JP3480027B2 - Fluid operated friction element fastening control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid-operated friction element such as a clutch or a brake which is involved in power transmission in a power transmission device such as an automatic transmission and which is appropriately operated (fastened). The present invention relates to a fastening control technique for a fluid transmission device that the user has.

[0002]

2. Description of the Related Art When a fluid-operated friction element such as a lock-up clutch is subjected to engagement control (slip control) depending on slip, in order to eliminate the influence of a dead zone on the control,
Open control such as precharge control and lamp control, and P
It is necessary to perform control while switching between feedback control such as ID control. The reason is that the feedback control cannot be established if there is no correlation between the control command value and the output of the control system.

As a conventional technique for performing the slip lock-up control of the lock-up clutch, for example, a predetermined switching line (threshold value) is set for the slip rotation speed of the lock-up clutch to switch the open control / feedback control. Some of them are carried out based on the result of the comparison of the value on the switching line and the current slip rotation speed.

Further, as another conventional technique, the lock-up application area is widened by reducing the speed of the lock-up application area or enabling the lock-up at a plurality of shift stages of the automatic transmission, and the lock-up clutch is In order to optimize the time until engagement, as shown in FIG. 7, the switching line (slip rotation speed threshold 1) when the lockup clutch is engaged from the torque converter state is set to the slip rotation speed at the start of precharge control. From a predetermined amount (eg 20
%) Is set to a reduced value, feedback control (PID control) is performed when the slip rotation speed falls below that value, and then the slip rotation speed is set to a predetermined value (for example, 20 rp).
m; there is a system in which the ramp control is started when the slip rotation speed threshold value 2) is exceeded, and the lockup clutch is released by the ramp control when the slip rotation speed exceeds the slip rotation speed threshold value 1.

[0005]

In order to realize a low speed or wide area of the lockup application area, the switching line for the slip rotation speed is fixed to a certain value and the open control / feedback control is performed by the switching line. It is difficult to optimize the time until fastening with the conventional technology that determines when to switch. Further, in the conventional technology that determines the timing of switching between the open control and the feedback control by using the reduction amount from the slip rotation speed at the start of control, the slip rotation speed changes regardless of whether the lockup clutch is controlled. There is a risk of malfunctioning during operation.

For example, when the slip rotation speed is controlled so as to reach a target value as shown in FIG. 8, the slip rotation speed decreases with a change in the motion state of the vehicle such as during acceleration of the vehicle. In this case, although the slip rotation speed does not change due to the effect of the control on the lockup clutch, when the slip rotation speed falls below the switching line (slip rotation speed threshold value 1), it is still in the dead zone. However, it is judged that the dead zone has been removed, and the open control (pre-charge control) is ended and the feedback control is switched to. As a result, as shown in FIG. 8, the control becomes uncontrollable due to the influence of the dead zone, resulting in excessive output due to PID control, which causes problems such as worsening of engagement shock, sticking of the lockup clutch, and deterioration of control stability. .

In order to solve the above problem, a method of determining the switching line by referring to the map based on the vehicle speed, the throttle opening, etc. can be considered, but in that case,
Considering the slowdown and widening of the lock-up application area, it is necessary to perform matching in an extremely wide range, and further, disturbances that are difficult to predict and detect, such as the slope of the road, are expected to cause a problem. Many are difficult to achieve.

The present invention provides a technique for constantly switching between open control and feedback control at optimum timing without being affected by changes in the slip rotation speed due to changes in the operating state of the vehicle, which are irrelevant to the control for the lockup clutch. It is intended to provide and thus solve the above problems.

[0009]

To this end, a fastening control device for a fluid actuated friction element according to the present invention comprises a fluid transmission device for transmitting a driving force from an engine, as shown in the concept of FIG. In an automatic transmission comprising a fluid-operated friction element that is installed in parallel with the fluid transmission and can limit a slip operation of the fluid transmission, an input transmission speed to the fluid transmission and the fluid-operated friction element is changed. Input rotation speed detection means for detecting, slip rotation speed detection means for detecting the slip rotation speed of the fluid-operated friction element, slip rotation speed control means for controlling the slip rotation speed, and slip rotation speed control means Control command value calculating means for calculating a control command value for, a fastening force control means for controlling a fastening force of the fluid operated friction element, the fluid transmission device and the fluid operated friction element An input torque detecting means for detecting an input torque, with comprises an automatic transmission control device having a slip torque detecting means for estimating a slip torque generated in accordance with the slip operation of the fluid power transmission device,
A mechanical model constructed by the input torque to the fluid transmission device and the fluid operation friction element, the slip torque, the engine speed, and the output speed of the fluid transmission device when the fluid operation friction element is engaged. And a control means for estimating the shared torque of the fluid-operated friction element based on the above and comparing the shared torque with a predetermined value so as to switch at least two kinds of control logics. is there.

[0010]

The fluid actuated friction element makes a loss stroke by the fluid pressure supplied by the precharge control, and is completely engaged by the further fluid pressure supply. In the meantime, the dead stroke of the control is caused by the loss stroke, and if the control logic is switched when the current control system is in the dead zone, the control becomes uncontrollable.

Therefore, in the present invention, the input torque to the system in which the fluid transmission device and the fluid-operated friction element are arranged in parallel, the slip torque generated according to the slip operation of the fluid transmission device, the engine speed, and A dynamic model is constructed based on the output speed of the fluid transmission, the shared torque of the fluid-operated friction element is estimated from the dynamic model, and the end of the loss stroke is judged based on this shared torque. The control logic is switched at the time of judgment.

Therefore, the timing for switching the control logic from the precharge control, which is an open control, to the PID control, which is a feedback control, is always an appropriate timing regardless of changes in operating conditions. Therefore, there is no problem such as deterioration of engagement shock, sticking of lock-up clutch, deterioration of control stability, etc. due to excessive output by open control when control is impossible, and the map is based on vehicle speed, throttle opening, etc. There is no need to perform a complicated matching operation when determining the switching line by referring to the above.

In the above construction, a torque converter and a lock-up clutch are used as the fluid transmission device and the fluid-operated friction element, respectively, and the slip torque detecting means is an input rotation to the torque converter and the lock-up clutch. Number, the output speed of the torque converter, and the characteristic of the torque converter, the slip torque is estimated, and the control means locks the slip torque based on a difference value between the slip torque and the input torque to the torque converter and the lockup clutch. Estimate the up-clutch share torque, and if this lock-up clutch share torque is less than a predetermined value, it is judged that the current control system is in the dead zone. There are two types based on these judgments Preferably configured so as to switch the control logic.

Further, in the configuration, when it is determined that the current control system is in the dead zone, the control logic is set to open control, and when it is determined that the current control system is in the controllable area, the control logic is fed back. Preferably, it is configured to switch to control. Further, in the configuration, when the lockup clutch sharing torque is less than the predetermined value even though the control command value is within the predetermined range, the current control system is in the dead zone due to the loss stroke of the lockup clutch. It is preferable that the precharge control is performed when it is determined that there is a certain amount, and then the loss stroke is determined to end when the lockup clutch sharing torque reaches a predetermined value, and the control is switched to the PID control.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 shows an embodiment of the device of the present invention applied to the engagement control of the lockup clutch in the torque converter. In the figure, 10 is an engine, 11 is its crankshaft, 12 is a flywheel, and 13 is the torque of an automatic transmission. A converter, 14 is an input shaft leading to a gear transmission mechanism of an automatic transmission.

The torque converter 13 has an input element (pump impeller) 13a driven by an engine and an output element (turbine runner) 13b installed opposite thereto as main constituent elements, and a lockup clutch 13c for directly connecting these input and output elements appropriately. have. The output element (turbine runner) 13b and the lock-up clutch 13c are drivingly connected to the transmission input shaft 14, respectively, and the torque converter 13 is supplied with the working fluid from the oil pump 15 and is supplied via the pressure-holding valve 16 to the working fluid. Is constantly drained to keep the converter pressure Pc in the torque converter 13 constant.
Full of working fluid. Therefore, the torque converter 13 fluidly drives the output element 13b via the internal working fluid by the input element 13a driven by the engine to transmit the engine power to the transmission input shaft 14, and when the lockup clutch 13c is engaged, the degree of engagement is changed. It is assumed that the ratio of directly transmitting the engine power to the transmission input shaft 14 mechanically in addition to the fluid drive is increased at a corresponding ratio.

The engagement control of the lockup clutch 13c is performed by the lockup control pressure Pu in the chamber 13d, and the lockup control pressure Pu is determined by the lockup control valve 17. The lock-up control valve 17 is constructed, for example, as shown in FIG. 2 of JP-A-5-296337, and stroke control is performed on a spool (not shown) by the pressure balance of the converter pressure Pc, the electronic control pressure Ps, and the lock-up control pressure Pu. As a result, the lockup control pressure Pu is adjusted. That is, when the electronic control pressure Ps disappears, the lockup control pressure Pu becomes equal to the converter pressure Pc, the lockup clutch 13c is released, and the electronic control pressure Ps is released.
As the lock-up control pressure Pu decreases as s rises, the engagement force of the lock-up clutch 13c increases, and when the electronic control pressure Ps exceeds a certain value, the lock-up control pressure Pu is maintained at 0, and the lock-up clutch 13c Is completely concluded.

The electronic control pressure Ps is controlled by the duty solenoid valve 19 using the line pressure as a base pressure. The opening of the duty solenoid valve 19 is controlled according to the drive duty D from the controller (automatic transmission control device) 21, and the opening is maximized at the duty D = 0% to eliminate the electronic control pressure Ps. As D increases, the opening is decreased to gradually increase the electronic control pressure Ps, and D = 100%
Finally, the drain port 18c is fully closed and the electronic control pressure P
Let s be the same maximum value as the line pressure PL.

With the above configuration, in the system of FIG. 2, the duty D is set to 0% and the torque converter 13 is set.
From the state (converter state) in which the lock-up clutch 13c of FIG. Depending on D), relative rotation (slip) between the input and output elements of the torque converter 13 can be limited or eliminated to achieve the slip control state or lockup state of the torque converter.

A signal from a torque sensor 22 for detecting an engine output torque (input torque to the torque converter 13 and the lockup clutch 13c) T1 in order to determine the drive duty D of the duty solenoid valve 19 is supplied to the controller 21. A signal from a torque sensor 23 that detects a transmission input shaft torque (torque converter output torque) T2, an engine speed (torque converter 1
3 and the input speed to the lockup clutch 13c)
The signal from the engine rotation sensor 24 that detects N1, the output rotation speed of the torque converter 13 (the turbine runner 13
The signal from the turbine rotation sensor 25 that detects the rotational speed b) N2, the signal from the vehicle speed sensor 26 that detects the vehicle speed Vsp, and the signal from the throttle opening sensor 27 that detects the throttle opening Tvo are input.

The controller 21 is operated by the power source + V, and executes the control program shown in FIG. 3 based on the input information, so that the lockup clutch engagement control aimed at by the present invention, that is, the lockup clutch 13c.
Control for switching between open control (for example, precharge control) and feedback control (for example, PID control; torque converter slip control and lockup control).

In FIG. 3, first, at step 51, it is judged whether or not the current state maintaining mode is in effect based on, for example, the vehicle speed Vsp and the throttle opening Tvo. For this determination, for example, a map as shown in FIG. 4 (which is the same as FIG. 4 of Japanese Patent Laid-Open No. 5-231531) is searched by Vsp and Tvo, and the current control area is a lockup (LU) area and slip ( It is determined which of the (SL) region and the converter (CV) region is applicable, and if there is no movement between the control regions (for example, a state change across the boundary between the two regions like CV ← → SL in the figure), the current state If it is determined that the mode is the maintenance mode, the control proceeds to step 52 and subsequent steps, and if there is movement, it is determined that the current state maintenance mode is not performed and the control proceeds to step 53 and subsequent steps.

In step 53, it is determined whether or not the lockup clutch 13c should be engaged by the same region determination as above. By this judgment, the current control area is CV
If it is a region, it is a region where the torque converter 13 should be in a converter state in which slip limitation is not performed. Therefore, the control proceeds to step 54 and the lockup drive duty D is set to 0.
The lockup clutch disengagement control is performed at a rate of%, and if it is outside the CV range, it is the range where the torque converter 13 should be slip limited. .

In step 56 following step 55, it is determined whether or not the lockup clutch shared torque estimated value obtained as described above exceeds a predetermined value (for example, the lockup clutch shared torque estimated value threshold value shown in FIG. 6). If it is determined and exceeded, feedback control (PID control) is performed in step 57 as shown in FIG. 6, and if not exceeded, open control (precharge control) is performed in step 58. These feedback control and open control are
It is repeatedly executed until the slip rotation speed (N1−N2) reaches the target value shown in FIG. 6 by the determination of step 59 following step 57, step 58, and step 54, and ends when the target value is reached. The precharge control is for causing the loss stroke of the lockup clutch to be performed in the shortest time within a range in which engagement shock does not occur, and is performed, for example, with a waveform as shown in FIG.

On the other hand, in the case of the current state maintaining mode in which the control proceeds from YES in step 51 to step 52, in step 52, it is determined whether or not the lockup clutch 13c should be slip-locked up by the same region determination as above. Make a decision. In this determination, if the current control region is the SL region, the control proceeds to step 60 and the torque converter 1
The slip lock-up control is executed for No. 3 to control the lock-up slip to a constant value, and if not in the SL region, the control proceeds to step 61. In step 61, it is determined whether or not the lockup clutch 13c should be locked up by the same region determination as above. In this determination, if the current control area is the LU area, the control proceeds to step 62 to maximize the lockup pressure for the torque converter 13, and if it is not the LU area, the control proceeds to step 63 to lock the torque converter 13. Minimize the up pressure. The control in steps 60, 62, and 63 is based on the determination in step 59 following these steps to determine the slip rotation speed (N1-N
2) is repeatedly executed until the target value shown in FIG. 6 is reached, and ends when the target value is reached.

Next, the lockup clutch sharing torque estimation logic will be described. Now, considering a behavior of the dynamic system in a steady state by constructing a dynamic model as shown in FIG. 5, the input torque T1 to the torque converter 13 and the lockup clutch 13c is determined by the dynamic model and the torque converter characteristics. , Torque converter output torque T2, pump impeller torque Tinp, turbine runner torque Ttur, and clutch sharing torque T
Each 1 clt is represented as follows. T1 = Tinp + T1clt (1) Tinp = τ (e) N1 ² (2) Ttur = t (e) Tinp (3) T1clt = T2clt (4) T2 = Ttur + T2clt (5) However, e = N1 / N2 (speed ratio) And (e) is e
It is a function of.

From the above equations (1) and (2), equation (6) is obtained. T1clt = T1−τ (e) N1 ² (6) This equation (6) is used to calculate the input torque T1 and the input rotation speed N1 to the dynamic system, and the torque converter output rotation speed N2.
And that the torque converter characteristics are known, it is possible to estimate the shared torque T1clt of the lockup clutch. This means that the input torque T1 to the dynamic system is
And the slip torque generated according to the slip operation of the torque converter are equivalent to being able to estimate the shared torque T1clt of the lockup clutch.

In the transient state, the above equation (6) is the following equation in which the inertia component on the input side of the engine, the torque converter, and the lockup clutch is added: T1clt = T1−τ (e) N1 ² −I · dN1 / dt (7) (where dN1 / dt represents the first derivative of N1). At this time, the torque capacity coefficient τ expressed as a function of the speed ratio e can be approximated by a steady-state value because the behavior of the fluid system changes sufficiently faster than the behavior of the dynamic system.

By the way, the dead zone refers to a state in which the shared torque of the lockup clutch does not change in response to a change in the control command value, and therefore the lock is performed using the above equation (6) or (7). By estimating the shared torque of the up-clutch, it becomes possible to monitor the engagement state of the lock-up clutch, and thus the influence of the dead zone on the dynamic system including the torque converter and the lock-up clutch can be eliminated. In particular, as for the dead zone due to the loss stroke of the lockup clutch, which is a big problem, the estimated torque T1clt for the lockup clutch is compared with a predetermined value (threshold value) as described above.
Since either the open control (pre-charge control) or the feedback control (PID control) is selectively performed based on the result, for example, slip rotation accompanying acceleration of the vehicle as shown in FIG. 8 is performed. Even in an operating state in which control is impossible due to the influence of the dead zone due to a change in the number, it is possible to optimize the time required to engage the lockup clutch as shown in Fig. 6 and perform control without adversely affecting drivability. Becomes

Further, once the loss stroke is completed and the lockup clutch is engaged, there is a correlation between the control command value and the actual slip rotation speed until the lockup clutch is released again. Since feedback control can be performed by using the above-mentioned predetermined value (threshold value), a value that can determine the engagement of the lock-up clutch may be used, and it can be considered that there is little possibility of being affected by the motion state of the vehicle. . Therefore, it is not necessary to perform matching in an extremely wide range as in the case of adopting the conventional technique in which the switching line is determined by referring to the map based on the vehicle speed, throttle opening, etc. Can be reduced.

[0031]

As described above, the engagement control device for the fluid actuated friction element according to the present invention, as described above, has an input torque to the system in which the fluid transmission device and the fluid actuated friction element are arranged in parallel,
A dynamic model is constructed from the slip torque generated according to the slip operation of the fluid transmission, the engine speed, and the output rotation speed of the fluid transmission, and the shared torque of the fluid-operated friction element is estimated from the dynamic model. Then, the end of the loss stroke is judged based on this allotted torque, and the control logic is switched when the end of the loss stroke is judged. Therefore, the control logic is changed from precharge control, which is open control, to PI, which is feedback control.
The timing for switching to D control is always the proper timing regardless of changes in operating conditions, and excessive output due to open control when control is impossible causes problems such as worsening of engagement shock, sticking of lockup clutch, and deterioration of control stability. In addition, there is no need for complicated matching work for determining the switching line by referring to the map based on the vehicle speed, the throttle opening, and the like.

In the above structure, a torque converter and a lockup clutch are used as the fluid transmission device and the fluid actuated friction element, respectively, and the slip torque detecting means is an input rotation to the torque converter and the lockup clutch. Number, the output speed of the torque converter, and the characteristic of the torque converter, the slip torque is estimated, and the control means locks the slip torque based on a difference value between the slip torque and the input torque to the torque converter and the lockup clutch. Estimate the up-clutch share torque, and if this lock-up clutch share torque is less than a predetermined value, it is judged that the current control system is in the dead zone. There are two types based on these judgments Preferably configured so as to switch the control logic.

In the configuration, when it is determined that the current control system is in the dead zone, the control logic is set to open control, and when it is determined that the current control system is in the controllable area, the control logic is fed back. Preferably, it is configured to switch to control. Further, in the configuration, when the lockup clutch sharing torque is less than the predetermined value even though the control command value is within the predetermined range, the current control system is in the dead zone due to the loss stroke of the lockup clutch. It is preferable that the precharge control is performed when it is determined that there is a certain amount, and then the loss stroke is determined to end when the lockup clutch sharing torque reaches a predetermined value, and the control is switched to the PID control.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a fastening control device for a fluid-operated friction element according to the present invention.

FIG. 2 is a system diagram showing an embodiment of the device of the present invention applied to the engagement control of the lockup clutch in the torque converter.

FIG. 3 is a flowchart showing a control program of lockup clutch engagement control executed by the controller of the example.

FIG. 4 is a diagram illustrating a map for determining which of a lockup region, a slip region, and a converter region the control region corresponds to in the lockup clutch engagement control of FIG. 3.

FIG. 5 is a diagram showing a dynamic model for explaining a lockup clutch sharing torque estimation logic in the same example.

FIG. 6 is a diagram for explaining the operation of the example in association with a change in slip rotation speed.

FIG. 7 is a diagram for explaining conventional lockup control.

FIG. 8 is a diagram for explaining the influence of a dead zone in conventional lockup control.

[Explanation of symbols]

10 Engine 13 Torque converter (fluid transmission) 13a Input element (pump impeller) 13b Output element (turbine runner) 13c Lockup clutch (fluid operated friction element) 14 Transmission input shaft 17 Lockup control valve 19 Duty solenoid valve 21 Controller (Automatic transmission controller) 22 Input torque sensor 23 Output torque sensor 24 Engine rotation sensor 25 Turbine rotation sensor 26 Vehicle speed sensor 27 Throttle opening sensor

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16H 61/14

Claims (4)

(57) [Claims] 1. An automatic transmission comprising: a fluid transmission device for transmitting a driving force from an engine; and a fluid-operated friction element installed in parallel with the fluid transmission device and capable of limiting a slip operation of the fluid transmission device. In the machine, input rotation speed detection means for detecting an input rotation speed to the fluid transmission device and the fluid operated friction element, slip rotation speed detection means for detecting a slip rotation speed of the fluid operated friction element, and the slip Slip rotation speed control means for controlling the rotation speed, control command value calculation means for calculating a control command value for the slip rotation speed control means, and fastening force control means for controlling the fastening force of the fluid-operated friction element. Input torque detecting means for detecting an input torque to the fluid transmission device and the fluid operated friction element, and a slip generated in response to a slip operation of the fluid transmission device. An automatic transmission control device having a slip torque detecting means for estimating a torque, and an input torque to the fluid transmission device and the fluid operation friction element and a slip torque when the fluid operation friction element is engaged. And at least two types by estimating the shared torque of the fluid-operated friction element based on a dynamic model constructed from the engine rotational speed and the output rotational speed of the fluid transmission device and comparing the shared torque with a predetermined value. A fastening control device for a fluid-operated friction element, comprising control means for controlling switching of the control logic of the above. 2. The engagement control device for a fluid operated friction element according to claim 1, wherein a torque converter and a lockup clutch are used as the fluid transmission device and the fluid operated friction element, respectively, and the slip torque detecting means is provided. , The input torque to the torque converter and the lockup clutch, the output torque of the torque converter and the characteristics of the torque converter to estimate the slip torque, the control means, the control means, the slip torque and the torque converter and lockup The lock-up clutch sharing torque is estimated from the difference value with the input torque to the clutch, and when the lock-up clutch sharing torque is less than a predetermined value, it is determined that the current control system is in the dead zone, and the torque is greater than or equal to the predetermined value. In this case, it is determined that the current control system is in the controllable area. A fastening control device for a fluid-operated friction element, characterized in that it is configured to switch off and switch between two types of control logic based on these judgments. 3. The fluid operation type friction element engagement control device according to claim 2, when the current control system is determined to be in a dead zone, the control logic is set to open control, and the current control system is in a controllable region. When it is determined that the control logic is switched to feedback control, the engagement control device for the fluid operated friction element is characterized in that 4. The engagement control device for a fluid actuated friction element according to claim 3, wherein when the control command value is within a predetermined range but the lockup clutch sharing torque is less than a predetermined value, Precharge control is performed by determining that the current control system is in the dead zone due to the loss stroke of the lockup clutch, and then determines that the loss stroke ends when the lockup clutch sharing torque reaches a predetermined value. An engagement control device for a fluid-operated friction element, which is configured to switch to PID control.