JPS6199763A - Slip control device of torque converter - Google Patents

Abstract

PURPOSE:To prevent sudden drop of engine rotating number by controlling connecting force of a direct connection clutch by feed forward during setting time after release of an accelerator pedal and controlling the force by feed back. CONSTITUTION:In a torque converter 4 in which slip amount is designed to be increased by drop of connecting force of a direct connection clutch 8, the direct connection clutch 8 is controlled by feed forward by a signal corresponding to the set slip amount of the torque converter 4 during setting time after release of an accelerator pedal 2. Then, the direct connection clutch 8 is controlled by feed back so that the torque converter 4 obtains objective slip amount. Therefore, the converter can obtain such a slip limit condition where engine torque fluctuation can be absorbed, and sudden drop of engine rotating number can be prevented.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a torque converter inserted into a power transmission system such as an automatic transmission for a vehicle, and controls the relative rotation (slip) between its input and output elements. The present invention relates to a slip control device for a torque converter.

(Prior art) Since a torque converter transfers power between its input and output elements via a working fluid, it has a torque fluctuation absorption function and performs smooth power transmission, but on the other hand, relative rotation between input and output elements. (slip) cannot be avoided, resulting in poor power transmission efficiency. Therefore, in order to limit the slip to the minimum necessary for absorbing torque fluctuations (vibration suppression), or to reduce the slip to zero, we have developed a slip control type torque control system that is equipped with a direct coupling clutch that mechanically directly connects input and output elements as appropriate. Some converters are already in use.

This type of torque converter generally has an input element driven by the engine, an output element driven by hydraulic oil stirred by the engine, and an output element that is hydraulically operated as appropriate to limit the relative rotation between the input and output elements. It is usually configured with a direct coupling clutch.

By the way, in such a torque converter, if the direct coupling clutch was operating when the engine accelerator pedal was released, the rapidly increasing engine torque fluctuation would be transferred from the engine to the subsequent transmission system via the operating direct coupling clutch. It is transmitted as it is, causing vibration. Therefore, conventionally, during coasting (coasting) running from the moment t0 when the accelerator pedal is released, as shown in KA in Fig. 9, to the moment t8 when the accelerator pedal is depressed again, the direct coupling clutch of the torque converter is not activated, as shown in KB in the same figure. A control method was adopted that brought the converter into a controlled state (non-slip state).

Ren: However, with this control method, the torque converter is kept in the converter state during coasting, so while the torque converter output rotation speed decreases as shown in C in Figure 9, the engine rotation speed decreases. As shown in Figure 2, there is a sudden drop.

On the other hand, today's engines are often equipped with a fuel cut device for fuel efficiency and emission control purposes, and this fuel cut device is designed to reduce the number of revolutions that make up one engine revolution, as shown in Japanese Patent Application Laid-open No. 57-886, for example. When coasting to a motor vehicle that is being operated at speeds higher than 7 engine speeds, the engine speed is cut off because power from the engine is not needed. When the engine speed becomes lower than the engine speed (for example, the fuel recovery speed as shown by E in FIG. 9), the fuel supply to the engine is restarted (7 fuel recovery) to prevent the engine from stalling.

By the way, when the engine rotational speed suddenly decreases as shown in the middle of Fig. 9, the fuel cut time TF□ becomes extremely short as shown in Fig. 9, and the fuel efficiency improvement effect and exhaust countermeasure effect of the fuel cut device are reduced. It will no longer be enough.

In order to solve this problem, it is possible to use the slip control technique disclosed in Japanese Patent Laid-Open No. 58-68589.

This technique puts the torque converter in the converter state only during the period of time from the viewpoint that engine torque fluctuations will become less large as the period of time passes after the transition to coasting driving.

(Problems to be Solved by the Invention) Such slip control technology can prevent a sudden drop in engine speed and lengthen the fuel cut time, but since the torque converter is kept in the converter state during the above period,
Even if the engine speed is not as high as described above, it still drops rapidly and cannot provide a sufficient solution to the problem. This is due to the fact that the torque converter's torque fluctuation absorbing function is greater than the value commensurate with the torque fluctuations during the lag period. It should be in a restricted state.

By the way, if feedback control is applied to the direct clutch in order to obtain this slip-limiting state, the torque fluctuation is large as described above, and the slip amount variation range of the torque converter is large during the period of oxidation, so feedback control is not necessary for this purpose. As a result, slip control becomes unstable and the desired slip restriction state cannot be maintained. In this case, every time the slip of the torque converter deviates from the intended slip-limiting state in the direction of being too small, jerky vibrations are generated, which is unpleasant.

Therefore, during this period, it is preferable to perform feedforward control of the slip of the torque converter (direct clutch) using a signal corresponding to the intended slip restriction state.

Further, in the slip control technique described in the above-mentioned document, the following problem occurs because the torque converter is returned to the lock-up state until the release of the accelerator pedal is stopped after the above-mentioned period of time has elapsed. In other words, even though the torque fluctuation after the above-mentioned period is not so large, it is much larger than during normal driving, and if the torque converter returns to this condition, it is difficult to absorb the torque fluctuation. You can't get any functionality at all, and you can't help but experience some vibration.

Therefore, during this time as well, it is necessary to cause the torque converter to slip to the extent that it can absorb engine torque fluctuations. Slip control for this purpose has a wide range of slip fluctuations (no longer), so it is better to use feedback control.
Accurate slip control can be expected, and the torque converter's torque fluctuation absorption function can be accurately matched to engine torque fluctuations.

(Means for Solving the Problems) The present invention attempts to solve the various problems described above by developing a device for performing slip control that satisfies the above-mentioned requirement K, and the concept thereof is shown in FIG. , which transmits the power from the engine 1 and is directly connected while the accelerator pedal 2 of the engine is released. □ Torque whose slip amount is increased by decreasing the coupling force of the latch 8; in the inverter number, the accelerator pedal An accelerator pedal release detection means 5 for detecting the release of the pedal 2, a timer means 6 for measuring the duration of the release of the accelerator pedal, and a signal corresponding to the set slip amount of the torque converter 4 during the set time after the release of the accelerator pedal are directly connected to each other. Direct-coupled clutch feedforward control means 7 for controlling the operation of the clutch 8; Direct-coupled clutch feedback control means 8 for feedback-controlling the direct-coupled clutch 8 so that the torque converter 4 reaches the target slip amount until the accelerator pedal release is stopped after the set time. It is made up of the following.

(Function) While the release duration of the accelerator pedal 2 measured by the timing means 6 is a set time, the means 7 applies a predetermined engagement force to the direct coupling clutch 8 by feedforward control, and causes the torque converter 4 to have a set slip amount. During this time, the torque converter is not in the converter state, but is in a state where slip is limited to the extent that it can absorb engine torque fluctuations immediately after the accelerator pedal is released, so a sudden drop in engine speed can be prevented and the fuel cut time can be This could be extended. Since this control is feedforward control, even if the range of change in the amount of slip increases during the set time, the slip control becomes unstable and deforms, which prevents jerky vibrations from occurring due to insufficient slip conditions. can.

Until the release of the accelerator pedal 2 is stopped after the set time, the means 8 feedback-controls the direct coupling clutch 8 to bring the torque converter 4 to the target slip amount. During this period, the torque: r/verter is not in a lock-up state and is set to a target slip amount that can absorb engine torque fluctuations during the period, thereby preventing vibrations from occurring. Since this control is feedback control, the torque converter charge can be accurately maintained at the target slip amount, and the above-mentioned vibration prevention can be reliably achieved.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows a slip-controlled torque converter system to be controlled by the device of the invention, which comprises a pump impeller (input element) I O, a turbine launch (output element) 11 and a stator (reaction element) 12, and Direct clutch B
Built-in. The pump impeller lO is drivingly connected to an engine 1 (see FIG. 1) via a converter cover 10a connected thereto, and is constantly rotated by the engine. The turbine runner 11 is riveted to the turbine hub 18, and this turbine hub is the torque converter output shaft 14! Dynamically combine. Further, the stator 12 is placed on a hollow fixed shaft 16 via a one-way clutch 15, and a hydraulic oil supply passage 18 is provided between the shaft and the shaft 17 that envelops it, and a hydraulic oil return passage is provided between the shafts 14 and 16. 19 respectively. The hydraulic oil from the passage 18 flows into the torque converter 4, and then the hydraulic oil flows through the passage 1.
The internal converter chamber zO of the torque converter 4 is maintained at the converter pressure Pc due to a pressure holding valve (not shown) in the middle.

The direct coupling clutch 8 has an inner circumferential portion slidably fitted onto the turbine hub IB, and has a clutch 7 acing 8a on its outer circumferential portion to cover a lockup chamber 21 separated from the converter chamber 20. and the cover 10a. The direct coupling clutch 8 is drivingly connected to the turbine 2 inner 11 through a conventional torsion damper 22, and the lockup chamber 21 is connected to the boat 24a' of the slip control valve 24 through the center hole 28 of the shaft 14.

The direct coupling clutch 8 is operated and controlled by a slip control valve 24 and a lock-up solenoid 25, and the valve 24 has a boat 24b and a drain boat 24c in addition to a boat 24a, and the converter pressure Pc is introduced to the boat 241). valve 24
The spool 24d is the port 2 when going right to the upper half position in the figure.
4a through the drain/boat 24cK to make the circuit from the boat 24a to the lockup chamber 21 through the hole z8 into a pressureless state, and when going left to the lower half position in the figure, the port 24a is connected to the boat 24bKM and from the boat 24a. A lock-up pressure PL, which is the same as the converter pressure Pc, to the lock-up chamber 21,
The lock-up pressure PLa/u from the boat 24a is regulated to a value corresponding to the spool position by outputting the boat 24b and 24c.

The position of the spool 24d is from the passage 24eK to the chamber 24fK.
It is determined by the derived lock amplifier pressure PL4/u and the control pressure Ps in the chamber 24g, and the chamber 24g receives the reference pressure (line pressure in the case of an automatic transmission) P through the orifice z7 by the passage z6.
While guiding L, drain boat 2 passes through orifice Z8.
Let it pass to 9. Then, the plunger 25a of the lock-up solenoid 25 is installed opposite to the oriice z8, and the non-lenoid normally projects the plunger 25a to the right half position in the figure to close the orifice 28, and when energized, the plunger 25a
It is assumed that the orifice 28 is opened by retracting the orifice 5a to the left half position in the figure.

The slip-controlled torque converter described above operates as follows.

Lock-up solenoid 250 de-energizes plunger 25a
When the orifice 28 is closed, the control pressure P becomes equal to the reference pressure Pt, and the spool 24d is placed in the lower half position in the figure. Thus, lock-up pressure PL/u is converter pressure P. The pressure inside the lock amplifier chamber 21 becomes equal to that of the converter chamber 20.

・For this reason, the direct coupling clutch 8 is connected to the converter cover 10a.
The torque converter transmits power in a so-called converter state. In addition, the chamber 24 of this valve opening z4
The lock-up pressure PL1/u reaches f as well and opposes the control pressure P in the chamber 24g, but since P8>PL,/11, the valve spool 24d is able to maintain the lower half position in the figure and the torque converter is Can be kept in converter state.

Plunger 25a is activated by lock-up solenoid z5.
When the orifice 28 is opened, the braking pressure P3 becomes zero, and the spool 24d becomes the lock amplifier pressure P in the chamber 24f.
It is placed in the upper half position in the figure by L/u. In this way, the lock-up pressure P57o is brought to zero, and the direct coupling clutch 8 is caused to close to the converter cover 10a by the pressure PC in the converter chamber 20.
is pressed against.

Therefore, the torque converter 4 has an input/output element of 10°11
Power is transmitted in a so-called lock-up state in which no relative rotation occurs between the two.

When the lock-up solenoid 25 is repeatedly energized and deenergized and the energization time width is controlled by duty as described later, as the duty increases, the control pressure P8
Although the spool 24d allows the boat 24a to communicate with both ports 24b and 24c, it gradually decreases the degree of communication with the boat 24b and gradually increases the degree of communication with the boat 24c. Therefore, the lock-up pressure PL/ changes to decrease as the duty increases, and the direct connection between 2 and 8
The torque converter 4 can be slip-controlled by duty-controlling the operating state of the torque converter 4 so that its coupling force changes.

In the present invention, the lock-up solenoid 25 is
The torque converter 4 is controlled by the microcomputer shown in the figure to perform slip control as intended by the present invention. A microcomputer has a central processing unit (CPU) 80 and a random access memory (80).
It consists of a RAM) 81, a read-only memory (ROM) 82, and an input/output interface circuit (i,"o)aa.

This microcomputer is the engine speed sensor 84
Engine speed signal phase from output shaft speed sensor 85
from the output shaft 14 (see Figure 2)
0, the accelerator pedal release signal I8 output from the idle switch 86 and the transmission gear position signal Gs output from the gear position sensor 87 are waveform-shaped by a waveform shaping circuit 88 and then input to the I/O BS. At the same time, the engine throttle opening signal TH from the throttle Ti degree sensor 89 is converted into a digital signal by the A/D converter 88a and then input to the I/O. Then, the microcomputer appropriately operates the lock-up solenoid 25 via the amplifier 40 based on the calculation results of these input signals.

Such a microcomputer performs normal slip control in addition to slip control of the torque converter, which is the object of the present invention, and the latter slip control will be briefly explained first.

1 Figure 4 shows an interrupt processing routine that is activated by the engine speed signals N and K that are generated every time the engine is ignited.
Calculate ne (torque converter input rotation speed). Fifth
The figure shows the output shaft rotational speed signal N generated every rotation of the output shaft 14 (see FIG. 2). This is an interrupt processing routine started by K, and after calculating the output shaft rotation speed (torque converter output rotation speed) no from the time interval of interrupt occurrence, the signal G
The gear position g of the transmission is detected from 8, and then this gear position f is detected.
f1g and output shaft rotation speed n. The transmission output rotation speed, that is, the vehicle speed V, is calculated by multiplying by

FIG. 6 shows a regular interrupt routine that is processed every fixed time ΔT. First, in step 41, the throttle opening signal TH is converted into a gender, and the throttle opening TH is read. The next step 42 is the idle signal worker. It is determined whether the idle switch 86 (see Fig. 8) is OFF or ON, and if the idle switch 86 is OFF and the accelerator pedal is depressed, the control proceeds to step 4B and thereafter the torque converter is operated normally as follows. Slip control.

That is, in step 48, the flag is reset to 5 to indicate that normal slip control is in progress, and in the next step 44, the torque converter is set to the converter state based on the throttle opening TH, gear position υg, and vehicle speed V. It is determined whether the operating range is the one that should be controlled, the one that should be in a lock-up state, or the one that should be slip-controlled. If it is the converter region, the output duty is set to 0% in step 45, and this is updated with the previous output duty in step 46. In this case, the lock-up solenoid 25 remains deenergized, allowing the torque converter to enter the converter state as desired, as previously described. If it is a lock-up area, the output duty is set to 100% in step 47.
and updates this with the previous output duty in step 46. In this case, lock-up solenoid z5
continues to be energized through amplifier 40 to bring the torque converter into lockup as desired, as previously described. If it is in the slip control region, in step 48, the torque converter's actual slip amount n e no and the set slip amount are determined based on the difference (proportional (P) and integral (I)).
Determine the output duty from Performance 3XK and use this in step 4.
6, the output duty is updated with the previous output duty. In this case, the lock-up solenoid 25 is repeatedly energized and deenergized via the amplifier 40 in a time width corresponding to the output duty, and the torque converter can be subjected to slip control as described above. And since this control is PI control,
The torque converter brings slip zne-n0 to G constant x lip ftK, and is maintained at this set slip amount.

By the way, in step 42, the idle switch 86
If it is determined that the accelerator pedal is released (see FIG. 8), the control proceeds to step 49, where the slip control aimed at by the present invention is performed as described below.

This slip control is executed by the subroutine shown in FIG.
Determine whether or not the value is greater than or equal to the value. If y<zoh/h, it is not possible to lengthen the fuel cut time even if the slip control aimed at by the present invention is performed, so the output duty is set to 0% in step 51, and the sixth By returning the control to step 46 in the figure and putting the torque converter into the converter state, the torque fluctuation absorbing function is fully utilized to suppress vibrations during coasting.

(2) If ≧20b/b or more, it is checked in step 58 whether the flag mentioned above is set to 1 or not. If this flag is not 1, that is, if the previous power-on driving without releasing the accelerator pedal has now shifted to coasting driving with the accelerator pedal released, then in step 54 it will indicate that coasting driving is in progress. After setting the flag to 1, in the next step 55 a counter for measuring the duration of release of the accelerator pedal is cleared, and then in step 56 the output duty is set to a predetermined value X%. This predetermined value X%
For example, the torque converter slip amount can be obtained such that the torque converter can reliably absorb large engine torque fluctuations immediately after shifting to sting driving.
Set to 0%. Thereafter, the control returns to step 46 in FIG. 6 in step 5z, and the lock-up solenoid 86 is energized for a period of time corresponding to the output duty predetermined value X%, causing the torque converter to coast. It is possible to create a slip state in which large engine torque fluctuations at the beginning of the transition are absorbed.

If the flag is 1 in step 58, that is, if coasting was being performed last time, the counter is incremented (sidewalk) in step 57, and in the next step 58, whether this counter indicates the set time T1 or more is determined. From ``No'' or ``K'', it is determined whether a set time T□ (for example, 0.4 seconds) or more has elapsed after the coasting run. If it is within the set time T0, the output duty is maintained at the predetermined value X% in step 59, and the set time T0 is
Thereafter, in step 60, the target slip amount of the torque converter is read from the table data corresponding to FIG. 8 based on the work/engine/rotational speed n8. This target slip amount is set for each engine speed so as to correspond to a value that allows the torque converter to just absorb engine torque fluctuations that differ for each engine speed n8 after the set time T0 has elapsed.

In the next step 61, the output duty is determined based on the difference between the actual slip amount ne-no of the torque converter and the target slip amount (PI operation n), and then the control returns to step 46 in FIG. 6 in step 52. As a result, the lock-up solenoid 25 is energized with a time width for one cycle corresponding to the output duty, and feedback control is performed so that the torque converter reaches the target slip amount shown in FIG. 8 after the set time J4 of the set time T has elapsed. I can do it.

The above operation is shown in a time chart as shown in FIG. 9 when both before and after coasting travel are in the lock-up region. The output duty during the set time T0 from the coasting start instant t1 is KPf as shown by F.
r is kept at a constant value of X%, and the torque converter is feedforward controlled to have a slip amount corresponding to this output duty.

As mentioned above, this amount of slip is such that the torque converter can reliably absorb large engine torque fluctuations at the beginning of the transition to coasting driving, thereby sufficiently preventing the occurrence of vibration. I can do it.

After the set time T0 until the instant t2 when coasting ends, the output duty is changed as shown by G, and the torque converter is feedback-controlled so that it reaches the target slip amount of the eighth factor set for each engine speed (example shown). Then P
I control). As described above, this amount of slip is such that the torque converter can absorb engine torque fluctuations that vary depending on the engine speed after one set time T1 has elapsed, thereby preventing vibrations from occurring. It is also possible to avoid a situation where the power transmission efficiency deteriorates due to excessive slip of the torque converter.

Also, by controlling the output duty as F and G instead of setting it to 0% during coasting and putting the torque converter in a slip control state, the engine speed will drop as shown by H, causing a fuel cut. It is possible to extend the time from T to TF□, and the fuel cut device can provide sufficient fuel efficiency improvement effects and exhaust countermeasure effects.

In addition, in the illustrated example, the reason why feedforward control is used instead of feedback control during the set time T0 is that the torque fluctuation is large during this time, and the engine speed is large (changes), so this is considered as one of the input information. This is because the feedback control cannot keep up and causes a hunting condition in which the slip amount repeatedly goes from being too large to too small from the appropriate amount, and each time the slip amount becomes too small, it becomes unable to absorb torque fluctuations.

(Effects of the Invention) Thus, as described above, the slip control device of the present invention engages the direct coupling clutch 8 during the set time T□ after the release of the accelerator pedal by the signal (output ratio X%) corresponding to the set slip amount of the torque converter. Since the configuration is such that the force is feedforward controlled and then the direct coupling clutch 8 is feedback controlled so that the torque converter reaches the target slip amount, the following effects may be diminished. That is, during the above-mentioned set time, the torque converter is placed in a slip-limited state to the extent that it can absorb engine torque fluctuations during this period, preventing a sudden drop in engine speed, and extending the fuel cut time further than the conventional technology described in the above-mentioned document. can do. [However, since this control is feedforward control, it may be difficult if the torque fluctuation is large and the range of change in torque converter slip amount during the set time is large.
The slip control does not become unstable and can prevent jerky vibrations caused by frequent occurrence of insufficient slip conditions.

Furthermore, after the set time has elapsed, the torque converter is set to a target slip amount that can absorb engine torque fluctuations during this period, and vibrations can be prevented from occurring. Since this control is feedback control, the torque converter can be accurately maintained at the target slip amount, and the above vibration prevention can be reliably achieved.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of the device of the present invention, FIG. 2 is a system diagram illustrating a torque converter to be subjected to slip control by the device of the present invention, and FIG. 8 is a block diagram of a microcomputer illustrating an example of the device of the present invention. 4 to 7 are flowcharts showing the control program of the microcomputer, FIG. 8 is a diagram illustrating the target slip amount of the torque converter to be set by the device of the present invention, and FIG. 9 is the operation by the device of the present invention. This is a time chart. l...Engine 2...Accelerator pedal 8
...Direct clutch number...Torque converter 5
. . . Accelerator pedal release detection means 6 . . Timing means 7 . . . Direct clutch feed forward control means 8.
・Direct coupling clutch feedback control means lO ・Bon pump engine 9 11 ・Turbine runner 12 ・・
Stator 1B...Turbine runner. 14...Torque converter output shaft 16...One-way clutch 20...Converter chamber 21...Lock-up chamber 22...Torsional damper 24...Slip control valve 25...Lock-up solenoid 2? , 28... Orifice 80... Central processing unit 81... Random access memory 82... Read-only menu 8B... Input/output interface circuit 84... Engine speed sensor 85... Torque Converter output rotation speed sensor 86...
・Idle switch 87...Gear position sensor 88・
...Waveform shaping circuit 89...Throttle opening sensor 40...Amplifier Fig. 4 Fig. 6 Fig. 7

Claims (1)

[Scope of Claims] 1. In a torque converter that transmits power from an engine and increases the amount of slip by reducing the coupling force of a direct coupling clutch while the accelerator pedal of the engine is released, the accelerator pedal an accelerator pedal release detection means for detecting the release of the accelerator pedal; a timing means for measuring the duration of the accelerator pedal release; and a timing means for measuring the duration of the accelerator pedal release; and controlling the operation of the direct coupling clutch using a signal corresponding to a set slip amount of the torque converter during a set time after the accelerator pedal is released. Direct-coupled clutch feedforward control means; Direct-coupled clutch feedback control means for feedback-controlling the direct-coupling clutch so that the torque converter reaches the target slip amount until the accelerator pedal release is stopped after the set time. Torque converter slip control device.