation means determines that the engine torque rise characteristic if the torque is not amplified or is not easily transmitted based on at least one of the state of the lockup mechanism and the downshift. Increase Thereby, even if it is in a lock-up state or a downshift is started, it is possible to realize the acceleration feeling required by the driver. As a result, for example, it is possible to provide a driving force control device that can obtain good acceleration characteristics during step-up acceleration.

  In the driving force control apparatus according to the second aspect of the invention, in addition to the configuration of the first aspect of the invention, when the control means detects that the lockup mechanism is in the off state, the lockup mechanism is in the on state. Compared to the case, it includes means for reducing the rising characteristic of the engine torque.

  According to the second aspect of the present invention, when the lockup mechanism is in the off state, the torque amplification action by the torque converter is exhibited. Therefore, the engine torque is reduced as compared with when the lockup mechanism in which the torque amplification action is not exhibited is in the on state. A desired acceleration can be realized by reducing the rising characteristic.

  In the driving force control apparatus according to the third aspect of the invention, in addition to the configuration of the first aspect of the invention, when the control means detects that the lockup mechanism is in the on state, the lockup mechanism is in the off state. Compared to the case, a means for increasing the rising characteristic of the engine torque is included.

  According to the third aspect of the present invention, when the lockup mechanism is in the on state, the torque amplification action by the torque converter is not expressed, so that the engine torque rises compared to when the lockup mechanism that exhibits the torque amplification action is in the off state. If the characteristic is not increased, the desired acceleration cannot be realized. Since the control means increases the rising characteristic of the engine torque, a desired acceleration can be realized.

  In the driving force control apparatus according to the fourth invention, in addition to the configuration of the first invention, the control means locks the lockup mechanism when it is determined that the lockup mechanism is on and the downshift is close. Means for increasing the rising characteristic of the engine torque as compared to when the up mechanism is in the off state or when the downshift is not close are included.

  According to the fourth aspect of the present invention, when the lockup mechanism is in the on state, the torque amplification effect by the torque converter is not expressed. Increase the characteristics. When the downshift is started, the frictional engagement element is changed in the automatic transmission and torque transmission becomes difficult. Therefore, the engine torque rising characteristic is increased as compared with the state where the shift is not started. As described above, when the lockup mechanism is in the on state and the downshift is close, it is difficult to generate the acceleration torque. Therefore, the desired acceleration can be realized by increasing the rising characteristic of the engine torque. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  A power train of a vehicle including the driving force control apparatus according to the present embodiment will be described. The driving force control apparatus according to the present embodiment is realized by a program executed by an ECU (Electronic Control Unit) 1000 shown in FIG. In the present embodiment, the automatic transmission will be described as a 5-speed automatic transmission having a gear-type transmission mechanism provided with a torque converter as a fluid coupling. Furthermore, the torque converter includes a lockup clutch.

  With reference to FIG. 1, the power train of the vehicle including the driving force control apparatus according to the present embodiment will be described. Specifically, the driving force control apparatus according to the present embodiment is realized by ECT (Electronic Controlled Automatic Transmission) _ECU 1020 shown in FIG.

  As shown in FIG. 1, the power train of this vehicle includes an engine 100, a torque converter 200 with a lock-up clutch, a gear-type transmission mechanism 300, and an ECU 1000. FIG. 1 shows only representative signals.

  The output shaft of engine 100 is connected to the input shaft of torque converter 200. Engine 100 and torque converter 200 are connected by a rotating shaft. Therefore, output shaft rotational speed NE (engine rotational speed NE) of engine 100 detected by the engine rotational speed sensor and input shaft rotational speed (pump rotational speed) of torque converter 200 are the same.

  The torque converter 200 has a lock-up clutch that directly connects the input shaft and the output shaft, a pump impeller on the input shaft side, a turbine impeller on the output shaft side, and a one-way clutch, and exhibits a torque amplification function. It consists of a stator. Torque converter 200 and gear type transmission mechanism 300 are connected by a rotating shaft. The output shaft rotational speed NT (turbine rotational speed NT) of the torque converter 200 is detected by a turbine rotational speed sensor. The output shaft rotational speed NOUT of the automatic transmission is detected by an output shaft rotational speed sensor.

  Such an automatic transmission includes a plurality of friction elements such as clutches and brakes. Based on a predetermined operation table, the hydraulic circuit is controlled so that the clutch element, which is a friction element, the brake element, and the one-way clutch element are engaged and released according to each requested gear stage. The The shift position of the automatic transmission includes a parking (P) position, a reverse travel (R) position, a neutral (N), and a forward travel (D) position.

  The ECU 1000 that controls these power trains includes an engine ECU 1010 that controls the engine 100 and an ECT_ECU 1020 that controls the automatic transmission. The driving force control apparatus according to the present embodiment is realized by ECT_ECU 1020 and calculates a torque required for engine ECU 1010. The engine ECU 1010 controls the opening degree of the electronic throttle valve so as to satisfy the required torque.

  ECT_ECU 1020 receives a signal representing output shaft rotational speed NOUT detected by the output shaft rotational speed sensor. ECT_ECU 1020 receives an engine speed signal representing engine speed NE detected by the engine speed sensor from engine ECU 1010.

  These rotation speed sensors are provided to face teeth of a rotation detection gear attached to the input shaft of the torque converter 200, the output shaft of the torque converter 200, and the output shaft of the automatic transmission. These rotational speed sensors are sensors that can detect slight rotations of the input shaft of the torque converter 200, the output shaft of the torque converter 200, and the output shaft of the automatic transmission. For example, they are generally referred to as semiconductor sensors. This is a sensor using a magnetoresistive element.

  Further, ECT_ECU 1020 outputs an engine control signal (for example, a throttle opening signal) to engine ECU 1010, and engine ECU 1010 controls engine 100 based on the engine control signal and other control signals. ECT_ECU 1020 outputs a lockup clutch control signal for torque converter 200. Based on this lockup clutch control signal, the engagement pressure of the lockup clutch is controlled. As a result, the lockup clutch is brought into an engaged (on) state (lockup state), a released (off) state (torque converter state), or an intermediate slip state.

  The ECT_ECU 1020 outputs a solenoid control signal to the automatic transmission. Based on this solenoid control signal, the linear solenoid valve and the on / off solenoid valve of the hydraulic circuit of the automatic transmission are controlled, and the friction engagement is performed so as to constitute a predetermined shift gear stage (first speed to fifth speed). The elements are controlled to be engaged and released. ECU 1000 has a memory in which various data (including maps) and programs are stored.

  In the driving force control apparatus according to the present embodiment, when acceleration of the accelerator pedal is requested by the driver of the vehicle, according to the state of the vehicle so that the vehicle can be accelerated smoothly, Change the engine torque. Particularly important as the state of the vehicle are the state of the lock-up clutch, the state of divergence to the downshift line, and the like.

  With reference to FIG. 2, the shift map stored in the memory of ECU 1000 as the driving force control apparatus according to the present embodiment will be described. The map shown in FIG. 2 is an example, and the present invention is not limited to the map shown in FIG. FIG. 2 shows only the downshift line. Corresponding upshift shift lines are set on the high speed side of the downshift shift lines.

  As shown in FIG. 2, this shift map is a map in which the horizontal axis is the vehicle speed and the vertical axis is the accelerator opening that is the driver's requested acceleration amount. The right side of FIG. 2 is the high vehicle speed side of the vehicle speed, and the upper side is the large opening side of the throttle opening.

  As shown by the solid line in FIG. 2, from the lower vehicle speed, 2nd (2nd speed) → 1st (1st speed), 3rd (3rd speed) → 2nd (2nd speed), 4th (4th speed) → 3rd (3rd speed) A downshift line of 5th (5th speed) → 4th (4th speed) is set. When downshifted, the gear ratio increases and acceleration performance improves.

  As shown in FIG. 2, for example, point A has a large deviation from the 4th (4th speed) → 3rd (3rd speed) shift line in the vertical axis direction, and this state is said to have a large hysteresis. At point B, the deviation from the 4th (4th speed) → 3rd (3rd speed) shift line in the vertical axis direction is small, and this state is called small hysteresis. At point B, when the accelerator opening is slightly increased (or at point B, the vehicle speed is slightly decreased and the accelerator opening is slightly increased), a downshift determination is performed.

  With reference to FIG. 3, a control structure of a program executed by ECT_ECU 1020 which is the driving force control apparatus according to the present embodiment will be described.

  In step (hereinafter step is abbreviated as S) 10, ECT_ECU 1020 detects the vehicle state. At this time, at least the accelerator pedal opening, the state of the lockup clutch 200 (engaged state, released state, slip state), and the current vehicle state on the shift diagram are detected.

  In S20, ECT_ECU 1020 determines whether or not there is an acceleration request. This determination is made based on the accelerator pedal opening signal. If it is detected that there is an acceleration request (YES in S20), the process proceeds to S100. Otherwise (NO at S20), this process ends.

  In S100, ECT_ECU 1020 determines whether or not the engine is in an idle-off (driving) state. If in the idle-off (driving) state (YES in S100), the process proceeds to S200. If not (NO in S100), the process proceeds to S110.

  In S110, ECT_ECU 1020 selects a map (standard) as a map that defines engine torque rising characteristics required for engine 100.

  In S200, ECT_ECU 1020 determines whether or not lock-up is on (lock-up clutch 200 is engaged). This determination is made based on the LC control signal. If the lock-up is in the lock-up state (not the torque converter state) (YES in S200), the process proceeds to S300. If not (NO in S200), the process proceeds to S210.

  At S210, ECT_ECU 1020 selects a map (small) as a map that defines the engine torque rising characteristics required of engine 100. The map (small) is a map that defines rising characteristics as shown in FIG. 4, for example.

  In S300, ECT_ECU 1020 determines whether the hysteresis with the downshift line is large. This determination is made based on the vehicle speed, the throttle opening, and the downshift map shown in FIG. If the hysteresis with the downshift line is large (YES in S300), the process proceeds to S400. If not (NO in S300), the process proceeds to S310.

  At S310, ECT_ECU 1020 selects a map (large) as a map that defines the engine torque rising characteristics required of engine 100. The map (large) is a map that defines rising characteristics as shown in FIG. 5, for example.

  In S400, ECT_ECU 1020 determines whether or not the gear stage is being regulated. This determination is made when the gear is being held or when the downshift gear step control is being performed. If the gear position is being restricted (YES in S400), the process proceeds to S510. If not (NO in S400), the process proceeds to S410.

  In S410, ECT_ECU 1020 selects a map (medium) as a map that defines the engine torque rising characteristics required of engine 100. The map (middle) is a map that defines rising characteristics as shown in FIG. 6, for example.

  In S510, ECT_ECU 1020 controls the throttle opening so as to increase the engine torque toward the engine torque requested of engine 100 using the selected map.

  The operation of the vehicle equipped with the driving force control apparatus according to the present embodiment based on the structure and flowchart as described above will be described.

[Acceleration from idle]
When acceleration is requested (YES in S20), if it is not idle-off (NO in S100), a standard map is selected (S110). At this time, the operation of the vehicle is expressed as a chip-in state in which the engine shown in FIG. 7 is switched from the driven state driven by the wheels to the driving state (so-called), or as shown in FIG. It may be expressed in a chip-in state during deceleration flex control.

  Note that the deceleration flex control is locked so that the differential rotation between the engine speed (Ne), which is the input side speed in the torque converter, and the turbine speed (Nt), which is the output side speed, is constant (for example, 50 rpm). In this state, the up clutch 200 is slip-controlled.

  When acceleration is requested (YES in S20), if the vehicle is idle off (YES in S100), the operation of the vehicle is in a driving state as shown in FIG.

[Acceleration from lock-up off state (= torque converter state)]
When acceleration is requested (YES in S20), idling is off (YES in S100), and lockup clutch 200 is not in an on state (lockup off state = torque converter state) (in S200). NO), the map (small) is selected (S210). At this time, the operating state of the vehicle is a driving state as shown in FIG. 9, and the torque of engine 100 is amplified by the torque converter. For this reason, since the acceleration is from the torque converter state, the initial pickup torque (acceleration torque) is expected to be large to some extent. For this reason, the rising characteristic of the engine torque may not be so large. As a result, the rising characteristic as shown in FIG. 4 is selected.

[Acceleration from lock-up on and close to downshift]
When acceleration is requested (YES in S20), the engine is idling off (YES in S100), and the lockup clutch 200 is on (lockup on state = lockup state) (S200). If YES in step S3) and the hysteresis with the downshift line is not large (NO in step S300), the map (large) is selected (S310). At this time, the operating state of the vehicle is a state where the torque of engine 100 is not amplified by the torque converter. For this reason, torque amplification by the torque converter cannot be expected, and downshift is close, so that it is difficult to transmit torque (including a state where it is not performed) by changing the friction engagement element. That is, this state is a state in which the pickup torque is least likely to be expressed. For this reason, the rising characteristic of the engine torque must be large. As a result, the rising characteristics as shown in FIG. 5 are selected.

[Acceleration from lock-up on and not close to downshift]
When acceleration is requested (YES in S20), the engine is idling off (YES in S100), and the lockup clutch 200 is on (lockup on state = lockup state) (S200). If YES at S300) and the hysteresis with the downshift line is large (YES at S300), the map (medium) is selected (S410). At this time, the operating state of the vehicle is a state where the torque of engine 100 is not amplified by the torque converter. For this reason, torque amplification by the torque converter cannot be expected, but since the downshift is not near, it is not difficult to transmit torque (including the state where it is not performed) by changing the friction engagement element. That is, this state is a state in which the pickup torque is hardly expressed when torque is not amplified by the torque converter, but is a state in which the pickup torque is expressed when no downshift is generated. For this reason, the engine torque rising characteristic may be moderate. As a result, the rising characteristics as shown in FIG. 6 are selected.

  FIG. 10 shows the state of the vehicle when acceleration is requested in the lock-up on state. As shown in FIG. 10, from time t (1) before the acceleration request is generated, it is assumed that lockup clutch 200 is in the on state (YES in S200), and the acceleration request is generated at time t (1). Even at this point, the torque amplification effect by the torque converter does not appear. For this reason, when the standard intake air amount is increased as in the prior art, torque sufficient for acceleration is not output from the engine due to the smooth increase of the intake air amount. As a result, sufficient acceleration does not appear even after the time t (2) has passed, and sufficient acceleration does not appear unless the time t (3) is reached.

  In the driving force control apparatus according to the present embodiment, when the lock-up clutch 200 is in the on state, the torque amplification action by the torque converter does not appear, so the throttle opening is controlled so that the intake air amount increases quickly. I did it. For this reason, compared with the past, the amount of intake air quickly increases (time t (2)), and even if the torque amplification effect by the torque converter does not appear, the engine torque sufficient for acceleration is output from the engine. As a result, sufficient acceleration can be generated at time t (2).

  Further, FIG. 11 shows a state of the vehicle when acceleration is requested in a state close to the downshift line in the lock-up on state. As shown in FIG. 11, from time t (1) before the acceleration request is generated, it is assumed that lockup clutch 200 is in the on state (YES in S200), and the acceleration request is generated at time t (1). Even at this point, the torque amplification effect by the torque converter does not appear. Further, the hysteresis with the downshift line is not large (NO in S300), and the frictional engagement element of automatic transmission 300 is changed during acceleration (from time t (2) to time t (3). (B) The output torque is insufficient and the acceleration torque is least likely to occur.

  For this reason, when the standard intake air amount is increased as in the prior art, torque sufficient for acceleration is not output from the engine due to the smooth increase of the intake air amount. This is because torque transmission is difficult until the Hi-side clutch hydraulic pressure is released and the Lo-side clutch hydraulic pressure is increased. As a result, when the shift is started (time t (2)), the acceleration is not sufficient until the shift is completed (time t (3)).

  In the driving force control apparatus according to the present embodiment, since the lock-up clutch 200 is in the on state, the torque amplification effect by the torque converter is not exhibited, and the downshift is close, so the intake air amount is excessive. The throttle opening was controlled so as to shoot (time t (2)). For this reason, compared to the conventional case, the intake air amount increases quickly and sufficiently, the torque amplification effect by the torque converter does not appear, and the engine torque sufficient for acceleration is generated even if the downshift is generated. (Time t (2)). As a result, sufficient acceleration can be generated.

  As described above, according to the driving force control apparatus according to the present embodiment, in a vehicle equipped with an engine and an automatic transmission equipped with a torque converter with a lockup clutch, when the driver requests acceleration, The engine torque is changed based on whether the torque converter is in the state or whether the hysteresis with the downshift line is large. For this reason, the engine torque rising characteristic is increased in the lock-up on state where the torque amplification function does not operate and in the state where the downshift is close and the generation of acceleration torque is unlikely. As a result, the driving force control apparatus according to the present embodiment can achieve desired acceleration.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a control block diagram of a vehicle including a driving force control device according to an embodiment of the present invention. It is a figure which shows the shift map memorize | stored in the driving force control apparatus which concerns on embodiment of this invention. It is a flowchart which shows the control structure of the program performed by ECT_ECU which is a driving force control apparatus which concerns on embodiment of this invention. It is a figure which shows the starting characteristic of the engine torque prescribed | regulated by the 1st map. It is a figure which shows the starting characteristic of the engine torque prescribed | regulated by the 2nd map. It is a figure which shows the starting characteristic of the engine torque prescribed | regulated by the 3rd map. It is a figure (the 1) which shows the state of a vehicle. It is a figure (the 2) which shows the state of a vehicle. FIG. 10 is a third diagram illustrating the state of the vehicle. It is a figure (the 1) which shows the state of a vehicle when a program is performed by ECU which is a driving force control apparatus which concerns on embodiment of this invention. FIG. 8 is a diagram (No. 2) illustrating a state of the vehicle when a program is executed by the ECU that is the driving force control apparatus according to the embodiment of the present invention.

Explanation of symbols

  100 engine, 200 torque converter, 300 gear-type transmission mechanism, 1000 ECU, 1010 engine ECU, 1020 ECT_ECU, 2200 brake sensor.

Claims (3)

A driving force control apparatus for a vehicle equipped with an engine and an automatic transmission having a torque converter having a lock-up mechanism, wherein the automatic transmission performs a downshift according to a previously prepared downshift shift line. Judged,
The driving force control device includes:
Means for detecting a state of the lock-up mechanism;
Determining means for determining whether the downshift is close based on the state of the vehicle and the downshift line;
Control means for increasing the engine torque toward the torque required for the engine during acceleration of the vehicle,
The control means includes means for increasing the engine torque by changing a rising characteristic of the engine torque based on at least one of the state of the lockup mechanism and the determination about the downshift .
The means for increasing the engine torque may be reduced when the lock-up mechanism is in an on state and when it is determined that the downshift is close, compared to when the lock-up mechanism is in an off state, or down. A driving force control apparatus including means for increasing the rising characteristic of the engine torque as compared to when shift shift is not close .   The control means includes means for reducing a rising characteristic of the engine torque when it is detected that the lockup mechanism is in an off state, compared to when the lockup mechanism is in an on state. The driving force control apparatus according to claim 1.   The control means includes means for increasing the rising characteristic of the engine torque when it is detected that the lockup mechanism is in an on state as compared to when the lockup mechanism is in an off state. The driving force control apparatus according to claim 1.

Images