JPH04357363A - Speed change controller for automatic transmission - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission.

0002

2. Description of the Related Art An automatic transmission selects a corresponding gear position by selectively engaging various friction elements, and shifts to another gear position by switching between engagement and release of the friction elements. As a conventional example of a shift control device that controls such a shift, there is one that performs hydraulic control as shown in FIG. 8, for example. For example, in the case of 1 → 2 upshift, the release side friction element (low speed side friction element)
The hydraulic pressure PL of the engagement side friction element (high speed side friction element) is decreased in the illustrated pattern, and the hydraulic pressure PH of the engagement side friction element (high speed side friction element) is increased in the illustrated pattern, thereby changing the friction elements.

0003

[Problems to be Solved by the Invention] In the above-mentioned conventional example, during the hydraulic control shown in FIG. 8, the instant t01 at which the release timing of the release side friction element is switched from the torque phase to the inertia phase (the instant at which the torque phase ends) is detected. Because the decision had been made without any prior knowledge, the actual timing for setting the release side oil pressure PL to 0 was at instant t02, which was delayed from the most desirable instant t01, resulting in torque pull-in as shown in the diagram, resulting in a large shift shock. . The timing of the end of the torque phase is estimated (predicted) by detecting the transmission torque of the friction element by turning the stroke switch ON and OFF, and by detecting the oil pressure of the friction element by turning ON and OFF the oil pressure switch that operates at a predetermined oil pressure. However, since none of these technologies is based on changes in the output shaft torque that actually appear, they are easily affected by variations in the frictional elements (clutches, etc.) Determining the timing is not practical.

An object of the present invention is to solve the above-mentioned problem by determining the timing of releasing a predetermined friction element based on the output shaft torque measured during gear shifting.

[0005]

[Means for Solving the Problem] For this purpose, the shift control device for an automatic transmission of the present invention measures output shaft torque in an automatic transmission that changes gears by switching between engagement and release of a plurality of friction elements. The present invention is characterized by comprising an output shaft torque measuring means and a friction element control means for releasing a predetermined friction element when the output shaft torque measured during gear shifting reaches a predetermined value.

[0006]

[Operation] According to the present invention, when an automatic transmission performs a gear shift by switching between engagement and disengagement of a plurality of friction elements, the friction element control means during gear shift is controlled by the output shaft torque measuring means in the first configuration. When the measured output shaft torque reaches a predetermined value, in the second configuration, when the ratio of the output shaft torque to the input shaft torque measured by the input shaft torque measuring means reaches a predetermined value, the torque phase is terminated. A predetermined friction element is released based on the judgment. As a result, the timing of releasing the predetermined friction element can be made to coincide with the accurately detected timing of the end of the torque phase, and it is possible to prevent torque pull-in and realize smooth gear shifting without gear shifting shock.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of an embodiment of a gear train of an automatic transmission to be controlled by the device of the present invention. In the figure, 1 indicates an input shaft and 2 indicates an output shaft. The gear train of this automatic transmission is "RE4R" published by Nissan Motor Co., Ltd.
01A Type Automatic Transmission Maintenance Manual" (A261C07), the first planetary gear set 3 is coaxially connected between the input and output shafts 1 and 2.
and a second planetary gear set 4, the first planetary gear set 3 is a simple planetary gear set consisting of a first sun gear 3S, a first ring gear 3R, a first pinion 3P and a first carrier 3C, and a second planetary gear Set 4 is also a simple planetary gear set including a second sun gear 4S, a second ring gear 4R, a second pinion 4P, and a second carrier 4C. The input shaft 1 receives rotation from an engine (not shown) through a torque converter T/C, and is connected to a second sun gear 4S. The input shaft 1 can further be connected to the first carrier 3C by a high clutch H/C, and a reverse clutch R.
/C enables coupling to the first sun gear 3S. 1st
The sun gear 3S can be further fixed by a band brake B/B, and the first carrier 3C can be further fixed by a low reverse brake LR/B, and a one-way clutch OWC can prevent rotation in the opposite direction to the input shaft 1. The second clutch is activated by overrun clutch OR/C.
Can be connected to ring gear 4R. Further, the first ring gear 3R and the second carrier 4C are drivingly coupled to each other and coupled to the output shaft 2. In such a gear train, friction elements H/C, R/C, B/B, LR/B
The relationship between engagement (indicated by a circle) and release (not marked) of the OR/C and the selected gear is shown in the following table.

[0008]

For speed change control of the automatic transmission, an engine rotation sensor 5 detects the engine rotation Ne, a turbine rotation sensor 6 detects the turbine rotation (transmission input rotation) Nt, and an output shaft rotation (transmission output rotation). An output shaft rotation sensor 7 for detecting No. and an output shaft torque sensor 9 for detecting output shaft torque To are provided, as well as a speed change control computer (hereinafter referred to as ATCU) 8. The ATCU 8 performs speed change control by executing the control programs shown in FIGS. 2 to 6 during auto-up (upshift during D range selection).

FIG. 2 shows the process of measuring signals that should be measured for the speed change control.
It is executed by a regular interrupt every sec). First, in step 21, engine rotation Ne, turbine rotation Nt (transmission input rotation), and transmission output rotation No. shown in FIG.
, throttle opening TVO of the engine (not shown) and ATF temperature Tatf from a temperature sensor (not shown)
At the same time as measuring the output shaft torque TO (
In this step 21, the ATCU 8 functions as an output shaft torque measuring means). In the next steps 22 and 23, the gear ratio gr = Nt /No of the transmission and the torque converter rotation ratio e = Nt /Ne are calculated, respectively.
After that, in step 24, the current read value Nt of the turbine rotation is
From the previous value Nt (OLD) and the previous value Nt (OLD), the turbine rotation change rate NTd is calculated as NTd = (Nt - Nt (OLD))
×100, and the current read value Nt is stored for use as Nt (OLD) in the next process, and in step 25, filter processing is performed to remove variations due to rotational fluctuations, errors, etc. in NTd. Furthermore, in step 26, the rotation ratio e is determined based on the torque converter performance data.
Torque ratio t(e) and torque capacity coefficient τ(
Look up e) and multiply these by Ne 2 to obtain the turbine torque (transmission input torque) Tt.
=t(e)×τ(e)×Ne 2 is calculated (in this step 25, the ATCU 8 functions as an input shaft torque measuring means).

FIG. 3 shows the release element LR/
A control signal output program is shown that outputs the hydraulic pressure PL of B and the hydraulic pressure PH of the fastening element B/B in step 31, and is executed by a regular interrupt every fixed time Δt.

FIG. 4 shows a shift control program for determining the oil pressures PL and PH, which are also processed by regular interrupts at fixed time intervals Δt. In step 41, a preferred gear is determined based on a previously memorized shift pattern from the throttle opening TVO and transmission output rotation number (vehicle speed), and this preferred gear is compared with the currently selected gear. Determine whether or not to shift gears, and if so, what kind of gear shifts to perform. In the next step 42, the oil pressure of the friction element to be released (for example, low reverse brake LR/B) is lowered and the oil pressure of the friction element to be engaged (for example, band brake B/B) is increased depending on the type of shift. As a result, the gear shift (for example, from 1 to 2 gear) is performed, and at this time, the oil pressures of both are sequentially controlled as shown in FIG. 7 by the control programs shown in FIGS. 5 and 6.

That is, during the torque phase control in FIG.
When it is determined in step 51 that it is the first time, that is, only once at the shift command instant t1 in FIG. The fastening element side ramp value Pramp (TVO) and the pre-shelf pressure Ppr (Ta
tf), timer setting time Ti for precharge control on the engagement side
1 respectively. In the next step 53, the engagement side oil pressure PH
Precharge control is performed to set the pre-shelf pressure Ppr (Tatf). Here, pre-shelf pressure Ppr (Tatf)
Since Tatf is expressed as a function of the ATF temperature Tatf read in step 21, this precharge control is performed by the preshelf pressure corresponding to the ATF temperature at that time. This pre-shelf pressure is set to, for example, a pressure equivalent to the return spring force in order to reduce the loss stroke of the fastening element, and the fastening element is fastened with this pre-shelf pressure Ppr (Tatf). There isn't.

[0014] After the second time in FIG. 5 (after the instant t1 in FIG. 7)
In the control, step 51 selects step 54, in which incrementing of counter C1 is started at instant t1. In the next step 55, the counter C
1 is equal to or greater than the timer setting time Ti1, and the control is switched to N0 in step 55 until the timer setting time Ti1 has elapsed (instants t1 to t2 in FIG. 7).
Then proceed to step 56. In step 56, the torque phase output shaft torque (torque phase pull-in torque)
Toh is expressed as follows: Toh=grmin×Tt +I× (d/d
t) ωt ......... Calculated by (1) (where grmin: equivalent gear ratio after shifting, for example, gear ratio after shifting x 1.02, I: output shaft equivalent value of inertia around the input shaft, ( d/dt) ωt;
In step 57, the output shaft torque To read in step 21 is determined as Toh.
It is determined whether or not the torque phase has ended by determining whether or not the torque has been reached. Note that the determination of the end of the torque phase may be made by making the content of step 57 a determination as to whether or not the ratio of the output shaft torque to the input shaft torque has become equal to or less than a predetermined value. During To > Toh when this determination is N0, in other words, during the torque phase, the control is returned to after step 51 and step 51
The above precharge control is continued by repeating the loop of -54-55-56-57-51, and To ≦ Toh
When the determination in step 57 becomes Yes, a zero command is given to the release side oil pressure PL in the next step 58, and
Release the release side friction element.

In the shift time chart illustrated in FIG. 7, the determination of the end of the torque phase in step 57 is made at the instant t3, which is after the instant t2 at which the precharge control timer setting time Ti1 ends. In some cases, it may be determined that the torque phase has ended before the end of time Ti1. In that case, after executing step 58, step 71 of inertia phase control in FIG. 6, which will be described later, is executed immediately. In this example, the engagement side oil pressure PH
Since the end of the torque phase has not yet been determined at instant t2 when the precharge control ends, step 55 selects step 59 after instant t2. Step 5
9, as shown in FIG.
Thereafter, ramp control is performed to increase the ramp value Pramp (TVO) until the oil pressure PH reaches the shelf pressure Pap (Tt). When the oil pressure PH reaches the shelf pressure Pap (Tt) due to this ramp control, the PH is increased to Pap (Tt).
) to maintain shelf pressure control. Note that the ramp control or shelf pressure control in step 59 is repeated until it is determined in step 57 that the torque phase has ended, and when it is determined that the torque phase has ended, the PL in step 58 is repeated.
After executing the zero command, the control program shown in FIG. 6 is continuously executed.

The inertia phase control shown in FIG. 6 is an open control that determines necessary physical quantities from a reference model, and in step 71 during this inertia phase control, ramp control or shelf pressure, which is the same as step 59, is performed for the engagement side oil pressure PH. Take control. During this control, shelf pressure Pap (
Tt ) is a calculated value that achieves the target turbine rotation rate of change, and as shown below, the turbine torque Tt
can be expressed as a function of In other words, regarding each torque during the inertia phase, if we establish an equation of motion from the torque share of each clutch and the inertia of each element, for example, in the case of a 1 → 2 shift during auto-up, the output shaft torque To is calculated by the following formula: To = K1× Tt +K2×Tbb−K3×
TLR/B-K4×(d/dt)ωt...(2)
(where K1 to K4; positive coefficient, Tbb;
Band brake transmission torque, TLR/B; low reverse brake transmission torque). In this equation (2), if the low reverse brake transmission torque TLR/B is 0, then (2)
Solving the equation for band brake torque Tbb results in (3)
Formula Tbb=K5×Tot-K6×Tt +K7
×(d/dt)ωt ……………(3) is obtained (however, K5 to K7: positive coefficient, Tot: shift period when torque before shift is To1 and torque after shift is To2) Torque during shifting during a period T1 shorter than T2, Tot=(T1/T2)×(To1-To2)
). Here, since the target values of the torque Tot during shifting and the input shaft rotation rate of change (d/dt) ωt are determined by calculation, the only actual variable in equation (3) is the turbine torque Tt, and the band brake oil pressure Pbb is Pbb=K8×Tbb…………(
4) (where K8; positive coefficient) is expressed as a function of Tt, so Pap(Tt) is also expressed as a function of Tt.

If it is determined that it is the first time in the next step 72 in FIG. 6, the counter C2 is reset in step 73, and the timer set time Ti2 for controlling the fastening side shelf pressure is read, and the control returns to steps 71 and 72. In the second and subsequent control, step 72 selects step 74, and in step 74, the increment of counter C2 is started, for example, at instant t4 in FIG. It is determined whether or not the set time Ti2 has passed. Here, if within the set time of C2<Ti2, the control advances from NO in step 75 to step 76, where it is determined whether or not the shift is completed depending on whether gr ≦ grmin, and the gear ratio gr = grmi.
NO in step 76 until instant t5 when n is reached -71-
72 NO - 74-75 NO - 76 NO The loop is repeated to continue the shelf pressure control of the engagement side hydraulic pressure PH. The gear ratio gr that gradually decreases as this shelf pressure control continues is gr
= grmin, and when the determination in step 76 becomes Yes at instant t5, the PH command value is set to the maximum value Pmax in step 77 to completely engage the engagement side friction element, and the shift control is ended. In addition, the above timer setting time Ti
2 is the instant t after the instant t5 when the shift completion is determined.
6, and since step 75 selects step 77 even after instant t6, the PH command value is held at Pmax.

The operation of the above control will be explained with reference to FIG. In the torque phase control shown in FIG. 5, when upshifting, by executing step 57, the output shaft torque T
Since it is determined that the torque phase has ended and the transition has been made to the inertia phase when A becomes less than the torque phase retraction torque Toh, in this step 57
The TCU 8 functions as friction element control means. that time,
The torque phase is determined by the physical equation (1), which adds the product of the turbine torque Tt and the equivalent gear ratio grmin after shifting, the output shaft conversion value I of the inertia around the input shaft, and the input shaft rotation rate of change (d/dt) ωt. Since the retracting torque Toh is determined and this Toh reflects a physical quantity that actually appears as a phenomenon, it is possible to accurately judge (detect) the end of the torque phase. Furthermore, the end of the torque phase is detected in any of the cases shown in FIG. 7, between instants t1 and t2 (during precharge control), between instants t2 and t4 (during ramp control), and after instant t4 (during shelf pressure control). However, by executing step 58, the release-side friction element is immediately released, so that the release-side friction element can be released at an appropriate timing to achieve smooth gear shifting without shift shock.

[0019] In this example, the explanation has been developed by taking as an example the 1 to 2 shift of auto-up shifting, but the invention is not limited to this, and in all auto-up shifting, the release side friction element and It goes without saying that the control of this example can be applied to hydraulic control of the friction element on the engagement side.

[0020]

As described above, the shift control device for an automatic transmission of the present invention determines the timing of releasing a predetermined frictional element based on the output shaft torque measured during gearshifting. This can be made to coincide with the accurately detected timing of the end of the torque phase, and it is possible to prevent torque pull-in and achieve smooth shifting without shift shock.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of a gear train of an automatic transmission to be controlled by a device of the present invention.

FIG. 2 is a flowchart showing a control program for signal measurement in the same example.

FIG. 3 is a flowchart showing a control program for outputting control signals in the same example.

FIG. 4 is a flowchart showing a control program for speed change control in the same example.

FIG. 5 is a flowchart showing a control program for torque phase control during shift control in the same example.

FIG. 6 is a flowchart showing a control program for inertia phase control during shift control in the same example.

FIG. 7 is a shift time chart of the same example.

FIG. 8 is a shift time chart of a conventional example.

[Explanation of symbols]

1 Input shaft 2 Output shaft 3 First planetary gear set 4 Second planetary gear set 5 Engine rotation sensor 6 Turbine rotation sensor 7 Output shaft rotation sensor 8 Shift control computer (ATCU) 9 Output shaft torque sensor LR/B Low reverse brake B/B band brake

Claims (1)

[Claims] [Claim 1] In an automatic transmission that changes gears by switching between engagement and release of a plurality of friction elements, an output shaft torque measuring means for measuring output shaft torque and when the output shaft torque measured during gear shifting reaches a predetermined value. 1. A speed change control device for an automatic transmission, comprising: friction element control means for releasing a predetermined friction element.