JP2877302B2 - Lock-up control device for automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lock-up control device for an automatic transmission. (Prior Art) Generally, in an automatic vehicle equipped with an automatic transmission, when traveling downhill in a travel range, for example, in a D range, in which access depressing is released (coasting traveling), usually,
The vehicle is in the fourth or third speed state. For this reason, when it is desired to apply the engine brake, it is customary to switch from the D range to the S range. (Problems to be Solved by the Invention) However, when performing the switching operation from the D range to the S range in this manner, a shift shock is likely to be caused, and particularly at a high vehicle speed, a sudden engine brake may be applied. And the driver may feel uncomfortable. By the way, it is known to set the lock-up release vehicle speed during coasting with the accelerator pedal released to a lower speed than the normal lock-up release vehicle speed to ensure the effect of engine braking (for example, Kaisho
57-37153). However, in this case, even if the vehicle speed is relatively low, the lock-up is always activated if the accelerator pedal is released, so that a torque shock occurs when shifting from the deceleration state to the acceleration state, This torque shock is particularly large at the time of re-acceleration from a state where the deceleration is large (lock-up operation state during coasting on a flat road where the vehicle is not accelerated or slightly uphill), which is disadvantageous in terms of ride comfort. The present invention has been made in view of the above circumstances, and performs lock-up control in a state where an accelerator pedal is depressed without deteriorating the engine braking effect and without deteriorating ride comfort of an occupant. An object of the present invention is to provide a lock-up control device for an automatic transmission that achieves both a braking action and an improvement in ride comfort. (Means for Solving the Problems) In order to achieve the above object, a solution of the present invention is to provide an automatic transmission equipped with a lock-up device, comprising: a step-off release detecting means for detecting a step-release of an accelerator pedal; A light load traveling state detecting means for detecting whether the traveling state of the vehicle is in a light load traveling state of a predetermined load or less corresponding to downhill traveling, and a signal from the stepping release detecting means and the light load traveling state detecting means. When it is detected that the accelerator pedal is in the released state and in the light load traveling state, the lock-up device is operated, while the accelerator pedal is in the released state and not in the light load traveling state. Control means for prohibiting the operation of the lock-up device upon detecting that the lock-up device has been operated. (Operation) According to the present invention, when the accelerator pedal is in the released state (coasting traveling state) and in the lightly loaded traveling state of downhill traveling, the lock-up device is activated, and the engine brake is activated. On the other hand, the operation of the lockup device is prohibited when the accelerator pedal is not depressed and the vehicle is not in the light-load running state. Therefore, when the vehicle is accelerated again from the deceleration state, the lockup device remains in the inoperative state, and the torque shock Does not occur, and discomfort of the occupant is prevented. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1 showing the overall configuration of a lock-up control device for an automatic transmission, reference numeral 1 denotes a torque converter, and the torque converter 1 includes a plurality of pump impellers 2 and a plurality of pump impellers 2 disposed opposite to each other. It comprises a turbine runner 3 and a stator 4 having a smaller diameter than the pump impeller 2 and the turbine runner 3. The pump impeller 2 is disposed between the core ring 5 and the converter cover 6 located outside the core ring 5.
The converter cover 6 includes a shell 6a and a cover body 6b welded to a peripheral portion of the shell 6a. The cover body 6b is connected to an engine output shaft 8 via a drive plate 7. Therefore, the pump impeller 2 is connected to the engine output shaft 8 via the converter cover 6. The turbine runner 3 is connected via its hub 9 to a converter output shaft 10 which is linearly arranged following the engine output shaft 8, and the converter output shaft 10 is connected to an input shaft of a transmission (not shown). Is connected. Shell of turbine runner 3 of torque converter 1
A damper piston 11 (lock-up clutch) is arranged between 3a and the converter cover 6 so as to face the converter cover 6. The damper piston 11 is
The center portion thereof is fixedly connected to the converter output shaft 10 via the hub 9. The friction member 11 a disposed on the outer periphery is pressed against the inner peripheral surface of the converter cover 6 to fasten the damper piston 11, whereby the engine is rotated. The output shaft 8 is directly connected to the converter output shaft 10 to transmit power. Reference numeral 12 denotes a lock-up control valve. The lock-up control valve 12 has a first chamber 12 on both sides of a valve body 12a to which a line pressure from an oil pump 13 acts.
b, and a second chamber 12d in which a spring 12c is interposed. Reference numeral 14 denotes a lock-up solenoid valve which, when excited, drains the line pressure from the oil pump 13. Reference numeral 15 denotes a drain passage. The drain passage 15 is connected to a first chamber 16 located between the damper piston 11 of the torque converter 1 and the converter cover 6, and in the middle of the drain passage 15, a lock-up control valve 12 and a relief valve 29 are interposed. An oil supply passage 17 supplies oil to a second chamber 18 located between the turbine runner 3 and the damper piston 11. Reference numeral 19 denotes a pressure holding valve of the torque converter 1, which is a pressure holding valve.
Reference numeral 19 is provided in the middle of a passage 21 connecting the torque converter 1 and the oil cooler 20. Reference numeral 22 denotes a D range switch, which is turned on when the select lever is at the D range position. 23 is a stop lamp switch, which is turned off when the foot brake is not depressed. Two
Reference numeral 4 denotes a water temperature switch, which is turned off when the engine cooling water temperature is equal to or higher than a set temperature (for example, 72 ° C.). Reference numeral 25 denotes a turbine sensor that detects a turbine speed as a vehicle speed sensor, 26 denotes a throttle sensor that detects a throttle valve opening, 27 denotes a speed sensor that detects an engine speed, and 28 denotes an idle switch as a depression release detecting means. Turns on when the accelerator pedal is released. 30 is a control unit, the above-mentioned D range switch
22, the stop lamp switch 23, the water temperature switch 24, the turbine sensor 25, the throttle sensor 26, the rotation speed sensor 27, and the idle switch 28. Each of the outputs is received. For example, in the case of the D range, the economy shown in FIGS. mode,
Control means 10 for performing shift control and lock-up control based on automatic shift diagrams in the power mode and the high power mode
With one. Further, the control unit 30 includes the turbine sensor 25
Receiving the respective outputs of the rotation speed sensor 27 and when the turbine rotation speed is greater than the engine rotation speed and the rate of change of the turbine rotation speed is positive, the traveling state of the vehicle is equal to or less than a predetermined load corresponding to downhill traveling. A light load traveling state detecting means 102 for determining that the vehicle is in a light load traveling state is provided. The control means 101 receives the outputs of the light load traveling state detecting means 102, the D range switch 22 and the idle switch 28, and When it is detected that the accelerator pedal is in the released state and is in the light load traveling state in the state, the lock-up is performed, while when it is detected that the accelerator pedal is in the released state and not in the light load traveling state. Lockup is not performed. The second example of the configuration of the control means 101 of the control unit 30 and the configuration for detecting whether or not the accelerator pedal is released in the D range state and whether or not the vehicle is in a light load traveling state are described below.
First, a D range signal S ₁ from a D range switch 22, a turbine sensor 25 and a rotation sensor 27 will be described.
By comparing the output with the turbine speed signal S ₂ when larger than the engine rotational speed at the AND circuit 31, checks that a coasting state, at the same time, the turbine speed change rate is positive the signal S ₃ when the when it is input to the control circuit 32, the lock-up signal S ₄ is outputted, so as to excite the lock-up solenoid valve 14. However, the signal S ₅ when the idle switch 28 is ON and the accelerator pedal is depressed, the signal S ₆ when the throttle valve opening is a certain value or more, or the turbine speed is a set value (lock-up release set speed described later). K ₁ ) less signal
S ₇ is, when entered into the OR circuit 33, the output of the lock-up signal S ₄ is prohibited. When the control unit 30 determines that lock-up has occurred, the lock-up solenoid valve 14 is turned on, and the valve body 12a of the lock-up control valve 12 is moved to the second chamber 12d.
The line pressure pushing to the side is drained. Thereby, the valve element 12a of the lock-up control valve 12 moves toward the first chamber 12b by the spring force of the spring 12c and the line pressure (the lock-up control valve in FIG. 1).
12 upper half). As a result, the oil in the first chamber 16 of the torque converter 1 is drained through the drain passage 15, and the oil is supplied from the oil supply passage 17 to the second chamber 16 of the torque converter 1.
Oil flows into 18 and both chambers 16 and 1 in torque converter 1
Since the damper piston 11 is pressed against the converter cover 6 via the friction member 11a by the differential pressure of 8, the lockup state is established, and power is transmitted directly. On the other hand, when the control unit 30 determines unlocking, the lock-up control valve 12
A line pressure is applied to push a toward the second chamber 12d, and the valve body 12a moves toward the second chamber 12d (see the lower half of the lock-up control valve 12 in FIG. 1). As a result, oil flows through the drain passage 15 to the first chamber of the torque converter 1.
Then, the oil pressure in the first chamber 16 becomes higher than the oil pressure in the second chamber 18, the damper piston 11 slides toward the second chamber 18, and the torque converter 1 operates as a fluid coupling. Next, the flow of lock-up control by the control unit 30 will be described with reference to FIG. In FIG. 6, the lock-up is indicated as L / u. The case of the 4th speed in the D range will be described. First, when started, it is determined whether or not the no-load area flag is 1 (step S ₁ ). No-load region flag, the map shown in FIG. 7, it exceeds line l ₃ in the direction of the throttle valve opening is increased 0, exceeds another line l ₄ in a direction to decrease 1. If the no-load region flag is 0, it is not a coasting state, then the lock-up region flag is determined whether the 1 (step S _2). Lockup region flag, the map shown in FIG. 7, exceeds the line l ₁ in the direction of the turbine speed is increased becomes 1, and 0 exceeds another line l ₂ in the direction of decreasing. If the lock-up area flag is 1, the lock-up prohibition conditions for determining whether the sensor and the solenoid are malfunctioning, whether the gear is being shifted, and whether the brake is operating are sequentially determined (steps S ₃ , S ₄ , S _5), if NO in all of them, the lock-up solenoid valve 14 and ON (step
S _6). Also, or a lockup region flag is 0, if it meets any of the above prohibition condition, the lock-up solenoid valve 14 and OFF (step S _7). Although such a normal lock-up control in the place, in the determination in step S _1, when no load region flag is 1 since it is coasting state, another control described below is performed. First, the turbine speed is determined whether greater than the engine speed (step S _8), with confirmation that a coasting state is performed, whether the turbine speed change rate is positive Is determined (step S ₉ ), and it is determined whether or not the running state of the vehicle is in a light-load running state of a predetermined load or less corresponding to downhill running. If the light load running state are all either the determination in step S ₈ and S ₉ YES, then ON the lock-up solenoid valve 14 (step S _10), the lock-up timer starts counting from T = 0 (step S _11). On the other hand, if the vehicle is not in the light load traveling state in which one of the determinations in steps S ₈ and S ₉ is NO, the lock-up solenoid valve 14
It is of ON not performed, and the flow returns to step S _1. Then, in order to prevent engine stall and muffled noise, the turbine speed is set to the lockup release set speed K ₁ (for example,
Determination of whether or not 1500 rpm) or less (step S _12), the determination of whether the accelerator depression state (step S _13), for determining whether or not the sensor and the solenoid is in failure (step S _14), shift Judgment of whether or not
S ₁₅ ), it is determined whether or not the brake is operating (step S
₁₆₎ and for determining whether or not the lock-up timer value T is the set value T _L u (step S ₁₇₎ is performed in the order, any of the above determination, if YES, the finished counting the lockup timer (step S _18), the lock-up solenoid valve 14 is turned OFF (opened step S _19), the flow returns to step S _1.
On the other hand, if the judgment is NO in all in the step S ₁₂ to S _17, until any one of the determination becomes YES, and repeated. The determination of whether or not the accelerator depression state at step S ₁₃ is, ON-OFF of the idle switch 28, or the throttle valve opening is carried out by such whether it is above a certain value. The setting value T _L u of the lockup timer value T is set from the too small hunting occurs, jerky feel at low speeds too slowed too large occurs, for example, approximately 2 seconds . (Effects of the Invention) As described above, according to the present invention, when the accelerator is depressed in the traveling range state and the vehicle is in the light load traveling state corresponding to downhill traveling, the engine brake is actuated by the lock-up operation. When the accelerator is not depressed and the vehicle is not in the light-load driving state, the lock-up is not activated, so that a jerky feeling at the time of re-acceleration from deceleration is prevented, so that both the engine braking effect and the improvement of the riding comfort can be achieved. I can do it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention. FIG. 1 is an overall configuration diagram of a lock-up control device for an automatic transmission, FIG. 2 is an explanatory diagram of a control unit, and FIGS. FIG. 5 is an automatic shift diagram in the economy mode, the power mode and the high power mode, FIG. 6 is a flowchart showing a lock-up control flow by the control unit, and FIG. 7 shows a no-load region and a lock-up region, respectively. FIG. 1 ... torque converter, 6 ... converter cover, 11
... damper piston, 12 ... lock-up control valve, 14 ... lock-up solenoid valve, 15 ...
... Drain passage, 17 ... Oil supply passage, 22 ... D range switch, 28 ... Idle switch, 30 ... Control unit, 101 ... Control means, 102 ... Light load traveling state detection means.

Claims (1)

(57) [Claims] In an automatic transmission equipped with a lock-up device, depressing release detecting means for detecting depressing of an accelerator pedal, and determining whether or not the traveling state of the vehicle is in a light load traveling state below a predetermined load corresponding to downhill traveling. When light load traveling state detecting means and a signal from the depression release detecting means and the light load traveling state detecting means are detected, and when it is detected that the accelerator pedal is in the released state and in the light load traveling state, And control means for prohibiting the operation of the lock-up device when detecting that the accelerator pedal is in the released state and not in the light-load running state while operating the lock-up device. A lock-up control device for an automatic transmission.