JPS628665B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control system for a lock-up clutch in an automatic transmission.

In a semi-automatic or fully automatic transmission configured with a hydraulic torque converter (hereinafter simply referred to as a torque converter) and an auxiliary transmission connected to the hydraulic torque converter and having a gear train capable of selecting one or more speed ratios, the torque converter is mechanically operated. When the lock-up clutch, which engages the engine and eliminates fluid slippage, operates, it eliminates slip loss in the torque converter section and greatly contributes to quieter cruising and improved fuel efficiency, but on the other hand, it also kills the torque amplification function of the torque converter. Because of this, power performance deteriorates when overtaking or on gentle uphill slopes.

Conventionally, a method has been proposed in which the lock-up clutch is released when the engine output exceeds a certain predetermined value, thereby preventing the reduction in power performance.

However, with this method, if the accelerator pedal is operated frequently near the default value of engine output,
The power plant system including the engine turns on the lock-up clutch due to engine torque fluctuations.
This results in a fluctuation equal to the torque fluctuation due to the off-state, which may cause unpleasant vibrations to the occupants. Also, a method has been proposed in which the lock-up clutch is released when the accelerator pedal is in the idle position, but even with this method, if the accelerator pedal is repeatedly depressed from the idle position, it may cause discomfort due to the same reasons as mentioned above. Vibrations may be transmitted to the passengers.

Such unpleasant vibrations can be solved to some extent by redesigning the mounting system of the power plant system, but this cannot be fundamentally solved.

In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 57-195956 discloses that when the amount of depression of the accelerator pedal is substantially zero, the lock-up clutch (direct coupling clutch 4) is set to the open state, and the accelerator pedal A time count is started from that time when the amount of depression substantially increases above zero, and when the time count ends, the lock-up clutch is inhibited from engaging, thereby alleviating the shock that occurs to the vehicle. A method has been disclosed.

However, according to such conventional methods, the lower limit of the amount of accelerator pedal depression (in this case, substantially zero)
However, no consideration has been given to its upper limit, so even when, for example, the predetermined amount of accelerator pedal depression is further increased toward a fully open throttle state,
The lock-up clutch is always engaged after a time count has elapsed, resulting in an uncomfortable ride and a poor sense of acceleration due to engine torque fluctuations.

The present invention has been made to solve the problems of such conventional methods, and includes a vehicle speed sensor that detects the vehicle speed, and a second throttle valve whose throttle opening is greater than or equal to the first opening value based on the accelerator pedal position. A throttle opening detection switch that opens when the throttle opening is within the first opening value and closes when the throttle opening is below the first opening value and exceeds the second opening value is connected to the throttle opening detection switch and the vehicle speed sensor, respectively. and a control signal for operating the lock-up clutch when the throttle opening detection switch is open and the vehicle speed is at least a first speed value, or when the vehicle speed is at least a second speed value. a selection circuit that outputs
The invention is characterized by comprising a delay circuit that delays the control signal of the selection circuit for a predetermined period of time, and a drive circuit that operates the lock-up clutch when the output of the delay circuit is obtained. To provide a control device for an automatic transmission which can ensure a comfortable ride at all vehicle speeds while alleviating an unpleasant shock when a lock-up clutch is activated by limiting the amount of depression of an accelerator pedal to a predetermined range. The purpose is to

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a shift characteristic diagram of the transmission, in which the horizontal axis shows the vehicle speed V, and the vertical axis shows the throttle opening degree θ, which is a parameter representative of the engine output. Note that the vertical axis is not limited to the throttle opening, and may also be, for example, the intake manifold negative pressure, but the most common throttle opening is illustrated here. Furthermore, the automatic transmission to be applied can be either a semi-automatic transmission or a fully automatic transmission, but in this example, the latter is selected, and the speed ratio that can be selected is also an extremely common three-speed forward transmission. ing.

Now, the very general shift characteristics of three forward gears are indicated by the two broken lines A and B shown as dotted lines in the figure, and the left side of broken line A is the 1st speed region, and the area between broken lines A and B is The area is the 2nd speed area, and the area to the right of broken line B is the 3rd speed area. Where each of these broken lines A and B passes varies depending on the individual case. Also, the solid line C in the figure
1 shows an example of the operating range of the lock-up clutch according to the present invention, where the area to the left of the solid line C is the release area, and the area to the right (shaded side) is the operating area. As is clear from this characteristic diagram,
Until the vehicle speed reaches _V1 (V< _V1 ), the lock-up clutch will not operate regardless of the throttle opening θ, and until the vehicle speed exceeds _V1 and reaches _V2 ( _V1 <V1). <V ₂ ), the throttle opening θ is between θ ₁ and _{θ 2}
The lock-up clutch operates only when the opening is in the range (θ ₁ < θ < θ ₂ );
θ ₁ , θ>θ ₂ ), it is canceled. Also, the vehicle speed is V ₂
(V ₂ <V), the lock-up clutch becomes activated regardless of the throttle opening θ.

Incidentally, when the automatic transmission to which the present invention is applied is a semi-automatic transmission, the broken lines A and B in FIG. 1 disappear.

Further, the straight line portion _C3 of the solid line C does not need to match the constant vehicle speed _V1 , and may of course be changed for each gear engagement state such as 1st, 2nd, and 3rd gears.

FIG. 2 is a block diagram of a control device for carrying out the control operation of the lock-up clutch shown in FIG. It is adapted to be hydrodynamically transmitted to the turbine impeller T. When there is a relative speed difference between both impellers P and T and a torque amplification effect is present, the stator S takes charge of the reaction force. The output torque of the turbine impeller T, that is, the output torque of the torque converter 2, is transmitted to the drive wheels 5 via the auxiliary transmission 3 and the differential gear 4. A lock-up clutch LC is disposed between the pump impeller P and the turbine impeller T to mechanically engage them, and this lock-up clutch LC is driven by a solenoid valve 6. There is.

The solenoid valve 6 is switched to a position 6A when the solenoid 6S is deenergized, and to a position 6B when the solenoid 6S is energized. In addition, a hydraulic source such as a hydraulic pump 7 is driven by a pump impeller P of a torque converter 2, and is connected to a lock-up clutch LC via a solenoid valve 6.
It is designed to supply pressure oil to the When the solenoid valve 6 is switched to position 6A, the lock-up clutch LC is connected to the tank 8a and the lock-up clutch LC is released (turned off). Also, when switched to position 6B, the lock-up clutch LC
is connected to the hydraulic pump 7, and the lock-up clutch LC is activated (on). That is, the lock-up clutch LC is selectively connected to the hydraulic pump 7 or the tank 8a by the solenoid valve 6, thereby being actuated or released.

Further, the pressure oil discharged from the hydraulic pump 7 is also supplied to the hydraulic control mechanism 3a of the auxiliary transmission 3, and is used to select the speed ratio. Note that the discharge pressure of the hydraulic pump 7 is controlled to a predetermined pressure by a regulator valve 9.

The lock-up clutch control device 10 is a solenoid valve 6
a vehicle speed sensor 11 that detects the vehicle speed V and outputs a corresponding pulse signal Pv;
a vehicle speed detection circuit 12 that converts this pulse signal Pv into a corresponding analog signal and outputs a vehicle speed signal V;
The accelerator pedal switch 13 serves as an accelerator opening detection switch that detects the accelerator pedal position and outputs a throttle opening signal Pa based on the accelerator opening. A vehicle speed throttle selection circuit 14 outputs a control signal Pc for actuating the lock-up clutch LC when the vehicle speed is greater than or equal to a first speed value _V1 , or when the vehicle speed is _greater than or equal to a second speed value V2. A delay circuit 15 that delays the time and a drive circuit 16 that is controlled by the output signal of the delay circuit 15 and drives the solenoid valve 6.
etc., in order to obtain the equality shown by the straight line C in FIG.

As shown in FIG. 3, the vehicle speed sensor 11 is composed of, for example, a reed switch LS and a magnet MG attached to a speedometer cable, and the rotation of the speedometer cable is detected by the reed switch LS. One end of the reed switch LS is grounded, and the other end is connected to the power supply Vc through a resistor _R1 of the vehicle speed detection circuit 12, and is connected to the input of the inverting amplifier _AMP1 through a filter circuit consisting of a resistor _R2 and a capacitor _C1 . It is connected to the. The resistor _R1 provides bias to the inverting amplifier _AMP1 when the reed switch LS is open (off). The output signal Pv of the vehicle speed sensor 11 is at a high level (below) when the reed switch LS is open.
Hi). This is a pulse signal that becomes low level (hereinafter referred to as L ₀ ) when closed, and its frequency is proportional to the vehicle speed. After the noise component is removed from this pulse signal Pv by the filter circuit, it is sent to the inverting amplifier AMP _1.
is inverted and amplified. The output of this inverting amplifier AMP ₁ is applied to a differentiating circuit made up of a capacitor C ₂ and a resistor R ₃ . This differentiator circuit is an inverting amplifier
The rising edge of the output waveform of AMP ₁ , that is, the reed switch LS
Detect the moment of closure. Then, the output signal of this differentiating circuit is inverted and amplified by the inverting amplifier AMP ₂ , and then applied to the monostable multivibrator MM. The monostable multivibrator MM consists of a two-input NAND gate NAD ₁ , a capacitor C ₃ , a resistor R ₄ and an inverting amplifier
It is composed of AMP ₃ , and when the differential signal is input, it outputs a pulse signal Pm with a predetermined pulse width. This pulse signal Pm is synchronized with the rotation of the meter cable.

This pulse signal Pm is applied to the base of the transistor Tr 1 via the resistor R ₅ and is applied to the base of the transistor Tr ₁ .
Turn on Tr ₁ . The emitter of the transistor _TR1 is connected to a positive voltage power supply, the collector is grounded via a resistor _R6 , and the transistor TR1 amplifies and outputs the input pulse signal Pm. And the output of transistor Tr ₁ is resistor
After being smoothed by a smoothing circuit composed of R ₇ and R ₈ and capacitors C ₄ and C ₅ , it is applied to differential amplifier AMP ₄ . The differential amplifier AMP ₄ impedance converts the input signal and outputs a vehicle speed signal V of the corresponding voltage. The vehicle speed signal V is a voltage signal proportional to the rotation of the speedometer cable, that is, the vehicle speed V.

The vehicle speed signal V is applied to each input terminal of comparators COMP ₁ and COMP ₂ of the vehicle speed throttle selection circuit 14. Reference _voltage signals V 1 and V 2 corresponding to set vehicle speeds V ₁ and V ₂ (FIG. 1) are applied to _the negative input terminals of these comparators COMP ₁ and COMP ₂ , respectively. These reference voltage signals V ₁ and V ₂ are formed by voltage dividing circuits of resistors R ₁₀ , R ₁₁ and R ₁₅ , R ₁₆ , respectively. The output of comparator COMP ₁ is when V > V ₁ , that is, when the current vehicle speed V exceeds the set vehicle speed V ₁ .
It becomes Hi.

Similarly, the output of comparator COMP ₂ is Hi when V > V ₂ , that is, when the vehicle speed V exceeds the set vehicle speed V ₂ .
becomes. Incidentally, the resistors R ₁₂ , R ₁₃ ; R ₁₇ and R ₁₈ connected to the comparators COMP ₁ and COMP ₂ are used to provide hysteresis to output changes and stabilize the operation.

Accelerator pedal switch 13 is an accelerator pedal
It consists of a cam CM fixed to the ACP and a limit switch LSW that is opened and closed by the cam CM. The cam CM has a throttle opening θ between the first opening value θ ₁ and the second opening value θ ₂ (θ ₁ < θ
<θ ₂ ), the limit switch LSW is opened, and when θ < θ ₁ and θ ₂ <θ, the limit switch LSW is closed. The contact on one side of the limit switch LSW is grounded, and the contact on the other side is connected to the input side of the 2-input Nandgate NAD ₂ and is connected to a resistor.
Connected to positive voltage power supply Vc.c. via _R19 .
Output signal Pa of this accelerator pedal switch 13
becomes Hi when the limit switch LSW is open, and becomes _L0 when it is closed.

The output of the comparator COMP ₁ is applied to a NAND gate NAD ₂ , and the output of this NAND gate NAD ₂ is applied to a two-input NAND gate NAD ₃ . Comparator COMP ₂
The output of the NAND gate is passed through the inverting amplifier AMP ₅
Added to NAD ₃ . The output of the NAND gate NAD ₂ is output when both inputs are Hi, that is, when the vehicle speed V exceeds the set vehicle speed V ₁ (V > V ₁ ) and the throttle opening θ is between θ ₁ and θ ₂ (θ ₁ <θ<θ ₂ )
It becomes L ₀ , and becomes Hi at other times. The output Pc of the NAND gate NAD ₃ is output when one of the two inputs is L ₀ , that is, when the vehicle speed V exceeds the second speed value V ₂ (V ₂ < V), or when the vehicle speed V exceeds the first speed value V 2 . Hi when the speed value V ₁ is exceeded (V ₁ < V) and the throttle opening θ is between the first opening value θ ₁ and the second opening value θ ₂ (θ ₁ < θ < θ ₂ ). becomes. That is, the output Pc of the NAND gate NAD ₃ becomes Hi level when the condition of the lock-up clutch operating region shown by the diagonal line C in FIG. 1 is reached. This signal Pc becomes a control signal for the lock-up clutch.

The delay circuit 15 is composed of a resistor R ₂₀ and a capacitor C ₆ , and is a charging circuit that is charged by a control signal Pc, and is connected in parallel to the resistor R ₂₀ to quickly discharge the charge of the capacitor C ₆ when the signal Pc is L ₀ . a diode D, which is set to a predetermined threshold level, and whose output becomes _L0 when the charging voltage of the charging circuit reaches the threshold level; and an inverting amplifier AMP ₆ that inverts and amplifies the output of the inverting amplifier AMP ₆ . It consists of an inverting amplifier AMP ₇ , etc.
Then, the output Pc of NAND gate NAD ₃ changes from L ₀ to Hi
For example, when the vehicle speed changes to V ₁ <V<
V ₂ , and when the accelerator pedal ACP is depressed, the throttle opening θ changes from the idle position to the first opening value θ.
When it exceeds ₁ , capacitor _C6 is charged. And the terminal voltage of capacitor C ₆ is inverting amplifier
When the threshold level of AMP ₆ is exceeded, the output of this amplifier AMP ₆ becomes L ₀ .

The accelerator pedal switch 13 is opened (θ ₁ <θ<
The time td from time t ₁ (FIG. 4a) at which θ ₂ ) reaches θ 2 until the terminal voltage of capacitor C ₆ reaches a specified threshold voltage is the delay time. This delay time td is determined by the time constant of the charging circuit including resistor R ₂₀ and capacitor C ₆ . delayed control signal
Pc' is applied to the base of the power transistor Tr ₂ of the drive circuit 16 via the inverting amplifier AMP ₇ and the resistor R ₂₁ to turn on the transistor Tr ₂ . The emitter of transistor Tr ₂ is grounded, and
The collector is connected to the solenoid 6S of the solenoid valve 6, and when the transistor Tr ₂ is turned on, the solenoid 6S of the solenoid valve 6 is energized (Fig. 4b), and the solenoid valve 6 is switched to position 6B and locked. Up clutch LC is activated.

When the output of NAND gate NAD ₃ changes from Hi to L ₀ , that is, for example, when the vehicle speed is V ₁ < V < V ₂ and the throttle opening θ exceeds the first opening value θ ₁ , it returns to the idle position. When this happens, the charge stored in the capacitor _C6 is rapidly discharged through the diode D, and no delay occurs at this time. Then, when the terminal voltage of the capacitor C ₆ becomes below the threshold voltage, the output of the inverting amplifier AMP ₇ becomes L ₀ , the transistor Tr ₂ is turned off, the solenoid 6S of the solenoid valve 6 is deenergized, and it is switched to the position 6A. , lockup clutch LC is released.

In this way, the lock-up clutch LC is activated with a delay, and released without any delay.

Assume now that the vehicle is traveling at a vehicle speed of _V0 , as shown in FIG. 1, and that the lock-up clutch LC is in the released state. Under such conditions, there are two different operating situations in which the lock-up clutch LC is activated. That is, there are cases where the throttle opening degree θ is depressed beyond _θ1 from the idle position (in the direction of arrow P), and cases where the throttle opening degree θ is returned to below _θ2 from the fully open position (in the direction of arrow Q). In any of these cases, the accelerator pedal switch 13 changes from closed to open (Fig. 4a), and the solenoid 6S is energized (Fig. 4b) after a time ta from time _t1 when the signal Pa is output. Ru. And the time when solenoid 6S was energized
The total delay time Td is the sum of the time lag ta of the solenoid valve 6 and the rise delay tb of the hydraulic pressure (see figure c) from t _1.
After (=td+ta+tb), the lock-up clutch LC becomes fully operational at time _t4 .

Although it is possible to make the above-mentioned times ta and tb larger in design, if such a method is used instead of the delay time td, the throttle opening degree can be made larger than _θ2 to release the lock-up clutch LC. There is also a time lag of the same size when the engine is moving, and the lock-up clutch LC is not released, resulting in an uncomfortable ride due to fluctuations in engine torque and a poor sense of acceleration, which is undesirable.

The lock-up clutch LC may be of various types, such as one that locks up completely or one that locks up only in the direction in which the driving torque from the engine is applied. It may be a formal one,
Alternatively, it may be an electro-hydraulic type.

Further, as a vehicle speed sensor, a magnet may be fixedly installed on the engine output shaft, and a pickup coil may be placed close to this magnet, and the induced voltage of this coil may be detected. Further, the accelerator pedal switch may be constructed of, for example, a photo interrupter and a shielding plate, in addition to the contact type as in this embodiment.

Furthermore, although this embodiment describes the case where the vehicle speed detection circuit is configured with a monostable multivibrator, a smoothing circuit, a differential amplifier, etc., the present invention is not limited to this, and other suitable frequency-voltage converters may be used. It's okay.

Furthermore, although the simplest circuit constructed of a diode, resistor, and capacitor was used as the delay circuit in this embodiment, the present invention is not limited to this, and it goes without saying that other suitable delay circuits may be used. be.

It goes without saying that the lock-up clutch control device 10 can also be realized by using functional elements such as the external microcomputer shown in the embodiment.

As explained above, according to the present invention, the throttle opening is opened when the throttle opening is greater than or equal to the first opening value and less than the second opening value based on the vehicle speed sensor that detects the vehicle speed and the accelerator pedal position. , a throttle opening detection switch that closes when the opening is less than the first opening value and greater than the second opening value, and the throttle opening detection switch and the vehicle speed sensor are respectively connected, and the throttle opening detection switch is connected to the vehicle speed sensor. is open and the vehicle speed is greater than or equal to a first speed value,
or a selection circuit that outputs a control signal for operating the lock-up clutch when the vehicle speed is equal to or higher than a second speed value; a delay circuit that delays the control signal of the selection circuit for a predetermined time; and a drive circuit for actuating the lock-up clutch when the lock-up clutch is activated, thereby limiting the operating range of the lock-up clutch so as to correspond not only to the lower limit but also to the upper limit of the amount of accelerator pedal depression; This reduces the unpleasant shock that occurs when the lock-up clutch is activated when the accelerator pedal is operated frequently, while ensuring a comfortable ride at all vehicle speeds. It has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing one embodiment of lock-up clutch control in the automatic transmission control device according to the present invention, and FIG. 2 is a control device for implementing the lock-up clutch control shown in FIG. 1. FIG. 3 is a detailed circuit diagram of the control device shown in FIG. 2, and FIGS. 4 a to 4 c are explanatory diagrams of the operation of the control device shown in FIG. 3. 1... Engine, 2... Torque converter, 3... Auxiliary transmission, 4... Differential device, 5... Drive wheel, 6...
Solenoid valve, 7... Hydraulic pump, 8a, 8b... Tank, 9... Regulator valve, 10... Lock-up clutch control device, 11... Vehicle speed sensor, 12
...Vehicle speed detection circuit, 13...Accelerator pedal switch, 14...Vehicle speed throttle selection circuit, 15...
...Delay circuit, 16...Drive circuit, _θ1 ...First opening value, θ2...Second opening value, _V1 ...First speed value, _{V2 ...} Second speed value.

Claims (1)

[Claims] 1. A control device for an automatic transmission that operates a lock-up clutch in response to a predetermined engine output to mechanically engage a hydraulic torque converter to eliminate fluid slippage, comprising a vehicle speed sensor that detects vehicle speed; Open when the throttle opening is greater than or equal to the first opening value and within the second opening value based on the accelerator pedal position, and when it is less than the first opening value and exceeds the second opening value. A throttle opening detection switch to be closed is connected to the throttle opening detection switch and the vehicle speed sensor, and when the throttle opening detection switch is open, and
a selection circuit that outputs a control signal for actuating the lock-up clutch when the vehicle speed is at least a first speed value or when the vehicle speed is at least a second speed value; 1. A control device for an automatic transmission, comprising: a delay circuit that delays the delay; and a drive circuit that operates the lock-up clutch when the output of the delay circuit is obtained.