JP4810882B2 - Control device for vehicles with automatic transmission - Google Patents

Description

  The present invention relates to a control device that performs fuel cut control for shutting off fuel supply to a power source during deceleration in a vehicle equipped with an automatic transmission having a lockup type torque converter and a forward / reverse switching mechanism.

  As such a control device for a vehicle equipped with an automatic transmission, there is one described in Patent Document 1, for example.

  In a vehicle equipped with an automatic transmission having such a lockup type torque converter, the torque converter is in a lockup state in which the output from the engine is directly input to the automatic transmission by engaging the lockup clutch, and the vehicle is When the vehicle is decelerating, fuel cut is performed to cut off the fuel supply to the power source (engine) to minimize the fuel consumption.

  In such a vehicle, when the vehicle is decelerated using the engine brake in the fuel cut state, if the vehicle speed drops to a predetermined value, the engine braking force due to the fuel cut becomes too strong. The lock-up state of the converter is to be released. After that, the engine speed is drastically decreased due to the fuel cut. When the engine speed is decreased to the predetermined engine speed, fuel cut recovery is performed to restart the fuel supply to the engine, and the engine speed is reduced to the idling state. Keep in number.

  However, when the above control is performed, the following problems occur. In other words, when fuel cut is performed during deceleration, the resultant force of the braking force generated by the driver's braking operation and the engine braking force generated by the fuel cut acts as a deceleration force to stop the vehicle. When cut recovery is performed, the engine torque amplified by the torque converter and the automatic transmission is transmitted to the wheels, and this acts as a driving force, so that the deceleration force is weakened, which is contrary to the driver's intention to stop the vehicle. .

  In particular, during sudden deceleration, the torque converter lock-up state is released earlier than during normal deceleration to prevent engine stall, so the engine torque described above is used despite the strong intention of the driver to stop the vehicle. Tends to act as a driving force.

Furthermore, when the automatic transmission is a V-belt type continuously variable transmission, the engine speed becomes a low idling speed after fuel cut recovery. There may be a case where the hydraulic pressure sufficient to make the low gear ratio (low gear stage) is not obtained, and the vehicle stops in the state of the high gear ratio (high gear stage).
Japanese Patent Laid-Open No. 11-51173

  In view of the above-described problems of the prior art, the present invention prevents a reduction in deceleration force even if fuel cut is performed at the time of deceleration and fuel cut recovery is performed thereafter, and shift operation to a low gear position of the automatic transmission It is an object of the present invention to provide a control device for a vehicle equipped with an automatic transmission that makes it possible to

For this purpose, the control device for a vehicle equipped with an automatic transmission according to the first invention is:
An automatic transmission that inputs a power rotation from a power source, shifts the power rotation at a predetermined gear ratio, and outputs the power rotation to a drive wheel;
A forward / reverse switching mechanism having a forward clutch and a reverse brake, disposed between the power source and an input side of a transmission mechanism constituting the automatic transmission ;
A lock-up type torque converter disposed between the power source and the input side of the forward / reverse switching mechanism;
In a vehicle equipped with an automatic transmission in which the lock-up torque converter is in a lock-up state and performs fuel cut to cut off fuel supply to the power source during deceleration,
When the vehicle reaches a predetermined vehicle speed during deceleration and during fuel cut, the forward clutch of the forward / reverse switching mechanism is released while maintaining the torque converter lockup state, and the power source Is reduced to a predetermined fuel cut recovery rotational speed or less, the fuel cut recovery is performed while the forward clutch is released while maintaining the lock-up state of the torque converter.

A control device for a vehicle equipped with an automatic transmission according to a second invention is the above-mentioned first invention,
When the vehicle stops, the lock-up state of the torque converter is released .

A control device for a vehicle equipped with an automatic transmission according to a third aspect of the invention is the first aspect,
When the fuel supply to the power source is resumed, the rotational speed of the power source is controlled to a value at which a hydraulic pressure that enables the automatic transmission to shift to a low speed is obtained. It is.

  In the first invention, the forward clutch is released when the vehicle is decelerated to a predetermined vehicle speed when the torque converter is in the lock-up state, and when the vehicle is decelerated using the engine brake by performing fuel cut of the power source.

  Therefore, by releasing the forward clutch without releasing the lockup of the torque converter, the engine torque is not transmitted to the wheels and the braking force is not weakened even if fuel cut recovery is performed. The braking distance can be shortened.

In the first invention, when the power source drops below a predetermined fuel cut recovery rotational speed , the fuel cut recovery is carried out without releasing the lock-up state of the torque converter even if the forward clutch is released.

  Normally, when the forward clutch is released, there is no input torque from the wheels, and engine stall is likely to occur due to a rapid decrease in engine speed. Therefore, by continuing the lock-up state, it is possible to moderate the decrease in the rotation speed and prevent the engine stall when performing the control according to the first invention.

In the second invention, when the vehicle stops, the lock-up state of the torque converter is released. In the third aspect of the invention, when the fuel cut recovery is performed, the engine speed is controlled to a value at which a hydraulic pressure that enables the automatic transmission to perform a shift operation to the low speed stage is obtained.

  As described above, especially when the automatic transmission is a V-belt type continuously variable transmission, the pulley of the transmission is not in a low gear ratio state due to a short braking distance at the time of sudden deceleration. According to the third invention, the engine speed is increased after releasing the forward clutch, and the hydraulic pressure necessary for the transmission pulley to be in the low gear ratio state is secured. It is possible to prevent the pulley from stopping in a high gear ratio state.

  In addition, since the forward clutch is released, the increase in driving force accompanying the increase in engine speed is not transmitted to the wheels, and there is no problem that the deceleration force is weakened. In addition, since the forward clutch is disengaged, the vehicle is in a neutral state (idling state) after stopping, so that it is possible to reduce fuel consumption.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a system diagram showing a configuration of a drive system and a control system of a vehicle equipped with a belt-type continuously variable transmission including a control device for a vehicle equipped with an automatic transmission according to the present invention.

  The illustrated V-belt type continuously variable transmission includes an input shaft 3 that receives rotation from an engine 1 via a torque converter 2, a forward / reverse switching mechanism 4, a V-belt continuously variable transmission mechanism 5, a differential gear device. It consists of six. The forward / reverse switching mechanism 4 includes a double pinion type planetary gear set 7 and can transmit the rotation of the input shaft 3 to the V-belt transmission mechanism 5 as it is when the forward clutch 8 is engaged, and the input shaft can be transmitted when the reverse brake 9 is engaged. It is assumed that the rotation of 3 can be reversed and transmitted to the V-belt continuously variable transmission mechanism 5. The torque converter 2 includes a lock-up clutch (not shown), and the lock-up clutch is engaged / released by hydraulic pressure.

  The V-belt type continuously variable transmission mechanism 5 includes a driving-side primary pulley 10 to which rotation from the forward / reverse switching mechanism 4 is input, a driven-side secondary pulley 11, and a V-belt that spans between these pulleys 10 and 11. It is composed of 12. Here, the primary pulley 10 and the secondary pulley 11 each rotate one flange together with the other flange, but are movable flanges that can be displaced in the axial direction, and the positions of these movable flanges can be controlled by hydraulic pressure.

  The V belt type continuously variable transmission mechanism 5 sequentially transmits the rotation to the primary pulley 10 to the secondary pulley 11 and the output shaft 13 via the V belt 12. During this transmission, the line pressure corresponding to the transmission input torque is supplied to the movable flange of the secondary pulley 11, and the shift control valve determined by the shift control valve using the line pressure as the original pressure to the movable flange of the primary pulley 10. By supplying the control pressure, the position of the movable flange of both pulleys 10 and 11 is determined by the ratio of the transmission control pressure to the primary pulley 10 with respect to the line pressure to the secondary pulley 11, and the V-belt for both pulleys 10 and 11 The winding arc diameter of 12, that is, the transmission ratio (transmission ratio) between pulleys is determined.

  Therefore, the V-belt type continuously variable transmission mechanism 5 can perform a speed change that continuously changes the speed ratio from the lowest speed ratio to the high speed side speed ratio by increasing the speed change control pressure. By reducing the control pressure, it is possible to perform a shift that continuously changes the gear ratio continuously and continuously toward the lowest speed gear ratio.

  The rotation from the V-belt type continuously variable transmission mechanism 5 to the output shaft 13 is input to a differential gear device 6 through a parallel shaft gear set 14, and the differential gear device 6 differentially drives left and right drive wheels of a vehicle (not shown). It shall be driven to.

  Next, a control system of the V-belt type continuously variable transmission will be described with reference to FIG.

  This control system is connected to the control unit 20 for electronically controlling the engine 1 and the control valve 15 connected to the torque converter 2, the forward / reverse switching mechanism 4 and the V-belt continuously variable transmission mechanism 5. With sensors.

  The control unit 20 includes an engine rotation sensor 21 that detects the rotation speed Ne of the output shaft of the engine 1, a turbine rotation sensor 22 that detects the rotation speed Nt on the turbine side (forward / reverse switching mechanism 4 side) of the torque converter, and an engine throttle A throttle opening sensor 23 for detecting the opening degree (not shown) is connected, and the engine speed, the turbine speed of the torque converter 2 and the throttle opening degree are input from these sensors.

  Further, the control unit 20 includes a select lever sensor 24 that detects the position of the select lever (not shown), a vehicle speed sensor 25 that detects the vehicle speed, and ON / OFF when the driver depresses a brake pedal (not shown). The brake switch 26 that switches off is connected. A shift range signal, a vehicle speed, and a brake switch signal are input from these sensors.

  The control unit 20 outputs an engine control signal based on the signal input from each sensor described above, and performs engine control. Here, the control unit 20 performs the fuel cut that cuts off the fuel supply to the engine 1 as described above when the torque converter 2 is in the lock-up state and the vehicle is decelerating.

  Further, the control unit 20 controls the control valve 15 to control the lockup signal for performing the lockup control of the torque converter 2, the forward clutch 8 and the reverse brake which are the starting friction elements of the forward / reverse switching mechanism 4. A starting friction element control signal and a shift control signal for controlling the V-belt type continuously variable transmission mechanism 5 are output.

  The lock-up signal is output to a lock-up solenoid 27 provided in the control valve 15. By turning on the lock-up solenoid 27, a lock-up clutch (not shown) of the torque converter 2 is fastened. As a result, the engine 1 and the V-belt type continuously variable transmission mechanism 5 are brought into a locked-up state. On the other hand, when the lock-up solenoid 27 is turned OFF, the lock-up clutch is released and the lock-up state is released.

  The starting friction element control signal is output to the clutch solenoid 28 provided in the control valve 15. The clutch solenoid 28 operates the forward / reverse switching valve 29 in the control valve 15. When the vehicle moves forward, that is, when the shift range signal from the select lever sensor 24 is the travel range (other than P, N, R), The forward / reverse switching valve 29 is switched to the forward side, and hydraulic pressure is supplied to the forward clutch 8 of the forward / reverse switching mechanism 4 to be engaged. On the other hand, when the shift range is the reverse range (R), the forward / reverse switching valve 29 is switched to the reverse side, and the hydraulic pressure is supplied to the reverse brake 9 of the forward / reverse switching mechanism 4 to be engaged. Further, when the vehicle is stopped (the shift range is P, N), the forward / reverse switching valve 29 is controlled so as to release both the forward clutch 8 and the reverse brake 9.

  Further, the control unit 20 outputs a shift control signal and shifts the speed with respect to the primary pulley 10 and the secondary pulley 11 of the V-belt type continuously variable transmission mechanism 5 by a solenoid valve (shift control valve) (not shown) in the control valve 15. By supplying the control pressure, the positions of the movable flanges of both pulleys 10 and 11 are determined. As a result, the transmission ratio of the V-belt type continuously variable transmission mechanism 5 is determined.

  FIG. 2 is a flowchart of control during vehicle deceleration by the control device according to the present invention. The control procedure will be described below according to this flowchart. Here, it is assumed that the torque converter is in a lock-up state at the time when control is started and the vehicle is decelerating.

First, in step S101, fuel cut is performed to cut off fuel supply to the engine. Next, in step S102 , it is determined whether or not the vehicle speed has fallen below the speed at which the lockup state is released (lockup OFF vehicle speed). If the vehicle speed is equal to or lower than the lockup OFF vehicle speed, the process proceeds to step S103. If the vehicle speed is greater than the lockup OFF vehicle speed, step S102 is repeated until the vehicle speed decreases to the lockup OFF vehicle speed.

  In step S103, the forward clutch is released, and in subsequent step S104, it is determined whether or not the engine speed (ENGREV) has decreased below the speed at which fuel cut recovery for restarting fuel supply to the engine (recovery speed) is performed. . At this time, if the engine speed is equal to or lower than the recovery speed, the process proceeds to step S105. If the engine speed is higher than the recover speed, step S104 is repeated until the engine speed decreases below the recover speed.

  Thereafter, in step S105, fuel cut recovery is performed. In step S106, it is determined whether the vehicle speed is 0, that is, whether the vehicle has stopped. If the vehicle speed is 0, the process proceeds to step S107. If the vehicle speed is not 0, step S106 is repeated until the vehicle speed becomes 0.

  In step S107, the lockup of the torque converter is released (lockup OFF). In a succeeding step S108, it is determined whether or not the vehicle brake is operating. If the brake is not operating (brake OFF), the process proceeds to step S109 assuming that the vehicle starts. If the brake is operating, step S108 is repeated until the brake is turned off.

  In step S109, the forward clutch is engaged again, and the process ends.

  FIGS. 3 and 4 show the brake, lock-up clutch, forward clutch operation, and changes in engine speed and vehicle speed, respectively, from vehicle deceleration to stop and re-start by the control according to the prior art and the present invention, respectively. It is a time chart which shows. Hereinafter, the operation by the control according to the present invention will be described while comparing these two time charts.

  FIG. 3 shows the case of control according to the prior art. First, the vehicle speed decreases when the driver removes his / her foot from the accelerator pedal, and then the brake is turned on when the driver steps on the brake pedal. . Thereafter, when the vehicle speed further decreases, the lock-up clutch is released (lock-up OFF), and the engine speed is rapidly decreased by performing fuel cut. Thereafter, fuel cut recovery is performed, so that the engine speed returns to the idle speed. The forward clutch is always in the engaged state.

  At this time, as described above, the fuel cut is performed during deceleration, so that the resultant force of the braking force generated by the driver and the engine braking force generated by the fuel cut acts as a deceleration force to stop the vehicle. However, if the fuel cut recovery is performed at this time, the engine torque amplified by the torque converter and the automatic transmission is transmitted to the wheels, and this acts as a driving force, so that the deceleration force is weakened and the braking distance is lengthened. There was a problem.

  Also, in the case of a V-belt type continuously variable transmission, the engine speed becomes a low idling speed after the fuel cut is recovered. There was a problem that the hydraulic pressure required to make the state (low gear) could not be obtained, and the vehicle stopped in a high gear ratio (high gear) state.

  On the other hand, the invention of the present application solves such problems, and the operation thereof is as shown in FIG.

  Also in the control according to the present invention, the vehicle speed decreases when the driver removes his / her foot from the accelerator pedal, and then the brake is turned on when the driver steps on the brake pedal. Thereafter, when the vehicle speed further decreases, the lock-up clutch is released (lock-up OFF), and the engine speed is rapidly decreased by performing fuel cut.

  Here, in the present invention, when the vehicle speed drops to a predetermined value, the forward clutch is released rather than the lockup clutch (portion indicated by symbol A in the figure). As a result, even if fuel cut recovery is performed, the driving force (engine torque) from the engine is not transmitted to the wheels, the deceleration force is not weakened, and the braking distance is shortened (the portion indicated by symbol B in the figure).

  Instead of releasing the forward clutch, the lockup clutch is not released until the vehicle stops. Therefore, compared to the conventional case where the lockup clutch is turned off during deceleration, the inertia force (engine inertia) of the engine rotation increases and the degree of decrease in the engine speed decreases, so that it is difficult to stall. The effect is obtained (the part indicated by symbol C in the figure)

  In addition, the pulley of the V-belt type continuously variable transmission is in a low gear ratio (LOW speed) state by increasing the engine speed from the fuel cut recovery to stopping the vehicle more than the idling speed (idle speed). The oil pressure required to achieve this is secured, and the pulley is prevented from stopping in a high gear ratio state (the portion indicated by symbol D in the figure).

  And, by setting the forward clutch to brake-off, that is, releasing the vehicle until the vehicle restarts, the engine speed is automatically reduced to the idle speed (neutral state) while the vehicle is stopped, thus reducing fuel consumption during idling. Can also be performed (part indicated by symbol E in the figure).

  As described above, according to the control device for a vehicle equipped with an automatic transmission according to the present invention, when the torque converter is in the lock-up state and the vehicle is decelerated using the engine brake by performing fuel cut of the power source, When the vehicle is decelerated to the vehicle speed, the forward clutch is released without releasing the lockup of the torque converter, so even if fuel cut recovery is performed, the engine torque is not transmitted to the wheels, and the braking force is weakened. In addition, the braking distance can be shortened and the engine stall can be prevented.

  In addition, when the fuel cut recovery is performed, the engine speed is controlled to a value that can obtain a hydraulic pressure that enables the automatic transmission to shift to the low speed stage. In the case of a continuously variable transmission, when the vehicle is suddenly decelerated, the braking distance is short, and the pulley of the transmission is not in a low gear ratio state, and the vehicle stops in a high gear ratio state. According to the above, the engine speed is increased after releasing the forward clutch, the hydraulic pressure necessary for the transmission pulley to be in the low gear ratio state is secured, and the pulley is stopped in the high gear ratio state. Can be prevented.

  In the above-described embodiment, the speed change mechanism is a V-belt type continuously variable transmission mechanism. However, the start control device according to the present invention may be a vehicle equipped with, for example, a toroidal type continuously variable transmission as long as it has a start friction element. It can also be applied to.

1 is a system diagram showing the configuration of a drive system and a control system of a vehicle with a V-belt type continuously variable transmission equipped with a control device for a vehicle with an automatic transmission according to the present invention. It is a flowchart of control by the control apparatus which concerns on this invention. It is a time chart which shows the control by the conventional control apparatus. It is a time chart which shows the control by the control apparatus which concerns on this invention.

Explanation of symbols

1 engine
2 Torque converter
3 Input shaft
4 Forward / reverse switching mechanism
5 V belt type continuously variable transmission mechanism
6 Differential gear unit
7 Planetary gear set
8 Forward clutch
9 Reverse brake
10 Primary pulley
11 Secondary pulley
12 V belt
13 Output shaft
14 Parallel gear set
15 Control valve
20 Control unit
21 Engine rotation sensor
22 Turbine rotation sensor
23 Throttle opening sensor
24 Select lever sensor
25 Vehicle speed sensor
26 Brake switch
27 Lock-up solenoid
28 Clutch solenoid
29 Forward / reverse selector valve

Claims (3)

An automatic transmission that inputs a power rotation from a power source, shifts the power rotation at a predetermined gear ratio, and outputs the power rotation to a drive wheel;
A forward / reverse switching mechanism having a forward clutch and a reverse brake, disposed between the power source and an input side of a transmission mechanism constituting the automatic transmission ;
A lock-up type torque converter disposed between the power source and the input side of the forward / reverse switching mechanism;
In a vehicle equipped with an automatic transmission in which the lock-up torque converter is in a lock-up state and performs fuel cut to cut off fuel supply to the power source during deceleration,
When the vehicle reaches a predetermined vehicle speed during deceleration and during fuel cut, the forward clutch of the forward / reverse switching mechanism is released while maintaining the torque converter lockup state, and the power source Equipped with an automatic transmission, wherein the fuel cut recovery is carried out while the forward clutch is released while maintaining the torque converter lock-up state when the engine speed drops below a predetermined fuel cut recovery speed Vehicle control device. The apparatus of claim 1.
A control apparatus for a vehicle equipped with an automatic transmission, wherein the lockup state of the torque converter is released when the vehicle stops. The apparatus of claim 1.
When the fuel supply to the power source is resumed, the number of revolutions of the power source is controlled to a value at which a hydraulic pressure that enables the automatic transmission to perform a shift operation to a low speed stage is obtained. Control device for vehicles equipped with automatic transmission.

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