JP2008008325A - Slip control device for torque converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control slip without releasing or fail-recovering a lock-up clutch even when engine torque is suddenly reduced with the load of an engine driving accessory. <P>SOLUTION: When engine torque Tes is suddenly reduced t1 so that its time change rate ΔTes is a sudden reduction determined value ΔTesref or smaller, an engine torque estimated value Teh is initialized in accordance with initializing torque Teint as a value for the sum of the Tes at this time and an engine torque additional value ΔTeup for increasing lock-up clutch fastening torque capacity when engine output torque is suddenly reduced. After the t1, an aging effect is given to the Teh as shown by a broken line so that the Teh is a negative value greater than a conventional engine torque estimated value shown by a dashed line. Thereby, a target lock-up clutch fastening torque capacity tT<SB>LUC</SB>found in accordance with the Teh is suddenly increased right after the t1 as shown by a solid line and it is greater than the conventional target lock-up clutch fastening torque capacity shown by the dashed line. Thus, right after the t1, the reduction of a toque converter input rotating number Nir can be so suppressed as shown by the solid line. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a relative rotation between input / output elements of a torque converter inserted in a transmission system such as an automatic transmission including a continuously variable transmission, that is, slip control for matching the slip rotation of the torque converter with the target slip rotation. The present invention relates to a device for performing as intended even when the output torque of a prime mover suddenly decreases.

Since the torque converter performs power transmission between the input / output elements via the fluid, it performs a torque fluctuation absorbing function and a torque increasing function, but has a poor transmission efficiency.
For this reason, under driving conditions that do not require the torque fluctuation absorption function or the torque increase function, the input / output elements of the torque converter are directly connected by a lock-up clutch, or slip control of the torque converter is performed by slip control of the lock-up clutch. Nowadays, lock-up torque converters that limit rotation are frequently used.

As a device for slip-controlling a lock-up clutch for these purposes, a device as described in Patent Document 1, for example, is conventionally known.
That is, since the torque converter in the slip control state transmits the prime mover output torque Te by the cooperation of the fluid transmission and the lockup clutch, the converter torque Tcnv transmitted by the torque converter by the fluid transmission and the lock transmitted by the lockup clutch Since the relationship of the following equation is established between the up clutch engagement torque capacity T _LUC and the motor output torque Te,
Te ＝ Tcnv ＋ T _LUC・ ・ ・ (1)
∴T _LUC ＝ Te −Tcnv ... (2)
A constant relationship exists between the converter torque Tcnv and the torque converter slip rotation Nslip for each torque converter, and the relationship between the two can be obtained in advance from the transmission characteristics of the torque converter. Based on the fact that the target converter torque to achieve this can be determined from the target slip rotation of the torque converter based on the required characteristics,
In the slip control technique described in Patent Document 1, first, as described above, the target converter torque for realizing the target slip rotation is obtained, and this is substituted for Tcnv in the above equation (2) to estimate the motor output torque. By substituting the value into Te in the above equation (2), the lockup clutch engagement torque capacity T _LUC obtained by calculating the equation (2) is defined as the target lockup clutch engagement torque capacity, and this should be realized. The target slip rotation is realized by controlling the fastening force of the lockup clutch.
JP 2002-257224 A

By the way, since the prime mover outputs torque with a predetermined response delay, the estimated value of the above-mentioned prime mover output torque needs to take into account the response delay of the actual device.
Therefore, in Patent Document 1, a dead time is set in the motor output torque estimated value from the motor controller or the like, or a filtering process is performed, and the motor output torque estimated value includes a response delay of the actual machine. The target converter torque is subtracted to obtain the target lockup clutch engagement torque capacity.

  However, if the dead time is set in the estimated output torque of the prime mover or the filter process is applied, the prime mover drive auxiliary machine such as an air conditioner is activated during coasting (running) with the prime mover operating at no load. To prevent the torque converter slip from becoming larger than the target slip rotation when the prime mover output torque to the wheel drive system suddenly decreases (when the negative reverse drive torque increases) When the lockup clutch engagement torque capacity is increased, the following problems occur.

The motor (engine) output torque changes over time as shown by the solid line in FIG. 8, and the motor (engine) output torque suddenly decreases with a large motor (engine) output torque change rate as shown in the instant t1.
Despite this sudden decrease in prime mover (engine) output torque, the estimated output value for prime mover (engine) output torque changes slowly as shown by the wavy line due to the dead time setting and filter processing described above. Then, the target lockup clutch engagement capacity obtained as described above based on the estimated value of the engine (engine) output torque gradually increases at t1 when the output torque suddenly decreases.

For this reason, the lock-up capacity of the torque converter that is slip-controlled based on the target lock-up clutch engagement capacity is temporarily insufficient, and the torque converter input element is transmitted with a sufficient turning force from the output element via the lock-up clutch. It becomes difficult.
As a result, the torque converter input rotation speed (prime motor rotation speed) temporarily decreases as shown in the figure at the time t1 when the output torque suddenly decreases, the torque converter slip amount increases rapidly, the lock-up clutch is released, This causes the problem that the torque converter input rotational speed (primary motor rotational speed) decreases to the fuel recovery rotational speed at the instant t2 and fuel efficiency is deteriorated by fuel re-injection.

  The present invention proposes a slip converter for a torque converter in which the target lock-up clutch engagement capacity at the time of a sudden decrease in the output torque of the prime mover is determined by a procedure different from the conventional one so that the above-described problems do not occur. Objective.

For this purpose, a slip control device for a torque converter according to the present invention, as claimed in claim 1,
Used for torque converter that transmits rotation from prime mover,
When the actual slip rotation that is the difference between the input rotation speed and the output rotation speed of the torque converter is matched with the target slip rotation by the slip control of the lockup clutch that controls the engagement between the torque converter input and output elements,
Obtaining the target converter torque for realizing the target slip rotation based on the relationship between the converter torque that is obtained in advance from the transmission characteristics of the torque converter and the converter torque transmitted by fluid transmission and the torque converter slip rotation,
Subtracting the target converter torque from a motor output torque estimated value obtained by estimating the output torque of the motor to include a response delay of the actual machine, and calculating a target lockup clutch engagement capacity of the lockup clutch;
In the device for slip control of the lockup clutch so that the actual engagement capacity becomes the target lockup clutch engagement capacity,
A prime mover output torque rapid decrease detection means for detecting a predetermined rapid decrease in the prime mover output torque;
The target lockup clutch engagement capacity when a predetermined sudden decrease in the prime mover output torque is detected by the means is smaller than the change ratio of the target lockup clutch engagement capacity obtained by subtracting the target converter torque from the estimated value of the motor output torque. It is configured to increase rapidly.

In the slip converter of the torque converter according to the present invention,
The target lockup clutch engagement capacity is obtained by subtracting the target converter torque for realizing the target slip rotation from the estimated output of the prime mover output torque obtained by estimating the output torque of the prime mover to include the response delay of the actual machine. Basically, the actual slip rotation of the torque converter is matched with the target slip rotation by controlling the lock-up clutch slip engagement so as to be realized.
Target lock-up clutch engagement capacity obtained by subtracting the target converter torque from the estimated value of the motor output torque as described above to determine the target lock-up clutch engagement capacity when the motor output torque rapid decrease detection means detects a predetermined sudden decrease in the engine output torque. Increase faster than the rate of change.

  Therefore, when the prime mover output torque suddenly decreases, the lockup capacity of the torque converter that is slip-controlled based on the target lockup clutch engagement capacity does not become insufficient, and the torque converter input rotational speed (primary motor rotational speed) decreases rapidly. Sometimes the torque converter slip amount suddenly increases or the lockup clutch is not released, and the torque converter input rotational speed (motor rotational speed) decreases to the fuel recovery rotational speed. The fuel re-injection is not performed, and the problem related to the deterioration of the fuel efficiency can be avoided.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a slip converter for a torque converter according to an embodiment of the present invention.
Since the torque converter 2 is well known and not shown in detail, a pump impeller as a torque converter input element that is coupled to a crankshaft of an engine that is a prime mover and driven by the engine, and an input of a gear transmission mechanism for an automatic transmission The lockup type torque converter includes a turbine runner as a torque converter output element coupled to a shaft, and a lockup clutch 2c that directly connects the pump impeller and the turbine runner.

  The fastening force of the lockup clutch 2c is determined by the differential pressure (lockup clutch fastening pressure) between the applied pressure Pa and the release pressure Pr before and after that, and if the apply pressure Pa is lower than the release pressure Pr, the lockup clutch 2c It is released so that the pump impeller and the turbine runner are not directly connected, and the torque converter 2 is allowed to function in a converter state without slip restriction.

When the apply pressure Pa is higher than the release pressure Pr, the lockup clutch 2c is engaged with a force corresponding to the differential pressure, and the torque converter 2 functions in a slip control state in which the slip is limited according to the engagement force of the lockup clutch 2c. Let
When the differential pressure between the apply pressure Pa and the release pressure Pr becomes larger than the set value, the lock-up clutch 2c is completely engaged and the relative rotation between the pump impeller and the turbine runner is eliminated, and the torque converter 2 functions in the locked-up state. Let

The apply pressure Pa and the release pressure Pr are determined by the slip control valve 3. The slip control valve 3 determines the apply pressure Pa and the release pressure according to the signal pressure Ps from the lockup solenoid 4 that is duty-controlled by the controller 5. Although the pressure Pr is controlled, the slip control valve 3 and the lock-up solenoid 4 are well known as described below.
That is, the lockup solenoid 4 uses the constant pilot pressure Pp as the original pressure, and increases the signal pressure Ps as the solenoid drive duty D from the controller 5 increases.

  On the other hand, the slip control valve 3 receives the signal pressure Ps and the released release pressure Pr in one direction, and receives the spring force of the spring 3a and the fed-back applied pressure Pa in the other direction, thereby increasing the signal pressure Ps. As a result, the engagement pressure of the lockup clutch 2c represented by the differential pressure (Pa-Pr) between the apply pressure Pa and the release pressure Pr is increased from a negative value to a positive value via 0, and this positive value Shall be further increased.

  Here, the negative value of the lockup clutch engagement pressure (Pa−Pr) means that the torque converter 2 is brought into the converter state by Pr> Pa, and conversely, when the lockup clutch engagement pressure (Pa−Pr) is positive. Means that as the value increases, the engagement capacity of the lock-up clutch 2c is increased, the slip rotation of the torque converter 2 is greatly limited, and finally the torque converter 2 is brought into the lock-up state.

The controller 5 that determines the solenoid drive duty D includes:
A signal from the throttle opening sensor 21 that detects the throttle opening TVO representing the engine load;
A signal from the impeller rotation sensor 22 for detecting the rotational speed Nir of the pump impeller (also the torque converter input rotation speed, that is, the engine rotation speed);
A signal from the turbine rotation sensor 23 for detecting the rotation speed Ntr (torque converter output rotation speed) of the turbine runner;
A signal from the oil temperature sensor 24 for detecting the hydraulic oil temperature Temp of the automatic transmission (torque converter 2);
A signal from the transmission output rotation sensor 25 that detects the transmission output rotation speed (corresponding to the vehicle speed VSP) No,
A signal from the transmission ratio calculation unit 26 that calculates a transmission ratio Ip (= Ntr / No) that is a transmission input / output rotation ratio;
A signal from the power supply voltage sensor 27 for detecting the power supply voltage Vig is input.

  Based on the input information, the controller 5 determines the drive duty D of the lockup solenoid 4 by calculation according to the functional block diagram shown in FIG. 2, and also determines the lockup solenoid drive duty according to the power supply voltage signal Vig. D is corrected, and predetermined slip control described in detail below is performed.

  In the target slip rotation calculation unit 31 in FIG. 2, the vehicle speed VSP, the throttle opening TVO, the oil temperature Temp, the transmission gear ratio Ip, and the like are taken into consideration, and the coasting (inertia) ) The target slip rotation tNslip of the torque converter 2 is set so that the fuel cut (fuel stop) of the engine is continued during traveling.

Precompensator 32 consists of reference model 32a and feedforward compensator 32b,
The former reference model 32a is assumed to have a transfer function Gr (s) such that the slip control of the torque converter 2 becomes a target response intended by the designer,
The latter feedforward compensator 32b is a transfer function Gm () expressed by the ratio of the transfer function Gr (s) of the reference model 32a to the transfer function P (s) that models the torque converter slip rotating part to be controlled. s) = Gr (s) / P (s).

The pre-compensator 32 passes the target slip rotation tNslip through the reference model 32a of the transfer function Gr (s), calculates the slip rotation reference value Nslipref expressed by the following equation,
Nslipref = Gr (s) × tNslip (3)
The target slip rotation tNslip is passed through the feed forward compensator 32b of the transfer function Gm (s) to calculate the slip rotation feed forward compensation amount Nslipff expressed by the following equation.
Nslipff ＝ Gm (s) × tNslip (4)

  The actual slip rotation calculating unit 33 calculates the actual slip rotation Nslip of the torque converter 2 by subtracting the turbine runner rotation speed Ntr that is the torque converter output rotation speed from the pump impeller rotation speed Nir that is the torque converter input rotation speed.

  The slip rotation deviation calculating unit 34 calculates a slip rotation deviation Nsliperr = Nslipref−Nslip of the actual slip rotation Nslip with respect to the slip rotation reference value Nslipref.

The final target slip rotation calculation unit 35 includes a feedback compensator 35a and an adder 35b.
The former feedback compensator 35a eliminates the slip rotation deviation Nsliperr and sets the slip rotation feedback compensation amount Nslipfb when the actual slip rotation Nslip is matched with the slip rotation reference value Nslipref to a proportional / integral control (PI Control),
Nslipfb = Kp · Nsliperr + (Ki / s) x Nsliperr (5)
Where Kp: proportional control constant
Ki: Integral control constant
s: Differential operator The latter adder 35b adds the slip rotation feedback compensation amount Nslipfb and the slip rotation feedforward compensation amount Nslipff to obtain a final target slip rotation tNslipfn.
This final target slip rotation tNslipfn is an actual slip rotation Nslip of the torque converter 2 whose transfer function is P (s), and the target slip rotation tNslip is determined by the designer's desired response defined by the reference model 32a of the transfer function Gr (s). Target slip rotation for matching

The slip rotation gain calculator 36 calculates a slip rotation gain Gslip defined as follows.
To explain the slip rotation gain Gslip,
To explain the relationship between the converter torque Tcnv, the slip rotation Nslip, and the turbine rotation speed Ntr, which is the torque converter output rotation speed, which can be obtained in advance from the transmission performance of the torque converter 2, as shown by the vertical axis in FIG. The ratio of slip rotation Nslip to Tcnv is the slip rotation gain Gslip
Gslip = Nslip / Tcnv (6)
When this is defined, the slip rotation gain Gslip varies depending on the turbine rotation speed Ntr as illustrated in FIG. 3, although it differs between the drive state and the coast state.
Based on this fact, the slip rotation gain calculation unit 36 searches and obtains the slip rotation gain Gslip from the turbine rotation speed Ntr based on the slip rotation gain map illustrated in FIG.

The target converter torque calculator 37 applies the final target slip rotation tNslipfn from the final target slip rotation calculator 35 to the slip rotation Nslip in the above equation (6) using the slip rotation gain Gslip, and 6) By calculating the equation, the target converter torque tTcnv (t) in every moment necessary to achieve the final target slip rotation tNslipfn under the current turbine speed Ntr
tTcnv (t) = tNslipfn (t) / Gslip (8)
Is calculated.

The engine output torque estimation unit 38 estimates the engine output torque based on the information from the engine controller 39 to obtain the engine output torque estimated value Teh.
For this reason, the engine output torque estimation unit 38 first acquires a signal related to the steady engine output torque Tes from the engine controller 39, and takes into account the response delay of the actual machine as will be described later with reference to the control program shown in FIG. A dead time is set, a predetermined filtering process is performed, and a process for achieving the object of the present invention is performed to obtain an engine output torque estimated value Teh.

The target lock-up clutch engagement torque capacity calculation unit 40 in FIG. 2 calculates the target lock-up clutch engagement torque capacity tT _LUC based on the above equation (2) if the vehicle is in the forward drive that drives the wheels by the power from the engine. However, since the present invention is subject to control when the engine output torque is suddenly reduced, that is, during coasting (in reverse drive with engine braking applied), the target converter torque is calculated by the following equation instead of the equation (2). A target lockup clutch engagement torque capacity tT _LUC is obtained by subtracting the engine output torque estimated value Teh from tTcnv.
tT _LUC = −Teh + tTcnv (9)

Lockup clutch engagement pressure command value calculating unit 41 searches the map corresponding to the lock-up clutch engagement pressure command value P _LUC to achieve the target lockup clutch engagement torque capacity tT _LUC described above in FIG.
Here, in FIG. 6, the relationship between the target lockup clutch engagement torque capacity tT _LUC and the lockup clutch engagement pressure command value P _LUC is obtained in advance by experiments.

The lockup solenoid drive signal calculation unit 42 determines the drive duty D of the lockup solenoid 4 for setting the actual lockup clutch engagement pressure to the lockup clutch engagement pressure command value _PLUC . At this time, the power supply voltage Vig The lockup solenoid drive duty D is appropriately corrected so as to avoid the influence due to the change in the output and output to the lockup solenoid 4 in FIG.

Incidentally, in the present embodiment, in order to achieve the object of the present invention, when the engine output torque estimating unit 38 in FIG. 2 estimates the engine output torque estimated value Teh, the estimation is performed as shown in FIG.
In step S1 of FIG. 4, a signal regarding the steady engine output torque Tes from the engine controller 39 (see FIG. 2) is acquired.
In the next step S2, a steady change amount (Tes time change rate) ΔTes of the engine output torque Tes during a predetermined time which is a multiple of the calculation cycle of FIG. 4 is calculated.

In the next step S3, the torque converter input rotational speed Nir and the torque converter output rotational speed Ntr are read, and the actual slip rotational speed Nslip = Nir−Ntr of the torque converter 2, which is the difference between them, is calculated.
In the next step S4, the slip rotation gain Gslip is obtained from the turbine rotation speed Ntr, which is the torque converter output rotation speed, based on the map illustrated in FIG.
In the next step S5, a setting value ΔTesref for engine output torque sudden decrease determination is calculated.

This engine output torque rapid decrease determination set value ΔTesref is an engine output torque change amount set value for determining whether or not the engine output torque is suddenly decreased that requires lockup clutch engagement torque capacity increase control according to the present invention.
During torque converter slip control in coasting condition, if the engine output torque decreases suddenly, the lockup clutch will be released, or the engine speed will be less than the fuel recovery speed Nsliplim The following equation for dividing (abnormal slip rotation judgment value) by the slip rotation gain Gslip obtained in step S4: ΔTesref = −Nsliplim / Gslip (10)
The engine output torque sudden decrease determination set value ΔTesref is obtained by the above calculation.

In step S6 corresponding to the engine output torque rapid decrease detecting means, the steady change amount of engine output torque Tes obtained in step S2 (time change rate of Tes) ΔTes (negative value because of coasting) is as described above. It is determined whether or not the engine output torque is suddenly decreased, which requires the lock-up clutch engagement torque capacity increase control according to the present invention, based on whether or not the engine output torque rapid decrease determination set value ΔTesref (negative value) is not more than.
In step S7, it is checked whether or not the engine output torque rapid decrease flag fCAPS that is set to 1 when the engine output torque rapid decrease determination is made, that is, whether or not the previous engine output torque rapid decrease determination has not been made.

If it is determined in step S6 that the engine output torque is not suddenly decreasing, which requires the lockup clutch engagement torque capacity increase control according to the present invention, the engine output torque rapid decrease flag fCAPS is set to 0 in step S8 to indicate this. After that, control proceeds to step S9 and step S10.
Also when it is determined in step S7 that the previous engine output torque sudden decrease determination has not been made, the control is advanced to step S9 and step S10.

In step S9, the engine response delay is set as the dead time Leng, the dead time Leng is set to the steady engine output torque Tes obtained in step S2, and the dead time set engine output torque represented by the following equation is set. Ask for Tedly.
Tedly ＝ e ^-LengS × Tes (11)
In step S10, the dead time set engine output torque Tedly is passed through a first-order lag filter using the engine dynamic characteristic time constant Tc _ED, and the dead time set engine output torque Tedly is filtered. Thus, an engine output torque estimated value Teh expressed by the following equation is obtained.
Teh = {1 / (1+ Tc _ED · s)} Tedly (12)

When it is determined in step S6 that the engine output torque has suddenly decreased and the lockup clutch engagement torque capacity increase control according to the present invention is required, and it is determined in step S7 that the previous engine output torque has not been rapidly decreased, that is, the engine output torque Immediately after the sudden decrease, the control proceeds to step S11 to step S15.
In step S11, since it is immediately after the sudden decrease of the engine output torque, the engine output torque rapid decrease flag fCAPS is set to 1 to indicate that the engine output torque has been suddenly decreased.
Since fCAPS = 1 causes step S7 to advance control to step S9, the loop including steps S11 to S15 is selected only once immediately after the engine output torque is suddenly reduced.

  In step S12 subsequent to step S11, a map relating to the engine torque addition amount ΔTeup for increasing the lockup clutch engagement torque capacity at the time of sudden decrease in engine output torque for achieving the object of the present invention, which is predetermined as illustrated in FIG. Based on the above, the engine torque addition amount ΔTeup for increasing the lockup clutch engagement torque capacity when the engine output torque suddenly decreases is obtained from the slip rotation speed Nslip.

In step S13, as the engine output torque suddenly decreases, the buffer related to the process for setting the dead time for the engine output torque (step S9) and the buffer related to the filter process for the engine output torque (step S10) are initialized. For this purpose, the engine output torque Teint when the engine output torque suddenly decreases is added to the steady engine output torque Tes obtained at step S1 and the engine torque for increasing the lockup clutch engagement torque capacity when the engine output torque suddenly decreases obtained at step S12 is added. The sum of the quantity ΔTeup is obtained by the following equation.
Teint = Tes + ΔTeup (13)

In step S14, the engine output torque dead time setting process buffer used in step S9 is initialized, and the dead time set engine output torque Tedly obtained by setting the dead time in step S9 is obtained in step S13. The engine output torque is initialized to Teint when it is suddenly reduced.
Tedly = Teint = Tes + ΔTeup (14)
In step S15, the filter processing buffer used in step S10 is initialized, and the engine output torque estimated value Teh obtained by the filter processing in step S10 is initialized for the engine output torque sudden decrease obtained in step S13. Initialize to torque Teint.
Teh = Teint = Tes + ΔTeup (15)

The operation and effect of the above embodiment will be described below with reference to FIG. 7 showing an operation time chart under the same conditions as in FIG.
The time variation ratio ΔTes of the steady engine output torque Tes becomes equal to or less than the set value ΔTesref for the engine output torque sudden decrease determination, and reaches the engine output torque sudden decrease t1 that requires the lockup clutch engagement torque capacity increase control according to the present invention. Time (step S6),
By the initialization torque Teint (step S13), which is the sum of the engine output torque Tes at the instant t1 and the engine torque addition amount ΔTeup for increasing the lockup clutch engagement torque capacity when the engine output torque is suddenly reduced obtained in step S12, In order to initialize the engine output torque estimated value Teh (step S15),
After the engine output torque sudden decrease t1, the engine output torque estimated value Teh shows a change over time as shown by a broken line, and the engine output torque estimated value Teh is shown by a one-dot chain line in the transition period immediately after the engine output torque sudden decrease t1. It becomes a negative value larger than the conventional estimated engine torque value (same as shown by the broken line in FIG. 8).

Therefore, the target lock-up clutch engagement torque capacity tT _LUC obtained by the calculation unit 40 of FIG. 2 using the engine output torque estimated value Teh by the equation (9) is a solid line in the transition period immediately after the engine output torque sudden decrease t1. As shown, it increases rapidly and becomes larger than the conventional target lock-up clutch engagement torque capacity (the same as shown in FIG. 8) indicated by a one-dot chain line.
Therefore, according to the present embodiment, the target lockup clutch engagement capacity tT _LUC is more rapid than the change rate of the conventional target lockup clutch engagement torque capacity indicated by the one-dot chain line in the transition period immediately after the engine output torque sudden decrease t1. Will be increased.

Therefore, immediately after the engine output torque suddenly decreases t1, the torque converter lockup capacity that is slip-controlled based on the target lockup clutch engagement capacity tT _LUC does not become insufficient, and the torque converter input rotational speed Nir decreases. It can be suppressed to the one shown by.
Therefore, it is possible to prevent the torque converter input rotational speed Nir from being greatly reduced as indicated by a one-dot chain line (same as indicated by the solid line in FIG. 8) immediately after the engine output torque suddenly decreases t1, and the torque converter slip amount Nslip does not increase rapidly or the lock-up clutch 2a is not released, and the torque converter input rotation speed Nir decreases to the fuel recovery rotation speed as indicated by the alternate long and short dash line, and fuel is re-injected. It is possible to avoid problems related to deterioration in fuel efficiency.

In this embodiment, when the target lockup clutch engagement capacity tT _LUC is increased more rapidly than the change rate of the conventional target lockup clutch engagement torque capacity as described above at the time t1 when the engine output torque suddenly decreases, the rapid increase The engine torque addition amount ΔTeup should be set so that a large amount corresponds to a sudden decrease in engine output torque.
In this case, not generated excess or deficiency rapid increase amount of the target lockup clutch engagement capacity tT _LUC is matched to the engine output torque rapidly decreases the amount of an excessive shock may occur in the target lockup clutch engagement capacity tT _LUC, target lock It is possible to prevent a situation in which the above-described operation and effect cannot be performed as prescribed due to a shortage of the up-clutch engagement capacity tT _LUC .

Further, in this embodiment, when the target lockup clutch engagement capacity tT _LUC is suddenly increased at the time t1 when the engine output torque is suddenly reduced, the buffer used for estimating the engine output torque is initialized and the estimated value of the engine output torque itself is set to a predetermined torque value. Thus, the above-mentioned effects can be achieved easily only by the initialization work.

In this embodiment, when the target lockup clutch engagement capacity tT _LUC is suddenly increased at the time t1 when the engine output torque suddenly decreases, the engine output torque estimated value Teh is increased by ΔTeup (this increase correction is performed by multiplying by a predetermined coefficient). However, since the target lock-up clutch engagement capacity tT _LUC is calculated based on the engine output torque estimated value Teint after this increase correction, the following effects can be obtained.

In other words, if the engine output accessory such as an air conditioner is an engine load and the engine output torque to the wheel drive system decreases rapidly, this is not accurately reflected in the steady engine output torque Tes, and the engine output torque The actual engine output torque may drop beyond the detection value of Tes.
For this reason, dead time setting and filter processing (initialization in steps S14 and S15) are not performed on the steady engine output torque Tes, and the steady engine output torque Tes is simply used as the estimated value Teh. Then, the target lock-up clutch engagement torque capacity tT _LUC for achieving the above-mentioned effects cannot be increased appropriately.
In this embodiment, the engine output torque estimated value Teh is increased and corrected by the engine torque addition amount ΔTeup for increasing the lockup clutch engagement torque capacity when the engine output torque is suddenly decreased, and the target is based on the engine output torque estimated value Teint after the increase correction. Since the lockup clutch engagement capacity tT _LUC is calculated, the above-mentioned effects can be reliably achieved by eliminating the above concerns.

When the engine output torque estimated value Teh is corrected to be increased by the engine torque addition amount ΔTeup for increasing the lockup clutch engagement torque capacity when the engine output torque is suddenly reduced, in the present embodiment, this is performed by initialization in step S14 and step S15. In order to realize this, after initialization, the engine output torque estimated value Teh is obtained by dead time setting and filtering in steps S9 and S10, and the engine output torque estimated value Teh is shown in FIG. After output torque suddenly decreases at t1, it converges smoothly to steady engine output torque Tes, and the target lockup clutch engagement capacity tT _LUC is increased only in the transition period immediately after engine output torque suddenly decreases at t1. It can be avoided.

  Further, in this embodiment, when the engine output torque estimated value Teh is corrected to be increased by the engine torque additional amount ΔTeup for increasing the lockup clutch engagement torque capacity when the engine output torque suddenly decreases, this engine torque additional amount ΔTeup is as shown in FIG. Since the larger the actual slip rotation Nslip of the torque converter 2 is, the larger the effect is as follows.

In other words, when the lockup clutch 2a is completely engaged so that the torque converter slip rotation Nslip becomes 0, the problem to be solved by the present invention even when the engine output torque suddenly decreases (the torque converter slip amount increases rapidly and the lockup clutch Or the torque converter input rotational speed (engine rotational speed) decreases to the fuel recovery rotational speed), and the increase amount of the lockup clutch engagement torque capacity may be small.
On the other hand, when the torque converter slip rotation Nslip is large, the problem to be solved by the present invention is likely to occur when the engine output torque is suddenly reduced, and it is necessary to increase the amount of increase in the lockup clutch engagement torque capacity.
When the engine torque addition amount ΔTeup for increasing the lockup clutch engagement torque capacity when the engine output torque is suddenly reduced is increased as the actual slip rotation Nslip of the torque converter 2 is increased as in the present embodiment, the engine meets the above requirements. The increase amount of the lockup clutch engagement torque capacity when the output torque is suddenly reduced can be made excessive or insufficient under any torque converter slip rotation Nslip.

Further, in this embodiment, during the torque converter slip control in the coasting state in step S5 of FIG. 4, the lockup clutch is released if the engine output torque is suddenly reduced, or the engine speed is reduced. The engine output torque rapid decrease determination set value ΔTesref is obtained by the calculation of the above equation (10) that divides the limit slip rotation Nsliplim (abnormal slip rotation determination value) that will be equal to or lower than the fuel recovery rotation speed by the slip rotation gain Gslip. In this case, it is determined whether or not the engine output torque is suddenly decreased, which requires the lock-up clutch engagement torque capacity increase control according to the present invention, based on whether or not the time change rate ΔTes of the steady engine output torque Tes is equal to or less than ΔTesref. For,
That is, the abnormal slip rotation determination value Nsliplim of the torque converter is converted into the converter torque, and when the engine output torque reduction amount is equal to or greater than the converter torque conversion value, it is detected that the engine output torque is suddenly reduced.
A sudden decrease in engine output torque can be detected more accurately and reliably.

  The limit slip rotation Nsliplim (abnormal slip rotation determination value) is determined according to the engine speed during coasting, the target slip rotation tNslip of the torque converter, and the fuel recovery speed of the engine. Needless to say.

1 is a schematic system diagram illustrating a slip control device for a torque converter according to an embodiment of the present invention. It is a block diagram according to function of the slip control which a controller performs in the Example. It is a characteristic diagram which shows the change characteristic of the slip rotation gain with respect to the turbine rotation speed of a torque converter. FIG. 3 is a flowchart showing a control program executed when an engine output torque estimation unit in FIG. 2 obtains an engine output torque estimated value. It is a change characteristic figure of engine torque addition amount for lockup clutch fastening torque capacity increase at the time of engine output torque sudden decrease. It is a relationship diagram of the fastening pressure and fastening capacity of a lockup clutch. FIG. 3 is an operation time chart showing slip control of the torque converter according to FIG. 2. FIG. It is a time chart which shows the slip control of the torque converter by the conventional apparatus.

Explanation of symbols

2 Torque converter
2a Lock-up clutch 3 Lock-up control valve 4 Lock-up solenoid 5 Controller
21 Throttle opening sensor
22 Impeller rotation sensor
23 Turbine rotation sensor
24 Oil temperature sensor
25 Transmission output rotation sensor
26 Gear ratio calculator
27 Power supply voltage sensor
31 Target slip rotation calculator
32a normative model
32b feedforward compensator
33 Actual slip rotation calculator
34 Slip rotation deviation calculator
35a feedback compensator
35b adder
36 Slip rotation gain calculator
37 Target converter torque calculator
38 Engine output torque estimator
40 Target lock-up clutch engagement torque capacity calculator
41 Lock-up clutch engagement pressure command value calculation section
42 Lock-up solenoid drive signal calculator

Claims (6)

Used for torque converter that transmits rotation from prime mover,
When the actual slip rotation that is the difference between the input rotation speed and the output rotation speed of the torque converter is matched with the target slip rotation by the slip control of the lockup clutch that controls the engagement between the torque converter input and output elements,
Obtaining the target converter torque for realizing the target slip rotation based on the relationship between the converter torque that is obtained in advance from the transmission characteristics of the torque converter and the converter torque transmitted by fluid transmission and the torque converter slip rotation,
Subtracting the target converter torque from a motor output torque estimated value obtained by estimating the output torque of the motor to include a response delay of the actual machine, and calculating a target lockup clutch engagement capacity of the lockup clutch;
In the device for slip control of the lockup clutch so that the actual engagement capacity becomes the target lockup clutch engagement capacity,
A prime mover output torque rapid decrease detection means for detecting a predetermined rapid decrease in the prime mover output torque;
The target lockup clutch engagement capacity when a predetermined sudden decrease in the prime mover output torque is detected by the means is smaller than the change ratio of the target lockup clutch engagement capacity obtained by subtracting the target converter torque from the estimated value of the motor output torque. A slip control device for a torque converter, characterized by being configured to increase rapidly. In the slip control device of the torque converter according to claim 1,
Slip control of a torque converter, wherein the rapid increase amount of the target lockup clutch engagement capacity when the prime mover output torque rapid decrease detecting means detects a predetermined rapid decrease of the prime mover output torque corresponds to the rapid decrease amount of the prime mover output torque apparatus. In the torque converter slip control device according to claim 2,
When the motor output torque sudden decrease detecting means detects a predetermined sudden decrease in the motor output torque, the motor output torque estimated value is increased and corrected, and the target lockup clutch is engaged based on the motor output torque estimated value after the increase correction. A slip control device for a torque converter, characterized in that a capacity calculation is performed so that the target lockup clutch engagement capacity is increased rapidly. In the slip control device of the torque converter according to claim 3,
A torque converter characterized in that an increase correction amount of the motor output torque estimated value when the motor output torque rapid decrease detecting means detects a predetermined sudden decrease in motor output torque is changed according to an actual slip rotation of the torque converter. Slip control device. In the torque converter slip control device according to claim 4,
A torque converter characterized in that an increase correction amount of the motor output torque estimated value when the motor output torque rapid decrease detecting means detects a predetermined sudden decrease in the motor output torque is increased as the actual slip rotation of the torque converter is increased. Slip control device. In the slip converter for a torque converter according to any one of claims 1 to 5,
The prime mover output torque rapid decrease detecting means converts the abnormal slip rotation determination value of the torque converter into the converter torque, and detects that the prime mover output torque is suddenly decreased when the decrease in the prime mover output torque is equal to or greater than the converter torque converted value. A slip control device for a torque converter.

Images