JPS5943664B2 - Lock-up control device for lock-up automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lockup control device for a lockup automatic transmission, and more particularly to an electronic lockup control device.

Automatic transmissions generally include a torque converter in a power transmission system for the purpose of increasing transmitted torque or absorbing fluctuations in transmitted torque to reduce vibration.

However, since the torque converter is configured to transfer power between the input element (pump impeller) and output element (turbine runner) via hydraulic oil, slippage between the stiff input and output elements cannot be avoided, resulting in power transmission. ineffective.

For this reason, lock-up torque converters have been proposed that do not require an increase in torque and can directly connect the input and output elements at relatively high vehicle speeds where torque fluctuations are not a problem. A lock-up automatic transmission equipped with this mechanism is used in some vehicles.

By the way, for example, when driving at high speed where the vehicle speed exceeds a set vehicle speed (lock-up vehicle speed) for each shift position (sometimes only at a specific shift position), the lock-up area of the automatic transmission that puts the lock-up torque converter in the lock-up state is, for example, the fourth lock-up area. As shown in the figure.

This figure shows the shift pattern in a three-speed forward automatic transmission.■1. v2. V3 motors 1st gear, 2nd gear, 3rd gear respectively
A, B, and C are the first lock-up vehicle speeds based on the 1→2 upshift line and the 2→3 upshift line, respectively.
These are the lock-up regions for 1st, 2nd, and 3rd speeds (the lock-up regions based on the 1←2 downshift line and the 2←3 downshift line are omitted to keep the drawing clear).

The lock-up control device controls the torque converter so as to obtain such a lock-up mode, and puts the torque converter in the lock-up state by a lock-up signal while driving within the above-mentioned lock-up areas A, B, and C, and puts it in the lock-up state while driving other than that. When the lock-up signal disappears, the torque converter is placed in a normal converting state in which the direct connection between the input and output elements is released.

Note that the lock-up release vehicle speed at each shift position for changing the torque converter from the lock-up state to the converter state is actually the lock-up vehicle speed (1) above to prevent hunting. V2. Although it is set slightly lower than V3, for convenience of explanation, the lock-up release vehicle speed will be explained here as being the same as the lock-up vehicle speed.

However, the conventional lock-up control device simply controls the lock-up by determining whether the vehicle speed is higher than the vehicle speed button pull-up regardless of the driving condition, so when suddenly braking in the lock-up state, the lock-up control device This caused an inconvenience to be explained.

That is, as shown in Fig. 2, when driving in a lock-up state, when the accelerator pedal is released at instant t1 and the foot is suddenly switched from the accelerator pedal to the brake pedal at instant t2, the engine speed (vehicle speed) is Since the brake system operates with a brake response delay of △TB after the moment t2 when the brake pedal is depressed, the engine speed starts to decrease from the moment t3, and the engine speed starts to decrease at the lock-up release speed (the set vehicle speed ■0.v2 or ■ The lock-up signal disappears at the instant t4 when the rotational speed decreases to a rotational speed corresponding to 3).

The lockup is released from the instant t4 when the lockup signal disappears, but this operation is delayed by the response delay ΔTL.
Since this cannot be avoided, the lock-up is actually released and the converter state is entered at the instant t5.

By the way, during sudden braking while driving in such a lock-up state, the engine speed decreases rapidly after instant t3, and due to the response delay ΔTL in releasing the lock-up,
At the moment t5 when the engine speed becomes lower than the idling speed, the converter state is actually switched to, and there is a high possibility that the engine stalls as shown in the change in engine speed (instant t and thereafter) in Figure 2. be.

In addition, during such sudden braking, the driving wheels are in a state of locking, and the engine, which is drive-coupled to the driving wheels via the locked-up torque converter, is forced to rapidly reduce its rotational speed, making it even more difficult to brake. The occurrence of engine stall is encouraged.

When the engine stalls, the power steering oil pump also stops rotating and the steering wheel suddenly becomes heavy, or the vacuum booster for the brakes becomes inoperable and the brakes suddenly become less effective, greatly reducing the vehicle's operability. In addition, the anti-skid device, which uses the oil pump as a hydraulic power source, also becomes inoperable, and the occurrence of such engine stalls becomes an obstacle to improving the safety of the vehicle.

The present invention is designed to reduce the time it takes to switch from the accelerator pedal to the brake pedal (△TF in Figure 2) during sudden braking when driving a vehicle.
is shorter than during normal braking, and if this switching time is shorter than the set time, it is judged as sudden braking and the output of the lock-up signal is blocked, and the normal lock-up control is ignored and the brake is immediately activated during braking. It is an object of the present invention to provide a lock-up control device configured to release the lock-up, thereby preventing the engine stall from occurring.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an example of the configuration of the lock-up control device of the present invention. In the figure, 1 and 2 indicate a 1-2 shift switch and a 2-3 shift switch, respectively. These switches are, for example, 1-2 shift valves of an automatic transmission. and incorporated into the 2-3 shift valve,
Each valve spool is configured to close when in the downshift position and open when in the upshift position.

These shift switches 1 and 2 are connected to the power supply +V via resistors 3 and 4, respectively, and 1-2 shift signals S1 and 2 are output from these switches in response to opening and closing of both switches 1 and 2, respectively.
-3 shift signal S23 is output.

Therefore, switches 1 and 2 have the opening and closing combinations shown in the following table at each shift position, and the shift signal S1□ is generated.

823 is a combination of levels shown in the following table at each shift position.

Note that H in the following table represents a high signal level or a low signal level, respectively.

Father, 5 in the diagram is the lock-up solenoid of the lock-up control valve that controls whether the torque converter is in the converter state or lock-up state.When this solenoid is deenergized, the torque converter is in the converter state. When energizing, the torque converter is assumed to be in a lock-up state.

The shift signal S129823 is input to the shift position determination circuit 6 and the shift detection circuit 7.

The shift position determination circuit 6 determines the current shift position from the combination of the levels of both shift signals S1□ and S23 by the light, and when the shift signals S1° and S23 are both at the level of 1st speed, the shift position is determined. Only the output 51 (1 stray signal) from is set to H, and only the level of shift signal S1□ is set to H.
Output 52 from gate b at 2nd speed (2nd speed signal)
When the shift signal S23 is in 3rd gear, only the output 53 (triple signal) is set to H.
It shall function in such a way as to

The shift detection circuit 7 includes an edge trigger circuit that detects the rise and fall of the shift signal S12, and a shift signal S23.
These edge trigger circuits are used in combination with an edge trigger circuit that detects the rise and fall of , and these edge trigger circuits respond when the corresponding shift signals S12 and S23 switch from L level to H level or from level to L level, respectively. When the valve spool of the shift valve moves from the downshift position or upshift position to the upshift position or downshift position to perform automatic gear shifting, a trigger pulse P1 of negative polarity shall be output, and the pulse width shall be adjusted to automatically shift gear. This corresponds to the time required for the actual gear shifting operation.

The vehicle speed sensor 8 supplies a vehicle speed signal ■ corresponding to the vehicle speed to the vehicle speed comparison circuit 9.

The vehicle speed comparison circuit 9 compares the vehicle speed signal ■ with the lock-up vehicle speed ■1 for the first gear, the lock-up vehicle speed ■2 for the second gear, and the lock-up vehicle speed ■3 for the third gear (all shown in FIG. 4), and calculates ■ It is assumed that when ≧■1, an H level signal is output from the gate a, and when ■≧■2, an H level signal is output from the gate b as well as from the gate c in the samurai history of V2V5.

In the present invention, an idle switch 10 that is closed during the release time of the accelerator pedal serves as an idle detection means for detecting release of the accelerator pedal, and a brake switch 10 that closes when the brake pedal is depressed is used as a braking detection means for detecting depression of the brake pedal. 11, and these switches 10 and 11 are connected to the power source through resistors 12 and 13, respectively.
, and the signal levels of the idle signal S□ and the brake signal SB output from these switches are determined according to the opening and closing of both switches 10 and 11, respectively.

The idle signal sI is supplied to the set terminal S of the flip-flop circuit 14 and also to a delay circuit 15, which is composed of a NOT gate 16, a resistor 17, a capacitor 18, and a NOR gate 19.

Since the idle signal S1 from the idle switch is set to H level while the accelerator pedal is depressed during normal driving and the idle switch 10 is open, the delay circuit 15 receives this I(level signal and outputs NOR). gate 1
9 outputs an L level signal, the idle hold signal S
The signal H is brought to an L level and supplied to the AND gate 20.

Therefore, regardless of the level of the brake signal SB supplied to the other input of the AND gate 20 via the NOT gate 21, the AND gate 20 supplies an L level signal to the reset terminal R of the flip-flop circuit 14, and the flip-flop At this time (during normal driving with the accelerator pedal depressed), the circuit 14 continues to supply the H level signal to the AND gate 22 from the output terminal Q since the H level signal is supplied to the set terminal S as described above. .

Thus, during normal driving with the accelerator pedal depressed, AN
Depending on the signal levels of the other two inputs of the D gate 22, normal lock-up control (shown in FIG. 4), which will be described below, is executed.

That is, the signals from the shift position determination circuit 6 and the vehicle speed comparison circuit 9 are supplied to AND gates 23 to 25, and these AND gates 23 to 25 determine the lockup areas AjB in the first, second, and third speed ranges. Alternatively, at C (see FIG. 4), two people perform an AND operation and output an H level signal.

When an H level signal is output from one of the AND gates 23 to 25 in this manner, this signal is supplied to the AND gate 22 via the OR gate 26.

At this time, if the speed change operation is not in progress and the pulse signal P1 from the speed change detection circuit 7 is not supplied to the AND gate 22,
All three inputs of the AND gate 22 become H level, and apply the H level lockup signal SL to the base of the transistor 28 via the resistor 27, making the transistor 28 conductive and energizing the lockup solenoid 5 with the power supply +■. By doing so, the torque converter can be brought into the lock-up state as required.

On the other hand, while the automatic transmission is in gear shifting operation and the pulse signal P0 is present, this is input to the AND gate 22 and causes the AND gate 22 to output an L level signal (disappearing the lockup signal SL). Even in the lock-up region, the lock-up solenoid 5 is deenergized by the non-conduction of the transistor 28.

Therefore, the torque converter is temporarily released from the lock-up state during the gear shifting operation and enters the converter state, thereby preventing the occurrence of gear shifting shock.

Note that the lock-up area A in FIG. While driving in modes other than B and C, both AND gates 23 to 25 output L level signals because the two human power inputs do not reach H level, and in this case, lock-up solenoid 5 is deenergized. This allows the torque converter to function as required in the converter state.

By the way, even if the vehicle is driving in the above-mentioned lock-up state, if the driver releases the accelerator pedal and then applies sudden braking by depressing the brake pedal within the set time described below, the lock-up is forcibly released by the following action. The effects described below can be achieved.

At this time, the idle switch 10 closes when the accelerator pedal is released, so the idle signal SI switches from the H level to the L level at the instant t1 when the accelerator pedal is released, as shown in FIG. is supplied to the set terminal S of the delay circuit 1.
5.

In the delay circuit 15, the idle signal SI at L level
is inverted to H level by the NOTOR gate 26 and used to charge the capacitor 18. However, this charging requires a time corresponding to the time constant determined by the resistor 17 and the capacitor 18, and during this time the NOR gate 19 is inverted to the H level. Since both inputs become L level, the delay circuit 15 outputs an H level signal, so the delay circuit 15 changes the time constant (set time) △ from the instant t□ in FIG.
An idle holding signal sH of H level is supplied to the AND gate 20 by TH.

During sudden braking such as depressing the brake pedal during this set time ΔTH, the brake switch 11 closes and the brake signal SB is switched to the L level at instant t2 as shown in FIG. Since it is inverted to H level and then supplied to the AND gate 20,
The AND gate 20 resets the flip-flop circuit 14 by outputting the H level signal, and the output from the terminal Q of the flip-flop circuit to the AND gate 22 is switched to the L level.

Therefore, the AND gate 22 prevents the output of the H level signal regardless of the signal levels of the other two signals, causing the lock-up signal SL to disappear at the instant t2 in FIG. You can release the lockup with

In addition, once the lock-up signal SL disappears in this way, the idle holding signal SH switches to the L level as shown in FIG. Even if the output signal level of the AND gate 20 becomes the H level again and the output signal level of the AND gate 20 becomes the L level, the flip-flop circuit 14 receives the γ idle signal S■ supplied to the set terminal S of the flip-flop circuit by pressing the accelerator pedal. The above reset state is maintained unless the lock-up signal 8 becomes H level.
L continues to disappear as shown in Figure 3, and the converter state can be maintained.

On the other hand, during slow braking, such as depressing the brake pedal after the above set time △TH has passed after the accelerator pedal is released,
When the brake signal SB, which has become L level due to depression of the brake pedal, is inverted by the NOT gate 21 and supplied to the AND gate 20, the brake holding signal SH has already become L level, as is clear from FIG. Therefore, the AND gate 20 can output an H level signal, but cannot reset the flip-flop circuit 14, so the flip-flop circuit is connected to the AND gate 22 from the terminal R.
The level signal continues to be supplied, and the above-mentioned normal lock-up control is performed.

Thus, as described above, the lock-up control device of the present invention ignores the normal lock-up control and issues a lock-up signal at the same time as the brake pedal is depressed during sudden braking when the time required to switch from the accelerator pedal to the brake pedal is shorter than the set time ΔTH. Since the structure is configured to forcibly release the lock-up by making the SL disappear, when the lock-up is released with a response delay of the lock-up control oil passage shown by △TL in Fig. 3, the shoes will also be affected, and the engine rotation will be reduced due to the sudden braking. If the number suddenly decreases from the instant t3 at which the brake operation starts, it means that the lock-up of the shoes has already been released at the instant t6, which is earlier than the instant t3, and even when the brakes are suddenly applied while driving in the lock-up state, due to the delay in releasing the lock-up. There is no possibility of engine stalling.

It should be noted that the present invention is applicable not only to an automatic transmission that detects the gear shift position from a shift valve as in the above embodiment, but also to an automatic transmission that uses an electric signal indicating the gear shift position for gear change control. it is obvious.

It is also obvious that the present invention can be applied to automatic transmissions in which the lock-up region is determined not only by vehicle speed but also by a combination of engine load such as throttle opening.

Further, from the above-mentioned gist of the present invention, it is clear that a configuration in which the lock-up vehicle speed disappears is also possible by a configuration in which the vehicle speed signal and the shift detection signal are changed, in addition to the above-described embodiments.

[Brief explanation of the drawing]

FIG. 1 is an electronic circuit diagram of the lock-up control device of the present invention, FIG. 2 is an operation time chart of the conventional lock-up control device, FIG. 3 is an operation time chart of the device of the present invention, and FIG. 4 is an automatic lock-up area illustrating the lock-up region. It is a shift pattern diagram of a transmission. 1...1-2 shift switch, 2...
2-3 shift switch, 3, 4, 12, 13, 17, 2
7...Resistor, 5...Lock-up solenoid, 6...Shift position determination circuit, 7...
...speed change detection circuit, 8...vehicle speed sensor, 9...
... Vehicle speed comparison circuit, 10 ... Idle switch (idle detection means), 11 ... Brake switch (braking detection means), 14 ... Flip-flop circuit, 15 ...Delay circuit, 16゜21
......NOT gate, 18...Capacitor, 19...NOR gate, 20.22~
25...AND gate, 26...OR
Gate, 28...Transistor.

Claims (1)

[Claims] 1. A lock-up automatic transmission that includes a torque converter in the power transmission system and can put the torque converter into a lock-up state in which its input and output elements are directly connected or in a converter state in which this direct connection is released depending on the presence or absence of a lock-up signal, An idle detection means for detecting the release of the accelerator pedal and a braking detection means for detecting the depression of the brake pedal are provided, and after the accelerator pedal release signal is output from the idle detection means, the braking detection means detects the depression of the brake pedal within a set time. A lock-up control device for a lock-up type automatic transmission, characterized in that the lock-up control device is configured to prevent output of the lock-up signal when the signal is output.