JPS6065952A - Lock-up control device of torque converter - Google Patents

Abstract

PURPOSE:To prevent a lock-up shock by changing a control constant of lock-up control means according to the result of comparison between the slip amount of a torque converter and at least a kind of a preset value at the time of shifting from a converter area to a lock-up area. CONSTITUTION:A lock-up clutch (d) of a torque converter (b) is in the connecting state when power from a prime mover (a) is transmitted directly to an output shaft (c), and the connection and disconnection of the clutch (d) is controlled by lock-up control means (e). In this case, slip amount detecting means (f) for detecting the slip amount of the torque converter is provided to compare the detection of the slip amount with at least a kind of a preset value (g) cy comparing means (h). At the time of shifting from a converter area to a lock-up area of the torque converter (b), according to the comparison result, a control constant of lock-up control means (e) is changed by control constant changing means (i).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a torque converter inserted into a power transmission system such as an automatic transmission, and particularly a lock-up torque converter capable of appropriately eliminating relative rotation (slip) between its input and output elements. This invention relates to a lock-up control device.

A normal torque converter transmits power by driving an output element (usually a turbine runner) through working fluid stirred by an input element (usually a pump impeller) driven by a prime mover, so it has a torque increasing function and absorbs torque fluctuations. Although this function provides good performance, relative rotation between the input and output elements, called slip, cannot be avoided, resulting in poor power transmission efficiency.

Therefore, in the operating state of the prime mover where the torque increase function and torque fluctuation absorption function are not required, the input and output elements are directly connected mechanically by a lock-up clutch, thereby eliminating the above-mentioned slip in the operating state and increasing the transmission efficiency. Lock-up torque converters are now being put into practical use. This type of torque converter is basically operated in a converge state in which the lock-up clutch is released in the operating state of the prime mover that requires a torque increase function and a torque fluctuation absorption function (converge region), and both functions are unnecessary. In the operating state of the prime mover, the lock-up clutch is engaged and operates in the lock-up state (lock-up region).
However, there are other ways that this type of pull-up torque converter can be controlled, such as allowing the prime mover to run at idle even in the lock-up region, or putting the lock-up torque converter in the converter state when the automatic transmission is in the neutral state. Lock-up control is performed so that the state changes frequently between the lock-up state and the lock-up state.

The lock-up clutch is normally configured to respond to the differential pressure between the lock-up pressure acting on its negative side and the converter pressure acting on the other side. Released and coupled when eliminating lockup pressure.

By the way, if the lock-up pressure is removed too quickly when switching from the converter state to the lock-up state,
The engagement speed of the lock-up clutch is also fast, and the torque converter produces lock-up shock. For this reason, an orifice is usually provided to gradually eliminate the lock-up pressure, but the reality is that even with this, the problem has not been solved.

That is, when the converter command is switched to the lockup command at instant t0 in FIG. 14, the lockup pressure decreases from a value equivalent to the converter pressure at a speed determined by the opening area of the orifice, and finally reaches the lowest value. At this time, the lock-up clutch starts actual engagement at instant t3, one hour after the lock-up pressure reaches a certain value, and completes engagement at instant t8, switching the torque converter from the converter state to the lock-up state. However, the lock-up pressure decreases in a quadratic curve with characteristics determined by its value and the opening area of the orifice, so the lock-up pressure decreases at an excessively high rate between instants t2 and t8, and the lock-up clutch's engagement torque The converter output torque has a peak torque α, which causes lock-up shock. 'However, if the opening area of the orifice is made small to prevent this, the time T
The lock-up torque converter becomes longer and the responsiveness of the lock-up control deteriorates, and during this time the rotational speed of the prime mover is kept high, resulting in deterioration of fuel efficiency and the fuel efficiency effect of using the lock-up torque converter becoming insufficient.

In the present invention, even if the lock-up clutch is operated rapidly until it actually starts to engage, it will not cause lock-up shock, and it should be operated rapidly in order to improve responsiveness, and after that, lock-up shock will not occur. The lock-up clutch should be operated at a slow speed to prevent this, and immediately before the lock-up clutch completes engagement, it should be operated at an even slower speed to completely eliminate lock-up shock (4).
), it is an object of the present invention to provide a lock-up control device for a torque converter that is capable of performing such lock-up control, for example.

For this purpose, the present invention provides a prime mover a as shown in FIG.
A lock-up torque converter that has both a transmission path that transmits the power from the engine to the output shaft C via the torque converter b, and a transmission path that directly transmits the power to the output shaft C via the lock-up clutch d, which is connected as appropriate. A torque converter lock-up system comprising a lock-up control means e that releases a lock-up clutch d when the operating state of the prime mover a corresponds to the converter region and engages the lock-up clutch d when the operating state of the motor a corresponds to the lock-up region. The control device includes a slip amount detection means for detecting the slip amount of the lock-up torque converter, a comparison means for comparing the slip amount with at least one set value g, and a slip amount detection means for detecting the slip amount of the lock-up torque converter, a comparison means for comparing the slip amount with at least one set value g, and a slip amount detection means for detecting the slip amount of the lock-up torque converter. The present invention is characterized in that it is provided with control constant changing means 1 for changing the control constant of the lock-up control means e in accordance with the comparison result.

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

FIG. 2 shows an embodiment of the lock-up control device of the present invention together with a lock-up torque converter for a vehicle automatic transmission to be controlled by the lock-up control device. foil,
Reference numeral 4 indicates a lock-up torque converter, and reference numeral 5 indicates a gear transmission mechanism.

The torque converter 4 includes a pump impeller (input element) 4a that is connected to the crankshaft 2 via a flywheel 8 and is constantly driven by the engine, a turbine runner (output element) 4b opposed to this, and a stake (reaction element). ) 4c, the turbine runner 4b is drivingly coupled to the output shaft (input shaft of the gear transmission mechanism 5) 7 of the torque converter 4, and the stator 4C is placed on a hollow fixed shaft 9 via a one-sided clutch 8. . The torque converter 4 supplies working fluid to its internal converter chamber 10 in the direction of arrow y, removes this working fluid in the direction of arrow 2, and closes the converter chamber by a pressure retaining valve (not shown) provided in the middle. 10
Maintain the pressure (converter pressure) Pc below the value inside the converter.

Thus, as described above, the pump impeller 4a driven by the engine stirs the internal working fluid, causes it to collide with the turbine runner 4b, and then flows through the stator 4c, during which time the torque of the turbine runner 4b is increased under the reaction force of the stator 4c. Rotate while rotating. Therefore, the power from the engine 1 is transmitted to the driving wheels via the torque converter 4, the output shaft 7, and the transmission mechanism 5, and the vehicle can be driven.

Further, the torque converter 4 has an input element 4a and an output element 4.
A lock-up clutch 11 is provided in order to provide a lock-up type that can be mechanically directly connected between b and 7. This is drive-coupled onto the output shaft 7 via a torsional damper 12, and is axially movable on the output shaft. Converter room 1o as possible
Separately, a lock-up chamber 18 is set within the torque converter 4. The lock-up clutch 11 is in the converter chamber 1
In response to the difference between the converter pressure Pc within 0 and the lockup pressure ``L/u'' within the lockup chamber 18, the element 4a moves to the left in the figure and uses a sword according to the differential pressure.

The slip of the torque converter 4 can be eliminated by drive-coupling between 4b and 4b.

The lock-up pressure "L/u" is adjusted by the slip control valve 14, but this valve is connected to the lock-up chamber 18.
14a and bow which leads to the front rudder converter pressure Pc)
14b and Dorenbo) 14c, spool 1
When 4d is in the neutral position shown, the boat 14a is moved between both boats l.
4b and 14c, and when the spool 14d moves to the right in the figure, the boat 14a becomes the bow) 14h, and when the spool 14d moves to the left in the figure, the boat 14a becomes the boat 14c.
shall be communicated with each other. And spool 14 (
1 is the lock-up pressure "L/u" that acts on the right end surface in the figure through the orifice 15, and the control pressure Ps that acts on the left end surface in the figure.
The control pressure P8 is created as follows in response to the differential pressure between the two.

That is, the transmission mechanism 5 is
The reference pressure (line pressure in the case of automatic transmission) that governs the gear shifting of P
L is supplied, and this line pressure is drained from the other end 16b of the circuit 16 via the refill 17.18, and the amount of drain is determined by the duty-controlled solenoid valve 19.
By creating a control pressure Ps between the two,

In normal state, the solenoid valve 19 is closed to the plunger 19 by the spring 19a.
When b is moved to the left in the figure, K closes the drain opening end 16b of the circuit 16, and each time the solenoid 19c is energized, the plunger 19b is moved to the rightward position as shown in the figure to open the drain opening end 16b. The above drainage shall be permitted. The solenoid 19c is energized by the lock-up control computer 20 as shown in FIG.
The duty control is performed so that it is performed during the pulse width C (on time) of the pulse signal as shown in bl. As shown in FIG. 8(a), when the duty (%) is small, the time during which the solenoid valve 19 opens the drain opening end 16b is short, so the control pressure P is equal to the line pressure P as shown in FIG. 4.

be equivalent to. Moreover, as the duty (%) increases as shown in FIG. 8 fb), the solenoid valve 19 starts to open the drain open end 16b for a long time, and therefore the control pressure P8 gradually decreases as shown in FIG. 4. However, it finally becomes a constant value determined by the difference in the opening area of the orifices 17 and 18.

In FIG. 2, as the control pressure P8 increases, this control pressure moves the spool 14d to the right as shown in FIG. 5(a), and gradually increases as shown in FIG. A constant value corresponding to the pressure Pc is set. As the control pressure Ps becomes lower, a lock-up pressure PL/
U moves the spoo #l4d to the left as shown in Figure 5 (bl) to connect the boat l4a to the boat 14c, and the lock-up pressure ``L/u'' is gradually decreased in the same relationship as above, until finally Then, when the lock-up pressure PL/u reaches a value corresponding to the control pressure P8, the slip control valve 14 returns the spool 14d to the neutral position shown in FIG. Keep this value to this lock
The pressure can be controlled by the control pressure PSE.

By the way, the control pressure P with respect to the duty (%)
8 is as shown in FIG. 4, and from this and the control pressure (Ps)-lockup pressure (PL/11) percentage relationship shown in FIG.
/. The change characteristics of are shown in FIG.

The lock-up control computer 20 is operated by a power supply v, and receives the engine rotation speed (
The output shaft rotation speed (vehicle speed) signal S from the output shaft rotation sensor z2 that emits a pulse signal corresponding to the output rotation speed of the transmission mechanism 5, the throttle opening sensor z8 Engine throttle opening signal STH'-
The gear position signal Sy from the gear position sensor 24 that detects the selected gear position of the transmission mechanism 5 and the engine cooling water temperature signal Sw from the water temperature sensor 25 are received, and the solenoid valve 19 is duty-controlled based on these force calculation results.

For this purpose, the computer 20 includes, for example, a microprocessor unit (MPU) as shown in FIG. 8(11).
) 26, a random access memory (RAM) 27, a read-only memory (ROM) 28, and an input/output interface circuit ('10) 29. The MPU 26 is connected to the sensors 21 to 2.
The solenoid valve 19 is duty-controlled by reading the signal from ``/'' through S9 and outputting the above calculation result to the drive circuit BO through 11029.
Since the signals S and S are pulse signals, a counter is needed to count the number of these pulses, and since the signal STH is an analog signal, an A/L converter is needed to convert it into a digital signal. Furthermore, since the result of the above calculation is a binary value, it is assumed that a counter is built-in for converting the result into a pulse signal for duty control.

The MPU 26 executes the control programs shown in FIG. 9 and FIG.
is determined as shown in FIG. 7 to control the operation of the lock-up clutch 11.

FIG. 9 shows a main routine, which is repeatedly executed at regular intervals of, for example, 100 ms. First, in step 81, it is determined based on the engine cooling water temperature signal Sw from the sensor 25 whether the engine cooling water temperature is higher or lower than, for example, 60° C., which is a standard for the completion of warm-up of the engine 1.

If it is low, the warm-up operation has not been completed and the engine output torque is unstable, so the control proceeds to step 82, where the output duty is set to 0%. At this time, lock-up pressure “L”
/u is set to a value equivalent to converter pressure Pc as shown in FIG. 7, and lock amplifier clutch 11 is released.
The torque converter 4 is in a converter state, and its torque fluctuation absorbing function absorbs fluctuations in engine output torque, and enables smooth power transmission even during warm-up operation.

If the engine cooling water temperature is high, the warm-up operation has been completed, so the control proceeds to step 8B, and normal lock-up control is executed as described below.

First, in step 8B, the transmission mechanism output rotation speed (vehicle speed) signal S from the sensor 22 is detected. r, the operating conditions of the engine 1 are determined based on the throttle opening signal STH from the sensor 28 and the gear position signal Sg from the sensor 24, and in the next step 84, the operating conditions are determined to bring the torque converter 4 into the converter state. Is it in the converter (%) area? Lockup (L/u) that should be in lockup state
It is determined whether it is in the area based on the map corresponding to the lockup area diagram in FIG. 12 (the diagonal line is the L/u area).

~ range, the lock-up clutch 11 is released as described above in step 82 to bring the torque converter 4 into the converting state as requested, and if the range is 14, step 85
It is determined whether or not there has been an area change. If there is no change, it means that the previous time was also in the L4 region, so the control proceeds to step 86, where it is determined whether the transmission mechanism 5 is changing gears based on whether or not the gear position signal S9 has changed.

If the gear is not being shifted, the output duty is set to 100% in step 87, and at this time the lock-up pressure PL/u is set to the minimum as shown in FIG.
1 is coupled, the torque converter 4 can transmit power in a lock-up state as required.

If it is determined in step 86 that the gear is being shifted, the control proceeds to step 8.
The process proceeds to step 8, where it is determined whether or not time T□ has elapsed since the start of the shift. This T□ time is the time from the start of shifting to the completion of shifting in the transmission mechanism 5, and since the shifting is not completed during the time T1, the torque converter 4 is kept in the converter state in the 14 range in step 82, and the shift shock is prevented. Prevent occurrence. After the T
control is executed to return the torque converter 4 from the released state to the coupled state and return the torque converter 4 from the converter state to the lock-up state.

If it is determined in step B5 that there has been an area change, from area 4 to L7. Therefore, the control proceeds from step 85 to step 89, where the output duty is changed from 0% to 100% (the lock-up clutch 11 is changed from the released state to the engaged state), and the torque converter 4 is turned on. Change from converter state to lockup state.

Incidentally, this step 89 is executed according to the control program shown in FIG. 1θ. First, in step 41, the number of revolutions No. of the engine 1 (the number of revolutions of the input element 4a) is calculated. In this calculation, the MPU 26 uses the signal Si from the sensor 21, but since this signal is a pulse signal as described above, the count value of the counter in the l1029 is held in the register every time the pulse is input. , calculate the engine rotation period by calculating the difference between the count values and calculate the engine rotation @N
Calculate E.

In the next step 42, the output rotational speed NT of torque converter 1 is calculated. In this calculation, MPtJz6 is the signal S from sensor z2. , but as mentioned above, this is also a pulse signal, so the engine rotation speed N. First, the output rotation speed of the transmission mechanism 5 is multiplied by the gear ratio corresponding to the selected gear position of the transmission mechanism 5 determined from the gear position signal Sg in the same manner as when the torque comparator (16) is set. The output rotation speed (rotation speed of the output element 4b) NT is calculated.

In the next step 4B, the slip amount of the torque converter 4, that is, the relative rotational speed ΔN between the input and output elements 4a and 4b is calculated by Δ
Based on the calculation of N''NENT, the slip amount ΔN and the set values N, , N are determined in the next step S44.

(where N, >N), the error between ΔN −N and ΔN
-N, is calculated.

In the next step 45, it is first determined whether the error ΔN-N is larger or negative than O, that is, whether the slip amount ΔN is larger or smaller than the set value N0.

If ΔN −N, ≧0, control proceeds to step 46;
Here, □ is set to Kp□ and 1□ to the proportionality constant and integral constant of p4 calculation, which will be described later. If ΔN-N is <0, control proceeds to step 47, where the error ΔN
-N is larger or smaller than O, that is, the slip amount Δ
It is determined whether N is larger or smaller than the set value N2. ΔN
−N ≧0, that is, N>ΔN≧K.

If 1, the control proceeds to step 48, where the proportional constant Kp is set to □ (where 1, <Kpo), and the integral constant Ki is set to 2 (where Ki, < Kpo). ΔN −N,
< 0, that is, ΔN < N2, the control proceeds to step 49, where the proportionality constant Kp is set to Kp8 (however, Kp8<Kp
2), and let K be the integral constant (however, 〈K1□
).

In this way, based on the parameters Kp and K□ of the P1 calculation, which are determined depending on whether the slip amount ΔN is greater than or equal to the set value N□, between the set values N, , N, or less than the set value N2, step At 50, the P1 calculation is performed as follows.

DUTY (lJEW) = DUTY (OLD)
+ K, -ΔXDUTY (OUT) = DUTY
(NEW) + Kp・ΔX However, DUTY (OLD
): Previous integral value DUTY (NEW'): Current integral value ΔX: Error between target slip amount and actual slip amount DUTY (OUT>: Output duty) The output duty determined by the P1 calculation is the 11th The lock-up pressure "L/u" increases each time the control program shown in the figure is repeated, and the lock-up pressure "L/u" is sequentially lowered to change from the converter state in which the torque converter 4 passes through a predetermined amount to the lock-up state, but during this period, the slip amount ΔN decreases to the set value N□. Until then, set the parameters Kp and K to large values, 0.K, □, and while the slip amount ΔN is between the set value N1.N, set the parameters Kp and K□ to small Kp, , K□, and When the slip amount ΔN is less than the set value N, the parameter Kp.

Kp8. Setting K□8 has the following advantages.

That is, to explain the operation time chart shown in FIG. 18 in the case of transition from the converter region to the lock-up region, from the region change instant t0 to the instant t2 when ΔN=N1.
(until the lock-up clutch 11 starts to engage), the large parameter Kp1. □, the output duty DUTY (OUT 'l) increases rapidly and the lock-up clutch is rapidly operated to the engagement start position, so the responsiveness of the lock-up control is improved by shortening the time T and fuel efficiency is improved. Until the slip amount ΔN reaches the set value Ns, that is, until the instant t8 when the lock-up clutch 11 starts to engage and reaches a state just before the engagement is completed, where lock-up shock is relatively likely to occur, the small parameter KpH' Kig is used. Output duty D
Since the rising speed of UTY (OtM') is slowed down and the operating speed of the lock-up clutch 11 is slowed down, the occurrence of lock-up shock can be prevented. After that, while the slip amount ΔN becomes less than the set value M2, that is, immediately before the moment t8 when the lock-up clutch 11 is fully engaged, when the lock-up shock is most likely to occur, the parameter KI) is even smaller.8. In addition, since the rising speed of the output duty DUTY (Ou'j) is further slowed down by 8, and the operating speed of the lock-up clutch is further slowed down, the lock-up shock can be reliably prevented from occurring during this time as well.

The output torque waveform of the engine 1 during such lock-up control is shown based on experimental data as shown in FIG. It turns out that it can be eliminated.

In the above example, when ΔN < N, the parameters Kp and K□ are set to the smallest value (20
) Kp8. K□8, but instead of this, feedback control is stopped and feedforward is performed so that the output duty DUTY (OU'I') per control is increased by, for example, 0.25% as shown in step 51 in Fig. 11. Needless to say, it may also be controlled.

Thus, as described above, the lock-up control device of the present invention adjusts the slip amount liN of the torque converter and at least one setting value N□ to bring the torque converter 4 from the converter state to the lock-up state during transition from the converter region to the lock-up region , N2 is configured so that the control constants , Ki are changed according to the comparison results with N2, so for example, as mentioned above, conflicting requirements such as increasing the responsiveness of lock-up control and preventing the occurrence of lock-up shock can be avoided. can be satisfied at the same time.

[Brief Description of the Drawings] Figure 1 is a conceptual diagram of the lock-up control device of the present invention, Figure 2 is a system diagram showing an embodiment of the device of the present invention, and Figures 8(a) and 8(b) are respectively A time chart showing how the duty changes outputted by the lock-up control computer in the device of the present invention, FIG. 4 is a change characteristic diagram of the control pressure with respect to the duty, and FIG. Figure 6 is an f-ratio characteristic diagram of lock-up pressure with respect to control pressure, Figure 7 is a change characteristic diagram of lock-up pressure with respect to duty, Figure 8 is a block diagram of a computer for lock-up control, and Figures 9 to 11. 12 is a flowchart showing the control program of the lock-up control computer, FIG. 12 is a line diagram showing the lock-up area of torque converter in the shift pattern of the gear transmission mechanism, FIG. 18 is an operation time chart of the device of the present invention, and FIG. The figure is an operation time chart of a conventional device. 1... Engine (prime mover a) 4... Lock-up torque converter 5... Gear transmission mechanism 7... Torque converter output shaft (C) lO... Converter chamber 11... Lock-up clutch (c3) 18... Lock-up chamber 14... Slip control valve 16... Control pressure generation circuit 19... Solenoid valve 20... Lock-up control computer 21...・Engine rotation sensor 22...Gear transmission mechanism output rotation sensor z8...Engine throttle opening sensor 24...Gear position sensor 25...Engine coolant temperature sensor 26...Microprocessor unit) (MPU) 27
...Random access memory (RAM) 28...
Read-only memory (ROM) 29...Input/output interface circuit (I, /6) 80...Drive circuit b...Torque converter e...Lockup control means f...Slip amount detection means g. ...Set value h...Comparison means 1...Control constant quality modification means. Patent applicant: Nissan Motor Co., Ltd. (24)

Claims (1)

[Claims] 1. A converter region of a lock-up torque converter that has both a transmission path that transmits power from the prime mover to the output shaft via a torque converter and a transmission path that transmits the power to the output shaft via a lock-up clutch that is appropriately coupled. In a lock-up control device for a torque converter, the lock-up clutch is released in an operating state of the prime mover corresponding to a lock-up region, and the lock-up clutch is engaged in an operating state of the prime mover corresponding to a lock-up region. slip amount detection means for detecting the slip amount of the torque converter; comparison means for comparing the slip amount with at least one set value; and lock-up control means according to the result of the comparison when transitioning from the converter region to the lock-up region. A lock-up control device for a torque converter, comprising: a control constant changing means for changing a control constant of the torque converter.