JPS5943669B2 - Automatic transmission lock-up control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lockup control method for an automatic transmission.

Automatic transmissions generally increase torque from the engine,
Furthermore, a torque converter is installed in the power transmission system to absorb torque fluctuations and achieve smooth power transmission, but this torque converter is the input element (pump impeller)
Because slippage is unavoidable between the transmission and the output element (turbine runner), although it is easier to operate than a manual transmission, it tends to have poor power transmission efficiency and poor fuel efficiency.

Therefore, lock-up automatic transmissions that do not require torque increase by a torque converter and can directly connect the input and output elements of the torque converter in relatively high vehicle speed ranges where engine torque fluctuations are not a problem are put into practical use in some vehicles. has been done. The present invention relates to a lockup control method for such an automatic transmission, in which the lockup region is normally
Taking a 1-speed automatic transmission as an example, the 1 → 2 upshift line and the 2
→3 The upshift line was determined as shown in FIG. 1, for example.

In this figure, V1', V,', and V3' are the first speed and second speed, respectively.
A', B', C' at lock-up vehicle speed in 3rd gear.
are the lock-up regions at 1st, 2nd, and 3rd speeds, respectively, and the regions other than regions A'3B'3C' at each shift position are converter regions where the input/output elements of the torque converter should not be directly connected. Yes, but the conventional lock-up vehicle speed V
1', V2', and V3' are determined based on the lock-up vehicle speeds V1', V2', and V3 at each shift position in order to enhance the effect of improving fuel efficiency by locking up the torque converter.
' was set to the lowest speed. However, at such lock-up vehicle speeds V7', V2', and V3', the torque increasing effect of the torque converter cannot be effectively utilized in driving conditions where the engine load is large, such as when driving uphill, and a decrease in power performance cannot be avoided.

Therefore, the lock-up vehicle speed of the shift position (first speed and second speed in the illustrated example) used in such driving conditions is determined to be higher than before, as shown by Vl and V2 in FIG. 2, for example. The lock-up vehicle speed V3 at the highest speed shift position (3rd speed in the illustrated example) is determined almost as before, and 1st speed, 2nd speed,
It has been considered to change the lock-up region of the third speed as indicated by A, B, and C in FIG. On the other hand, Figures 1 and 2
Regardless of which lockup control mode shown in the figure is adopted, in the case of an automatic transmission that locks up the torque converter at a lockup vehicle speed or higher for each shift position, it is necessary to keep the accelerator pedal depressed relatively deeply (manifold During automatic speed change driving (with high-load operation where the absolute pressure value is relatively small), lock-up areas A7, B', C' or A,
Since B and C touch the shift lines next to each other, a
The torque converter is kept in a locked-up state during the gear change indicated by ', b' (see FIG. 1) or A, b (see FIG. 2).

However, if a shift is performed with the torque converter in the locked-up state in this manner, the torque converter cannot absorb torque fluctuations, resulting in a large shift shock. Therefore, in this type of lock-up automatic transmission, even in the above-mentioned lock-up region, as shown in FIG.
1 to the instant T2 when the automatic transmission actually completes the gear shift (although it varies depending on the engine load and type of gear shift)
→ Approximately 1 second in the case of 3-speed shifting), the lock-up is temporarily released by a lock-up off signal, and the torque converter is returned to the converter state during the shifting operation.

However, automatic transmissions do not immediately shift from the pre-shift gear position to the post-shift gear position after the instant T.
Due to the hydraulic activation delay, for example, the shift gear position is held until instant T3, and then the shift gear position is shifted to the post-shift gear position, so the lock-up is temporarily released at the low-speed gear position before shifting between instants t1 to T3. It turns out. Because of this,
As shown in Figure 3 with diagonal lines, the engine speed suddenly increases and the engine starts revving, which causes a large output shaft torque between T3 and T2 when the actual gear shift is performed, as shown in Figure 3. This caused a change in gears, causing a fairly large shift shock. Therefore, as shown in FIG. 4, the applicant did not generate the lock-up off signal at the instant t1 when the gear shift signal was generated, but waited until the instant T3 when the gear position change actually started, and generated the lock-up off signal. We have previously proposed a lock-up control device that prevents large changes in output shaft torque due to engine racing.

However, if the above-mentioned lock-up control method is adopted in the lock-up automatic transmission having the lock-up control mode shown in FIG. In the converter region, the lock-up region immediately occurs after shifting (third speed in this case), resulting in the following inconvenience.

That is, as shown in FIG. 5, the lock-up off signal that was generated until the instant T when the shift signal was generated is in the converter region, but after that, it is in the lock-up region (in this case, C in FIG.
This lock-up signal occurs again between the instants T3 and T2 as described above with reference to FIG. Therefore, in an automatic transmission, the torque converter is once locked up immediately after the moment t1, resulting in a sudden change in the output shaft torque and engine speed Tr.
1 and RPM1, a lock-up shock is generated once, and then the gear position is switched between instants T3 and T2, resulting in a sudden change in output shaft torque and engine speed Tr, similar to that in FIG. and R.P.
M2 occurs again and a shift shock occurs. In other words, the automatic transmission generates two shocks during the shift, resulting in a poor shift feeling. In order to solve this problem, the present invention provides lock-up control of the torque converter of an automatic transmission in such a manner that the converter area is in the converter area before the gear change and the lock-up area is immediately after the gear change. This invention attempts to provide a lock-up control method for an automatic transmission that prevents the occurrence of lock-up shock as described above during the gear change by keeping the torque converter in the converter state until the change is actually completed. be.

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

Figure 6 shows an example of the configuration of a lock-up control circuit used to carry out the method of the present invention. It is configured to perform lock-up control in accordance with the embodiments shown, and therefore, parts that are not directly related to the gist of the present invention, such as the power transmission train of the automatic transmission, the shift control hydraulic circuit, and the lock-up control hydraulic circuit, will be described here. is the same as that disclosed in the above-mentioned earlier application, and the explanation thereof will be replaced by the one disclosed in the above-mentioned earlier application.

In Fig. 6, 1 is a 1-2 shift switch, and 2 is a 2-3 shift switch, and these switches 1 and 2 are the 1-2 shift valve of the automatic transmission and the 2-3 shift switch as described in the earlier application. It is assembled into a 2-3 shift valve and connected to a power supply +V, and configured to be closed depending on the position of each valve spool, that is, when the valve spool is in the downshift position, it is closed and when the valve spool is in the upshift position, it is opened. Therefore, when the automatic transmission selects the first gear position, both valve spools are in the downshift position and both shift switches 1 and 2 are closed.
These switches have corresponding shift valve signals S1■, S, respectively.
,■ are set to low L level. When the 2nd gear position is selected, only the valve spool of the 1-2 shift valve is in the upshift position and opens shift switch 1, so this switch sets the shift valve signal SlV to a high H level. There is. Further, when the third speed is selected, the valve spool of the 2-3 shift valve also moves to the upshift position and opens the shift switch 2, so this switch sets the shift valve signal S2V to H level. In other words, at each gear position, the shift valve signal Sl
What are the combinations of V and S2V levels as shown below? Ru. Both of the shift valve signals SlV and S2■ are respectively input to the gear position determination circuit 3, and this circuit determines the current gear position from the combination of the levels of the borrowed signals SlV and S2V. The speed signal S1 is set to H level, the 2nd speed signal S2 is set to H level for 2nd speed, and the 3rd speed signal S3 is set to H level for 3rd speed, but these signals Sl, S2, and S3 are set to L level for other times. shall be maintained.

A vehicle speed sensor 4 supplies a vehicle speed signal V corresponding to the vehicle speed to a vehicle speed comparison circuit 5, and this circuit 5 locks up the input vehicle speed signal V to vehicle speeds Vl, V2, and V3 (see FIG. 2 for each). In comparison, when the vehicle speed becomes higher than the lock-up vehicle speed ■1, an H level signal is sent from the corresponding gate, and when the vehicle speed becomes higher than the lock-up vehicle speed ■3, an H level signal is also sent from the corresponding gate y. Furthermore, when the vehicle speed becomes higher than the lock-up vehicle speed V2, an H level signal is also output from the corresponding gate 7, respectively.

These signals are supplied to AND gates 11 to 13 of the lockup determination circuit 10 together with the signals Sl, S2, and S3.

The AND gate 11 performs a logical product of the signal output from the gate of the vehicle speed comparator circuit 5 and the first speed signal S1, and in the first speed lockup region A in FIG. 2 where both of these signals become H level, Outputs a level signal. AND gate 12
calculates the logical product of the signal output from the gate of the vehicle speed comparator circuit 5 and the second speed signal S2, and obtains an H level signal in the second speed lockup region B in FIG. 2 where both of these signals become H level. Output. Also, the AND gate 3 is the vehicle speed comparison circuit 5.
The logical product of the signal output from gate y and the 3rd speed signal S3 is taken, and an H level signal is output in the 3rd speed lockup region C in FIG. 2 where both of these signals become H level.
In this way, if an H level signal is output from one of the AND gates 11, 12 or 13, the NOR gate 14 of the lock-up determination circuit 10 that receives this signal will therefore select one of the AND gates shown in FIG. Lockup area A, B or C
A lock-up permission signal SL at L level is supplied to one input terminal of the NOR gate 6 while the vehicle is running. The output terminal of the NOR gate 6 is connected to the base of a Darlington transistor 7, which connects the lock-up solenoid 8 to the power supply +V via its collector-emitter path.

The lock-up solenoid 8 is also the same as that in the prior application, and when energized, the torque converter of the automatic transmission is placed in the lock-up state, and when de-energized, the torque converter is placed in the converter state. 20 and 30 are timer circuits, respectively, 1e2 timer 21 and 31, and 2←
It is composed of three timers 22, 32 and AND gates 23, 33, and supplies the shift valve signal S1■ to the timers 21, 31, and the shift valve signal S2V to the timers 22, 332, and also supplies the shift valve signal S2V to the timers 22, 332. A signal ST corresponding to the throttle opening (engine load) from the throttle sensor 9 is commonly supplied to the two.

The timers 21, 22, 31, and 32 are triggered by the shift valve signal in synchronization with the rise and fall of the corresponding shift valve signal S1■ or S2■, that is, the shift valve operation of the automatic transmission (occurrence of the shift signal). The output signal level, which is normally kept at H level, is set to L level for a predetermined period of time to output negative polarity pulse signals Pl and P2. The pulse width of the pulse signal P1 generated by the timers 21 and 22 is
Hydraulic activation delay time when the automatic transmission performs the corresponding 1e2 gear shift and 2e3 gear shift (from instant t1 in Figures 3 to 5)
The pulse width of the pulse signal P2 generated by the door timers 31 and 32 corresponds to the pulse width of 1+
This corresponds to the total operating time (between instants t1 and T2 in FIGS. 3 to 5) when performing +2 speed change and 2e3 speed change. In addition,
Automatic transmissions generally change the line pressure, which is the operating oil pressure for each shift, according to the engine load, and increase it as the engine load increases, so the oil pressure activation delay time and total operation time also change depending on the engine load. However, as the engine load increases, these times become shorter. From this, each timer 21, 22, 31, 32 responds to the input throttle opening (engine load) signal ST.
It functions to always make the pulse width of the output pulse signals Pl and P2 accurately correspond to the hydraulic actuation delay time and the total actuation time under any engine load. That is, the timers 21 and 31 use this as a trigger signal when the automatic transmission attempts to perform a 1e2 shift and the shift valve signal S1■ rises or falls, and the pulse signals Pl and P2 are set according to the type of shift. AND gates 23, 32 from the gate
and timers 22 and 32 are supplied to the automatic transmission.
When the shift valve signal S2■ rises or falls in order to perform a ++3 speed change or a 2e3 speed change, this is used as a trigger signal and the above pulse signal numbers Pl and P2 are applied to the AND gates 23 and 33 through the gates corresponding to the type of speed change. supply to.

Thus, when the negative polarity pulse signals Pl and P2 are input to the inputs of the automatic transmission 1 during gear shifting, the AND gates 23 and 33 maintain the external power at the H level, as is clear from the above description. These pulse signals are supplied as they are to the lockup control circuit 40 for shifting. However, as a result of the timers 21, 22, 31, and 32 continuing to supply H level signals to the AND gates 23 and 33 except when shifting, the AN
D gates 23 and 33 are the lock-up control circuit 4 for shifting gears.
0 exclusive 0R gate 41 and 0R gate 4
Input the H level signal to 2.

Therefore, at this time, the exclusive 0R gate 41 outputs an L level signal since both human powers are at H level, and after this signal is inverted to H level by the NOT gate 43, the NA
is supplied to one input terminal of the ND gate 44, and
As a result of the 0R gate 42 directly supplying the H level signal from the AND gate 33 to the other input terminal of the NAND gate 44, the NAND gate 44 supplies the L level signal to the NOR gate 6. Thus, except when changing gears, the NOR gate 6 determines the output signal level based only on the lockup permission signal SL from the NOR gate 14, and can execute the following lockup control. That is, if the vehicle is traveling in the lockup region A, B, or C in FIG. This H level signal makes the transistor 7 conductive and energizes the lock-up solenoid 8 with the power supply +V, so that the torque converter of the automatic transmission can be kept in the lock-up state as specified. Furthermore, while driving outside the lockup region, the lockup permission signal SL is at the H level as described above, so the NOR gate 6 sets the lockup signal SL/u to the L level and turns off the torque converter. The converter state can be maintained as specified. Next, lockup control during gear shifting will be explained.

First, when an automatic transmission performs a shift indicated by a or b in FIG. 2, that is, when it performs a shift on a line where both the front and rear of the shift line are lock-up regions, as is clear from this figure, the shift is Since this occurs when the vehicle speed is higher than V2, the signal output from the gate of the vehicle speed comparison circuit 5 becomes H as shown in FIG.
level, and the 0R gate 4 receives this H level signal.
2 continues to output an H level signal to one input terminal of the NAND gate 44. On the other hand, the shift valve signal S1■ (in the case of shift a in Fig. 2) or the shift valve signal S2
When V (in the case of shift b in FIG. 2) rises at an instant t1 as shown in FIG. In response to P2, a signal is output that falls all at once at instant t1 as shown in FIG. 7, and rises at instant T3 after the hydraulic operation delay time and at instant T2 after the entire operation time.
Excloop 0R gate 41 connects these AND gates 2
Upon receiving the output signals from 3 and 33, the instant T3 is generated as shown in Fig. 7.
- T2 (during which the automatic transmission actually changes the gear position after the hydraulic pressure delay) outputs a signal that becomes H level. This signal is inverted by NOT gate 43 as shown in FIG. 7 and is supplied to NAND gate 44, so that this NAND gate outputs the same signal as the output of exclusive 0R gate 41 as shown in FIG. Therefore, the NOR gate 6 receiving the output of the NAND gate 44 is
Since the lock-up signal SL/u is at the L level during the shift period, the shift line is also in the lock-up region before and after the shift line (even if the lock-up permission signal SL is at the L level). Between T3 and T2, when the automatic transmission actually changes the gear position, the torque converter is temporarily returned to the converter state, and the lock-up control described above with reference to FIG. 4 can be executed to prevent the occurrence of shift shock. can. Next, when the automatic transmission performs the shift shown by C in Fig. 2, the gear position before the shift (2nd gear) is in the converter region, but after the shift (after the shift to 3rd gear) When a shift is performed on a shift line that immediately becomes a lock-up region, as is clear from the figure, the shift is performed at a vehicle speed of V2.
Since the following occurs, the signal output from the gate 7 of the vehicle speed comparator circuit 5 is at L level as shown in FIG. Determine the level of the signal supplied to the

On the other hand, when the shift valve signal S2■ and the third speed signal S3 rise at the instant t1 as shown in FIG.
The D gates 23 and 33 are connected to the timers 22 and 33, respectively, as described above.
In response to the pulse signals Pl and P2 from 32, as shown in FIG. 8, the four output signals fall all at once at instant t1, and rise at instant T3 after the hydraulic activation delay time and instant T2 after the full operation time. . Exclusive 0R Gate 4
1 receives the output signals from these AND gates 23 and 33 and outputs a signal that becomes H level between instants T and T2 as shown in FIG. 8, and this signal is inverted by the NOT gate 43 as shown in FIG. and is supplied to the NAND gate 44. A
The output signal from the ND gate 33 is also supplied to the 0R gate 42, which takes the logical sum of this signal and the signal from the gate i, and outputs the output signal from the AND gate 3 as shown in FIG.
The same signal as the output from 3 is applied to NAND gate 44. Therefore, the NAND gate 44 outputs a signal that becomes H level between instants t1 and T2, as shown in FIG. 8, and supplies this to the NOR gate 6. On the other hand, as shown in FIG. 8, the lock-up permission signal SL is kept at the H level until instant t1 by the action of the lock-up determination circuit 10 because the second speed before shifting is in the converter region, and after that, Since the third speed after the shift is in the lockup region, the lockup determination circuit 10 changes to the L level due to the above-mentioned action. Thus, the NOR gate 6, which receives the output of the NAND gate 44 and the lock-up permission signal SL, outputs the lock-up signal SL/u whose level changes as shown in FIG. can be maintained in the converter state until instant T2 when the gear shift is completed. As described above, in the lock-up control method of the present invention, when a shift is performed such that the shift is in the converter region before the shift (second speed in the illustrated example) and the lock-up region is immediately after the shift (third gear in the illustrated example), Lockup signal SL/
Since the torque converter is kept in the converter state by keeping u at the signal level that does not lock up before the shift until the shift completion instant T, that is, even if the torque converter enters the lockup region after the shift signal generation instant t1 as shown in FIG. Since the lock-up off signal before the shift is continued as it is until the shift completion instant T2 to keep the torque converter in the converter state, the lock-up off signal during the shift changes to the hydraulic pressure between the instants t1 and T3 as described above with reference to FIG. This eliminates the problem of shock occurring as a result of temporary lock-up of the torque converter due to temporary interruption during operation delays, and this is clear from Figure 9, which shows the shock as a change in output shaft torque and engine speed. 1 due to shifting gears
This can be done only once and can improve the feeling.

In the example described above, the present invention has been explained for the case where the lock-up control shown in FIG. 2 is performed on a three-speed forward automatic transmission. For gears that shift in such a way that the front is the converter region and immediately enters the lock-up region after shifting,
It goes without saying that the method of the present invention can be applied to all automatic transmissions.

Furthermore, although the control circuit used to carry out the method of the present invention is constructed of a logic circuit in the above-mentioned example, it is of course possible to construct this by a microcomputer so as to be able to implement the method of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an upshift diagram of an automatic transmission showing a general example of a lockup region, FIG. 2 is an upshift diagram of an automatic transmission illustrating a lockup region to be controlled by the method of the present invention, and FIG. The figure is an operation time chart of general lockup control during gear shifting, Figure 4 is an operation time chart of lockup control during gear shifting that was previously proposed by the applicant, and Figure 5 is a second diagram of lockup control. 6 is an electronic circuit diagram of a lock-up control device used to carry out the method of the present invention; FIGS. 7 and 8 The figure is a flow chart of various signals in the electronic circuit, and FIG. 9 is an operation time chart of lock-up control according to the method of the present invention. 1...1-2 shift switch, 2...
2-3 Shift switch, 3...Gear position discrimination circuit, 4...Vehicle speed sensor, 5...Vehicle speed comparison circuit, 6...NOR gate, 7... ... Darling Tran transistor, 8 ... Lockup solenoid, 9 ... Throttle sensor, 10 ...
. . . Lockup determination circuit, 20, 30 . . . Timer circuit, 40 . . . Lockup control circuit for shifting.

Claims (1)

[Claims] 1. The torque converter of an automatic transmission that automatically changes the gear position in response to a gear shift signal is a converter area where the input and output elements should not be directly connected before gear shifting, and the input and output elements should not be directly connected immediately after gear shifting. When performing lock-up control according to the aspect of the lock-up area that should be directly connected,
A lock-up control method for an automatic transmission, characterized in that the torque converter is maintained in a converter state until the gear position change is actually completed after the shift signal is generated.