JP3430869B2 - Lock-up control method for continuously variable transmission for vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lock-up of a lock-up type torque converter of a continuously variable transmission used in a vehicle having an engine control device for controlling the operation of an engine. The present invention relates to a lock-up control method which is suitable for use in controlling the control by a transmission control device separate from the engine control device. It should be noted that the "rotation speed" in this specification means the rotation speed per unit time. 2. Description of the Related Art A continuously variable transmission for a vehicle such as a V-belt type continuously variable transmission or a toroidal type continuously variable transmission smoothes the transmission of torque or increases the torque between the engine and a preceding stage. In many cases, a torque converter is interposed because of the necessity of causing the torque converter to operate. [0003] In general, a continuously variable transmission for a vehicle generally includes:
A lock-up type torque converter that can be in a lock-up state in which an input / output element is directly connected in an operation region (high vehicle speed region) where a torque fluctuation absorbing function or a torque increasing function of the torque converter is not required is frequently used. In the case of a continuously variable transmission, for example, as described in JP-A-3-292462, the lock-up region is defined by an engine throttle opening degree operated by an accelerator pedal and a vehicle speed. The transmission control device that controls the operation of the torque converter normally performs lock-up control of the torque converter so that the lock-up region is maximized as long as the driving performance is not adversely affected. In recent vehicles, the amount of fuel supplied to the engine, the ignition timing, and the like are adjusted in accordance with the engine throttle opening and the like so that the performance of the engine is sufficiently exhibited and the exhaust gas is as clean as possible. Such an engine control device is often provided with an engine control device for controlling the fuel consumption during running of the vehicle, as described in, for example, JP-A-2-3748. The fuel cut is executed to cut off the fuel supply to the engine when the engine throttle stall is at or above the lower limit of the fuel cut speed for preventing engine stall and the accelerator pedal is released. Usually, cut control is adopted. [0005] However, such an engine control device is usually provided independently of the transmission control device. On the other hand, when the lock-up is released during fuel cut, the engine speed decreases. Therefore, it is necessary to immediately stop fuel cut and restart fuel supply in order to prevent stall, and if the engine cooling water temperature is low or the engine speed is low, the torque fluctuation of the engine output rotation will increase. The operation state of the engine and the lock-up control of the torque converter are closely related to each other, such as the fact that the torque converter needs to absorb the torque fluctuation by inhibiting the lock-up. Conventionally, therefore, the transmission control device determines the operating state of the engine to perform lock-up control of the torque converter.
It is necessary to connect the same many communication lines connected to the engine control unit to the transmission control unit as for the data input for the engine control unit to determine the operating state of the engine. There was a problem that it is becoming. SUMMARY OF THE INVENTION An object of the present invention is to provide a lock-up control method that advantageously solves the above-mentioned problems, and a lock-up control method according to the present invention. A method includes controlling the lock-up of a lock-up type torque converter of a continuously variable transmission used in a vehicle including an engine control device for controlling operation of an engine by a transmission control device separate from the engine control device. In the engine control device, the engine is driving a compressor of an air conditioner and the speed of the vehicle is equal to or less than a first predetermined speed, or the engine is not driving a compressor of the air conditioner, Engine-related predetermined lock speed that the speed of the engine is equal to or lower than a second predetermined speed lower than the first predetermined speed. A determination is made as to whether or not a lock-up prohibition condition has been satisfied.If it is determined that the predetermined lock-up prohibition condition has been satisfied, a lock-up prohibition signal is sent to the engine control device to the transmission control device. By outputting
The transmission control device prohibits the torque converter from being locked up. According to such a lock-up control method, the engine control device determines whether or not a predetermined engine-related lock-up prohibition condition is satisfied. The control device outputs a lock-up prohibition signal to the transmission control device to prohibit the transmission control device from putting the torque converter into the lock-up state. Therefore, according to this lock-up control method, data on whether the predetermined engine-related lock-up prohibition condition is satisfied is transmitted from the engine control device to the transmission control device through one type of communication line. Can eliminate the need to connect the same number of communication lines to the transmission control device as the number of communication lines connected to the engine control device for data input to determine the operating state of the engine,
The communication line can be simplified, the space efficiency of the vehicle can be increased, and the manufacturing cost of the vehicle can be reduced. In the present invention, the predetermined lock-up prohibition condition is satisfied when the engine is driving the compressor of the air conditioner and the vehicle speed is the first speed.
Or the engine is not driving the compressor of the air conditioner and the speed of the vehicle is equal to or lower than a second predetermined speed lower than the first predetermined speed. When the engine is driving the compressor of the air conditioner, the load on the engine is greater than when the compressor is not driven, and the rotational resistance of the continuously variable transmission is reduced by the gear type stepped transmission. Because of the synergistic effect of being larger than that of the engine, the engine braking force of the vehicle when the accelerator pedal is released at low vehicle speed tends to be excessive, conventionally, a signal indicating whether the compressor is driven The lock-up release was not input to the transmission control device, so it was difficult to change the vehicle speed depending on whether the compressor was driven or not, so the lock-up release during deceleration in the engine brake state where the accelerator pedal was released The vehicle speed is set high on the assumption that the engine is driving the compressor, and lockup is performed at this high vehicle speed. For example, if the fuel cut is stopped and the fuel supply is restarted immediately afterwards to prevent the engine from stalling, the fuel cut period cannot be made sufficiently long at the time of deceleration, and the fuel consumption during running of the vehicle The effect of suppressing is impaired in this respect,
According to the present invention, as described above, the lock-up prohibition condition is set when the engine is driving the compressor of the air conditioner and the speed of the vehicle is equal to or less than the first predetermined speed, or the engine is driven by the compressor of the air conditioner. Is not driven and the speed of the vehicle is equal to or lower than a second predetermined speed lower than the first predetermined speed, so that the lock-up release vehicle speed is determined depending on whether the compressor is driven or not driven. Since the fuel cut period can be made different, the fuel cut period can be made sufficiently long at the time of deceleration while the compressor is not driven, and the effect of suppressing the fuel consumption during running of the vehicle can be sufficiently increased. Further, according to the present invention, indirect control of lock-up release by outputting the lock-up prohibition signal to the transmission control device by the engine control device itself, and fuel cut by stopping fuel cut-off. Since the control to restart the supply can be performed, the release of the lock-up and the restart of the fuel supply for preventing the engine stall can be reliably and sequentially performed in a time-series manner when the vehicle is decelerated. Therefore, the inconvenience that the shock of releasing the lockup and the increase in driving force due to the restart of fuel supply overlap with each other and the longitudinal vibration occurs in the vehicle immediately before the vehicle stops, causing the lower limit of the engine fuel cutoff speed and the continuously variable transmission. The prevention can be surely achieved irrespective of the gear ratio of the machine. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an integrated control system for a continuously variable transmission for a vehicle and an engine including a transmission control device and an engine control device for executing an embodiment of the lock-up control method of the present invention. . In the figure, reference numeral 1 denotes an engine, 2 denotes a V-belt type continuously variable transmission, and a lock-up type torque converter 3 for transmitting the rotation of the engine 1 to the continuously variable transmission 2 between the two.
The torque converter 3 is turned on by a lock-up solenoid 5 in the control valve 4.
(Drive duty D = 100%), an internal lock-up clutch (not shown) is engaged, and a lock-up (L / U) state is established in which the input / output elements are directly connected, and the lock-up solenoid 5 is turned off (driving). (Duty D = 0%), the lock-up clutch is disengaged, the converter (C / V) is released, and the output rotation of the engine 1 is reduced under the torque increasing function and the torque fluctuation absorbing function. The transmission to the step transmission 2 is very general. The continuously variable transmission 2 is a known type that is continuously variable in speed to a speed ratio according to the rotational position of the step motor 6 in the control valve 4. The drive duty D of the lock-up solenoid 5 and the rotational position of the step motor 6 are controlled by a transmission controller 7 having a usual microcomputer as a transmission control device. 1 throttle opening TVO
A signal from a throttle opening sensor 8 for detecting a signal from a speed sensor 9 that detects a vehicle speed VSP, a signal from an engine rotation sensor 10 for detecting an engine speed N _e, the transmission output speed N _o ON when the brake pedal is depressed and the signal from the output rotation sensor 11 that detects
It is a brake switch 1 outputs a brake signal S _b
A signal from 2, and the signal from the idle switch 13 which outputs an ON has been idle signal S _i (when not depressed) when release of the accelerator pedal, a predetermined lock-up prohibition condition of the engine relationship described below holds When the determination is made that the lockup inhibition signal IL / U is output, a signal from the engine controller 14 as the engine control means is input. The transmission controller 7 outputs the lock-up control signal CL / U to the engine controller 14 while the torque converter 3 is in the lock-up state. The engine controller 14 has a normal microcomputer, and controls the amount of fuel supplied to the engine 1 and the amount of the engine 1 in order to sufficiently exhibit engine performance and to make exhaust gas as clean as possible. In addition to controlling the ignition timing and the like by a known method in accordance with the throttle opening TVO and the like, the engine speed is reduced to prevent the engine from stalling in order to suppress the fuel consumption during running of the vehicle. A known fuel cut control for performing fuel cut to cut off fuel supply to the engine when the engine speed is equal to or higher than the lower limit and the accelerator pedal is released and the engine throttle opening is minimized is also performed. For such control, the engine controller 1
Reference numeral 4 denotes a lock-up control signal CL / U indicating that the torque converter 3 is in a lock-up state from the transmission controller 7, a signal indicating the throttle opening TVO from the throttle opening sensor 8, and a vehicle speed. a signal indicating the vehicle speed VSP from the sensor 9, a signal indicating the engine speed N _e from the engine rotation sensor 10, a signal S _i from the idle switch 13 indicating that the accelerator pedal is in released condition, and the interior air temperature a compressor drive signal S _c which is output in by engagement of the clutch engagement of the clutch from the air conditioner controller 15 for driving the air conditioner compressor of the vehicle to the engine 1 in accordance with the differentially between the set temperature, the engine 1 the cooling a signal indicative of the coolant temperature T _e from the water temperature sensor 16 for detecting the water temperature are input. Further, based on the above-mentioned input information, the engine controller 14, as shown in FIG. 2 in connection with the control method of this embodiment, determines whether any of the predetermined lock-up prohibition conditions relating to the engine is satisfied. It is determined whether or not is established. That is, here, in step 21, it is determined whether or not the condition that the engine cooling water temperature _Te is equal to or lower than a predetermined temperature is satisfied. If not, then in step 22, it is determined that the engine speed _Ne is equal to or lower than the predetermined speed. It is determined whether or not the condition is satisfied. If not, then in step 23,
Vehicle speed VSP with accelerator pedal released when signal _Si is ON
It is determined whether or not the precondition that the torque converter 3 is running up at a predetermined vehicle speed or more and the lock-up control signal CL / U is being output is being locked up. in the engine 1 from the compressor drive signal S _c is determined whether being driven compressor of the air conditioner, the engine 1 is proceeds to step 25 if it is in driving the compressor,
It is determined whether the vehicle speed VSP is equal to or lower than the first predetermined speed DLVSP1. If the engine 1 is not driving the compressor, the process proceeds to step 26, where the vehicle speed VSP is lower than the first predetermined speed DLVSP1. Predetermined speed DLVSP
It is determined whether it is 2 or less. [0022] Then, whether the engine coolant temperature T _e is less than or equal to the predetermined temperature at step 21, whether the engine speed N _e in step 22 is equal to or less than the predetermined rotational speed, vehicle speed VSP in step 25 is the first predetermined speed DLVSP1 If not, or if the vehicle speed VSP is equal to or lower than the second predetermined speed DLVSP2 in step 26, it is determined that the engine-related lock-up prohibition condition is satisfied, and step 27 is performed.
To output the lock-up prohibition signal IL / U to the transmission controller 7, and the signal output is continued while the above condition is satisfied. If the engine 1 changes from driving the compressor to non-driving while the vehicle speed VSP is equal to or lower than the first predetermined speed DLVSP1, although not shown in FIG. The output of the lock-up inhibition signal IL / U is continued until the cut lower limit vehicle speed FRVSP2 is reached. On the other hand, the transmission controller 7 executes the control program of FIG. 3 on the basis of the input information described above to perform the shift control of the continuously variable transmission 2 as described below. By executing the control program, the lockup control of the torque converter 3 is performed as follows in cooperation with the engine controller 14. First, the shift control will be described. In this control, the transmission controller 7 determines in step 31 of FIG.
Throttle opening TVO, reads the vehicle speed VSP, and the transmission output speed N _o, then at step 32, the throttle opening TVO and vehicle speed VSP, a target input rotation of the transmission based on the shift map corresponding to FIG. 5 The number N _t ^* is obtained by a search, and in a subsequent step 33, the target input speed _Nt ^* is divided by the transmission output speed N _o to obtain a target speed ratio RTO corresponding to the target input speed N _t ^*.
Is calculated. Then, in the next step 34, the rotational position of the step motor 6 for achieving the target gear ratio RTO is searched as the motor step number STP, and this is output to the step motor 6. In the continuously variable transmission 2, the step motor 6 is rotated to a position corresponding to the number of motor steps STP.
The speed is continuously changed so as to attain the target speed ratio RTO, and as a result, the speed change is controlled based on the speed change pattern of FIG. Next, lock-up control of the torque converter 3 will be described. In this control, the transmission controller 7 determines in step 41 of FIG.
O, vehicle speed VSP, a brake switch signal S _b, the idle switch signal S _i and the lock-up prohibition signal IL / U
And in the next step 42, an operation for setting the torque converter 3 to the lock-up (L / U) state from the above signals based on the lock-up area map corresponding to the lock-up diagram illustrated in FIG. State or converter (C
/ V) It is determined whether the operating state is to be set. [0027] That is, in step 42, the idle switch signal or S _i is and the vehicle speed VSP not ON is equal to or less than the lock-up release vehicle speed DLVSP3 in depression accelerator pedal, lock-up prohibition signal or IL / U is output, the brake Whether the switch signal _Sb is ON,
Whether the throttle opening TVO has increased rapidly and the vehicle speed VS
It is determined whether or not P has suddenly decelerated, and if any of them is applicable, the torque converter 3 is connected to the converter (C
/ V) state, and if not, the torque converter 3 is locked up (L / V).
U) It is determined that the operating state is to be brought to the state. Here, the solid line in FIG. 6 indicates that the torque converter 3 is in the lock-up (L / U) state from the converter (C /
V) indicates the boundary to be set, and the dashed line in FIG.
The boundary where the torque converter 3 should be changed from the converter (C / V) state to the lockup (L / U) state is shown.
The boundary at which the torque converter 3 should be changed from the converter (C / V) state to the lockup (L / U) state is larger than the boundary at which the torque converter 3 should be changed from the lockup (L / U) state to the converter (C / V) state. The vehicle speed is set to be slightly higher, whereby a hysteresis is set between the two to prevent hunting between the converter (C / V) state and the lock-up (L / U) state. If it is determined in step 42 that the torque converter 3 is in the operation state in which the torque converter 3 should be set to the converter (C / V) state, the control proceeds to step 43,
Here, the drive duty D of the lock-up solenoid 5 is set to 0%, and the torque converter 3 is brought into the converter state as required. On the other hand, if it is determined in step 42 that the operation state is such that the torque converter 3 should be brought into the lock-up (L / U) state, the control proceeds to step 44, where the drive duty D of the lock-up solenoid 5 is reduced. The torque converter 3 is set to 100%, and the torque converter 3 is locked up as required. In this embodiment, the engine controller 14 satisfies the lock-up prohibition condition relating to the compressor of the air conditioner in step 25 or 26 in FIG. 2 and outputs the lock-up prohibition signal IL / U in step 27. If the fuel cut is being performed at the beginning of the transmission, the transmission controller 7 that has input the IL / U signal can only bring the torque converter 3 into the converter state from the time when the output of the IL / U signal is started. After a while, stop the fuel cut and restart the fuel supply to the engine. Thus, according to the lock-up control method of this embodiment, whether the predetermined lock-up prohibition condition relating to the engine is satisfied or not is transmitted from the engine controller 14 to the transmission controller 7 through one type of communication line. Since the lock-up prohibition signal IL / U indicating the establishment is sent, the same transmission lines as the multiple communication lines connected to the engine controller 14 for inputting data for the engine controller 14 to determine the operation state of the engine are transmitted. The necessity of connecting to the controller 7 can be eliminated, and the communication line can be simplified, so that the space efficiency of the vehicle can be increased and the manufacturing cost of the vehicle can be reduced. When the vehicle is running with the accelerator pedal released (in a state where the accelerator pedal is not depressed), when the lock-up is released, the direct connection between the input and output elements of the torque converter 3 is eliminated and the engine speed decreases. In order to prevent the stall of the engine 1, especially where it is necessary to associate the operating state of the engine 1 with the lock-up control of the torque converter 3, according to the lock-up control method of this embodiment, the vehicle travels with the accelerator pedal released. During this time, the engine controller 14 makes a determination as to whether or not a predetermined engine-related lock-up prohibition condition has been satisfied. Therefore, it is necessary to appropriately associate the operating state of the engine 1 with the lock-up control of the torque converter 3. Can be. Further, when the cooling water temperature of the engine 1 is equal to or lower than a predetermined value, the behavior of the vehicle becomes jerky when locked up because the output torque of the engine 1 fluctuates greatly. According to the lock-up control method of this embodiment, even if the engine speed is kept low and the warm-up operation takes a long time, the condition that the coolant temperature of the engine 1 is equal to or lower than the predetermined value is satisfied under the predetermined lock-up prohibition condition. Because it includes
When the cooling water temperature is equal to or lower than the predetermined value, lock-up can be prohibited, the output torque fluctuation of the engine 1 can be absorbed by the torque converter 3, and the engine speed can be increased to shorten the warm-up operation time. Further, when the engine speed is equal to or less than the predetermined value, the behavior of the vehicle becomes jerky when locked up due to large fluctuations in the output torque of the engine. For example, since the predetermined lock-up prohibition condition includes a condition that the rotation speed of the engine 1 is equal to or lower than a predetermined value, the lock-up can be prohibited when the rotation speed of the engine 1 is equal to or lower than the predetermined value, and the torque can be reduced. Converter 3 can absorb fluctuations in output torque of engine 1. When the engine 1 drives the compressor of the air conditioner, the load on the engine 1 is larger than when the compressor is not driven, and the rotational resistance of the continuously variable transmission 2 The synergistic effect of being larger than that of the stepped variable transmission, the lock-up control of this embodiment is used when the engine braking force of the vehicle when the accelerator pedal is released at low vehicle speed is likely to be excessive. According to the method, in a predetermined lock-up prohibition condition, the engine is driving the compressor of the air conditioner and the vehicle speed is equal to or less than the first predetermined speed, or the engine is not driving the compressor of the air conditioner. And includes a condition that the speed of the vehicle is equal to or lower than a second predetermined speed lower than the first predetermined speed. The lock-up release vehicle speed can be made different depending on whether the vehicle is running or not, and therefore, the compressor can be operated while preventing the engine braking force from being excessive when the accelerator pedal is released at low vehicle speeds. The fuel cut period can be made sufficiently long at the time of deceleration during non-driving, and the effect of suppressing fuel consumption during running of the vehicle can be sufficiently enhanced. In addition, according to the lock-up control method of this embodiment, the engine controller 14 itself
The lockup inhibition signal IL / U is transmitted to the transmission controller 7
And the control to stop fuel cut and restart fuel supply, it is possible to release lockup and prevent the engine 1 from stalling when the vehicle decelerates. The fuel supply is restarted in chronological order, so the shock of unlocking and the increase in driving force due to the restart of fuel supply overlap each other, causing longitudinal vibration of the vehicle immediately before the vehicle stops. The inconvenience of doing so can be reliably prevented irrespective of the fuel cut lower limit rotation speed of the engine 1 and the gear ratio of the continuously variable transmission 2. Although the present invention has been described with reference to the illustrated examples, the present invention is not limited to the above-described examples. For example, in the above-described embodiment, the description has been given of the V-belt type continuously variable transmission. The present invention can be applied to other types of continuously variable transmissions such as a stepped transmission, and a predetermined lock-up prohibition condition related to an engine can also be applied when the engine is driving a compressor of an air conditioner and the vehicle speed is low. The condition that the vehicle speed is equal to or lower than a first predetermined speed or the engine is not driving a compressor of an air conditioner and the speed of the vehicle is equal to or lower than a second predetermined speed lower than the first predetermined speed is left. Other than the above, the conditions are not limited to those of the above-described embodiment, and other conditions can be set.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a vehicle continuously variable transmission and an integrated control system of an engine including a transmission controller and an engine controller for executing one embodiment of a lock-up control method of the present invention. FIG. FIG. 2 is a flowchart showing a process for the engine controller to determine whether an engine-related lockup prohibition condition is satisfied. FIG. 3 is a flowchart showing a process in which the transmission controller performs a shift control of a continuously variable transmission. FIG. 4 is a flowchart showing a process in which the transmission controller performs lockup control of a torque converter. FIG. 5 is a shift pattern diagram showing a shift pattern used by the transmission controller to perform shift control of a continuously variable transmission. FIG. 6 is a lockup diagram showing a lockup line used by the transmission controller to perform lockup control of the torque converter. [Description of Signs] 1 engine 2 stepless transmission 3 torque converter 4 control valve 5 lock-up solenoid 6 step motor 7 transmission controller 8 throttle opening sensor 9 vehicle speed sensor 10 engine rotation sensor 11 output rotation sensor 12 brake switch 13 idle Switch 14 Engine controller 15 Air conditioner controller 16 Water temperature sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-173726 (JP, A) JP-A-5-149423 (JP, A) JP-A-3-260463 (JP, A) JP-A-62-1987 244729 (JP, A) JP-A-7-71590 (JP, A) JP-A-8-42684 (JP, A) JP-A-62-24057 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) F16H 61/14

Claims (1)

(57) [Claim 1] The lockup of a lockup type torque converter of a continuously variable transmission used in a vehicle having an engine control device for controlling the operation of an engine is defined as the engine control device. In controlling by a separate transmission control device, the engine is controlled by the engine control device.
The compressor speed of the vehicle is
1 is lower than the specified speed or the engine is
The conditioner compressor is not running and the vehicle
The speed is equal to or less than a second predetermined speed lower than the first predetermined speed.
It is determined whether or not a predetermined lock-up prohibition condition relating to the engine is satisfied. If it is determined that the predetermined lock-up prohibition condition is satisfied, the engine control device causes the engine control device to perform the transmission control device. A lock-up control method for a continuously variable transmission for a vehicle, comprising: outputting a lock-up prohibition signal toward the transmission to prohibit the transmission control device from setting the torque converter in a lock-up state.