JP4890698B2 - Shift control device for continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device for a continuously variable transmission mounted on an automobile.
[0002]
[Prior art]
As a continuously variable transmission (CVT) applied to the power transmission system of an automobile, there are a belt type continuously variable transmission, a toroidal type continuously variable transmission, and the like. It is automatically controlled.
[0003]
In such a transmission control device for a continuously variable transmission, the target primary pulley rotational speed is referred to the basic transmission speed characteristic map based on parameters indicating the operating state such as the throttle opening, the vehicle speed, or the engine rotational speed. Is set so that the actual primary pulley rotation speed converges to the target primary pulley rotation speed, thereby continuously setting the gear ratio in the continuously variable transmission from low to overdrive.
[0004]
Here, the basic shift characteristic map for determining the shift characteristic is often set in advance by experiments or the like so that the vehicle can optimally travel on a flat road with a standard weight. Therefore, when the speed ratio for a flat road is set based on the basic speed change characteristic map when traveling on an uphill road, torque shortage occurs and the driver feels uncomfortable. Further, when traveling on a downhill road, the optimum engine braking force cannot be obtained, which similarly gives a sense of incongruity.
[0005]
Therefore, a shift control device has been developed in which the amount of increase in running resistance when traveling on a flat road is calculated to determine whether the vehicle is traveling uphill or downhill, and the shift characteristics are corrected to the downshift side according to the amount of increase in running resistance. Has been. In such a shift control device, a target driving force that does not give the driver a sense of incongruity is set based on the amount of increase in running resistance when traveling on an uphill / downhill road. The achieved driving force estimated by the corrected shift characteristic is calculated, and the gear ratio correction amount is set so that the achieved driving force converges with respect to the target driving force. Then, using this gear ratio correction amount, the target primary pulley rotation speed stored in the basic shift characteristic map provided in advance is corrected to the downshift side, and the shift characteristic is determined by the corrected target primary pulley rotation speed. .
[0006]
In addition, a transmission that uses travel resistance as a criterion for determining a travel situation may not be able to make a normal determination when resistance due to brake operation or the like is applied. For example, Japanese Patent Laid-Open No. 9-112682 discloses a brake operation. A technique is disclosed in which correction of the target primary pulley rotational speed at the time is prohibited and the previous target primary pulley rotational speed is maintained.
[0007]
[Problems to be solved by the invention]
However, in the case where the gradient of the traveling road changes while the driver is operating the brake, the gear ratio set by the target primary pulley rotation speed corresponds to the road surface gradient before the brake operation. The road surface gradient that actually runs after the brake operation was not dealt with.
[0008]
For this reason, on a road surface that changes from a gentle slope to a steep slope, if the brake operation is performed before the correction to the target primary pulley rotation speed corresponding to the steep slope is completed, the amount of downshift may be insufficient. Even when the road surface changes from a steep slope to a gentle slope, if the brake operation is performed before the correction is completed, the amount of downshift may be excessive. In addition, when the driver operates the brake at the change of the slope, it feels as if the amount of downshift is changed by the driver's operation, which may give the driver a sense of incongruity.
[0009]
Furthermore, when operating an air conditioner compressor driven by the crankshaft of the engine, acceleration / deceleration is generated in the vehicle due to fluctuations in engine torque, so that the amount of increase in running resistance can be calculated accurately and the shift characteristics can be determined. It may not be possible.
[0010]
An object of the present invention is to provide a continuously variable transmission that avoids unnecessary fluctuations in speed change characteristics due to changes in running resistance that are unrelated to changes in road slope, and does not give the driver a sense of incongruity on a road surface where the slope changes. The object is to provide a shift control device.
[0011]
[Means for Solving the Problems]
The transmission control device for a continuously variable transmission according to the present invention shifts the rotation of an input-side rotator driven by an engine in a stepless manner via a power transmission element and transmits it to the output-side rotator. A control device for detecting that the vehicle is traveling on an uphill / downhill road; and when the vehicle is traveling on an uphill / downhill road, a target driving force is determined based on an increase in travel resistance of the vehicle. Comparing the target driving force calculating means to calculate, the target driving force and the achieved driving force when the throttle is fully opened or when the throttle is fully closed at the current vehicle speed, and when the achieved driving force is smaller than the target driving force, When a correction amount setting means for increasing and updating the correction amount of the target rotational speed of the input side rotating body and a variation factor that causes a load variation in the engine when the vehicle is traveling on an uphill / downhill road are generated , the variation factor And a hold control means for performing hold control for calculating the target driving force based on the running resistance increment before occurring, the correction amount setting means, under a state where the hold control is executed If the achieved driving force is smaller than the previous SL target driving force, characterized by the Turkey to prohibit the increase updating of the correction amount of the target rotational speed.
[0012]
The transmission control device for a continuously variable transmission according to the present invention shifts the rotation of an input-side rotator driven by an engine in a stepless manner via a power transmission element and transmits it to the output-side rotator. A control device for detecting that the vehicle is traveling on an uphill / downhill road; and when the vehicle is traveling on an uphill / downhill road, a target driving force is determined based on an increase in travel resistance of the vehicle. Comparing the target driving force calculating means to calculate, the target driving force and the achieved driving force when the throttle is fully opened or when the throttle is fully closed at the current vehicle speed, and when the achieved driving force is smaller than the target driving force, A correction amount setting means for increasing and updating the correction amount of the target gear ratio of the continuously variable transmission to the downshift side, and a variable factor that causes load fluctuations in the engine when the vehicle is traveling on an uphill / downhill road If it happens Has a hold control means for executing a hold control for calculating the target driving force based on the travel resistance increase amount before the variation factor occurs, and the correction amount setting means is configured to execute the hold control. Under the condition, when the achieved driving force is smaller than the target driving force, an increase update to the downshift side of the correction amount of the target gear ratio is prohibited .
[0013]
According to the present invention, in a situation where there is a possibility that the road surface gradient that is a reference for calculating the amount of increase in running resistance and the road surface gradient that actually travels may be separated, the increase correction of the gear ratio correction amount that sets the gear ratio characteristic is prohibited. As a result, an unnecessary increase in the rotational speed of the input-side rotator is prevented, so that unnecessary downshift correction can be prevented and a sense of incongruity to the driver can be prevented.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a schematic diagram showing a power transmission system 11 of an automobile having a continuously variable transmission 10. As shown in FIG. 1, the power transmission system 11 includes a starting clutch 12 constituted by a torque converter or the like, a forward / reverse switching device 13 constituted by a planetary gear or the like for converting the rotational direction of power, and a stepless speed change. The power transmission system 11 is built in a case 14.
[0016]
The crankshaft 16 of the engine 15 is connected to the start clutch 12, and the output shaft 27 of the start clutch 12 is connected to the forward / reverse switching device 13. A primary fixed pulley 18a is fixed to an input shaft 17 that is connected to the forward / reverse switching device 13 and receives rotational output. The primary movable pulley 18b is slidably mounted on the input shaft 17 by a ball spline or the like. The primary pulley 18 as the input side rotating body is formed by the two pulleys 18a and 18b.
[0017]
A secondary fixed pulley 20a is fixed to an output shaft 19 that is rotatably mounted in the case 14 and is parallel to the input shaft 17. The secondary movable pulley 20b is slid against the output shaft 19 by a ball spline. The secondary pulley 20 that is an output side rotating body is formed by two pulleys 20a and 20b.
[0018]
A primary hydraulic chamber 21 and a secondary hydraulic chamber 22 are formed in the primary pulley 18 and the secondary pulley 20, respectively, and the volume is increased by supplying hydraulic pressure to these hydraulic chambers 21 and 22, and the two movable pulleys 18b. 20b are slid in the axial direction. Further, a drive belt 23 as a power transmission element is stretched between the primary pulley 18 and the secondary pulley 20, and the drive belt 23 is changed by changing the cone surface interval by sliding of the movable pulleys 18b and 20b. The pulley diameter to be held changes, and a continuously variable transmission from the input shaft 17 to the output shaft 19 becomes possible.
[0019]
The output shaft 19 is connected to the drive wheels 26 via the reduction gear train 24 and the differential device 25, and the driving force generated from the engine 15 is determined in the rotational direction by the forward / reverse switching device 13 to be continuously variable. It is converted into an appropriate driving force by the machine 10, the reduction gear train 24, and the differential device 25 and transmitted to the driving wheel 26.
[0020]
FIG. 2 is a schematic diagram showing a control system for operating the aforementioned continuously variable transmission 10. As shown in FIG. 2, the hydraulic oil from the oil pump 30 is regulated and supplied as the primary hydraulic pressure in the primary hydraulic chamber 21, and the gear ratio is variably set by operating the primary pulley 18. Similarly, the regulated secondary hydraulic pressure is supplied to the secondary hydraulic chamber 22, and the secondary pulley 20 is operated to apply a pressure necessary for torque transmission to the drive belt 23. The oil pressure adjusted in this way is set based on the traveling state of the vehicle by a signal from the CVT control unit 31 described later, and the cone surface distance between the two pulleys 18 and 20 is controlled.
[0021]
As shown in FIG. 2, the CVT control unit 31 includes a microcomputer or the like. As shown in FIG. 2, the input port includes a brake switch 32 that is turned ON when the brake pedal is depressed, a range detection sensor 33 that detects a selected select range, and an accelerator pedal. A throttle opening sensor 34 that detects the operation amount, a primary pulley rotation speed sensor 35 that detects the rotation speed of the primary pulley 18, a secondary pulley rotation speed sensor 36 that detects the rotation speed of the secondary pulley 20, and an engine control unit 37 are connected. The engine speed data calculated based on the output signal of the crank angle sensor 38 and the various calculation data calculated based on the output signals of the various sensors 39 are input from the engine control unit 37. Further, proportional solenoids 40a and 41a of a shift control valve 40 and a line pressure control valve 41 for regulating the primary hydraulic pressure and the secondary hydraulic pressure are connected to the output port of the CVT control unit 31, respectively.
[0022]
A line pressure control valve 41 is connected to an oil passage 42 that connects the oil pump 30 and the secondary hydraulic chamber 22, and hydraulic oil that has been regulated from the discharge pressure of the oil pump 30 to the line pressure is used as a secondary hydraulic pressure. The secondary hydraulic chamber 22 is supplied. A shift control valve 40 is connected to an oil passage 43 that branches from the oil passage 42 and connects to the primary hydraulic chamber 21, and the primary hydraulic pressure regulated from the line pressure is supplied to the primary hydraulic chamber 21. .
[0023]
Hereinafter, functions of the CVT control unit 31 will be described. The CVT control unit 31 functions as follows in order to control the operation amount of the proportional solenoid 40a connected to the transmission control valve 40.
[0024]
The CVT control unit 31 calculates a travel resistance increase amount ΔR based on a flat road as a travel reference, and takes this travel resistance increase amount ΔR into consideration, thereby giving the driver a sense of discomfort when traveling on an uphill road or traveling on a downhill road. The target driving force Ftrgt that can travel without being calculated is calculated. By comparing this target driving force Ftrgt with the achieved driving force F (t) that is expected to occur when the throttle is fully opened or fully closed at the current vehicle speed, the deviation is converged within a predetermined range. The target primary pulley rotational speed correction amount ΔNP is set so that the target primary pulley rotational speed NP is corrected by the correction amount ΔNP, so that the engine rotational speed Ne and the engine torque T after the shift are predicted, and the vehicle travels on an uphill road. The target speed ratio is is set as the final basic speed change characteristic when traveling on a downhill road. The primary hydraulic pressure supplied to the primary hydraulic chamber 21 of the primary pulley 18 is controlled so that the actual speed ratio i approaches the target speed ratio is set in this way.
[0025]
The CVT control unit 31 has a travel resistance increase amount calculating means for calculating the travel resistance increase amount ΔR, and the travel resistance increase amount ΔR is calculated from the difference between the generated driving force Fo of the drive wheels and the travel resistance R. Is done. The generated driving force Fo is calculated using the engine torque T, the actual transmission ratio i of the continuously variable transmission 10, the reduction ratio Gear from the continuously variable transmission 10 to the driving wheels 26, and the driving wheel diameter.
[0026]
The engine speed Ne calculated by the engine control unit 37 based on the output signal of the crank angle sensor 38 is input as a parameter referring to the engine torque map, and the engine torque is calculated based on the engine speed Ne and the throttle opening THo. The engine torque T is set by referring to the map with interpolation calculation. The actual speed ratio i is calculated from the ratio between the actual primary pulley rotation speed NPi and the actual secondary pulley rotation speed NSo calculated based on the output signals of the pulley rotation speed sensors 35 and 36.
[0027]
Further, the CVT control unit 31 has a target driving force calculating means for setting the target driving force Ftrgt. The target driving force Ftrgt is set so that a marginal driving force corresponding to the travel resistance increase amount ΔR can be obtained in the same manner as in flat road traveling in uphill traveling and downhill traveling. In the uphill traveling, a target driving force Ftrgt that can obtain a marginal driving force equivalent to the travel resistance increase amount ΔR when the throttle is fully opened is set, and in the downhill traveling, the travel resistance increase amount ΔR when the throttle is fully closed. A target driving force Ftrgt is set that allows the engine braking force to be applied with a sufficient margin.
[0028]
Further, the CVT control unit 31 has a gear ratio correction amount setting means for setting the target primary pulley rotational speed correction amount ΔNP, and is fully open when traveling on an uphill road and fully closed when traveling on a downhill road. In addition, the target primary pulley rotational speed correction amount for correcting the target gear ratio when the throttle is fully opened or fully closed so that the driving force F (t) at the current vehicle speed V converges within a predetermined range with respect to the target driving force Ftrgt. ΔNP is set.
[0029]
Note that the vehicle speed V uses the actual secondary pulley rotation speed NSo, the reduction ratio Gear, and the driving wheel diameter calculated by the vehicle speed detection means provided in the CVT control unit 31 based on the output signal of the secondary pulley rotation speed sensor 36. Is calculated.
[0030]
Further, there is provided a shift characteristic correcting means for offsetting the entire target primary pulley rotation speed NP stored in the basic shift characteristic map as the basic shift characteristic to the downshift side by the target primary pulley rotation speed correction amount ΔNP. As a result, when traveling on an uphill road or traveling on a downhill road, the basic shift characteristic map is referred to with interpolation calculation based on the vehicle speed V and the throttle opening THo, and the target primary pulley rotational speed NP is set in the same manner as on a flat road. Even so, it is possible to obtain a marginal driving force corresponding to the travel resistance increase amount ΔR when traveling on an uphill road, and it is possible to effectively operate the engine brake when traveling on a downhill road.
[0031]
In this way, using various means provided in the CVT control unit 31, the speed change characteristic according to the road surface gradient is adopted when traveling on the uphill / downhill. Further, a hold control means is provided in the CVT control unit 31 in order to detect a factor that causes an unnecessary change in the travel resistance increase amount ΔR. When there is a possibility that the travel resistance increase amount ΔR corresponding to the weight gradient resistance cannot be accurately calculated by the hold control means, hold control is executed to prohibit the calculation of the travel resistance increase amount ΔR and maintain the previous value. Is done.
[0032]
Next, the shift characteristic correction process for setting the shift characteristic according to the uphill / downhill traveling by the CVT control unit 31 will be described. This shift characteristic correction process is executed every predetermined period. FIG. 3 is a flowchart showing a hold control determination process by the shift control apparatus according to the embodiment of the present invention, and shows a hold control determination procedure by the hold control means. The hold control determination process constitutes a part of the shift characteristic correction process.
[0033]
First, as shown in FIG. 3, a traveling state of the vehicle that affects the traveling resistance increase amount ΔR for determining the road surface gradient, that is, a state in which the engine 15 is subjected to a load fluctuation more than a predetermined value is determined. In step S1, it is determined whether or not the brake is being operated by reading an output signal from the brake switch 32. In step S2, a predetermined value A that is set in advance is compared with a vehicle acceleration to obtain a predetermined value or more. In step S3, it is determined whether or not the vehicle is decelerating more than a predetermined value by comparing a predetermined value B set in advance with the vehicle deceleration.
[0034]
In step S4, it is determined whether a sudden increase or decrease in engine torque has occurred. In steps S5 and S6, it is determined whether the fuel cut that causes engine torque fluctuations is returned and started. Similarly, steps S7 and S8 are performed. Then, it is determined when the air conditioner compressor driven by the crankshaft 16 is started and stopped.
[0035]
Then, when any of the above-mentioned traveling conditions is applicable, there is a possibility that the road surface gradient may be erroneously determined. Therefore, the process proceeds to step S9, the hold flag is set, the calculation of the traveling resistance increase amount ΔR is prohibited, and the previous calculation is performed. While it is determined that the hold control is to maintain the running resistance increase amount ΔR, the process proceeds to step S10 when the running resistance can be stably detected without corresponding to any of the above-described vehicle conditions, and the hold flag is released. Is done.
[0036]
FIG. 4 is a flowchart showing a calculation process of the running resistance increase amount ΔR by the speed change control apparatus according to the embodiment of the present invention. The travel resistance increase amount calculation process constitutes a part of the shift characteristic correction process. When the above-described hold control determination process is completed, the hold control is determined in step S11 shown in FIG. 4, and when the hold flag is released, the process proceeds to step S12 and the running resistance increase amount ΔR is calculated. Here, the travel resistance increase amount ΔR is a travel resistance increase amount ΔR when traveling on a flat road recorded in advance, and corresponds to a weight gradient resistance value when traveling on an uphill or downhill road. On the other hand, when the hold flag is set, the process proceeds to step S13, and the newly calculated travel resistance increase amount ΔR is maintained without calculating the new travel resistance increase amount ΔR. Subsequently, in step S14, a road surface gradient value based on the travel resistance increase amount ΔR is calculated.
[0037]
Next, the uphill / downhill detection means provided in the CVT control unit 31 determines whether the road corresponds to any of uphill road travel, downhill road travel, or flat road travel based on the calculated travel resistance increase amount ΔR. . The gradient state of the traveling road is determined by comparing the traveling resistance increase amount ΔR with preset ascending road judgment values and downhill road judging values.
[0038]
Here, in order to obtain a marginal driving force equivalent to that on a flat road when traveling on an uphill road, it is only necessary to control so that the driving force when the throttle is fully opened is generated by an amount corresponding to the increase in travel resistance ΔR. In order to obtain an engine braking force equivalent to that on a flat road even during traveling, it is only necessary to perform control so that the engine braking force when the throttle is fully closed is activated by the traveling resistance increase amount ΔR.
[0039]
First, when traveling on an uphill road, the engine torque T at the current vehicle speed V when the throttle is fully opened is set. That is, the target primary pulley rotation speed NP when the throttle is fully opened is set by referring to the throttle fully open characteristic line of the basic shift characteristic map based on the current vehicle speed V. The basic shift characteristic map used at this time uses the vehicle speed V and the throttle opening THo as parameters to obtain a target primary pulley rotational speed NP suitable for flat road running in advance by simulation or experiment, and the CVT control unit 31 It is recorded in memory.
[0040]
Then, the target primary pulley rotational speed NP is adopted as a parameter of the engine rotational speed Ne, and the engine torque T when the throttle is fully opened is set with reference to the throttle fully open characteristic line of the engine torque map. This engine torque map is obtained by previously calculating the engine torque T by simulation or experiment using the engine speed Ne and the throttle opening THo as parameters, and is recorded in the memory of the CVT control unit 31.
[0041]
Similarly, when it is determined that the vehicle travels on a downhill road, the target primary pulley rotational speed NP when the throttle is fully closed is set with reference to the throttle fully closed characteristic line of the basic transmission characteristic map. Next, the target primary pulley rotational speed NP is adopted as a parameter of the engine rotational speed Ne, and the engine torque T when the throttle is fully closed is set with reference to the throttle fully closed characteristic line of the engine torque map. It should be noted that the basic shift characteristic map and the engine torque map that are referred to in both the uphill traveling and the downhill traveling are the same.
[0042]
When traveling on an uphill / downhill road, first, a target speed ratio rs when the throttle is fully opened or fully closed is calculated based on the target primary pulley rotational speed NP and the actual secondary pulley rotational speed NSo. Based on the target speed ratio rs, the engine torque T when the throttle is fully opened or closed, the total reduction ratio Gear, and the driving wheel diameter, the driving force Fs when the throttle is fully opened or fully closed on a flat road is calculated. The driving resistance increase amount ΔR is added to the driving force Fs to calculate a target driving force Ftrgt that is a target value of the actual achieved driving force F (t). In addition, you may add what carried out weighting correction | amendment to travel resistance increase amount (DELTA) R in each speed range of a vehicle.
[0043]
Next, the achieved driving force F (t) is calculated by updating the current target primary pulley rotational speed correction amount ΔNP (t) with the target primary pulley rotational speed correction amount ΔNP set during the previous shift characteristic correction process. . This achieved driving force F (t) is an estimated driving force obtained by correcting the gear ratio when the throttle is fully opened or fully closed, that is, by offsetting the gear ratio to the downshift side.
[0044]
In order to calculate the achieved driving force F (t), first, the throttle gear is fully opened or fully closed by using the target speed ratio rs and the actual secondary pulley rotational speed NSo in consideration of the target primary pulley rotational speed correction amount ΔNP (t). The primary rotation speed NP (t) generated at the time is calculated.
[0045]
Next, the generated primary engine speed NP (t) is adopted as a parameter of the engine engine speed Ne, and when traveling uphill, the throttle fully open characteristic line in the engine torque map is referred to, while when traveling downhill, the throttle fully closed characteristic line is used. Referring to this, the engine torque T (t) generated when the throttle is fully opened or fully closed is set. Then, the achieved driving force F (t) is calculated from the generated engine torque T (t) and the target speed ratio rs taking into account the target primary pulley rotation speed correction amount ΔNP.
[0046]
The absolute value of the difference between the target driving force Ftrgt and the achieved driving force F (t) calculated in this way is compared with a preset set value h, and the achieved driving force Ftrgt is compared with the target driving force Ftrgt. It is determined whether or not (t) has converged within a range determined by a set value h that does not give the driver a sense of incongruity. When the convergence is completed, the update of the target primary pulley rotational speed correction amount ΔNP is terminated. On the other hand, when the achieved driving force F (t) has not converged to the target driving force Ftrgt, the target primary pulley is incremented by a predetermined value set in advance until convergence. The rotational speed correction amount ΔNP is updated.
[0047]
As described above, in order to update the target primary pulley rotational speed correction amount ΔNP, the traveling resistance increase amount ΔR is again compared with the uphill road determination value and the downhill road determination value, and the current driving is uphill road driving and downhill road driving. Or whether the vehicle is traveling on a flat road. Then, the target primary pulley rotational speed correction amount ΔNP is updated separately for uphill traveling and downhill traveling.
[0048]
First, the update process of the target primary pulley rotation speed correction amount ΔNP when traveling on an uphill road will be described. FIG. 5 is a flowchart showing the target primary pulley rotation speed correction amount calculation process. As shown in FIG. 5, the CVT control unit (correction amount setting means) 31 compares the target driving force Ftrgt with the achieved driving force F (t) in step S15. When Ftrgt> F (t), the process proceeds to step S16, and the setting of the hold flag is confirmed to determine whether or not the hold control is being executed. When the hold flag is released, the process proceeds to step S17, and since the marginal driving force when the throttle is fully opened is insufficient, the previously set target primary pulley rotation speed correction amount ΔNP is increased by a specified value, and the current target primary pulley while setting the rotational speed correction amount ΔNP (t), in step S16, when the hold flag is set, the compensation amount setting means that is provided to the CVT control unit 31, the target primary pulley speed correction amount DerutaNP Increment calculation is prohibited.
[0049]
Next, the previous achieved drive force F (t-1) is updated with the current achieved drive force F (t), and the current achieved drive force F based on the current target primary pulley rotation speed correction amount ΔNP (t). Calculate (t). Subsequently, the calculated current achieved driving force F (t) is compared with the updated previous achieved driving force F (t−1).
[0050]
If it is determined by comparison that F (t) ≦ F (t−1) and no increase in driving force can be expected even if the gear ratio is offset to the downshift side by a specified value, the target primary pulley rotation speed correction amount ΔNP Finish updating.
[0051]
Further, when it is determined that F (t)> F (t−1), an increase in driving force can be expected by offset processing to the downshift side by a specified value, so the target primary pulley rotation speed correction amount calculated this time The target primary pulley rotational speed correction amount ΔNP is updated with ΔNP (t). Subsequently, the above-described processing is repeated until the achieved driving force F (t) converges within the set value h with respect to the target driving force Ftrgt.
[0052]
On the other hand, if it is determined in step S18 that Ftrgt <F (t) and the marginal driving force when the throttle is fully open is excessive, the process proceeds to step S19, where the previous target primary pulley rotational speed correction amount ΔNP is decreased by a specified value. The target primary pulley rotational speed correction amount ΔNP (t) for this time is set.
[0053]
The previous achieved drive force F (t-1) is updated with the current achieved drive force F (t), and the current achieved drive force F (t (t)) based on the current target primary pulley rotational speed correction amount ΔNP (t). ) Is calculated again. Then, the calculated current achieved driving force F (t) is compared with the updated previous achieved driving force F (t−1). If it is determined by comparison that F (t) ≧ F (t−1) and no further reduction in driving force can be expected even if offset processing is performed to the upshift side by the specified value, the target primary pulley rotational speed correction amount The update of ΔNP is terminated.
[0054]
Further, when it is determined that F (t) <F (t−1), a reduction in driving force can be expected by offset processing to the upshift side by a specified value, so the target primary pulley rotation speed correction amount calculated this time The target primary pulley rotational speed correction amount ΔNP is updated with ΔNP (t). Subsequently, the above-described processing is repeated until the achieved driving force F (t) converges within the set value h with respect to the target driving force Ftrgt.
[0055]
In addition, when it does not correspond to steps S15 and S18 and it is determined that Ftrgt = F (t), the previous target primary pulley rotation speed correction amount ΔNP is maintained.
[0056]
Hereinafter, the update process of the target primary pulley rotation speed correction amount ΔNP during downhill travel will be described. When it is determined that the vehicle is traveling on a downhill road, as in the case of traveling on an uphill road, the target driving force Ftrgt is compared with the achieved driving force F (t) in step S15 shown in FIG. When Ftrgt> F (t), the process proceeds to step S16, and the setting of the hold flag is confirmed to determine whether or not the hold control is being executed. When the hold flag is released and it is determined that the engine braking force due to the fully closed throttle is insufficient at the current vehicle speed V, the previously set target primary pulley rotational speed correction amount ΔNP is increased by a specified value in step S17, and this time the while increasing the down-shift amount by setting the target primary pulley speed correction amount ΔNP (t), in step S16, when the hold flag is set, the compensation amount setting that provided CVT control unit 31 By means, the increase calculation of the target primary pulley rotation speed correction amount ΔNP is prohibited.
[0057]
Next, the previous achieved drive force F (t-1) is updated with the current achieved drive force F (t), and the achieved drive force F (t (t) is based on the current target primary pulley rotation speed correction amount ΔNP (t). ), And the calculated current achieved driving force F (t) is compared with the updated previous achieved driving force F (t-1). If the engine braking force cannot be further reduced even if offset processing is performed to the upshift side by the specified value with F (t) ≦ F (t−1), the target primary pulley rotation speed correction amount ΔNP Finish the update. Further, when F (t)> F (t−1), it is possible to expect a decrease in engine braking force due to the offset process toward the upshift side by a specified value. Therefore, the target primary pulley rotation speed correction amount ΔNP calculated this time The target primary pulley rotational speed correction amount ΔNP is updated by (t).
[0058]
On the other hand, if it is determined in step S18 that Ftrgt <F (t) and the engine braking force when the throttle is fully closed at the current vehicle speed V is excessive, the process proceeds to step S19, where the previously set target primary pulley rotational speed correction amount ΔNP is set. Is reduced by a specified value and the current target primary pulley rotation speed correction amount ΔNP (t) is set to limit the downshift amount.
[0059]
The previous achieved drive force F (t-1) is updated with the current achieved drive force F (t), and the current achieved drive force F (t (t)) based on the current target primary pulley rotational speed correction amount ΔNP (t). ) Is calculated. Then, the calculated current achieved driving force F (t) is compared with the updated previous achieved driving force F (t−1), and it is determined that F (t) ≧ F (t−1), and the gear ratio is determined. If no further increase in engine braking force can be expected even if offset processing is further offset to the downshift side by the specified value, the update of the target primary pulley rotation speed correction amount ΔNP is terminated.
[0060]
Further, when it is determined that F (t) <F (t-1), an increase in engine braking force can be expected by further offset processing of the gear ratio to the downshift side by a specified value. The target primary pulley rotation speed correction amount ΔNP is updated with the primary pulley rotation speed correction amount ΔNP (t). The above process is repeated until the achieved driving force F (t) converges within the set value h with respect to the target driving force Ftrgt.
[0061]
In addition, when it does not correspond to steps S15 and S18 and it is determined that Ftrgt = F (t), the previous target primary pulley rotation speed correction amount ΔNP is maintained.
[0062]
Using the target primary pulley rotational speed correction amount ΔNP set in this way, the entire basic speed change characteristic of the target primary pulley rotational speed NP stored in the basic speed change characteristic map is set as the target primary pulley rotational speed when the throttle is fully opened. As an upper limit, an offset process is performed on the downshift side by the target primary pulley rotation speed correction amount ΔNP.
[0063]
The basic shift characteristic map offset-shifted in this way is referred to with interpolation calculation based on the vehicle speed V and the throttle opening THo, and the target primary pulley rotational speed NP is set. As described above, the target speed ratio is is calculated from the ratio between the target primary pulley speed NP and the actual secondary pulley speed NSo, and the solenoid current for converging the actual speed ratio i to the target speed ratio is is calculated. By setting and outputting a drive current to the proportional solenoid 40a of the transmission control valve 40, the primary hydraulic pressure is regulated by the transmission control valve 40 and the movable primary pulley 18 slides in the axial direction, and the actual primary pulley rotation speed NPi, The engine speed Ne is controlled to converge to the target primary pulley speed NP.
[0064]
By correcting the basic shift characteristic map as described above, the shift is controlled in the same way as on a flat road, thereby optimizing the downshift amount of the continuously variable transmission 10 when traveling on an uphill road or traveling on a downhill road. It is possible to prevent engine over-rotation due to shift and prevent deterioration of vibration and noise, and to improve driving feeling.
[0065]
In this way, during the execution of the hold control, by prohibiting the addition calculation of the target primary pulley rotation speed correction amount ΔNP that sets the gear ratio characteristic, an unnecessary increase in the target primary pulley rotation speed NP is prevented, and the calculation Therefore, unnecessary downshift correction due to the separation of the road surface gradient that is the reference of the vehicle from the actual road surface gradient can be prevented, and the driver can be prevented from feeling uncomfortable.
[0066]
It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, although the above embodiment has been described as a shift control device for a belt-type continuously variable transmission, the present invention is not limited to this and may be applied to other transmissions such as a toroidal continuously variable transmission.
[0067]
Further, the target primary pulley rotation speed correction amount ΔNP is used as the correction amount of the basic shift characteristic map. However, the present invention is not limited to this, and the shift obtained from the target primary pulley rotation speed correction amount ΔNP and the actual secondary pulley rotation speed NSo. A ratio correction amount may be used. Further, the primary pulley rotational speed may be calculated from the engine rotational speed Ne.
[0068]
【Effect of the invention】
According to the present invention, in a situation where there is a possibility that the road surface gradient obtained by the travel resistance increase amount calculation and the road surface gradient actually traveling are separated from each other, the increase correction of the gear ratio correction amount for setting the gear ratio characteristic is prohibited. Thus, an unnecessary increase in the rotational speed of the input-side rotator is prevented, so that unnecessary downshift correction can be prevented and a sense of incongruity to the driver can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a power transmission system of an automobile having a continuously variable transmission.
FIG. 2 is a system schematic diagram showing a transmission control device for a continuously variable transmission according to an embodiment of the present invention.
FIG. 3 is a flowchart showing a hold determination processing procedure.
FIG. 4 is a flowchart showing a running resistance increase amount calculation processing procedure.
FIG. 5 is a flowchart showing a target primary pulley rotation speed correction amount calculation processing procedure;
[Explanation of symbols]
10 continuously variable transmission 15 engine 18 primary pulley (input side rotating body)
20 Secondary pulley (output side rotating body)
23 Drive belt (power transmission element)
31 CVT control unit (uphill / downhill detection means, target driving force calculation means, hold control means, hold control correction means)
Ftrgt Target driving force F (t) Achieved driving force ΔR Travel resistance increase amount

Claims (2)

A transmission control device for a continuously variable transmission that continuously changes the rotation of an input-side rotator driven by an engine via a power transmission element and transmits it to an output-side rotator,
An uphill / downhill detecting means for detecting that the vehicle is traveling on the up / downhill road;
Target driving force calculating means for calculating a target driving force based on the amount of increase in the running resistance of the vehicle when the vehicle is traveling on an uphill / downhill road;
When the target driving force is compared with the achieved driving force when the throttle is fully open or when the throttle is fully closed at the current vehicle speed, and the achieved driving force is smaller than the target driving force, the target rotational speed of the input-side rotor Correction amount setting means for increasing and updating the correction amount;
A hold for calculating the target driving force based on the amount of increase in running resistance before the fluctuation factor occurs when a fluctuation factor causing load fluctuation occurs in the engine when the vehicle is traveling on an uphill / downhill road and a hold control means for performing control,
The correction amount setting means, wherein when said achieving driving force than before Symbol target driving force under the state where the hold control is executed is small, Turkey to prohibit the increase updating of the target speed correction amount A transmission control device for a continuously variable transmission. A transmission control device for a continuously variable transmission that continuously changes the rotation of an input-side rotator driven by an engine via a power transmission element and transmits it to an output-side rotator,
An uphill / downhill detecting means for detecting that the vehicle is traveling on the up / downhill road;
Target driving force calculating means for calculating a target driving force based on the amount of increase in the running resistance of the vehicle when the vehicle is traveling on an uphill / downhill road;
When the target driving force is compared with the achieved driving force when the throttle is fully opened or fully closed at the current vehicle speed, and the achieved driving force is smaller than the target driving force, the target speed ratio of the continuously variable transmission A correction amount setting means for increasing and updating the correction amount to the downshift side,
A hold for calculating the target driving force based on the amount of increase in running resistance before the fluctuation factor occurs when a fluctuation factor causing load fluctuation occurs in the engine when the vehicle is traveling on an uphill / downhill road Hold control means for executing control,
The correction amount setting means updates the correction amount of the target gear ratio to the downshift side when the achieved driving force is smaller than the target driving force under the state where the hold control is executed. A transmission control device for a continuously variable transmission, which is prohibited .

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