JPS634062B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lock-up control device for a lock-up type automatic transmission that includes a torque converter in a power transmission system and can put the torque converter into a lock-up state where its input and output elements are directly connected. The automatic transmission includes a torque converter in the power transmission system for the purpose of absorbing torque fluctuations from the engine as well as increasing the torque from the engine and transmitting the increased torque to the planetary gear type transmission mechanism at the rear. The torque converter uses an input element (usually a pump impeller) driven by the engine to circulate the internal hydraulic oil.
This hydraulic oil causes the output element (usually a turbine runner) to rotate while increasing its torque under the reaction force of the stator (converter state). Therefore, in a torque converter, the input and output elements are not mechanically coupled, and slippage between the input and output elements is unavoidable.For this reason, although automatic transmissions are easy to operate, they require high power transmission efficiency. Therefore, in a relatively high vehicle speed range where a torque increase function is not required and torque fluctuations from the engine are not a problem, a torque converter with a direct coupling clutch (lock-up state) is used to directly connect input and output elements by operating a direct coupling clutch (lock-up state). A lock-up automatic transmission equipped with this type of torque converter is now in practical use in some vehicles. By the way, for example, when driving at a 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 region of an automatic transmission that puts the torque converter with a direct coupling clutch in the lock-up state is, for example, As shown in Figure 3. This figure shows a shift pattern in an automatic transmission with three forward speeds. V ₁ , V ₂ , and V ₃ are lock-up vehicle speeds for 1st, 2nd, and 3rd speeds, respectively, and A, B,
C is the lock-up area for 1st gear, 2nd gear, and 3rd gear based on the 1→2 upshift line and 2→3 upshift line, respectively (based on the 1←2 downshift line and 2←3 downshift line) The lockup area has been omitted for clarity of the drawing). The lockup control device performs such lockup control to control the lockup areas A and B.
Or, while driving in C, the torque converter is in the lock-up state, and while driving other than that, the torque converter is in the converter state, but if the accelerator pedal is suddenly released in the lock-up state, the power transmission is switched to the manual transmission. In the same way, the torque converter did not have the effect of absorbing torque fluctuations, so the power transmission shaft (propeller shaft, etc.) and suspension system, which were twisted when the accelerator pedal was depressed and the power was turned on, were twisted. As a result of the leaf spring returning to its original state and being twisted or bent in the opposite direction due to the reverse driving force from the vehicle drive wheels, the axle torque oscillates as shown by a in Figure 4. This vibration is transmitted to the vehicle body, causing discomfort to the occupants. Therefore, when the accelerator pedal is released while driving in the lock-up state, the torque converter is set to the converter state even in the lock-up region, and as a result, the axle torque during coasting (voluntary) driving with the accelerator pedal released is as shown in Figure 4. It is conceivable that the above-mentioned problem can be solved by making the voltage drop smoothly as shown by b in FIG. By the way, when the brake pedal is depressed during such coasting driving, the driving condition requires relatively large engine braking, and in this case as well, the torque converter is set to the converter state in response to the release of the accelerator pedal as described above. If the torque converter is left in place, the required large engine brake cannot be obtained due to slippage of the torque converter. Therefore, even if the torque converter is temporarily placed in the converter state by releasing the accelerator pedal, if the brake pedal is subsequently depressed, the lock-up control of the torque converter is returned to normal control, and the torque converter is placed in the lock-up state. This paper attempts to propose a lock-up control device for an automatic transmission that is capable of ensuring large engine braking as required. 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 2-3 shift valves, and each valve spool is configured to close when the valve spool is in the downshift position and open when the valve spool is in the upshift position. Furthermore, these shift switches 1 and 2 are connected to the power supply + via resistors 3 and 4, respectively.
V, and when both switches 1 and 2 open and close, 1-2 shift signals S ₁₂ and 2 are output from these switches, respectively.
-3 so that the shift signal _S23 is output. Therefore, the switches 1 and 2 have the opening/closing combinations shown in the table below at each shift position, and the shift signals S ₁₂ and S ₂₃ have the combinations of levels shown in the table below at each shift position. Note that in the following table, H represents a high signal level, and L represents a low signal level.

[Table] Also, 5 in the figure 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. It is assumed that the torque converter is locked up when the torque converter is energized. The above shift signals S ₁₂ and S ₂₃ are provided by the shift position determination circuit 6
and is input to the speed change detection circuit 7. The shift position determination circuit 6 determines the current shift position from the combination of the levels _of both shift signals S ₁₂ and _{S 23 according} to the table above. Output S ₁ from hour gate (1st speed signal)
In the 2nd speed, when only the level of the shift signal S ₁₂ is H, only the output S ₂ (2nd speed signal) from the gate is set to H, and the level of the shift signal S ₂₃ is also H. It is assumed that the function is such that only the output S ₃ (3rd speed signal) from the speed gate becomes H. The shift detection circuit 7 is a combination of an edge trigger circuit that detects the rising and falling edges of the shift signal _S12 and an edge trigger circuit that detects the rising and falling edges of the shift signal _S23 . Signal S ₁₂ , S ₂₃
is switched from the L level to the H level or from the H level to the L level, that is, when the valve spool of the corresponding 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 is output, and its pulse width is made to correspond to the time required for the automatic transmission to perform an actual gear shifting operation. The vehicle speed sensor 8 supplies a vehicle speed signal V corresponding to the vehicle speed to the vehicle speed comparison circuit 9. The vehicle speed comparison circuit 9 converts the vehicle speed signal V into a lock-up vehicle speed V 1 for the first speed and a lock-up vehicle speed V ₁ for the second speed.
In comparison with the lock-up vehicle speed V ₂ for the first gear and the lock-up vehicle speed V ₃ for the third gear (see Figure 3 for both), when V≧V ₁ , from the gate ′, and when V≧V ₂ , from the gate ′, When V≧V ₃ , an H level signal is also output from the gate'. In the present invention, an idle switch 10 is provided as means for detecting release of the accelerator pedal,
This is connected to the power supply +V via a resistor 11. The idle switch 10 is linked to the accelerator pedal, and is turned on when the accelerator pedal is released, and turned off otherwise. Thus, idle switch 1
0 sets the idle signal (accelerator pedal release signal) S _I to L level when the accelerator pedal is released, and otherwise keeps the idle signal S _I at H level. In the present invention, a brake switch 20 is further provided as means for detecting depression of the brake pedal, and this is connected to the power supply +V via a resistor 19. The brake switch 20 is linked to the brake pedal, and turns on when the brake pedal is depressed to issue a brake signal.
S _B is set to L level, otherwise the brake signal S _B
is kept at H level. Idle signal S _I passes through NOT gate 25 and becomes AND
The brake signal S B is inputted to the gate 21 and inputted directly to the AND gate 22, and the brake signal S _B is inputted to the AND gate 21 via the NOT gate 24.
Input it as is to the AND gate 22. Also, AND
A signal output from the gate ' of the vehicle speed comparison circuit 9 is separately supplied to the gate 21 . The vehicle speed comparison circuit 9 receives the vehicle speed signal V and the set vehicle speed V ₄ (third
Based on the comparison result with V≦V ₄ , an H level signal is output to the AND gate 21, and the set vehicle speed V ₄ is the upper limit of the vehicle speed range in which sufficient engine braking cannot be obtained with the torque converter in the converter state. For example, it is set to 40 km/h. The outputs of AND gates 21 and 22 are connected to two inputs of OR gate 23, respectively, and the output of OR gate 23 is connected to the two inputs of OR gate 23.
Connect to one input of AND gate 12. Thus, while driving with the accelerator pedal depressed without the brake pedal being depressed, the brake signal S _B becomes H.
Since the idle signal S _I is at H level, the AND gate 22 passes through the OR gate 23.
Continue to supply the H level signal to the AND gate 12.
Therefore, during the power-on running, normal lock-up control (shown in FIG. 3), which will be explained below, is executed. That is, the shift position determination circuit 6 and the vehicle speed comparison circuit 9
The signals from are supplied to AND gates 13 to 15, and these AND gates 13 to 15 are
Lock-up area A in the 2nd and 3rd speed ranges,
B or C (see Figure 3) individually ANDs the two inputs and outputs an H level signal. in this way
When an H level signal is output from one of the AND gates 13 to 15, this signal is supplied to the AND gate 12 via the OR gate 16. At this time, the pulse signal from the speed change detection circuit 7 is not during the speed change operation.
If P ₁ is not supplied to AND gate 12, then
All three inputs of AND gate 12 are at H level,
A high-level lockup signal S _L is applied to the base of the transistor 18 through the resistor 17, making the transistor 18 conductive and causing the lockup solenoid 5 to become conductive.
By energizing the torque converter with the power supply +V, the torque converter can be put into the lock-up state as required. On the other hand, the automatic transmission is shifting and the pulse signal is
While P ₁ exists, this is AND gate 12
In order to cause this AND gate 12 to output an L level signal (to eliminate the lockup signal S _L ), the lockup solenoid 5 is deenergized by the non-conduction of the transistor 18 even in the lockup region. Therefore, the torque converter is temporarily released from the lock-up state during the shift operation and enters the converter state, thereby preventing the occurrence of shift shock. Note that the lockup area A in FIG.
While driving in areas other than B and C, AND gates 13 to 1
5 outputs an L level signal since both of the two inputs never become H level, and in this case, the lock-up solenoid 5 is deenergized and the torque converter cannot function in the converter state as required. can. By the way, even while driving in the lock-up state, when the driver releases the accelerator pedal and shifts to coasting driving, the idle switch 10, which closes in response to this, switches the idle signal S _I to L as described above. In order to supply this to the AND gate 22, the AND gate changes the output signal level to the L level. If the brake pedal is not depressed at this time, the H-level brake signal S _B from the brake switch 20 is inverted to L-level by the NOT gate 24 and supplied to the AND gate 21, and the L-level signal is sent to the AND gate 21. In order to output, the OR gate 23
As a result of both inputs being at L level, AND gate 1
An L level signal is supplied to 2. Therefore, this
The AND gate 12 outputs an L level signal regardless of the other two inputs (blocks the output of the lockup signal S _L ), makes the transistor 18 non-conductive, and deactivates the lockup solenoid 5 to set the torque converter in the converter state. It can be done. Therefore, even if the axle torque tries to vibrate as shown by a in FIG. 4 during running, this vibration is reliably absorbed by the torque converter in the converter state, and the axle torque changes to the level shown by b in FIG. 4. The object of the present invention can be achieved by smoothly lowering the vehicle body and preventing the vehicle body from vibrating. After that, when the driver depresses the brake pedal and the brake signal S _B from the brake switch 20 goes to the L level, this is turned to the H level by the NOT gate 24.
is inverted to the level and supplied to the AND gate 21,
The AND gate is further supplied with the L-level idle signal S _I as described above, which is inverted to H-level by the NOT gate 25. Further, the AND gate 21 is separately supplied with a signal output from the gate ' of the vehicle speed comparison circuit 9, and thus
Gate 21 outputs an H level signal because all three inputs become H level if the vehicle speed is less than the set value _V4 when the driver has released the accelerator pedal and then depressed the brake pedal. It is supplied to the AND gate 12 via the OR gate 23. Therefore, in the device of this example, even if the torque converter is once set to the converter state as described above by releasing the accelerator pedal, if the brake pedal is subsequently depressed, engine braking will be impaired while the torque converter is in the converter state. In the vehicle speed range V≦V ₄ , the second object of the present invention is to return the lock-up control of the torque converter to normal control, put the torque converter in the lock-up state, and secure a large engine brake as required. can. After that, either the brake pedal is released and the brake signal S _B becomes H level, or the vehicle speed becomes V>
V ₄ and the vehicle speed comparator circuit 9 starts outputting an L level signal from the gate ', the AND gate 21 starts outputting an L level signal again.
By blocking the output of the lock-up signal S _L , it is possible to prevent the axle torque from vibrating again due to release of the accelerator pedal. In this example, the brake signal is used to return the lock-up control of the torque converter to normal control.
Two conditions were set: S _B being at the L level and vehicle speed being V≦V ₄ , but the vehicle speed condition is not necessarily necessary, and the second objective of the present invention can be achieved with just the brake condition. be able to. However, in reality, when the vehicle speed is in the range of V > V ₄ , the driver does not feel a lack of engine braking even if the torque converter is in the converter state, so in that vehicle speed range, the torque converter must be in the lock-up state. is meaningless, and in this case, it is more advantageous to keep the torque converter in the converter state in the sense that vibrations in the axle torque can be suppressed, and it is better to set the above vehicle speed condition in this respect. FIG. 2 shows still another configuration example of the device of the present invention,
In this example, when the example in Fig. 1 performs coasting driving in which the brake pedal is repeatedly depressed and released, the state of the torque converter repeatedly changes to the lock-up state and to the converter state each time. Therefore, in order to prevent this inconvenience, once the lock-up control of the torque converter returns to normal control by depressing the brake pedal and the torque converter is placed in the lock-up state, the torque converter will not be activated even when the brake pedal is released. The configuration is such that no state change occurs due to this. For this purpose, in this example,
AND gate 21 and NOT gates 24, 25
AND gates 26, 27, OR gates 28 and
Replace with NOT gates 29 and 30. When the idle signal S _I from the idle switch 10 becomes L level due to release of the accelerator pedal,
This causes the AND gate 22 to output an L level signal, and if the brake pedal is not depressed at this time,
The H-level brake signal S _B from the brake switch 20 is inverted to L-level by the NOT gate 29 and supplied to the AND gate 26, which outputs an L-level signal to one input terminal of the OR gate 28. The output of the AND gate 27 is supplied to the other input terminal of the OR gate 28,
The AND gate 27 is supplied with a signal output from the gate ' of the vehicle speed comparator circuit 9. Here, if the vehicle speed is V>V ₄ , the output from gate ' is at L level, and AND gate 27 receiving this output supplies an L level signal to OR gate 28 . Thus, OR
The gate 28 has both inputs at L level and outputs an L level signal. Therefore, under such running conditions, the OR gate 23 is connected to the AND gate 22 and
In response to the L level signal from the OR gate 28, an L level output is supplied to the AND gate 12 to bring the torque converter into the converter state even in the lockup region, thereby achieving the first object of the present invention as in the previous example. can be achieved. After that, when the driving car depresses the brake pedal and the brake signal S _B from the brake switch 20 goes to L level, this is turned to H level by the NOT gate 29.
is inverted to the level and supplied to the AND gate 26,
This AND gate is further supplied with the above-mentioned L-level idle signal S _I which has been inverted to H-level by the NOT gate 30, so the AND gate 26 sends an H-level signal to the OR gate 28 by its H-level output. Output. This output is supplied to the AND gate 12 via the OR gate 23, and the first
The second object of the present invention can be achieved in the same manner as in the illustrated example. On the other hand, the H level signal from OR gate 28 is
The signal from the gate ', which is also supplied to the AND gate 27 and is separately supplied to this AND gate, is the V of the vehicle speed that decreases when the brake pedal is depressed.
≦V ₄ When the signal becomes H level according to the condition, the AND gate 27 continues to output an H level signal until the vehicle speed becomes V>V ₄ and the output from gate ' becomes L level, and this signal is sent to the OR gate. It is supplied to the AND gate 12 via 28 and 23. Therefore, once the operating state in which the object of the present invention is achieved as described above is achieved by depressing the brake pedal, this state is continued even when the brake pedal is released.
To prevent a torque converter from repeatedly changing its state between a lock-up state and a converter state and causing a shock even when coasting driving is performed in which the brake pedal is repeatedly depressed and released. Can be done. Then, when the brake pedal is released and the accelerator pedal is depressed to accelerate, the brake signal S _B and the idle signal S _I , which both become H level at this time, are supplied to the AND gate 22, which causes it to output an H level signal. Since this signal is further supplied to the AND gate 12 via the OR gate 23, normal lockup control can be performed without causing any inconvenience. Incidentally, at this time, both the above-mentioned signals S _B and S _I which are at H level are turned to L by NOT gates 29 and 30, respectively.
Since the level is inverted and supplied to the AND gate 26, the low level is sent from this AND gate to the OR gate 28.
A level signal is provided. Also, if the vehicle accelerates further and the vehicle speed becomes V > V ₄ , the signal from the gate' becomes L.
level, and from AND gate 27 to OR gate 2
The signal going to 8 also becomes L level. Therefore, the OR gate 28 comes to output an L level signal,
Since this signal is supplied to the AND gate 27, the circuit storing the braking is cleared as described above and can prepare for the next operation. In addition, in all of the above-mentioned embodiments, the detection of the gear shift position is performed in steps 1-2.
1-2 built into shift valve and 2-3 shift valve
Although an example has been shown in which shift switches 1 and 2-3 are used to control the shift switch 2, even if the automatic transmission performs shift control electrically, the electric signal indicating the shift position is directly transmitted to the shift detection circuit 7, It goes without saying that the present invention can be applied and its effects obtained by inputting the information to the shift position determining circuit 6.

[Brief explanation of the drawing]

FIG. 1 is an electronic circuit diagram showing one embodiment of the lock-up control device of the present invention, FIG. 2 is an electronic circuit diagram similar to FIG. 1 showing another example of the present invention, and FIG. 3 is an example of the lock-up area. FIG. 4, which is a shift pattern diagram of the automatic transmission, is an explanatory diagram of changes in axle torque when the accelerator pedal is released while in the locked-up state. 1...1-2 shift switch, 2...2-3 shift switch, 5...lock up solenoid, 6...shift position discrimination circuit, 7...shift detection circuit, 8...vehicle speed sensor, 9...vehicle speed comparison circuit, 10...idle switch , 13-15, 21, 22, 26, 27...
AND gate, 16, 23, 28...OR gate, 1
8...Transistor, 20...Brake switch, 2
4, 25, 29, 30...NOT gate.

Claims (1)

[Scope of Claims] 1. A torque converter is provided in the power transmission system, and the torque converter is placed in a lock-up state in which its input and output elements are directly connected depending on the presence or absence of a lock-up signal, or in a converter state in which the direct connection between these input and output elements is released. In a lock-up automatic transmission that can be implemented as
means and a second detecting the depression of the brake pedal.
lock-up prevention means for blocking the output of the lock-up signal in response to an accelerator pedal release signal from the first means; and when the second means generates a brake pedal depression signal even after the prevention, the torque converter 1. A lock-up control device for an automatic transmission, comprising a lock-up prevention and release means that enables normal lock-up control of the automatic transmission. 2. The lockup prevention release means is configured to
2. The lock-up control device for an automatic transmission as claimed in claim 1, wherein when the means issues a brake pedal depression signal, the torque converter can be normally locked-up controlled when the vehicle speed is below a set value. 3. The lockup prevention canceling means is configured to
3. The lock-up control device for an automatic transmission according to claim 2, wherein once the brake pedal depression signal is issued, the torque converter can be normally locked-up controlled even when the brake pedal is released.