JP3890464B2 - Control device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic transmission control device, and more particularly to an automatic transmission control device including a torque converter with a lock-up clutch.
[0002]
[Prior art and problems to be solved]
2. Description of the Related Art A torque converter of an automatic transmission is provided with a lockup clutch that fastens between input and output shafts. By suppressing the inherent relative slip generated between the input and output shafts of the torque converter with the lock-up clutch, the running fuel efficiency of the vehicle can be improved. (See JP-A-11-325237)
In this type of automatic transmission, if the lockup clutch is fastened rapidly, the engine speed will drop sharply and give the driver a sense of incongruity. Generally, the lockup clutch engagement hydraulic pressure is smoothed using a duty solenoid valve, etc. Smooth lock-up control to change to is performed.
[0003]
The lower the vehicle speed at which the lockup clutch is engaged, the greater the fuel efficiency improvement effect due to the lockup. However, since the relative slip of the torque converter is larger at lower vehicle speeds, if you attempt to lock up at a vehicle speed that is lower than a certain limit, the engine speed will drop rapidly even if you apply the smooth lockup control described above. It becomes difficult to avoid. Also, lockup at low vehicle speeds suppresses relative slip in the region where the torque converter exhibits a large torque ratio, so the change in acceleration at the time of engagement is also large, and so-called when starting acceleration, etc. The uncomfortable feeling due to the acceleration step is also increased.
[0004]
Because of these problems, the conventional technology cannot set the vehicle speed at which the lockup is performed sufficiently low, and there is a corresponding limit in the fuel consumption improvement effect.
[0005]
[Means for Solving the Problems]
According to a first aspect of the present invention, a torque converter that transmits engine torque to a transmission is provided with a lockup clutch that fastens an input / output shaft of the torque converter, and the lockup clutch is released in a predetermined converter region, and the converter Means for setting a target driving force on the basis of operating conditions of a vehicle and an engine in an automatic transmission for a vehicle, wherein a lock-up clutch is engaged when transitioning from a region to a predetermined lock-up region; Means for setting the target engine torque and the target gear ratio according to the driving force; , B Lock-up step reduction control that provides a period during which the target driving force is reduced from the start of engagement to the completion of engagement. And determining whether or not the lockup step reduction control is possible when shifting from the converter region to the lockup region, and performing normal lockup control when determining that the lockup step reduction control is impossible, When it is determined that the lockup step reduction control is possible, the vehicle speed at which the lockup clutch starts to be engaged is set to a low speed compared to the normal lockup control. It was supposed to be.
[0006]
In the second aspect of the invention, the driving force that is reduced by the lockup step reduction control is set based on the target driving force when the lockup clutch is completely engaged.
[0007]
The third invention is In the first or second invention, When driving force is generated that causes the vehicle acceleration to exceed a predetermined value Judge that lock-up step reduction control is possible It was supposed to be.
[0008]
According to a fourth aspect of the present invention, in the first or second aspect of the invention, the required load and the vehicle speed represented by the accelerator operation amount, the throttle opening degree, or the fuel injection amount are detected as the operating state.
[0009]
The fifth invention is: Said first or In the second invention ,car The road slope during both runs is less than the specified value. under When Judge that lock-up step reduction control is possible It was supposed to be.
[0010]
According to a sixth aspect of the present invention, in the lockup step reduction control according to the third aspect of the present invention, the vehicle speed at which the lockup clutch is started to be engaged is set to a relatively low speed and the engagement speed of the lockup clutch is reduced, so that the lockup clutch The vehicle speed at which the engagement is completed is set to be approximately the same as that in the normal lockup control in which the acceleration when shifting from the converter region to the lockup region is less than a predetermined value.
[0011]
According to a seventh aspect of the invention, the means for setting the target driving force according to the first aspect includes a process of calculating the first target driving force tFd1 in accordance with the operating state and the first target driving force at a predetermined ratio. The process of calculating the corrected target driving force αtFd1 reduced in step 1, the process of calculating the target driving force tTd # n in the operation state when the lockup clutch engagement is completed, and the corrected target driving force αtFd1 and the target driving force tTd when the engagement is completed The means for calculating the second target driving force tFd2 based on #n and setting the target engine torque and the target gear ratio is based on the target engine torque from the second target driving force tFd2 and the actual gear ratio. The processing for calculating tTe and the processing for calculating the target speed ratio tRATIO from the second target driving force tFd2 and the vehicle speed are performed.
[0012]
In an eighth aspect based on the seventh aspect, the processing for calculating the first and second target driving forces applies the target driving force according to the vehicle speed detected as the driving state and the accelerator operation amount. This is executed by referring to a map set in advance.
[0013]
[Action / Effect]
According to each of the first and subsequent inventions, since the driving force until the lockup clutch is completely engaged at the time of starting acceleration or the like is reduced, the acceleration step and the engine speed when the lockup clutch is engaged are reduced. Thus, the discomfort and driving shock given to the driver when the lock-up clutch is engaged can be reduced accordingly.
[0014]
In addition, the lockup clutch can be engaged from a lower speed while setting the vehicle speed when the lockup clutch is completely engaged to the same level as during normal lockup control, as much as the acceleration and rotational speed steps can be reduced. The effect of improving the fuel consumption can be enhanced by substantially expanding the lockup region to the lower speed side.
[0015]
In addition, the engagement speed of the lock-up clutch is low and the driving amount is reduced, so that the occurrence of clutch vibration (judder) when the lock-up clutch is engaged can be suppressed, and the clutch facing can be prevented from wearing and burning. The durability of the up clutch can be increased.
[0016]
The lockup step reduction control according to the present invention is not performed on an uphill with a road gradient of a certain level or more, so that it is possible to avoid the disadvantage that the acceleration performance is impaired due to insufficient driving force at the time of the uphill gradient.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a vehicle provided with a driving force control apparatus according to the present invention. This vehicle includes an engine 1 and a continuously variable transmission (hereinafter referred to as “CVT”) 2, and the output of the engine 1 is transmitted to the drive wheels 4 via the CVT 2, a final gear (not shown), and the drive shaft 3. It has a configuration.
[0018]
The engine 1 is a gasoline engine having an electronically controlled throttle 20 that can be controlled independently of the driver's accelerator operation, and controls the throttle opening of the electronically controlled throttle 20 according to the accelerator pedal operation by the driver. Thus, the engine torque is adjusted. When the engine 1 is a diesel engine, the engine torque is adjusted by adjusting the fuel injection amount with an injector.
[0019]
The CVT2 is a belt-type continuously variable transmission that includes a pair of pulleys 2a and 2b and a V-belt 2c that is wound between them. By changing the groove width of the pulleys 2a and 2b, the gear ratio (pulley) Can be changed steplessly. The CVT 2 includes a torque converter 6 with a lock-up mechanism, a forward / reverse switching mechanism (not shown) that switches the transmission direction of the engine rotation, and the like.
[0020]
Further, the vehicle includes an accelerator operation amount sensor 10 as an accelerator operation amount detection means by a driver, a vehicle speed sensor 11 as a vehicle speed detection means, an input rotation speed sensor 12 as an input rotation speed detection means of the CVT2, and an output rotation speed. Various sensors for detecting the operating state, such as an output rotation speed sensor 13 as a detecting means, a throttle sensor 21 for detecting the throttle valve opening degree, an oil temperature sensor 22 for detecting the oil temperature of the torque converter 6, and the like are attached. Various signals detected by the sensors are input to the integrated controller 9. Since the vehicle speed and CVT output rotation speed can be obtained by calculation if one is obtained, the vehicle speed sensor 11 and the output rotation speed sensor 13 may be configured to have only one of them. it can. The integrated controller 9 is configured as a microcomputer including, for example, a CPU and its peripheral devices, calculates a target driving force based on the input operating conditions, and uses the calculated target driving force as a predetermined engine torque. And driving force control realized by CVT gear ratio.
[0021]
The torque converter 6 includes a pump impeller 6a as an input element driven by the engine 1, a turbine runner 6b as an output element coupled to the input shaft of the CVT 2, and a lock that directly connects the pump impeller 6a and the turbine runner 6b. This is a lock-up type torque converter including an up clutch 6c.
[0022]
The fastening force of the lock-up clutch 6c is determined by the differential pressure between the applied pressure PA and the release pressure PR before and after that (PA-PR; hereinafter referred to as “lock-up clutch fastening differential pressure”), and the applied pressure PA is greater than the release pressure PR. If it is lower, the lock-up clutch 6c is released so that the pump impeller 6a and the turbine runner 6b are not directly connected to each other, and the torque converter 6 is functioned in a slip-free state (hereinafter referred to as “converter state”). When the apply pressure PA is higher than the release pressure PR and the differential pressure becomes larger than the set value, the lockup clutch 6c is engaged and the relative rotation between the pump impeller 6a and the turbine runner 6b is eliminated (hereinafter this state is referred to as “lock”). "Up state"). In the present embodiment, the lockup control system that determines the lockup clutch engagement differential pressure itself to perform predetermined lockup control has the following configuration. However, it is needless to say that the lock-up clutch engagement differential pressure can be set by any method, for example, by the configuration described in Japanese Patent Laid-Open No. 8-13881.
[0023]
FIG. 2 shows an outline of the control system of the lockup clutch 6c. The lockup control valve 14 in the figure uses the line pressure PL as a source pressure, and the signal pressure from the lockup solenoid 15 duty-controlled by the controller 8. The differential pressure (PA-PR) between the apply pressure PA and the release pressure PR is determined according to PS.
[0024]
The lockup solenoid 13 generates a signal pressure PS corresponding to a lockup control command LUdty (ON duty) from the controller 8 using a constant pilot pressure Pp as a source pressure. The lock-up control valve 14 receives the signal pressure PS and the released release pressure PR in one direction, and receives the spring force of the spring 14a and the fed-back applied pressure PA in the other direction. Take control. In other words, as the signal pressure PS from the lockup solenoid 13 increases as the lockup control command LUdty (ON duty) increases, the lockup control valve 14 detects the differential pressure between the apply pressure PA and the release pressure PR, that is, the lock The up-clutch engagement differential pressure is increased as shown in FIG. 3 (a), and the lock-up clutch 6c can be engaged with a positive value of the lock-up clutch engagement differential pressure. Put the converter in lockup state. Conversely, the lockup control valve 14 changes the lockup clutch engagement differential pressure as shown in FIG. 3 (a) as the signal pressure PS from the lockup solenoid 15 decreases as the lockup control command LUdty (ON duty) decreases. As shown in FIG. 5, the engagement force of the lockup clutch 6c is decreased, and finally, the lockup clutch 6c is released by the negative value of the lockup clutch engagement differential pressure, and the torque converter 6 is brought into the converter state.
[0025]
The engagement torque capacity Tcap of the lockup clutch 6c is determined by the above-mentioned lockup clutch engagement differential pressure. Now, if the outer diameter of the facing of the lockup clutch 6c is r1, the inner diameter of the facing is r2, the central diameter of the facing is r3, the friction coefficient of the facing is μ, and the safety coefficient is KS, the fastening torque capacity Tcap of the lockup clutch is 1).
[0026]
Tcap = [(PA-PR) (r1 ² -r2 ² ) × π × μ × r3] / KS (1)
Here, the lockup clutch engagement differential pressure for determining the engagement torque capacity Tcap of the lockup clutch 6c in this way is the lockup control command LUdty (ON duty) to the solenoid 13, as shown in FIG. Therefore, the relationship between the engagement torque capacity Tcap of the lockup clutch and the lockup control command LUdty (ON duty) can be obtained in advance as indicated by LUC in FIG.
[0027]
The controller 8 that determines the lockup control command LUdty (ON duty) of the solenoid 15 stores the relationship between the fastening torque capacity Tcap and the lockup control command LUdty shown in FIG. Is used for lock-up control described later. For the lockup control, the controller 8 includes an engine throttle opening TVO, an engine rotational speed Ne (= torque converter input rotational speed), a turbine runner 6b rotational speed Nt (torque converter output rotational speed), a speed change. An oil temperature signal for outputting a voltage value ADatf corresponding to the machine output rotational speed No and the transmission hydraulic oil temperature is input.
[0028]
Next, details of the driving force control and the lockup control with the above-described configuration will be described. FIG. 4 is a flowchart showing a basic routine of the driving force control. This control routine is repeatedly executed periodically by the integrated controller 9 during operation of the engine and the vehicle. In the following description and flowcharts, the numbers indicated with the symbol S are processing step numbers.
[0029]
First, an overview will be given. In general driving force control, the driving force is added and corrected with respect to the increase in travel resistance, and the engine torque is controlled using the corrected target driving force. In the driving force control, a decrease correction is performed by further multiplying the target driving force subjected to the addition correction by a predetermined coefficient.
[0030]
Specifically, first, in S11, the vehicle speed VSP, the accelerator operation amount APO, and a lockup signal indicating the state of the lockup clutch of the torque converter 6 are read. Next, in S12, a first target driving force tFd1 is set according to the vehicle speed VSP and the accelerator operation amount APO. This is set, for example, by searching a map set in advance so as to give tFd1 corresponding to VSP and APO as shown in FIG. Next, in S13, a corrected drive value is set by multiplying, for example, 20% in this case as the correction amount α in consideration of the driving force realization performance at the time of transition from the first target driving force tFd1. In S14, the accelerator operation amount APO and the target driving force tTd # n at the vehicle speed preset as the lockup engagement completion vehicle speed are set by searching FIG. In S15, the second target driving force tFd2 is set by adding the target driving force tTd # n at the vehicle speed at which the lockup engagement is completed to the corrected value (20% value of tFd1). Next, in S16, the target engine torque tTe is set by dividing the second target driving force tFd2 by the actual speed ratio RATIO so that the second target driving force tFd2 is realized. In S17, the target gear ratio tRATIO of CVT2 is calculated from the second target driving force tFd2 and the vehicle speed VSP. This is obtained, for example, by searching a map set in advance so as to give tRATIO corresponding to tFd2 and VSP as shown in FIG. The target engine torque tTe and the target speed ratio tRATIO set as described above are output to the engine controller 7 and the CVT controller 8 in S18, respectively. The engine controller 7 controls the intake air amount of the engine 1 (fuel injection amount in the case of a diesel engine) by an electronically controlled throttle so that the actual engine torque becomes the target engine torque tTe, and the CVT controller 8 has an actual gear ratio. Adjust the pulley ratio of CVT2 to achieve the target gear ratio tRATIO.
[0031]
On the other hand, the controller 8 performs lock-up control of the torque converter 6 by the processing shown in FIG. FIG. 7 shows a condition determination routine for performing lock-up control at the time of start acceleration of the vehicle. According to S21 to S21, the lock according to the present invention at the time of start where the road gradient during driving is low and the accelerator operation amount is not so large. Perform the up-step reduction control (S23) to reduce the rotational step at the time of lock-up engagement, and normal lock-up control when the driving resistance is large and the acceleration resistance is large when the accelerator opening is large. (S24) is performed. The gradient estimation method is arbitrary, and for example, the one disclosed in Japanese Patent Application Laid-Open No. 2000-104614 can be applied.
[0032]
FIG. 8 shows the basic processing of the lockup control. In FIG. 8, (a) shows signal measurement processing, (b) shows lockup control processing, and (c) shows signal output processing. In the signal measurement process (a), first, in S31, the throttle opening TVO, the engine speed Ne, the transmission input speed Nt, the transmission output speed No, and the oil temperature sensor output value ADatf are read. Next, at S32, the torque converter input / output rotational deviation absolute value | Ne-Nt | is obtained and set to Nerr, and the oil temperature sensor output value ADatf is referred to a preset map as shown in FIG. Then, the transmission hydraulic fluid temperature Temp is obtained, and the engine torque Te is obtained from the throttle opening TVO and the engine speed Ne based on the known engine performance diagram, and the speed ratio (Nt / Ne ) To obtain the transmission input torque Tin, and the transmission output rotational speed No to the constant K to obtain the vehicle speed VSP. In the lock-up control (b), first, in S33, it is determined whether or not to lock-up by the processing shown in FIG. 10 (described later), and then in S34, the lock-up control based on the determination is performed in FIG. This is performed by the process shown (described later). The signal output process of (c) is a process of outputting the lockup control command LUdty determined by the lockup control of (b) of FIG. 8 to the solenoid 13 in S35.
[0033]
Next, the lock-up determination in FIG. 10 will be described. However, in the following description, the operation region in the lock-up state is referred to as “lock-up region”, and the operation region in the converter state is referred to as “converter region”. First, in S41, it is determined whether the transmission hydraulic oil temperature Temp is in a temperature range equal to or higher than a set temperature Tmpth at which the lock-up of the torque converter 6 should be permitted or lower than a set temperature Tmpth at which lock-up should be prohibited. If it is a high temperature range in which lockup is permitted, it is determined in S42 whether the lockup region determination flag LU is 0 or not, whether it was the previous converter region or the lockup region.
[0034]
When it is determined in S42 that the previous time was the converter area, it is determined in S43 and 44 whether or not the lockup area is entered on the right side of the lockup ON line LUTon indicated by the solid line in FIG. That is, first, in S43, the lockup ON opening TVOon on the lockup ON line LUTon shown by the solid line in FIG. 9 is retrieved from the vehicle speed VSP from a map set in advance corresponding to FIG. Whether or not the current time has entered the lock-up region is determined based on whether or not the degree TVO is less than the above-described lock-up ON opening TVOon. Note that the vehicle speed LUTon set here as the lock-up area threshold is set to 15 km / h during normal lock-up control, for example, and changed to 5 km / h during lock-up step reduction control. The lockup control is started at a relatively low vehicle speed when starting.
[0035]
When it is determined that the lock-up area has been entered this time, a lock-up area determination flag LU indicating this is set to 1 in S45 to prepare for the next determination in S42. On the other hand, if it is determined in S44 that it is not in the lockup area this time, the lockup area determination flag LU is maintained at 0 by ending the control as it is to prepare for the next determination in S42.
[0036]
If it is determined in S42 that the previous time was the lock-up region, it is determined in S46, 47 whether or not the converter region on the left side of the lock-up OFF line LUToff indicated by the broken line in FIG. That is, first at S46, the lockup OFF opening TVOoff on the lockup OFF line LUToff indicated by the broken line in FIG. 9 is retrieved from the vehicle speed VSP, and then at S47, the throttle opening TVO is the above lockup OFF opening TVOoff. Whether or not the current time has entered the converter area is determined based on whether or not this is the case.
[0037]
When it is determined that the converter area has been entered this time, the lockup area determination flag LU is reset to 0 in S48 to prepare for the next determination in S42 and when the converter area is switched to the lockup area as described later. The initialization flag FLGf for initialization of the above is reset to 0. On the other hand, if it is determined in S47 that it is not in the converter area this time, the control is terminated as it is, so that the lockup area determination flag LU is maintained at 1 to prepare for the next determination in S42. When it is determined in S41 that the transmission hydraulic oil temperature Temp is a low oil temperature at which lockup should be prohibited, S42 to 47 are skipped and only S48 is executed, and the lockup region determination flag LU is reset to 0. At the same time, the initialization flag FLGf is reset to zero.
[0038]
Next, lockup control based on the lockup region determination result will be described in detail with reference to FIG. First, in S51, whether the lockup area or the converter area is determined by checking whether the lockup area determination flag LU is 1 or not. If the converter area is LU = 0, the control is terminated as it is, and the torque converter 6 is brought into the converter state. If the lockup area is LU = 1, the lockup control of the torque converter 6 is executed as follows. .
[0039]
That is, first, in S52, it is determined whether or not the initialization flag FLGf is 0. Here, since the initialization flag FLGf is reset to 0 in S48 of FIG. 9 when entering the converter area, the control proceeds from S52 to S53, and then the initialization flag FLGf is set to 1 in S54. After performing the setting process, the control is terminated. As a result, the initial setting in S53 is executed only once at the beginning of entering the lockup area, and thereafter, the initialization flag FLGf is set to 1 in S54. Therefore, the control proceeds to S55 to S59 by S53 and will be described later. Lockup control is executed.
[0040]
Explaining the initial setting in S53, based on the relationship between the engagement torque capacity Tcap of the lockup clutch 6c obtained in advance as described above and the lockup control command LUdty (ON duty) to the solenoid 13, The lockup control command initial value LUDi that provides the initial capacity LUC (0) corresponding to the engagement torque capacity Tcap = 0 is obtained, and also corresponds to the transmission input torque Tin (torque converter transmission torque) obtained in S32 of FIG. A lockup control command target value TCAPdty that obtains a fastening torque capacity Tcap = LUC (Tin) is obtained. Next, the lockup required time LUTIM for increasing the engagement torque capacity Tcap of the lockup clutch 6c from the initial capacity LUC (0) to the target capacity LUC (Tin) corresponding to the transmission input torque Tin is read. This lockup required time LUTIM is a time that balances the reduction of lock-up clutch engagement shock and the prevention of clutch facing burning due to heat generation, which are in a trade-off relationship. The fastening time is set so that the problem of fastening shock does not occur, and the lockup step reduction control is set in a longer time than in the normal control. This time may be set in advance, but here, calculation is performed so that the lockup engagement completion speeds in the normal control and the lockup step reduction control are the same. For example, during lockup step reduction control, the speed at which lockup control is started is 5 km / h as described above, so the time required to start lockup control during normal control up to 15 km / h is calculated from the vehicle acceleration. The time added to the lockup required time LUTIM used during normal control is defined as the lockup required time. In this case, the vehicle speed at which lock-up engagement is completed is the same during normal control and during lock-up step reduction control.
[0041]
Then, by dividing the step (TCAPdty-LUDi) between the lockup control command target value TCAPdty and the lockup control command initial value LUDi by the lockup required time LUTIM, the engagement torque capacity Tcap is determined as the initial capacity LUC ( A time change gradient DFFdty of the lockup control command LUdty for gradually increasing to the target capacity LUC (Tin) from 0) to the lockup required time LUTIM is calculated. Further, the time change gradient DFFdty of the lockup control command is compared with the lower limit value DFFmin of the time change gradient of the lockup control command so that the lockup clutch 6c does not cause judder, and the larger max (DFFdty, DFFmin ) And set to DFFdty. That is, judging of the lockup clutch 6c is prevented by preventing the time change gradient DFFdty of the lockup control command LUdty from becoming smaller than the lower limit value DFFmin.
[0042]
Finally, the lockup control command initial value LUDi is set to the lockup control command LUdty, which is output to the lockup solenoid 13 in step 35 of FIG. As a result of the control, as shown in FIG. 12A, the lockup control command LUdty is applied to the engagement torque capacity at the transition time t1 from the converter area where the lockup area flag LU switches from 0 to 1 to the lockup area. The control command initial value LUDi for the initial capacity LUC (0) corresponding to Tcap = 0 will rise rapidly, and the lockup clutch 6c will quickly complete the loss stroke not involved in the shock and delay the lockup response. To prevent.
[0043]
In the second and subsequent processes after the completion of the first loop, the ramp converter input / output rotational deviation absolute value Nerr = | Ne−Nt | obtained in S32 of FIG. 8 is greater than the set value Nth in S55. It is judged whether it is a control area or a lamp fixed area. If it is the ramp control range, in S56, the lockup control command LUdty is increased with the above-mentioned time-varying gradient DFFdty = max (DFFdt.y, DFFmin) as at time t1 and thereafter in FIG. Outputs to lockup solenoid 13 at 35. Then, the torque converter input / output rotational deviation absolute value Nerr = | Ne-Nt | becomes the lamp fixed range less than the set value Nth as the lock-up control proceeds, and after time t2 in FIG. Until it is determined that the control command LUdty has reached the set duty Dtyth, the lockup control command LUdty is raised at a fast fixed time-varying gradient RMP2 at S58, and this is increased at step 35 in FIG. 4 (c). Then, in S59, the lockup control command LUdty is raised at a slightly slow fixed time change gradient RMP1, and this is output to the lockup solenoid 13 in step 35 of FIG. Therefore, after time t1 in FIG. 12 (a), the lockup control command LUdty is changed from the control command initial value LUDi for the initial capacity LUC (0) corresponding to the engagement torque capacity Tcap = 0 to the lockup required time LUTIM. Is applied to the lockup control command target value TCAPdty to obtain the engagement torque capacity Tcap = LUC (Tin) corresponding to the transmission input torque Tin (torque converter transmission torque) until the time point t2, the time-varying slope DFFdty Increase gradually. In this way, transient control that achieves both reduction of lock-up shock and prevention of burn-up of lock-up clutch facing can be realized without requiring enormous matching man-hours.
[0044]
FIG. 12 (b) shows the state of occurrence of an acceleration step or the like during start acceleration by conventional lock-up control (normal lock-up control). As can be seen from comparison with this, FIG. According to (a)), both the rotational speed step and the acceleration step are sufficiently reduced, and a good driving feeling can be obtained. In FIG. 12, APOST is the accelerator pedal operation amount, G is the vehicle acceleration, LU differential pressure is the lockup clutch engagement differential pressure (PA-PR), Ne is the engine speed, Nt is the turbine speed of the torque converter, c represents the torque transmission region (half-clutch region) of the lockup clutch.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a mechanical configuration according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of the lockup control system of FIG. 1;
FIG. 3 is an explanatory diagram showing the relationship between a lockup solenoid control command, a lockup control differential pressure (a), and a lockup clutch engagement torque capacity (b).
FIG. 4 is a first flowchart showing the contents of an embodiment of automatic transmission control according to the present invention.
FIG. 5 is an explanatory diagram of a map that gives a target driving force tFd according to a vehicle speed VSP and an accelerator operation amount APO.
FIG. 6 is an explanatory diagram of a map that provides a target speed ratio tRATIO according to the vehicle speed VSP and the second target driving force tFd2.
FIG. 7 is a second flowchart showing the contents of an embodiment of automatic transmission control according to the present invention.
FIG. 8 is a third flowchart showing the contents of an embodiment of automatic transmission control according to the present invention.
FIG. 9 is an explanatory diagram of a converter area and a lockup area.
FIG. 10 is a fourth flowchart showing the contents of an embodiment of automatic transmission control according to the present invention.
FIG. 11 is a fifth flowchart showing the contents of an embodiment of automatic transmission control according to the present invention.
FIG. 12 is a timing chart for explaining the effect (a) of the present invention in comparison with the prior art (b).
[Explanation of symbols]
1 engine
2 Continuously variable transmission (CVT)
6 Torque converter
6c Lock-up clutch
7 Engine controller
8 CVT controller
9 Integrated controller
10 Accelerator operation amount sensor
11 Vehicle speed sensor
12 Input rotation speed sensor
13 Output rotation speed sensor
14 Lock-up control valve
15 Lock-up solenoid
20 Electronically controlled throttle
21 Throttle opening sensor
22 Oil temperature sensor

Claims (8)

The torque converter that transmits engine torque to the transmission is equipped with a lock-up clutch that fastens the input / output shaft of the torque converter. In an automatic transmission for a vehicle in which a lockup clutch is engaged when transitioning to a region,
Means for setting a target driving force based on the driving state of the vehicle and the engine;
Means for setting a target engine torque and a target gear ratio according to the target driving force;
A lock-up step reduces the control means for providing a time to reduce the target driving force between the lock-up clutch engagement start until the engagement completion,
With
When shifting from the converter area to the lock-up area, it is determined whether or not the lock-up step reduction control is possible. When it is determined that the vehicle speed at which the lockup clutch starts to be engaged is set to a low speed compared to the normal lockup control.
A control device for an automatic transmission.   2. The automatic transmission control device according to claim 1, wherein the driving force reduced by the lockup step reduction control is set based on a target driving force at the completion of lockup clutch engagement. Control system for an automatic transmission according to claim 1 or claim 2 wherein the lock-up step reduces controllable and determines when the driving force acceleration of vehicles becomes a predetermined value or more occurs.   The control apparatus for an automatic transmission according to claim 1 or 2, wherein a required load and a vehicle speed represented by an accelerator operation amount, a throttle opening amount, or a fuel injection amount are detected as the driving state. Control apparatus for an automatic transmission of a road gradient during the car both traveling according to claim 1 or 2 determines that the lock-up step reduces controllable when the following predetermined value.   In the lock-up step reduction control, the vehicle speed at which the lock-up clutch is started to be engaged is set to a relatively low speed, and the lock-up clutch engagement speed is reduced, so that the vehicle speed at which the lock-up clutch is completely engaged is locked from the converter area. 4. The control device for an automatic transmission according to claim 3, wherein the acceleration at the time of shifting to the up region is substantially the same as that at the time of normal lockup control less than a predetermined value. The means for setting the target driving force includes:
A process of calculating a first target driving force tFd1 according to the operating state;
A process of calculating a corrected target driving force αtFd1 obtained by subtracting the first target driving force by a predetermined ratio;
Processing to calculate the target driving force tTd # n in the operation state at the time of completion of the lockup clutch engagement;
A process of calculating a second target driving force tFd2 based on the corrected target driving force αtFd1 and the target driving force tTd # n at the completion of engagement;
The means for setting the target engine torque and the target gear ratio is:
A process of calculating a target engine torque tTe from the second target driving force tFd2 and the actual gear ratio;
The control apparatus for an automatic transmission according to claim 1, wherein processing for calculating a target speed ratio tRATIO is performed from the second target driving force tFd2 and a vehicle speed.   The processing for calculating the first and second target driving force is executed by referring to a map set in advance so as to give the target driving force according to the vehicle speed detected as the driving state and the accelerator operation amount. The control device for an automatic transmission according to claim 7.

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