JPS634061B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lock-up type automatic transmission which includes a torque converter in a power transmission system and can put the torque converter into a lock-up state in which its input and output elements are directly connected by means of an electrical lock-up signal, and particularly outputs the lock-up signal. This invention relates to an electronically controlled lockup control device that controls whether or not to lock up the lockup. 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 the 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 inevitable.As a result, although automatic transmissions are easy to operate, they have poor 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, where V ₁ , V ₂ , and V ₃ are the first speed and
Lockup vehicle speed for 2nd and 3rd gears, A,
B and C are 1st gear, 2nd gear, and 3rd gear based on the 1→2 upshift line and the 2→3 upshift line, respectively.
(The lockup areas based on the 1←2 downshift line and the 2←3 downshift line are omitted for clarity of the drawing). Such lock-up control is performed depending on the presence or absence of an electrical lock-up signal, that is, the torque converter is placed in the lock-up state by the output of the lock-up signal while the vehicle is traveling within the lock-up region A, B, or C, and the torque converter is placed in the lock-up state while the vehicle is traveling outside the lock-up region. In the case of a so-called electronically controlled lock-up control device that puts a torque converter into a converter state when a signal disappears, a vehicle speed sensor that electrically detects the current vehicle speed is essential. This vehicle speed sensor generates a pulse signal with a period corresponding to the vehicle speed as shown by P in _FIG . The number of pulses of P is counted and the count value is output as a vehicle speed signal. However, in such a vehicle speed sensor, when the period of the pulse signal P becomes longer as shown in FIG. 4b due to a decrease in vehicle speed, the pulse number count value within the gate time T _G decreases, which tends to cause an error in the vehicle speed signal. However, if the gate time T _G is made longer, it will take time to output the vehicle speed signal, and the responsiveness of the lock-up control that should be performed based on this vehicle speed signal will deteriorate. Therefore, as shown in Figure 4c, the number of pulses of the clock pulse signal R of a constant period during the time T _P from the rising (or falling) of the pulse signal P emitted by the vehicle speed sensor to the next rising (or falling) is calculated. Totally count,
A vehicle speed detection method is adopted that outputs the count value as a vehicle speed signal. However, with this vehicle speed detection method, if the wheels lock due to sudden braking at instant X in Figure 4c, for example, the pulse signal will not produce the next rise (or fall) as shown by P'. , vehicle inspection becomes impossible. If the torque converter is locked up at this time, not only will the release be delayed and the engine stall, but the brakes, which are boosted by engine suction negative pressure, will suddenly become heavier, or oil from the engine-driven oil pump will cause the engine to stall. The power steering that is being activated suddenly becomes heavy, which is extremely dangerous. From this point of view, the present invention provides an electronically controlled lock-up control device that never locks up the torque converter during sudden braking above a certain level where there is a risk of the wheels locking up.
Therefore, it is an attempt to avoid the above-mentioned danger. 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. , the torque converter shall be placed in a locked-up state when 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 transmission position determination circuit 6 determines the transmission position from the combination of the levels of both shift signals S ₁₂ and S ₂₃ according to the table above.
NOR gate 203, AND gate 204, 205
and NOT gate 206, and when the signal levels of both shift signals S ₁₂ and S ₂₃ are both at L level, only the output S ₁ (1st speed signal) of NOR gate 203 becomes H level, and the shift signal When only the signal level of S ₁₂ becomes H level, only the output S ₂ (2nd speed signal) from the AND gate 204 becomes H level, and the signal level of shift signal S ₂₃ becomes H level.
It functions so that only the output S ₃ (third speed signal) from the AND gate 205, which is at the H level, becomes the H level. The shift detection circuit 7 includes an edge trigger circuit 8 for detecting the rise and fall of the shift signal _S12 , an edge trigger circuit 9 for detecting the rise and fall of the shift signal _S23 , and a NOR gate 10. The edge trigger circuit 8 has a NOT gate 211,
Resistor 212 and capacitor 2 forming a delay circuit
13, a rise detection AND gate 214,
It consists of a NOR gate 215 for falling detection.
Similarly, the edge trigger circuit 9 also connects the NOT gate 2.
16, a delay circuit composed of a resistor 217 and a capacitor 218, an AND gate 219, and a NOR
It consists of a gate 220. edge trigger circuit 8,
9, the corresponding shift signals S ₁₂ and S ₂₃ are respectively L.
When switching from level to H level or from H level to 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, NOR A positive pulse signal (the pulse width is determined by the delay circuit described above) is supplied to the corresponding input terminal of the gate 10. At this time, the NOR gate 10 inverts the pulse signal and outputs a trigger pulse _P1 of negative polarity, and the pulse width of each of these pulse signals is appropriately set by the delay circuit described above, so that the automatic transmission performs actual gear shifting operation. Adapt it to the time required. The vehicle speed sensor 11 supplies a vehicle speed signal V corresponding to the vehicle speed (as is clear from the above, the pulse number count value) to the vehicle speed comparator circuit 12, and this circuit locks up the vehicle speed signal V to the first speed vehicle speed _V1. ,
Comparing the lock-up vehicle speed V ₂ for 2nd gear and the lock-up vehicle speed V ₃ for 3rd gear (see Figure 3 for both), when the vehicle speed V exceeds these lock-up vehicle speeds, the corresponding gate... The signal in the lock-up determination circuit 13 is
It is assumed that the signal is supplied to one input terminal of AND gates 223 to 225. Also, AND gate 223~
The other input terminal of 225 is supplied with the first, second, and third speed signals S ₁ , S ₂ , and S _{3 ,} respectively. Thus,
AND gates 223 to 225 are first speed, second speed,
Lock-up area at 3rd speed, ie A in Fig. 3,
In regions B and C (only the regions based on the 1→2 upshift line and the 2→3 upshift line are shown),
Individually output H level signals, AND gate 22
When an H level signal is output from one of the gates 3 to 225, this signal causes the OR gate 226 to output an H level signal. This H level signal is supplied to one input terminal of the AND gate 227 as an activation signal for the lock-up solenoid 5. The other two input terminals of the AND gate 227 are provided to respond to the output of the NOR gate 10 and means for detecting the braking state of the vehicle provided according to the present invention, for example, the pressure of the brake hydraulic system. Brake signal S _B from brake fluid pressure switch 14
and supply. The switch 14 is assumed to be closed when the brake fluid pressure (braking force) is relatively high in a region where the brake fluid pressure may cause wheels to lock up, and is open at other times, and this switch is connected to the power supply +V via the resistor 15. Connecting. Therefore, during the former braking, the brake signal S _B goes to L level because the switch 14 is closed, and at other times, because the switch 14 is open, the brake signal S B goes to H level by the power supply +V. Thus, the AND gate 227 functions as a means for inhibiting the output of the lock-up signal S _L during braking exceeding a certain level that may cause the wheels to lock. Or, in C, the H level signal is input from the OR gate 226 as described above, the gear is not being changed, the pulse signal _P1 is not input from the NOR gate 10, and the switch is not activated in a braking state where the wheels are locked. When the brake signal S _B from 14 is at H level, a lockup signal S _L at H level is output. This lockup signal is applied to the transistor to make it conductive, and by energizing the lockup solenoid 5 with the power supply +V, the torque converter can be placed in lockup as desired. By the way, when the automatic transmission is changing gears, the pulse signal
While P ₁ exists, this is AND gate 22
In order to cause this AND gate to output an L level signal (to eliminate the lockup signal S _L ), the lockup solenoid 5 is deenergized even in the lockup region. Therefore, the torque converter 1 is released from the lock-up state and enters the converter state, thereby preventing the occurrence of a shift shock. Note that in operating conditions other than the lockup areas A, B, and C in FIG. 3, the AND gates 223 to 225 are
Neither of them can output an H level signal, and in this case too, the lock-up solenoid 5 is deenergized and the torque converter 1 can be brought into the converter state as required. In addition, in a braking state where there is a possibility that the wheels may lock, this is detected and the switch 14 closes, and the brake signal S _B becomes L level and the AND gate 22 is activated.
7, the AND gate can output a low level signal (disappearing the lockup signal S _L ) regardless of the other input signal levels to ensure that the torque converter is never locked up. Thus, the lock-up control device of the present invention is configured as described above, and in a braking state in which the wheels are locked, the torque converter is placed in the converter state in advance so that it will never be locked up. Even if the wheels lock up, the engine will not stall, and the risk of the negative pressure booster brakes or power steering suddenly becoming heavy due to the engine stalling can be prevented. It goes without saying that similar effects can be obtained by replacing the brake fluid pressure switch 14 in the above example with a deceleration sensing switch that closes in response to vehicle deceleration that may cause the wheels to lock. . Further, in the present invention, as shown in FIG. 2, the sudden braking memory circuit 17 can be configured to prevent the torque converter from being locked up during braking that would cause the wheels to lock. This circuit 17 includes a brake fluid pressure switch 14 and a resistor 1 similar to those described above.
In addition to the switch 5, an idle switch 18 is provided, and this switch is connected to the power supply +V via a resistor 19, so that an idle signal S _I can be output in accordance with the opening/closing of the switch 18. The idle switch 18 is closed when the accelerator pedal is released to set the idle signal S _I to L level, and is opened at other times to set the idle signal S _I to H level by the power supply +V. During braking that causes the wheels to lock, the brake signal S _B , which has become L level as described above, is inverted to H level by NOT gate 243 and then input to OR gate 245, which outputs an H level signal. let On the other hand, this H level signal
As a result of being inverted to the L level by the NOT gate 247 and then being supplied to the AND gate 227, during such braking, the torque converter can be maintained in the converter state and the desired purpose can be achieved as in the above example. . The H level signal from the OR gate 245 is then supplied to one input terminal of an AND gate 246, and the other input terminal of the AND gate 246 is at an L level because the accelerator pedal is naturally released at this time. The idle signal S _I , which is currently in use, is inverted to H level by NOT gate 244 and supplied. Therefore, the AND gate 246 ANDs both inputs and supplies an H level signal to the OR gate 245. Once the braking state is reached, the brake fluid pressure decreases and the OR gate 245 outputs the brake signal S. Even if _B is switched to H level, the H level signal continues to be output, so that control that never locks up the torque converter can be continued. When the driver moves his foot from the brake pedal to the accelerator pedal and depresses the accelerator pedal, the idle signal S _I goes to H level, this signal is inverted to L level by NOT gate 244, and sent to OR gate 245 by AND gate 246. To make it impossible to output an H level signal. At this time, the brake fluid pressure is zero and the brake signal S _B is at H level.
Inverted to L level by NOT gate 243
Since the signal is supplied to the OR gate 245, the OR gate 245 outputs an L level signal. This L level signal is inverted to H level by NOT gate 247 and input to AND gate 227, so that normal lockup control is executed. In this example, the same effects as those of the previous example can be obtained as described above, and once a braking condition in which the wheels are locked is reached, the accelerator pedal is not depressed even if the braking force is relaxed. Since the configuration continues to perform control to prevent the torque converter from locking up as long as possible, the torque converter will not lock up repeatedly during braking in which the brake pedal is repeatedly operated near the boundary state of whether or not wheel lock occurs. This can prevent deterioration of the feeling caused by repeated lock-up shocks. In addition, during the above-described repeated operation of the brake pedal, the torque converter is prevented from locking up due to a delay in response of the lock-up control hydraulic system even though the braking is instantaneous and causing the wheels to lock, thereby preventing the engine from stalling due to the wheels locking. However, the intended purpose of the present invention can be fully achieved.

[Brief explanation of the drawing]

FIG. 1 is an electronic circuit diagram showing an example configuration of a lockup control device according to 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 automatic circuit diagram illustrating a lockup area. FIG. 4 is a shift pattern diagram of the transmission and is an explanatory diagram of the vehicle speed detection procedure of the vehicle speed sensor used in the lock-up control device. 1...1-2 shift switch, 2...2-3 shift switch, 5...lock-up solenoid, 6...shift position discrimination circuit, 7...shift detection circuit, 8, 9...edge trigger circuit, 11...vehicle speed sensor, 12...vehicle speed Comparison circuit, 13...Lockup judgment circuit, 14...
Brake fluid pressure switch, 16...Transistor, 1
7...Sudden braking memory circuit, 18...Idle switch.

Claims (1)

[Claims] 1. In 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 by an appropriate electric lock-up signal, there is provided a means for detecting the braking state of the vehicle. 1. A lock-up control device for a lock-up type automatic transmission, comprising means for prohibiting output of the lock-up signal using a future signal when the means detects a braking force exceeding a certain level.