JP3230275B2 - Output estimation device for internal combustion engine with torque converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine in which a torque converter having a lock-up mechanism is connected to an engine output shaft, using an output torque (turbine torque) of the torque converter during lock-up using a torque sensor. The present invention relates to an output estimating device for an internal combustion engine with a torque converter for estimating the output without using a torque converter.

[0002]

2. Description of the Related Art Many automatic transmissions used in internal combustion engines for automobiles have a configuration in which a torque converter and an auxiliary transmission are combined.
One provided with a lock-up mechanism for directly connecting the pump side and the turbine side is also widely used. In the above-described auxiliary transmission, the gears are switched by selectively operating friction elements such as a plurality of clutches. However, in order to reduce the shock during the gear shift, the input to the auxiliary transmission is performed. It is desired to detect the torque, that is, the turbine torque of the torque converter, and control the clutch engagement hydraulic pressure and the like according to the turbine torque. However, the torque converter and auxiliary transmission have a very close layout,
Since it is housed in a substantially integral housing, it is difficult in terms of layout to arrange a torque sensor for detecting turbine torque between the torque converter and the auxiliary transmission.

Therefore, various methods have been devised for estimating the turbine torque from other parameters. For example, in Japanese Patent Application Laid-Open No. 1-116363 previously proposed by the present applicant, utilizing the fact that the fuel injection pulse width is substantially proportional to the output torque of the engine, a table is obtained from the fuel injection pulse width and the engine speed. An optimal line pressure is determined by a lookup method.

[0004]

However, in the above-mentioned method, it is difficult to accurately detect the torque of the engine and the torque loss due to the driving of the auxiliary equipment, so that it is difficult to obtain a high estimation accuracy of the turbine torque. Even if the loss torque is determined experimentally in advance and is reflected in the value of the data table, the loss torque actually generated has a considerable variation, so that an error is involved.

On the other hand, the present applicant has previously filed Japanese Patent Application No. 2-209.
No. 867, using a known capacity coefficient C of a torque converter, a turbine torque Tt is obtained as Tt = te × C × Ne ² from the capacity coefficient C, the engine speed Ne and the torque ratio te. In this case, the turbine torque Tt can be accurately detected in the region where the torque converter operates, but the calculation cannot be performed in the lock-up region where the torque converter does not operate.

[0006]

Accordingly, in the present invention,
The loss torque is obtained as a learning value during non-lockup, and the turbine torque is accurately estimated using this learning value during lockup. That is, the output estimating device for an internal combustion engine with a torque converter according to the present invention is:
As shown in FIG. 1, in an internal combustion engine in which a torque converter 2 having a lock-up mechanism 1 is connected to an engine output shaft, an engine speed detecting means 3 for detecting an engine speed Ne, and a turbine of the torque converter 2 Turbine rotational speed detecting means 4 for detecting the rotational speed Nt, and generated torque estimating means 5 for estimating the generated torque Ti to be generated by the internal combustion engine based on a parameter indicating the amount of air taken into the cylinder.
A capacity coefficient setting means 6 for obtaining a torque converter capacity coefficient C based on the torque converter speed ratio e at that time during the non-lock-up of the lock-up mechanism 1, this torque converter capacity coefficient C and the engine speed Ne. A pump torque estimating means 7 for estimating a pump torque Te of the torque converter 2 from the torque converter 2, a loss torque Tf is determined as a difference between the pump torque Te and the generated torque Ti, and the loss torque Tf is determined as a learning value using the loss load condition as a parameter. Learning means 8 for successively updating and learning, and loss torque setting means 9 for setting a loss torque Tf corresponding to a loss load condition at that time during lock-up of the lock-up mechanism 1 based on the learning value. Loss torque Tf and generated torque T
and turbine torque estimating means 10 for obtaining the turbine torque Tt of the torque converter during lock-up from i.

[0007]

The generated torque Ti that should be generated by the internal combustion engine as it burns is substantially proportional to the amount of air drawn into the cylinder of the engine. The amount of intake air in the cylinder is
For example, it is indicated as Q / Ne from the engine intake air amount Q detected by the air flow meter and the engine speed Ne.
Then, a value obtained by subtracting a loss torque Tf such as friction or accessory drive torque from the generated torque Ti is a torque output to the outside, that is, a pump torque Te input to the torque converter 2.

On the other hand, the capacity coefficient C of the torque converter 2
Is defined as C = Te / Ne ^2. However, since this capacity coefficient C changes according to the known characteristics, if the torque converter speed ratio e is known, the corresponding capacity coefficient C can be obtained. . The speed ratio e is obtained as e = Nt / Ne from the engine speed Ne and the turbine speed Nt. Therefore, in the pump torque estimating means 7, Te = C ×
Estimating a pump torque Te based on the relation Ne ^2.

The difference (Ti-Te) between the generated torque Ti and the pump torque Te is the loss torque Tf at that time. The loss torque Tf is relatively large due to the auxiliary equipment such as a compressor for an air conditioner, an alternator, an oil pump, and the like, and the friction torque occupies a relatively large specific gravity. The value varies depending on the loss load condition such as the cooling water temperature which affects the temperature. Therefore, the learning means 8 uses the calculated loss torque T as a learning value using these loss load conditions as parameters.
f is assigned and updated sequentially. Therefore, during the operation of the engine and during the non-lockup, the loss torque Tf corresponding to various loss load conditions is given as a learning value.

When the lock-up mechanism 1 is locked up, it is impossible to estimate the pump torque Te using the capacity coefficient C. In this case, based on the loss load condition at that time, that is, the ON / OFF state of the compressor or the magnitude of the electric load of the alternator, the corresponding loss torque Tf is obtained from the learning value. Since the torque to be generated by combustion of the internal combustion engine, that is, the generated torque Ti is also obtained during the lock-up by the generated torque estimating means 5, the loss torque Tf is subtracted from the generated torque Ti to obtain the turbine torque Tt (during lock-up). Is equal to the pump torque Te).

[0011]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a mechanical structure of a drive system and a control system of an automobile having an output estimating apparatus according to the present invention. In the figure, 11 is an electronically controlled fuel injection type internal combustion engine, 12 is a torque converter connected to an output shaft 13 of the internal combustion engine 11, and 14 is a torque converter 12
It is an auxiliary transmission that constitutes the automatic transmission 33 together.
An output shaft 15 of the auxiliary transmission 14 is linked to a drive wheel 17 via a differential gear 16. The pump 12a of the torque converter 12 is connected to the output shaft 13 of the internal combustion engine 11, and the turbine 12b is connected to the input shaft 18 of the auxiliary transmission 14. Further, the torque converter 12 includes a lock-up mechanism 19 for directly connecting the turbine 12b to the output shaft 13 of the internal combustion engine 11.

In this embodiment, an engine control unit 20 for comprehensively controlling the fuel injection amount, ignition timing, and the like of the internal combustion engine 11, a changeover of the gear position of the automatic transmission 33, a control of the lockup mechanism 19, and a line An AT control unit 21 for controlling pressure and the like is provided separately from each other. The AT control unit 21 controls supply of hydraulic pressure to various friction elements of the auxiliary transmission 14 via a control valve 22, and controls line pressure via a line pressure control duty solenoid 23.

The main sensors include an intake air amount sensor 24 such as a hot wire air flow meter for measuring the engine intake air amount Q, a throttle sensor 25 for detecting the throttle opening, and an output shaft 15 of the auxiliary transmission 14. Rotation speed N
The output shaft speed sensor 26 for detecting the engine speed N and the engine speed N
e, an engine speed sensor 27 for detecting
A turbine speed sensor 28 for detecting the speed of the input shaft 18, that is, the turbine speed Nt, is provided, and respective detection signals are input to the engine control unit 20 or the AT control unit 21. The vehicle speed VSP is determined by the output shaft rotation speed No of the auxiliary transmission.
Is required.

A water temperature sensor 29 for detecting an engine cooling water temperature temp as sensors indicating a loss load condition.
And the ON / OFF state SWa of the compressor of the air conditioner
c, an alternator current sensor 31 for detecting the magnitude of a current Iagc acting as a load on the alternator, and a line pressure PL of the automatic transmission 33.
And a line pressure sensor 32 for detecting the pressure, and the respective detection signals are input to the engine control unit 20 or the AT control unit 21.
Necessary signals are exchanged between the engine control unit 20 and the AT control unit 21.

Although the loss torque Tf is caused by several factors, in this embodiment, the loss Tc due to the air conditioner compressor, the electric load Ta of the alternator, the friction (including the pumping loss) Tfr, and the oil pump friction Top We are focusing on the following four. Here, the air conditioner compressor loss Tc can be considered as a function of the SWac and the engine speed Ne. Similarly, it can be considered that the electric load Ta is a function of the current Iagc, the friction Tfr is a function of the water temperature temp and the engine speed Ne, and the oil pump friction Top is a function of the line pressure PL and the engine speed Ne. Therefore, the entire loss torque Tf is set to 5 of SWac, Ne, Iagc, temp, and PL.
It can be indicated by a dimensional parameter. In this embodiment,
As an example, the loss torque Tf is learned using the five-dimensional parameter array.

Next, the operation of the above embodiment will be described with reference to the flowcharts of FIG. In this embodiment, the estimated turbine torque Tt is finally used for controlling the clutch engagement hydraulic pressure in the auxiliary transmission 14.

FIGS. 3 and 4 show the flow of the output estimating process executed, for example, every 10 ms in the engine control unit 20. Here, the calculation and learning of the turbine torque Tt are mainly performed. .

First, in step 1, various detection signals are read. Specifically, the engine speed Ne, the turbine speed Nt, and the output shaft speed No of the auxiliary transmission 14
, The signal SWac of the air conditioner switch 30, the alternator current Iagc, the cooling water temperature temp, and the line pressure P
And L. In step 2, the gear ratio gr of the auxiliary transmission 14 is obtained as gr = Nt / No, and the speed ratio e of the torque converter 12 is obtained as e = Nt / Ne. Further, in step 3, the torque ratio te is searched from a predetermined data table based on the speed ratio e. FIG. 7 shows an example of the relationship between the speed ratio e and the torque ratio te, and the torque ratio te is given according to this characteristic.

Next, at step 4, the generated torque Ti to be generated by the internal combustion engine 11 is estimated. Specifically, a generated torque Ti corresponding to the operating condition at that time is retrieved from a map in which the engine intake air amount Q and the engine speed Ne having the characteristics shown in FIG. 8 are used as parameters. In this example, Q /
The value of Ne is a parameter indicating the amount of air actually sucked into the cylinder, and the generated torque Ti is obtained substantially in proportion to this. In addition, the intake pipe pressure downstream of the throttle or the throttle opening and the engine speed Ne or the like also indicates the amount of air actually sucked into the cylinder.
Based on these, the generated torque Ti can be estimated.

Next, in step 5, it is determined whether or not it is the first time. Only the first time proceeds to step 6, where the initial value of the loss torque Tf is set based on the previous learning value. More specifically, since the learning value of the loss torque Tf is stored in the five-dimensional parameter array of SWac, Ne, Iagc, temp, and PL serving as the loss load condition as described above,
A learning value corresponding to a loss load condition such as air conditioner ON / OFF at that time is read from the learning memory, and this is set as an initial value of the loss torque Tf.

If it is not the first time, the routine proceeds to step 7, where it is determined whether or not the lock-up mechanism 19 is in the lock-up state. This is determined based on a lock-up signal for driving the lock-up mechanism 19.

If the lock-up state is not established, the process proceeds to steps 8 and 9, where the pump torque T
e and the turbine torque Tt are estimated using known characteristics of the torque converter 12. That is, the capacity coefficient C of the torque converter 12 is defined as C = Te / Ne ² , and changes according to a predetermined characteristic with respect to the speed ratio e of the torque converter 12 as shown in FIG. Therefore, first, a capacity coefficient C corresponding to the speed ratio e at that time is searched from a characteristic map as shown in FIG. 7 (step 8). Then, using the capacity coefficient C and the engine speed Ne, the pump torque Te is calculated as Te = C × Ne ² . Further, using the torque ratio te obtained in Step 2, the turbine torque Tt is calculated as Tt = Te × te (Step 9). The above pump torque Te
Corresponds to the torque that the internal combustion engine 11 actually outputs to the outside during the non-lockup. Also, the turbine torque Tt
Is the torque input to the auxiliary transmission 14.

In step 10 following step 9, the difference between the pump torque Te corresponding to the external output torque and the generated torque Ti estimated from the cylinder intake air amount (Ti-T
As e), the loss torque Tf is calculated. Then, in step 11, SWac, Ne, Ia serving as loss load conditions
The loss torque Tf is learned as a learning value for a five-dimensional parameter array of gc, temp, and PL.

Therefore, if the operation is continued in the non-lockup state, the learning value of the loss torque Tf assigned to various loss load conditions is updated successively.

On the other hand, if it is determined in step 7 that the lock-up is being performed, the process proceeds to step 12, where the loss torque Tf corresponding to the loss load condition at that time is set based on the learned value. That is, the learning value corresponding to the loss load condition is read from the learning memory having the five-dimensional parameter array, and is set as the loss torque Tf. Then, in step 13, using the loss torque Tf, a turbine torque Tt output from the internal combustion engine 11 to the outside is calculated as a difference (Ti-Tf) between the generated torque Ti and the loss torque Tf. In addition, since it is in a lockup state, the pump torque Te and the turbine torque Tt are equal.

Next, control of the clutch engagement hydraulic pressure using the turbine torque Tt and the like will be described. The flowchart of FIG. 5 shows the control of the clutch engagement hydraulic pressure at the time of this shift. The control signal itself of the clutch engagement hydraulic pressure Pcl determined here is output, for example, every 10 ms by the routine shown in FIG.

Step 21 in the flowchart of FIG.
This is a shift determining unit that determines the timing and mode of the shift according to a predetermined shift pattern, and a detailed description thereof will be omitted. Then, only when the shift determining unit determines that the shift is to be executed, the process proceeds to the shift control unit after step S22.

In step 22, it is determined whether or not this shift control section routine is to be executed for the first time. In this step 23, first, the counter CNT for counting the number of executions of the routine of the shift control unit is reset, and the target gear ratio grm of the shift is determined. The target gear ratio grm corresponds to the gear ratio of the third speed at the end of the shift if the shift determination unit intends to perform the shift from the second speed to the third speed, for example. Further, the optimum shift time tmr is determined based on the engine operating conditions. The shift time tmr is a value that is set in advance for each operating condition and, for example, becomes shorter in a high-speed rotation range (FIG. 9).
(A)). Note that the shift time tmr may be set by combining the engine operating conditions and the shift speed.

Next, the process proceeds to a step 24, wherein the transmission output shaft torque To immediately before the shift is calculated from the turbine torque Tt and the like based on the following equation.

To = Tt × gr + Nodt × Io where the gear ratio gr is the gear ratio immediately before shifting, and
In the example of the speed → the third speed, the gear ratio of the second speed corresponds. The turbine torque Tt is determined in step 9 or step 13 described above.
Are used. Nodt is a rotational change rate obtained by differentiating the rotational speed No of the transmission output shaft 15, and in other words, corresponds to the vehicle acceleration. Io is a drive system inertia given in advance.

Next, the routine proceeds to step 25, where an initial value of the rotation change rate target value Ntdt of the transmission input shaft 18 is set based on the transmission output shaft torque To. Specifically, an initial value of Ntdt is searched from a predetermined data table using the output shaft torque To as a parameter. Then, in step 26, the initial value of Ntdt is divided by the shift time tmr to obtain a ratio Ntdt of Ntdt to be changed per unit time.
On the other hand, in the second and subsequent routines, the process proceeds from step 22 to step 27 and thereafter. In step 27, the counter CNT is incremented, and in step 28, the value is set to a predetermined period tm.
r is determined. If it has reached tmr, it is determined that the shift has been completed, and the routine proceeds to step 33. Also, tmr
If it is less than, it is determined in step 29 whether the actual gear ratio gr has reached the target gear ratio grm. Target gear ratio gr
If it has reached m, it is determined that the shift has been completed, and the process proceeds to step 33. In step 33, a full command is output to set the clutch engagement hydraulic pressure Pcl to the maximum hydraulic pressure.

Until it is determined in steps 28 and 29 that the shift is completed, the processing of steps 30 to 32 is repeated.
That is, in step 30, the necessary clutch engagement force Tcl is calculated by the following equation.

Tcl = Tt × I1 + Ntdt × I2 + Nodt × I3 where I1 to I3 are coefficients obtained from the inertia and the gear ratio gr of the respective predetermined parts. Also, Nt
As dt, a value sequentially obtained as a rotation change rate target value in step 32 described later is used. Further, Nodt is a rotational change rate obtained by differentiating the rotational speed NO of the transmission output shaft 15 as described above, and is sequentially calculated. Similarly, the turbine torque Tt is determined in step 9 or step 1 described above.
The values sequentially obtained in step 3 are used.

In step 31, the necessary clutch engagement hydraulic pressure Pcl is sequentially obtained by dividing the clutch engagement force Tcl by a predetermined clutch coefficient kcl. In step 32, the fixed value Nt determined in step 26 from the rotation change rate target value Ntdt of the transmission input shaft 18 at that time.
The next rotation change rate target value Ntdt is set by subtracting step. The new rotation change rate target value Ntdt obtained here
Is used in the calculation in step 30 of the next routine. Therefore, the rotation change rate target value Ntdt gradually decreases during the shift time tmr. Then, the clutch engagement hydraulic pressure Pcl is controlled so that the rotation change rate of the transmission input shaft 18 is in line with the target value Ntdt.

FIG. 9 shows, for example, (a) the transmission output shaft torque To when the gear is automatically shifted from the second gear to the third gear.
And (b) the rotation change rate target value Ntd of the transmission input shaft 18
FIG. 10 is a time chart showing a comparison between a change in the clutch engagement hydraulic pressure Pcl and an initial value of the rotation change rate target value Ntdt from the transmission output shaft torque To immediately before the shift, as shown in FIG. The rotation change rate target value Ntdt changes at a constant rate so that it becomes exactly 0 when the shift time tmr has elapsed. Then, the clutch engagement hydraulic pressure Pcl is controlled so as to conform to the gradually decreasing rotation change rate target value Ntdt. At the beginning of the shift, the actual oil pressure is slightly delayed from the command oil pressure indicated by the dotted line as indicated by the solid line.

Accordingly, in the above embodiment, as shown in FIG. 9A, the transmission output shaft torque To smoothly connects the value To1 before the start of the shift and the value To2 at the end of the shift, Shift shock can be reduced. In particular,
Since the turbine torque Tt, which is the transmission input torque, can be accurately detected both during non-lockup and during lockup, the initial value of the rotation change rate target value Ntdt can be appropriately given, and a highly accurate hydraulic pressure can be obtained. Control can be realized.

The output estimating apparatus according to the present invention is capable of estimating the turbine torque Tt of the torque converter without using a torque sensor. Needless to say, it can be used for various purposes.

[0039]

As is apparent from the above description, according to the output estimating apparatus for an internal combustion engine with a torque converter according to the present invention, the turbine torque Tt is determined based on the intake air amount and the like even during lock-up of the torque converter. It is possible to estimate, and the turbine torque Tt can be detected without using a torque sensor. In particular, since the loss torque Tf is learned as a learning value using the loss load condition as a parameter during non-lockup, and the lockup is estimated based on the learning value, the load variation and the size of the auxiliary equipment are affected. An accurate estimation can be performed without being performed. Therefore,
For example, it is possible to detect the input torque of the auxiliary transmission arranged close to the torque converter.

[Brief description of the drawings]

FIG. 1 is a claim correspondence diagram showing a configuration of an output estimation device according to the present invention.

FIG. 2 is a configuration explanatory view showing a mechanical configuration of one embodiment of the present invention.

FIG. 3 is a flowchart showing the first half of the flow of an output estimation process in the embodiment.

FIG. 4 is a flowchart showing the second half of the same.

FIG. 5 is a flowchart showing a flow of a process at the time of shifting.

FIG. 6 is a flowchart illustrating a control signal output routine.

FIG. 7 is a characteristic diagram showing a relationship among a speed ratio e, a torque ratio te, and a capacity coefficient C in the torque converter.

FIG. 8 shows an engine intake air amount Q, a rotation speed Ne, and a generated torque T.
FIG. 4 is a characteristic diagram showing a relationship with i.

FIG. 9 is a time chart showing changes of each signal at the time of shifting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Lock-up mechanism 2 ... Torque converter 3 ... Engine speed detection means 4 ... Turbine speed detection means 5 ... Generated torque estimation means 6 ... Capacity coefficient setting means 7 ... Pump torque estimation means 8 ... Learning means 9 ... Loss torque setting Means 10: Turbine torque estimation means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01L 5/00 F02D 29/00 F02D 45/00

Claims (1)

(57) [Claims] In an internal combustion engine in which a torque converter having a lock-up mechanism is connected to an engine output shaft, an engine speed detecting means for detecting an engine speed Ne, and a turbine speed Nt of the torque converter are detected. Turbine rotation speed detection means; generated torque estimation means for estimating generated torque Ti to be generated by the internal combustion engine based on a parameter indicating the amount of air taken into the cylinder; A capacity coefficient setting means for obtaining a torque converter capacity coefficient C based on the torque converter speed ratio e at the time; a pump torque estimating means for estimating a pump torque Te of the torque converter from the torque converter capacity coefficient C and the engine speed Ne. The loss torque Tf is determined as the difference between the pump torque Te and the generated torque Ti, Learning means for sequentially updating and learning the loss torque Tf as a learning value with the loss load condition as a parameter; and a loss torque Tf corresponding to the loss load condition at that time during the lock-up of the lock-up mechanism. Loss torque setting means for setting based on the torque loss Tf and generated torque Ti, and turbine torque estimating means for obtaining a turbine torque Tt of the torque converter during lock-up from the loss torque Tf and the generated torque Ti. apparatus.