JPH02142970A - Lockup controller for torque converter - Google Patents

Abstract

PURPOSE:To perform the smooth clamping of a lockup piston by detecting reversal of a pressure level between a clamping side oil chamber and a releasing side oil chamber of the lockup piston, and outputting a command for checking any increase of clamping capacity. CONSTITUTION:At time of lockup, a clamping control pack (k) of a lockup control means (h) gradually increases the clamping capacity of a lockup piston (d) in a range from lockup command starting to a reversal time when hydraulic pressure in a clamping side oil chamber (f) goes over a releasing side oil chamber (g). When reversal of a pressure level with a stroke of the lockup piston (d) is detected by a pressure reversal detecting part (j), an increasing rate of the clamping capacity is held down to smaller than up to the reversal time till an actual slip value being detected by a slip value detecting part (i) comes to the setting slip value, and after it becomes less than the setting slip value, feedback control is carried out so as to cause the actual slip value to become the desired value. Thus, vibrations at time of slip clamping starting can be prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a lock-up control device for a torque converter applied to a drive power transmission system of an automatic transmission for a vehicle.

(Prior Art) Conventionally, as a lock-up control device for a torque converter, a device as described in, for example, Japanese Unexamined Patent Publication No. 59-217056 is known.

This conventional device is designed to prevent lock-up shock caused by sudden engagement of the lock-up piston when the lock-up pressure is removed and the lock-up is released to the lock-up engaged state at the time of the lock-up command. A duty control valve is used as a feedback control to monitor the amount of slip between the input and output elements and transition from the slip engagement state to the lockup engagement state.

(Problem to be solved by the invention) However, in such a conventional lock-up control device, while monitoring the difference △N between the engine rotation speed N6, which is the slip I, and the turbine rotation speed N, this difference is Δ
Since feedback control was performed so that N matches the target value, a command to increase the engagement capacity continues to be output even during the lock-up piston stroke where ΔN does not change, and ΔN begins to change. At the start of slip engagement, the engagement capacity becomes larger than necessary, which results in sudden and slow engagement of the lock-up piston, leaving the problem that vibrations occur in a portion of the damper of the lock-up piston.

That is, the characteristics during lock 7 pump control are as shown in the time chart shown in FIG.

In particular, when slip engagement control is performed at a low gear with a large gear V ratio, vibrations in a part of the damper of the lock-up piston are amplified by the gear train of the automatic transmission, resulting in large fluctuations in the lock-up piston torque TP. Hail.

The present invention has been made in view of the above-mentioned problems, and aims to develop a lock-up control device for a torque converter that effectively prevents vibrations generated in a part of the damper of the lock-up piston at the start of slip engagement. Take it as a challenge.

(Means for Solving the Problems) In order to solve the above problems, in the lock-up control device for a torque converter of the present invention, as shown in the diagram corresponding to claims in FIG. ,
A torque converter e provided with an output element C driven via hydraulic oil, a lock-up piston d that can directly connect the input/output elements c, and a fastening formed by sandwiching the lock-up piston d. It is connected to the side oil chamber f and the release side oil chamber 9, and when a lock-up command is issued, both chambers f,
In the lock-up control device for a torque converter, the torque converter lock-up control device is provided with a lock-up control means for transitioning from a slip engagement state to a lock-up engagement state by pressure control of at least one of the locks 7 and 9, wherein the lock-up control means is A slip amount detection section i that detects the slip amount of the input/output elements S and c, and a pressure reversal detection section j that detects the reversal of the pressure levels between the engagement side oil chamber f and the release side oil chamber 9.
Then, from the start of the lockup command until the time of reversal when the oil pressure in the engagement side oil chamber f exceeds the oil pressure in the release side oil chamber 9, a tightening capacity increase command is output to gradually increase the engagement capacity, and from the time of reversal, the actual slip amount is increased. Until the actual slip amount reaches the set slip amount, a fastening capacity suppression command is output to suppress the increase rate of the fastening capacity to a smaller value until the time of reversal, and after the actual slip amount becomes less than the set slip amount, the actual slip amount and a lockup engagement control section that outputs a predetermined feed puncture control command while monitoring the actual slip amount so that the actual slip amount matches the target slip amount.

(Function) When a lock-up command is issued, the lock-up engagement control section k of the lock-up control means gradually increases the engagement capacity from the start of the lock-up command until the time when the oil pressure in the engagement side oil chamber exceeds the oil pressure in the release side oil chamber. A tightening capacity increase command is output to reduce the amount of slip, and a tightening capacity suppression command is output to suppress the increase rate of the tightening capacity to a smaller value until the actual slip amount reaches the set slip amount from the time of reversal. After the slip amount becomes equal to or less than the set slip amount, a predetermined feedback control command is output while monitoring the actual slip amount so that the actual slip amount matches the target slip amount.

Therefore, the reversal of the pressure levels between the engagement-side oil chamber and the disengagement-side oil chamber as the lock-up piston strokes is detected by the pressure reversal detector j, and based on this detection, the engagement Since the command to suppress the increase in capacity is output, it is possible to prevent the tightening capacity from becoming excessively large than necessary at the start of slip tightening when the amount of slip starts to change.

(Example) Embodiments of the present invention will be described below based on the drawings.

First, the configuration will be explained.

FIG. 2 shows a lock-up control device for a torque converter according to an embodiment, and the torque converter 1 is connected to an engine (not shown).
A pump impeller 2 (input element) driven by a drive source), a turbine runner 3 (output element) driven via hydraulic oil, a stator 5 fixed to the case via a one-way clutch 4, and the pump A lock-up piston 6 that can directly connect the impeller 2 and the turbine runner 3 is provided.

In addition, the turbine runner 3 and the intake piston 6
A clutch damper 7 using a torsion spring is provided between the clutch damper 7 and the clutch damper 7 to suppress excessive torque fluctuations during lock-up engagement.

An apply pressure oil passage 10 is provided in the lock-up apply pressure chamber 8 (closing side oil chamber) and the lock-up release pressure chamber 9 (release side oil chamber) that are formed by sandwiching the lock-up piston 6.
and the release pressure oil passage 11 are connected, and these oil passages ? 0
．． +1, a lock-up control valve 12, a torque converter relief valve 13, a lock-up solenoid valve 14, and the like constitute a lock-up hydraulic control section.

The aforementioned two-port pump control valve 12 is an oil passage switching valve that performs lock-up release, slip engagement, and lock-up engagement, and has a spool T2b and a plug in the valve hole 12a. 2c, sleeve 12d and spring 1
2e, and the valve hole 12a has ports +2f, 12
g, 12h, 12i+2j, 12, 12f2. ,+2
m is formed.

The port 12f communicates with the pilot oil passage 15, and pilot pressure PP is supplied when the lock-up solenoid valve 14 is OFF, and drained when the valve 14 is ON. Also, port 129 is a drain boat,
Ports 12h and 12m are ports that communicate with release pressure oil passage 11, port 12i is a port that communicates with torque converter pressure oil passage 16, port 12j is a port that communicates with apply pressure oil passage 10, and port 12 is a port that communicates with the oil cooler 17 along with ports +2i and T2j, and port 12β is a port to which pilot pressure Pp is always supplied.

The torque converter relief valve 13 is a valve that prevents the torque converter pressure P□ from becoming excessive.
The valve hole 13a is provided with a sub-rule 13b with an oil hole and a spring 13c, and when the torque converter pressure P from a pressure regulator valve (not shown) is high, the upper limit pressure is determined by a drain.

The lock-up solenoid valve 14 is a valve that closes when the solenoid is OFF to supply pilot pressure PP to port +2f, and opens when the solenoid is ON to train pilot pressure PP.

Further, a lock-up electronic control unit is configured by using a lock-up duty solenoid 20 provided in the lock-up solenoid valve 14 as an actuator, an AT control unit 21 that issues commands to the solenoid 20, and a sensor neck that provides various input information. There is.

The sensors include an engine rotation speed sensor 22 that detects the engine rotation speed NE, and a transmission output shaft rotation speed N. AT output shaft rotation speed sensor 23 detects the throttle opening TH, and a throttle opening sensor 24 detects the throttle opening TH.
, a pressure reversal switch 25 for detecting reversal of the pressure levels between the lock-up apply pressure chamber 8 and the lock-up release pressure chamber 9 is provided.

Note that the contact point of the pressure reversal switch 25 is connected to the apply pressure oil line 1.
It is comprised of a spool 26 (installed inside the valve unit or in the parts constituting the circuit, such as in the converter housing, oil pump, etc.), to which hydraulic pressure from the 0 and release pressure oil passages 11 acts on both end faces.

The AT control unit 21 includes a shift control program that performs shift control by outputting a command to a shift solenoid according to predetermined shift point characteristics, and a shift control program that performs shift control by outputting a command to a line pressure duty solenoid according to predetermined line pressure characteristics. In addition to a line pressure control program that performs pressure control, a lock-up control program that performs lock-up control by outputting commands to the lock-up device 20 according to a predetermined intake/unload schedule as shown in FIG. 3, for example, is incorporated. It is.

That is, the lock-up hydraulic control section and the lock-up electronic control section together constitute a lock-up control means that moves from the sleeve engagement state to the lock-up engagement state at the time of a predetermined lock-up instruction. .

Next, the effect will be explained.

First, in the lockup schedule shown in Figure 3, 4
When entering the lock-up region from the high-speed torque converter region, or when entering the half region set on the low-speed side of the lock-up region, the half-clutch state is maintained for a while due to slip engagement, and then the transition to the lock-up region occurs, so-called half lock. Up control is performed.

Next, the flow of the lock-up control operation started by the lock-up command issued when entering the half region will be explained based on the flow chart of FIG. 4 and the time chart of FIG. 7.

In step 40, input signals from each sensor are read.

In step 41, it is determined whether the current vehicle state is in the half region based on the throttle opening TH, the vehicle JV (=transmission output shaft rotational speed N), and the lock-up schedule.

If the current vehicle state is in the half region, the process proceeds to step 42, where the slip amount ΔN is calculated using the following equation.

ΔN　”　N　E　N　r NE-No-G However, N□, turbine rotation speed, G, gear ratio.

In step 43, it is determined whether the signal from the pressure reversal switch 25 is ON.

When the signal from the pressure reversal switch 25 is OFF, an initial lockup duty is output in step 44,
In step 45, it is determined whether the time t from the start of output of the initial lockup duty is less than or equal to the set time T.

That is, when the vehicle state enters the half region and the lock-up command is started, the signal from the pressure reversal switch 25 becomes O.
Until the change from FF to ON (within the set time T), the time t shown in FIG. As shown from to tl, an initial up/down duty that increases the duty ratio at a constant increasing slope from the initial duty value is output.

Then, as the lock-up piston 6 strokes, the lock-up apply pressure PA exceeds the lock-up release pressure PR, and the signal from the pressure reversal switch 25 turns OFF.
When it changes from F to ON, step 43 to step 4
6, and in step 46, a constant lockup duty with a constant duty ratio is output.

In step 47, it is determined whether the slip amount ΔN has become smaller than the preset slip amount ΔN, and the constant lock-up duty output is continued until ΔN becomes smaller than ΔN1 (see FIG. 7). time tl
~tz).

When ΔN<ΔN1, the process proceeds to step 48 and thereafter, and a feedback command is output to increase, decrease or maintain the duty ratio so that the slip amount ΔN matches the target slip amount ΔN2 (after time t2 in FIG. 7).

That is, when ΔN≦△N, ±α, the process proceeds to step 46 and the duty ratio is held; when △N>ΔN2+α, the process proceeds to step 50, where the duty ratio is increased and △N<△N2
-α, the process proceeds to step 51 and the duty ratio is decreased.

The relationship between the differential pressure between the lock 7 and apply pressure PA and the lock up release pressure PR with respect to the lock up duty shows the characteristics shown in Fig. 5, and the lock up apply pressure P
The relationship between the differential pressure between A and the lockup release pressure PR and the lockup capacity shows the characteristics shown in FIG.

As explained above, in the lock-up control device for the torque converter of the embodiment, by detecting the pressure reversal between the lock-up apply pressure PA and the lock-up release pressure PFl, the lock-up control device of the torque converter according to the embodiment is able to lock up the lock-up control device with no change in the slip amount ΔN. Since a command to maintain the fastening capacity is output during the stroke of the up piston 6, it is possible to prevent the fastening capacity from becoming excessively large at the start of slip fastening when the slip amount ΔN begins to change. Therefore, the lock-up piston 6 is smoothly engaged, and vibrations generated in the clutch damper 7 of the lock-up piston 6 at the start of slip engagement can be effectively prevented.

That is, as shown in the characteristics of the lockup piston torque Tp in FIG. 7, torque fluctuations that cause vibrations during lockup control are suppressed.

In particular, when performing slip engagement control at a low gear with a large gear ratio, vibrations in a part of the damper of the lock-up piston are amplified by the gear train of the automatic transmission, resulting in large fluctuations in the lock-up piston torque Tp. Therefore, it is a very effective technique when applied not only to lock-up control in 4th gear as shown in the embodiment, but also to lock-up control in low gears below 3rd gear.

Although the embodiment has been described above based on the drawings, the specific configuration is not limited to this embodiment, and even if there is a design change within the scope of the gist of the present invention, it is included in the present invention. .

For example, in the embodiment, an example of a pressure reversal switch that is mechanically operated as a pressure reversal detection unit was shown, but it is also possible to directly detect oil pressure with a pressure sensor and input it to the AT control unit as an electrical signal to monitor pressure reversal. It's okay to have a means.

In addition, in the embodiment, an example was shown in which a command to maintain the duty ratio is output from the time of reversal until the actual slip amount reaches the set slip amount in order to suppress the increase rate of the engagement capacity to a smaller value until the time of reversal. The engagement capacity may be suppressed by setting the duty ratio increase rate to be sufficiently smaller than the duty ratio increase rate at the initial duty, or by outputting a command to slightly decrease the duty ratio.

In addition, in the embodiment, the lock-up hydraulic control is set to 0.
Although an example has been shown in which duty control is performed based on the N-OFF time ratio, hydraulic control may be performed using current value control.

(Effects of the Invention) As explained above, in the lock-up control device for a torque converter of the present invention, by detecting the reversal of the pressure levels between the engagement side oil chamber and the release side oil chamber, the amount of slip can be reduced. By outputting a command to suppress the increase in engagement capacity during the stroke of the lock-up piston, which does not change, it is possible to prevent the engagement capacity from becoming excessively large than necessary at the start of slip engagement, when the amount of slip begins to change. , As a result, the lock-up piston is tightened smoothly,
It is possible to effectively prevent vibrations generated in a part of the damper of the lock-up piston at the start of slip engagement.

[Brief explanation of the drawing]

Fig. 1 is a complaint correspondence diagram showing a lock-up control device for a torque converter according to the present invention, Fig. 2 is an overall view showing a lock-up control device for a torque converter according to an embodiment, and Fig. 3 is a diagram showing a lock-up schedule in the embodiment device. FIG. 4 is a flowchart showing the flow of lock-up control operation in the embodiment device, FIG. 5 is a piston differential pressure characteristic diagram with respect to lock-up duty, and FIG. 6 is a diagram showing lock-up capacity with respect to piston differential pressure. FIG. 7 is a time chart showing each characteristic during lock-up control in the embodiment device, and FIG. 8 is a characteristic chart showing each characteristic during lock-up control in the conventional device. ... Drive source ... Input element ... Output element ... Lock 7, engine piston ... Torque converter ... Closing side oil chamber ... Release side oil chamber ... Lock-up control means ... Slip amount detection section -- Pressure reversal detection section ... Lockup tightening control section

Claims (1)

[Scope of Claims] 1) A torque converter provided with an input element driven by a drive source, an output element driven via hydraulic oil, and a lockup piston that can directly connect the input/output element; It is connected to an engagement side oil chamber and a release side oil chamber formed across the lockup piston, and when a lockup engagement command is issued, the pressure of at least one of both chambers is controlled to pass through a slip engagement state and enter a lockup engagement state. In a lockup control device for a torque converter, the lockup control device includes a slip amount detection section that detects a slip amount of the input/output element, and a slip amount detection section that detects a slip amount of the input/output element, and a slip amount detection section that detects a slip amount of the input/output element, and a slip amount detection section that detects a slip amount of the input/output element, and A pressure reversal detection part detects the reversal of the pressure level with the oil chamber, and a pressure reversal detection part is used to gradually increase the engagement capacity from the start of the lockup command until the time of reversal when the oil pressure in the engagement side oil chamber exceeds the oil pressure in the release side oil chamber. A fastening capacity increase command is output, and from the time of reversal until the actual slip amount reaches the set slip amount, a fastening capacity suppression command is output to suppress the increase rate of the fastening capacity to a smaller value until the time of reversal, and the actual slip amount is set. and a lock-up engagement control section that outputs a predetermined feedback control command while monitoring the actual slip amount so that the actual slip amount matches the target slip amount after the slip amount becomes equal to or less than the target slip amount. Features a torque converter lock-up control device.