JPH029225B2 - - Google Patents

Description

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

(Prior art) Torque converters transfer power between their input and output elements via working fluid, so they have a torque fluctuation absorption function and perform smooth power transmission.
On the other hand, relative rotation (slip) between input and output elements 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 eliminate the slip, we developed a slip control type torque clutch equipped with a direct coupling clutch that directly mechanically 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 a direct connection that is hydraulically operated as appropriate to limit the relative rotation between the input and output elements. It is usually composed of a clutch.

By the way, in such a torque converter, if the direct coupling clutch was operating when the engine accelerator pedal was released, then 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 instant _t1 when the accelerator pedal is released as shown at A in Fig. 8 to the instant _t2 when it is depressed again, the torque converter is directly connected as shown at B in the same figure. A control method was adopted that placed the converter in a state in which the clutch was deactivated (slip non-limiting state).

However, in this control method, the torque converter is kept in the converter state throughout the coasting run, so the engine speed significantly drops during this period as shown by C in the figure.

On the other hand, today's engines are often equipped with a fuel cut device for fuel efficiency and emission control, and this fuel cut device is designed to reduce the engine speed to a certain number of revolutions ( For example, if you shift to coasting while driving at a speed higher than the fuel cut speed (as shown by D in Fig. 8), the fuel supply to the engine is cut off (fuel cut) because power from the engine is not needed. When the rotational speed falls below a certain rotational speed (for example, the fuel recovery rotational speed as shown by E in FIG. 8), the fuel supply to the engine is restarted (fuel recovery) to prevent the engine from stalling.

By the way, when the engine speed decreases significantly as shown in C in Fig. 8, the fuel cut time T _F1 becomes extremely short as shown in Fig. 8, and the fuel cut device does not have sufficient fuel efficiency improvement effect and exhaust countermeasure effect. It ceases to be something.

In order to solve this problem, it is possible to use the slip control technique disclosed in Japanese Patent Application Laid-Open No. 58-68539. As shown by F in Fig. 8, this technique is based on the fact that after a certain time _T2 elapses after transition to coasting driving, engine torque fluctuations will attenuate and become less large _. Only the torque converter is placed in the converter state.

(Problem to be Solved by the Invention) However, with this slip control technology, the torque converter is forced to maintain its torque throughout the entire ₂ hours during which the torque fluctuation absorption function of the torque converter is required, regardless of the magnitude of the required function. In order to maintain the converter state in which the fluctuation absorption function is maximized, the time T ₂ in which the converter state is maintained becomes longer than necessary. Therefore, during this period, the engine speed decreased significantly as shown by C in Figure 8, and after ₂ hours T, by reducing the slip of the torque converter, the engine speed increased as shown by G in the same figure. However, the fuel cut rotation speed D cannot be exceeded, and the fuel cut cannot be performed again. Therefore, even with this slip control technique, the fuel cut time remains T _F1 , and the problem of the short fuel cut time still cannot be solved.

(Means for Solving the Problem) In order to solve this problem, the present invention transmits power from an engine 1 as shown in FIG. an accelerator pedal release detection means 5 for detecting release of the accelerator pedal 2 in the torque converter 4 in which the amount of slip is increased by non-operation of the direct coupling clutch 3 during a set time;
A clock means 6 for measuring the duration of release of the accelerator pedal, and a direct coupling clutch control means for controlling the operation of the direct coupling clutch 3 so that the torque converter 4 gradually reduces the slip amount from the increased slip amount after the set time. It is something that has been established.

(Operation) The timing means 6 measures the time period during which the release of the accelerator pedal 2 detected by the means 5 continues, and instructs the direct clutch control means 7 to do so. The direct coupling clutch control means 7 controls the operation of the direct coupling clutch 3 so that the slip amount of the torque converter 4 is gradually decreased from the increased slip amount after the set time.

In this way, the torque converter sufficiently absorbs the large torque fluctuation at the beginning of the transition to coasting driving when the accelerator pedal is released by increasing the amount of slip during the set time, and then the torque gradually decreases due to attenuation. The torque converter absorbs the torque fluctuations while gradually reducing the amount of slip to match the fluctuations, thereby preventing the occurrence of vibrations due to torque fluctuations during coasting. Then, the torque converter can delay the engine speed from dropping significantly and becoming below the fuel recovery speed during the gradual decrease of the amount of slip, and can extend the fuel cut time.

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

FIG. 2 shows a slip-controlled torque converter 4 to be controlled by the device according to the invention, which comprises a pump impeller (input element) 10, a turbine runner (output element) 11 and a stator reaction element) 12, and further includes a direct coupling clutch. Built-in 3. The pump impeller 10 is connected to the converter cover 10.
It is drive-coupled to an engine 1 (see FIG. 1) via a, and is constantly rotated by this engine. A turbine runner 11 is riveted to a turbine hub 13 drivingly coupling the turbine hub to a torque converter output shaft 14 . 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 a shaft 17 surrounding the shaft.
Further, a hydraulic oil return path 19 is provided between the shafts 14 and 16, respectively. There is a passage 1 inside the torque converter 4.
The hydraulic oil from passage 8 flows, and then the hydraulic oil flows through passage 1.
The internal converter chamber 20 of the torque converter 4 is maintained at the converter pressure P _c by a pressure holding valve (not shown) in the middle.

The direct coupling clutch 3 connects its inner periphery to the turbine hub 1.
3, and has a clutch facing 3a on the outer periphery of the converter chamber 2.
A lockup chamber 21 partitioned from 0 is defined between the converter cover 10a and the converter cover 10a. The direct coupling clutch 3 is then dynamically coupled to the turbine runner 11 through a conventional torsional damper 22 and connects the lockup chamber 21 to the port 24a of the slip control valve 24 through the center hole 23 of the shaft 14.

The direct coupling clutch 3 is operated and controlled by a slip control valve 24 and a lock-up solenoid 25, and the valve 24 has a port 24b and a drain port 24c in addition to a port 24a, and the converter pressure P _c is introduced into the port 24b. The spool 24d of the valve 24 connects the port 24a to the drain port 24c when moving to the right in the upper half of the figure, making the circuit from the port 24a through the hole 23 to the lock-up chamber 21 in an unpressurized state, and in the lower half of the figure. When moving to the left to the intermediate position, port 24a is connected to port 24b, and a lock-up pressure PL/U, which is the same as the converter pressure P _c , is output from port 24a to the lock-up chamber 21.
4a is connected to ports 24b and 24c, and the lockup pressure PL/U from port 24a is regulated to a value corresponding to the spool position.

The position of the spool 24d is determined by the lock-up pressure PL/U introduced into the chamber 24f by the passage 24e and the
The control pressure P _s in the chamber 24g is determined by the control pressure P s in the chamber 24g.
6 leads the reference pressure (line pressure in the case of an automatic transmission) PL through an orifice 27 and connects it to a drain port 29 through an orifice 28. Then, the plunger 25a of the lock-up solenoid 25 is disposed opposite to the orifice 28, and this solenoid normally projects the plunger 25a to the right half position in the figure to close the orifice 28, and when energized, the plunger 25a moves to the left half position in the figure. The orifice 28 shall be opened by retreating to the lower position.

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

When the lock-up solenoid 25 is deenergized and the plunger 25a closes the orifice 28, the control pressure _Ps becomes equal to the reference pressure _PL , and the spool 24
Place d in the lower half position in the figure. Thus, the lockup pressure PL/U becomes equal to the converter pressure _Pc , and the pressure inside the lockup chamber 21 becomes the same as that of the converter chamber 20. Therefore, the direct coupling clutch 3 is not pressed against the converter cover 10a, and the torque converter 4 transmits power in a so-called converter state. In addition,
During this period, lock-up pressure P is also applied to the chamber 24f of the valve 24.
L/U reaches and opposes the control pressure P _s in the chamber 24g, but since P _s > PL/U, the valve spool 24d can maintain the lower half position in the figure, and the torque converter is placed in the converter state. can be kept.

When the lock-up solenoid 25 is energized to open the plunger 25a orifice 28, the control pressure _Ps becomes zero, and the spool 24d is brought to the upper half position in the figure by the lock-up pressure PL/U in the chamber 24f. Thus, the lock-up pressure PL/U is brought to zero, and the direct coupling clutch 3 reduces the pressure in the converter chamber 20.
It is pressed against the converter cover 10a by P _c .
Therefore, the torque converter 4 is the input/output element 1.
Power is transmitted in a so-called lock-up state where no relative rotation occurs between 0 and 11.

Then, the lock-up solenoid 25 is energized.
When deenergization is repeated and the energization time width is duty-controlled as described below, as the duty increases, the control pressure P _s decreases, and the spool 24d allows the port 24a to communicate with both ports 24b and 24c. , the degree of communication to port 24b is gradually decreased, and the degree of communication to port 24c is gradually increased. Therefore,
The lockup pressure PL/U changes to decrease as the duty increases, and by controlling the duty of the operating state of the direct coupling clutch 3 so that its coupling force changes, the torque converter 4 can be subjected to slip control.

In the present invention, the lock-up solenoid 2
5 is controlled by a microcomputer shown in FIG. 3 to enable slip control of the torque converter 4 as intended by the present invention. A microcomputer has a central processing unit (CPU) 3
0 and random access memory (RAM) 31
, a read-only memory (ROM) 32, and an input/output interface circuit (i/0) 33.

This microcomputer receives the engine speed signal N _E from the engine speed sensor 34, the rotation signal N ₀ regarding the output shaft 14 (see FIG. 2) from the output shaft speed sensor 35, and the idle switch 3.
The accelerator pedal release signal I _s output from the gear position sensor 37 and the gear position signal G _s of the transmission output from the gear position sensor 37 are waveform-shaped by the waveform shaping circuit 38 and then input to the I/O 33 . The engine throttle opening signal TH from the throttle angle sensor 39 is converted into a digital signal by the A/D converter 33a and then input to the I/O. and,
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.

FIG. 4 shows an interrupt processing routine that is activated by an engine rotational speed signal N _E generated every time the engine is ignited, and calculates the engine rotational speed (torque converter input rotational speed) N _e from the time interval between interrupt occurrences. Figure 5 shows an interrupt handling routine that is activated by the output shaft rotational speed signal _N0 generated every revolution of the output shaft 14 (see second reference).The output shaft rotational speed (torque converter After calculating the output rotation speed) N ₀ , the gear position g of the transmission is detected from the signal G _s , and then this gear position g
The transmission output rotation speed, that is, the vehicle speed V, is calculated by multiplying by the output shaft rotation speed _N0 .

FIG. 6 shows a regular interrupt routine that is processed every fixed time ΔT. First, in step 41, the throttle opening signal TH is A/D converted, and the throttle opening TH is read. In the next step 42, it is determined from the idle _signal Is whether the idle switch 36 (see Figure 3) is OFF or ON, and when the idle switch 36 is OFF and the accelerator pedal is depressed,
The control proceeds to step 43, after which the torque converter is normally slip-controlled as follows.

That is, in step 43, the flag I is reset to 0 to indicate that normal slip control is in progress, and in the next step 44, the throttle opening is
Based on TH, gear position g, and vehicle speed V, it is determined whether the torque converter is in a driving range in which it should be in a converter state, in a lock-up state, or in a driving range in which slip control is to be performed. In step 45, which is the converter region, the output duty is set to 0%,
This is updated with the previous output duty in step 46. In this case, lockup 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, set the output duty to 100% in step 47, and then set it to 100% in step 46.
The output duty is updated with the previous output duty. In this case, the lock-up solenoid 25 is connected to the amplifier 47.
continues to be energized through the torque converter, allowing the torque converter to be locked up as required, as described above. If it is in the slip control region, the output duty is determined in step 48 by proportional (P) and integral (I) calculations based on the difference between the actual slip amount n _e -n ₀ of the torque converter and the set slip amount, and this is calculated in step 46 from the previous time. Update the output duty. In this case, the lock-up solenoid 25 is repeatedly energized and de-energized via the amplifier 40 with a time width corresponding to the output duty, and the torque converter can be subjected to slip control as described above.
Since this control is PI control, the torque converter brings the slip amount n _e −n ₀ to the set slip amount, and is maintained at this set slip amount.

By the way, if it is determined in step 42 that the idle switch 36 (see FIG. 3) is ON and the accelerator pedal is released, the control is transferred to step 49.
Then, slip control, which is the object of the present invention, is performed as follows. This slip control is the seventh
It is executed by the subroutine shown in the figure, and first the step
50, it is determined whether the vehicle speed V is 20 km/h or more. If V<20 Km/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 output duty is set to 0% in the next step 52. By returning control to step 46 in the middle and placing the torque converter in the converter state, vibrations during coasting can be suppressed by making full use of its torque fluctuation absorbing function.

If V≧20 Km/h or more, it is checked in step 53 whether the above-mentioned flag is set to 1 or not. If this flag is not 1, that is, if the car was previously running with power on without releasing the accelerator pedal and has now transitioned to coasting driving with the accelerator pedal released, it is set to indicate that coasting driving is in progress at step 54. At the same time, the flag is set to 1, and a counter that measures the duration of release of the accelerator pedal is cleared, and in the next step 55, the output duty is set to 0%, and the counter is set within the set time _T1 described later. Set the flag to 1 to indicate that the Thereafter, the control returns to step 46 in FIG. 6 at step 52, so that the torque converter is placed in the converter state with the output duty of 0%, thereby reliably preventing large engine torque fluctuations at the beginning of transition to coasting driving. Can be done.

If the flag is 1 in step 53,
In other words, if the vehicle was coasting the previous time, the above-mentioned counter is incremented in step 56, and in the next step 57, it is determined whether or not this counter indicates the set time T1 _or more. Setting time T ₁ (e.g. 0.4
(seconds) or more has elapsed. This set time T ₁ is set based on the time when large engine torque fluctuations to be absorbed due to the converter state of the torque converter are attenuated and reduced. Therefore, within the set time _T1 , the output duty is kept at 0% in step 58, the torque converter is maintained in the converter state, and large engine torque fluctuations during this period are continued to be absorbed, thereby preventing the occurrence of vibration. do.

After the set time _T1 has elapsed, the control proceeds to step 59, where it is determined whether the flag is 1, that is, whether or not the set time _T1 has just elapsed.
If so, in step 60, the output duty is set to a predetermined value of X%, and in the next step 61, the set time is
The flag is reset to 0 to indicate that after T ₁ has elapsed. Output duty predetermined value X%
is the output duty corresponding to the slip amount of the torque converter that can absorb the engine torque fluctuation at the instant of elapsed time T ₁ , for example, 50%.
shall be. In this way, the torque converter is placed in a slip state that absorbs the instantaneous torque fluctuations, and vibrations can be prevented from occurring.

After that, step 61 is executed, so step 59 selects step 62, and this step 62 skips step 63 and returns to step 52.
Until the output duty is selected, that is, the output duty is
The output duty is gradually increased by 1% by executing step 63 until it reaches 100%. This gradual increase in output duty causes the torque converter to gradually decrease its slip amount and reach a lock-up state. The rate of gradual decrease in the amount of slip does not have to be the above-mentioned 1% increments, but is determined to correspond to the rate of attenuation of the torque fluctuation to be absorbed. In this way, the torque converter's torque fluctuation absorbing function is controlled to gradually reduce the amount of slip so as to match the torque fluctuation to be absorbed after the set time _T1 , and by absorbing this torque fluctuation, vibration can be prevented from occurring.

The above operation is shown in a time chart as shown in FIG. 8 when both before and after coasting are in the lockup region. The output duty is maintained at 0% as indicated by H during the set time T1 from _the coasting start instant _t1 , and the torque converter is maintained in the converter state. Therefore, the torque converter can reliably absorb large engine torque fluctuations at the beginning of transition to coasting driving, and can prevent vibrations from occurring.

When the set time _T1 has elapsed, the output duty is set to a predetermined value X%, and the torque converter is brought into a corresponding slip state.Then, the output duty is then increased with a predetermined time gradient as shown by, and the torque converter is caused to slip by the amount Slip control is performed so that the amount is gradually decreased. This control matches the torque converter's torque fluctuation absorption function one by one with the attenuating engine torque fluctuation that should be absorbed after the set time T ₁ has elapsed, and during this period, the torque converter reliably absorbs engine torque fluctuations to prevent vibrations from occurring. can be prevented.

As a result of this slip control, the torque converter is placed in a slip-limited state during the T ₃ -T _{2 -T} hour, so although the engine speed decreases as shown by J, it is maintained above the fuel recovery rotation speed E. The sag time is extended, the fuel cut time can be extended from T _F1 to T _F2 , and the fuel cut device can enhance the fuel efficiency improvement effect and the exhaust countermeasure effect.

(Effects of the Invention) As described above, the slip control device of the present invention is configured to gradually reduce the slip amount of the torque converter after the set time _T1 has elapsed since the release of the accelerator _pedal . Even if it is a short time corresponding to the time when a large engine torque fluctuation occurs at the time of pedal release, the occurrence of vibration can be prevented as explained above,
Further, by shortening the set time _T1 in this way, it is possible to lengthen the time until the engine speed drops below the fuel recovery speed, and the fuel cut time can be extended.

[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. 3 is a block diagram of a microcomputer showing an example of the device of the present invention.
4 to 7 are flowcharts showing the control program of the microcomputer, and FIG. 8 is an operation time chart of the apparatus of the present invention. DESCRIPTION OF SYMBOLS 1... Engine, 2... Accelerator pedal, 3... Direct coupling clutch, 4... Torque converter, 5... Accelerator pedal release detection means, 6... Timing means, 7... Direct coupling clutch control means, 10... Pump impeller, 11...
Turbine runner, 12... Stator, 13... Turbine hub, 14... Torque converter output shaft, 15...
One-way clutch, 20...Converter chamber, 21
...Lockup chamber, 22...Torsional damper,
24... Slip control valve, 25... Lock-up solenoid, 27, 28... Orifice, 30... Central processing unit, 31... Random access memory, 3
2... Read-only memory, 33... Input/output interface circuit, 34... Engine rotation speed sensor, 35...
Torque converter output rotation speed sensor, 36... Idle switch, 37... Gear position sensor, 38... Waveform shaping circuit, 39... Throttle opening sensor, 40
…amplifier.

Claims (1)

[Scope of Claims] 1. In a torque converter that transmits power from an engine and increases the amount of slip by deactivating a direct coupling clutch for a set time after the release of the accelerator pedal of the engine. , an accelerator pedal release detection means for detecting the release of the accelerator pedal; a timer for measuring the duration of the release of the accelerator pedal; and after the set time, the torque converter causes the slip amount to be gradually reduced from the increased slip amount. 1. A slip control device for a torque converter, comprising direct coupling clutch control means for controlling the operation of said direct coupling clutch.