JP4203391B2 - Continuously variable transmission control device - Google Patents

Description

  The present invention relates to a continuously variable transmission control device for controlling a continuously variable transmission that continuously changes the output shaft rotational speed of an engine in a vehicle and transmits it to a wheel shaft.

  2. Description of the Related Art A continuously variable transmission that continuously changes the output speed of an engine output shaft and transmits it to a wheel shaft in a vehicle has been developed and put into practical use. By using a continuously variable transmission, it is possible to achieve a smooth speed change and to select an appropriate engine speed according to the driving situation, thereby reducing fuel consumption.

  On the other hand, there is a vehicle that employs an auto-cruise function that assists driving operation when traveling at a constant speed mainly on an expressway or the like.

  When driving with auto-cruise in a vehicle equipped with a continuously variable transmission and an auto-cruise function, the continuously variable transmission of the continuously variable transmission is maintained so as to maintain smooth driving characteristics without irregularly changing the engine speed or torque. It is desirable to appropriately control the gear ratio. For this reason, a method for smoothing the throttle operation during the auto-cruise mode (see, for example, Patent Document 1), a method for fixing the gear ratio for a predetermined time (for example, see Patent Document 2), and a control gain when torque fluctuation occurs. There has been proposed a method of changing (see, for example, Patent Document 3).

JP 2000-318486 A JP 2000-320658 A JP 2002-29286 A

  According to the related arts disclosed in Patent Documents 1, 2, and 3 described above, it is possible to perform smooth driving with less discomfort to the driver during auto-cruising, which is preferable.

  However, these prior arts work particularly effectively when the load on the vehicle is large, such as when traveling on a slope road, but when the load is light such as running on a flat road, the change characteristic of the speed ratio of the continuously variable transmission is In some cases, it becomes sluggish, acceleration / deceleration delays occur, and fuel efficiency cannot be optimized.

  The present invention has been made in consideration of such problems, and realizes smooth driving without being affected by fluctuations in the load applied to the vehicle, as well as responsiveness and fuel consumption performance during acceleration and deceleration at light loads. It is an object of the present invention to provide a continuously variable transmission control device that can maintain a stable state.

A continuously variable transmission control device according to the present invention is a continuously variable transmission control device for controlling a continuously variable transmission that continuously changes the output shaft rotational speed of an engine in a vehicle and transmits it to a wheel shaft. A travel control means for automatically controlling the vehicle speed of the vehicle, a throttle opening degree detecting means for detecting the throttle opening degree of the engine, a vehicle speed detecting means for detecting the vehicle speed, and the vehicle speed based on the throttle opening degree and the vehicle speed. A gear ratio control means for controlling a gear ratio of the step transmission, and a driving condition detection means for detecting a driving condition value corresponding to a load applied to the vehicle, wherein the gear ratio control means is the driving control means. and when when the vehicle is automatic speed control, when the absolute value of the traveling condition value is greater than a predetermined threshold value, the rate of change of the speed ratio, that the vehicle is not automatic speed control by Was changed to be smaller in compare, further, difference in rotational speed between the output shaft speed and the speed command by the travel control means, the speed of change of the speed ratio is smaller than a predetermined differential rotation threshold value A dead zone that becomes 0 is provided, and when it is equal to or greater than the differential rotation threshold, the speed at which the speed ratio changes according to the excess width from the differential rotation threshold is made close to the value when the vehicle is not under automatic speed control. and changes as (first aspect of the present invention).

  In this way, when the vehicle is automatically controlled by the automatic traveling control means, the change in the change ratio of the speed ratio is changed based on the traveling state value that affects the load on the vehicle, thereby affecting the variation in the load. Smooth operation can be obtained without receiving. In addition, fuel efficiency can be improved without impairing responsiveness during acceleration / deceleration at light loads. Here, the automatic speed control by the traveling automatic control means includes control for achieving a constant target vehicle speed, and follow-up control for keeping the distance between the vehicle and other vehicles ahead at a certain distance or more than a certain distance.

  In this case, the running state value is a road slope value, and the speed ratio control means is configured to change the speed ratio based on the slope value when the vehicle is automatically controlled by the travel control means. May be changed (the invention according to claim 2).

  Since the load applied to the vehicle is greatly influenced by the gradient value, driving performance can be improved by performing control based on the gradient value.

Further, the speed ratio control means provides a dead zone where the speed at which the speed ratio changes becomes zero when the running state value is smaller than a predetermined threshold value when the vehicle is automatically controlled by the travel control means. since the running characteristics gear ratio is fixed you more stable when load fluctuation is small.

Furthermore, the travel state value is a travel resistance value, and the speed ratio control means is configured to change the speed ratio based on the travel resistance value when the vehicle is automatically controlled by the travel control means. May be changed (the invention according to claim 3 ).

  According to the continuously variable transmission control device according to the present invention, when the vehicle is automatically speed controlled as during auto-cruising, the change characteristic of the transmission ratio is changed based on the running state value corresponding to the load on the vehicle. By doing so, smooth operation can be obtained without being affected by load fluctuations. Further, the fuel efficiency can be maintained in a good state without impairing the responsiveness during acceleration / deceleration at light loads.

  Hereinafter, an embodiment of the continuously variable transmission control device according to the present invention will be described with reference to FIGS.

  The continuously variable transmission control apparatus 10 according to the present embodiment continuously changes the rotational speed of the output shaft 12a of the engine 12 in the vehicle and transmits it to the wheel shaft 14 (hereinafter referred to as CVT (Continuously Variable). (Transmission)) for controlling 16. The continuously variable transmission control device 10 controls the engine 12 and also performs a main controller (running control means) 20 for performing auto-cruising in accordance with an instruction from the vehicle driver, and a CVT control unit (shift) Ratio control means) 22 and various sensors (described later) connected to the main controller 20 and the CVT control unit 22.

  First, the CVT 16 and the drive mechanism of the vehicle on which the CVT 16 is mounted will be described with reference to FIG.

  A throttle valve 28 is disposed in the intake pipe 26 connected to the engine 12, and the throttle valve 28 is linked to the operation of an accelerator pedal (not shown) in the driver's seat and is controlled by the main controller 20 and the vacuum valve 30. Open and close.

  The output shaft 12 a of the engine 12 is connected to the torque converter 32. In the torque converter 32, the torque converter cover 32a connected to the output shaft 12a rotates the pump impeller 32b and rotates the turbine impeller 32c relative to the torque converter shaft 34 via oil filled therein. At this time, the transmission torque can be increased by the action of the stator 32d. Further, in the torque converter 32, the rotation of the output shaft 12a can be directly transmitted to the torque converter shaft 34 by engaging the torque converter cover 32a and the torque converter shaft 34 by the lock-up clutch 32e.

  The torque converter shaft 34 is connected to a planetary gear type forward / reverse switching mechanism 36 of the CVT 16. The planetary gear type forward / reverse switching mechanism 36 includes an input rotation unit 36a that is integrally connected to the torque converter shaft 34, a forward clutch 36b that connects the input rotation unit 36a and the input shaft 38 of the CVT 16, and an input rotation unit 36a. And a ring gear 36c integrally formed. The planetary gear type forward / reverse switching mechanism 36 includes a sun gear 36d provided on the input shaft 38 and a plurality of planetary gears 36e meshing with the ring gear 36c, a carrier 36f for rotating and supporting the planetary gear 36e, and the carrier A reverse clutch 36g that engages the outer periphery of 36f with the housing.

  In the planetary gear type forward / reverse switching mechanism 36, the input rotating portion 36a and the input shaft 38 can be integrally rotated in the same direction by engaging the input rotating portion 36a and the input shaft 38 with the forward clutch 36b. it can. Further, when the forward clutch 36b is released and the carrier 36f and the housing are engaged by the reverse clutch 36g, the carrier 36f is fixed, and the input shaft 38 can be driven via the planetary gear 36e. In this case, the input shaft 38 rotates in the opposite direction to the rotation of the input rotating portion 36a, and the vehicle can be moved backward.

  The CVT 16 includes a planetary gear type forward / reverse switching mechanism 36, a drive pulley 40 supported by the input shaft 38, and a driven pulley 44 that rotates following a rotation of the drive pulley 40 via a metal belt 42. And an output shaft 48 for transmitting the rotation of the driven pulley 44 to the intermediate shaft 46. The metal belt 42 is configured, for example, by attaching a large number of push pieces to two straps.

  The drive pulley 40 includes a fixed-side pulley half 40a fixed to the input shaft 38 and a movable-side pulley half 40b slidable in the axial direction of the input shaft 38 by hydraulic pressure acting on the hydraulic oil chamber 50. The groove width of the groove 40c of the drive pulley 40 can be changed by the sliding position of the movable pulley half 40b.

  Similarly, the driven pulley 44 includes a fixed-side pulley half 44 a fixed to the output shaft 48, and a movable-side pulley half 44 b slidable in the axial direction of the output shaft 48 by hydraulic pressure acting on the hydraulic oil chamber 52. The groove width of the groove 44c of the driven pulley 44 can be changed by the sliding position of the movable pulley half 44b.

  The hydraulic oil supplied to the hydraulic oil chamber 50 is supplied from the pump 54 via the control valve 56 and the oil passage 38 a passing through the axial center of the input shaft 38, and is similarly supplied to the hydraulic oil chamber 52. Is supplied from the pump 54 through an oil passage 48 a that passes through the axial center of the control valve 58 and the output shaft 48. The control valves 56 and 58 operate under the control of the CVT control unit 22 and can change the pressure of the hydraulic oil chambers 50 and 52. Thereby, the movable pulley halves 40b and 44b can be slid in the axial direction in conjunction with each other, and the widths of the grooves 40c and 44c can be continuously changed. Therefore, the ratio of the diameter around which the metal belt 42 is wound, that is, the transmission ratio can be changed steplessly. In FIG. 1, the drive pulley 40 and the driven pulley 44 are such that the upper half centered on the axes of the input shaft 38 and the output shaft 48 is in a state where the transmission ratio is OD (Over Drive), and the lower half centered on each axis. Each schematically shows a low state.

  The rotational speed of the input shaft 38 is steplessly changed by the CVT 16 and transmitted to the output shaft 48. The rotational speed of the output shaft 48 is decelerated by the intermediate shaft 46 and transmitted to the differential gear 60.

  The differential gear 60 can travel by driving the wheel shaft 14 and the drive wheels 64 via a gear mechanism 60a for absorbing the difference in rotational speed between the inner ring and the outer ring during curve traveling.

  Connected to the main controller 20 are a throttle opening sensor 70 that detects a throttle opening TH that is the opening of the throttle valve 28, and a pressure sensor 72 that detects an absolute pressure PB downstream of the throttle valve 28. The main controller 20 includes a crank angle sensor 74 that detects the crank angle of the engine 12, a water temperature sensor 76 that detects the engine water temperature, a rotation speed sensor 78 that detects the engine rotation speed Ne, and the rotation of the torque converter shaft 34. A rotation speed sensor 80 that detects the number and a vehicle speed sensor 82 that detects the vehicle speed V are connected. Although not shown, the vehicle speed sensor 82 is provided with a total of four vehicle speed sensors 82 for the left and right drive wheels 64 and the left and right driven wheels.

  In addition, a steering switch (not shown) in the driver's seat is provided with a set switch for inputting a target vehicle speed during auto-cruise, a resume switch for resuming auto-cruise after being interrupted, and a cancel switch for canceling auto-cruise. Are connected to the main controller 20, respectively. The main controller 20 recognizes the driver's instructions for starting, ending, interrupting, and restarting auto-cruise from these switch outputs, and executes automatic travel control via the throttle actuator. The main controller 20 may be configured to be separated into a plurality of units such as a plurality of units such as an engine control device and a traveling control means for performing auto cruise.

  The CVT control unit 22 includes a rotation speed sensor 84 that detects the rotation speed of the output shaft 48 by teeth provided on the outer peripheral portion of the fixed pulley half 44a, and a shift range (D, N, A position switch 86 that outputs a signal indicating P) is connected. Further, a throttle opening sensor 70, a pressure sensor 72, a crank angle sensor 74, rotation speed sensors 78 and 80, and a vehicle speed sensor 82 are connected to the CVT control unit 22. Further, the main controller 20 and the CVT control unit 22 are connected by a communication line 88, and mutual communication such as data is possible.

  As shown in FIG. 2, the CVT control unit 22 includes a CPU (Central Processing Unit) 100 as a main control unit, a RAM (Random Access Memory) 102 and a ROM (Read Only Memory) 104 as recording units, It has an input interface (IF) 106 for inputting sensor signals, a driver 108 for driving the control valves 56 and 58, and a bus 110 for connecting these elements.

  The CPU 100 reads the program 112 recorded in the ROM 104, and performs processing based on the description content of the program 112 in cooperation with the RAM 102, the ROM 104, the input interface 106, and the driver 108.

  Next, the operation of the continuously variable transmission control device 10 configured as described above will be described with reference to FIGS. In the following description, in order to facilitate understanding, the lock-up clutch 32e and the forward clutch 36b are engaged, and the rotational speed of the output shaft 12a indicating the engine rotational speed Ne and the rotational speed of the input shaft 38 are illustrated. Are the same.

  The CVT control unit 22 performs basic shift processing with reference to the target engine speed map 120 (see FIG. 3) recorded in the ROM 104 under the control of the CPU 100. A plurality of throttle opening lines 120a are recorded in the target engine speed map 120, and one of the throttle opening lines 120a is selected according to the detected throttle opening TH, or based on the throttle opening TH. The throttle opening line 120a is selected by interpolation. The throttle opening line 120a in FIG. 3 corresponds to the case where the upper line corresponds to a large throttle opening TH, and corresponds to the case where the lower line is small.

  The CPU 100 selects (or interpolates) the throttle opening line 120a based on the detected throttle opening TH, and searches for the target engine speed NED with reference to the vehicle speed V at that time. Further, the CPU 100 controls the gear ratio of the CVT 16 so that the retrieved target engine speed NED matches the actual engine speed Ne. For example, when the throttle opening TH is increased by depressing the accelerator pedal, the vehicle speed V does not react immediately, so the target engine speed NED first increases and the gear ratio shifts to the low side. As a result, the engine speed Ne and torque increase, the vehicle accelerates and the vehicle speed V increases, and the operation of the accelerator pedal is followed.

  The gear ratio is limited by a low-side gear ratio limit line 120b and an OD-side gear ratio limit line 120c in the target engine speed map 120.

  Next, the procedure for controlling the gear ratio based on the target engine speed map 120 will be described in detail with reference to FIGS. Among these, the processing of FIG. 4 is mainly performed by the CPU 100 and is repeatedly executed continuously every predetermined minute time to perform so-called real-time processing.

  First, in step S1 of FIG. 4, signals such as the throttle opening TH, the engine speed Ne, and the vehicle speed V at that time are read from the throttle opening sensor 70, the rotation speed sensor 78, the vehicle speed sensor 82, and the like.

  Next, in step S2, the target engine speed NED is searched with reference to the target engine speed map 120 based on the throttle opening TH and the vehicle speed V.

  Next, in step S3 (traveling state detecting means), a slope value θ of the road surface on which the vehicle is traveling is calculated. Specifically, first, a running resistance R and a wheel driving force P corresponding to a load applied to the vehicle are obtained. The running resistance R is obtained by adding the rolling resistance, air resistance, acceleration resistance, and inertia correction amount of the vehicle. The wheel driving force P is obtained based on the output torque and the gear ratio of the CVT 16 at that time by obtaining the output torque of the engine 12 by searching a predetermined map using the engine speed Ne and the absolute pressure PB as parameters. The

On the other hand, the wheel driving force P for running the vehicle is expressed by the following equation.
Wheel driving force P = running resistance R + vehicle weight × sin θ

  Accordingly, the gradient value θ is obtained by subtracting the running resistance R from the wheel driving force P and dividing the subtracted value by the vehicle weight to obtain the sine value sin θ. The gradient value θ may be obtained by performing an inverse transformation on the sine value sin θ with respect to the trigonometric function.

  In addition, as a calculation method of gradient value (theta), you may obtain | require, for example by the method proposed in Unexamined-Japanese-Patent No. 2001-182760, a suitable approximate expression, etc. Alternatively, the gradient value θ may be directly detected using a predetermined inclinometer or the like.

  Next, in step S4, it is confirmed whether or not a hysteresis determination flag FlgUp for giving a hysteresis characteristic to the switching of the speed change control method in the ascending slope is “1”. When the hysteresis determination flag FlgUp is “0”, the process proceeds to step S5, and when it is “1”, the process proceeds to step S7.

  In step S5, it is confirmed whether or not the gradient value θ is larger than a predetermined gradient set value θA. When θ> θA, the process proceeds to step S6, and when θ ≦ θA, the process proceeds to step S9.

  In step S6, it can be determined that the gradient value θ is large, and FlgUp ← 1 is set for the hysteresis determination flag FlgUp in order to execute load handling control in step S18 described later. Thereafter, the process proceeds to step S9.

  On the other hand, in step S7 (when hysteresis determination flag FlgUp = 1), the gradient setting value θB slightly smaller than the gradient setting value θA is compared with the gradient value θ. When the gradient value θ is smaller than the gradient set value θB, the process proceeds to step S8, and when larger, the process proceeds to step S9.

  In step S8, during the execution of the load handling control, the slope value θ is further lower than the slope setting value θB that is slightly smaller than the slope setting value θA indicating the execution start condition of the load handling control. Therefore, the load handling control is terminated, and FlgUp ← 0 is set for the hysteresis determination flag FlgUp. Thereafter, the process proceeds to step S9.

  Next, in step S9, it is confirmed whether or not a hysteresis determination flag FlgDn for giving a hysteresis characteristic to the switching of the speed change control method in the downward gradient is “1”. When the hysteresis determination flag FlgDn is “0”, the process proceeds to step S10, and when it is “1”, the process proceeds to step S12.

  In step S10, it is confirmed whether or not the gradient value θ is smaller than a gradient set value θC that is a predetermined negative value. When θ <θC, the process proceeds to step S11, and when θ ≧ θC, the process proceeds to step S14.

  In step S6, it can be determined that the absolute value of the gradient value θ is large, and FlgDn ← 1 is set for the hysteresis determination flag FlgDn in order to execute load handling control in step S18 described later. Thereafter, the process proceeds to step S14.

  On the other hand, in step S12 (when hysteresis determination flag FlgDn = 1), the gradient setting value θD, which is a minus value slightly larger (smaller in absolute value) than the gradient setting value θC, is compared with the gradient value θ. When the gradient value θ is larger than the gradient set value θD, the process proceeds to step S13, and when smaller, the process proceeds to step S14.

  In step S13, during the execution of the load handling control, the slope value θ further exceeds the slope setting value θD that is slightly larger than the slope setting value θC indicating the execution start condition of the load handling control. Therefore, the load handling control is terminated, and FlgDn ← 0 is set for the hysteresis determination flag FlgDn. Thereafter, the process proceeds to step S14.

  Next, in step S <b> 14, it is confirmed based on information transmitted from the main controller 20 via the communication line 88 whether or not the traveling state of the vehicle is during auto-cruising. When it is during the autoruze, the process proceeds to step S15, and when it is in the normal running mode, the process proceeds to step S17.

  In step S15, it is confirmed whether or not the hysteresis determination flag FlgUp is “1”. When the hysteresis determination flag FlgUp is “1”, the process proceeds to step S18, and when it is “0”, the process proceeds to step S16.

  In step S16, it is confirmed whether or not the hysteresis determination flag FlgDn is “1”. When the hysteresis determination flag FlgDn is “1”, the process proceeds to step S18, and when it is “0”, the process proceeds to step S16.

  In steps S17 and S18, normal control and load handling control, which will be described later, are executed by a subroutine, and the current process in the flowchart shown in FIG. 4 is terminated. Thereafter, the process is repeatedly executed from step S1 again after a predetermined minute time.

  As described above, when either one of the hysteresis determination flags FlgUp and FlgDn is “1”, that is, when the slope of the road surface is steep, the load handling control in step S18 is executed. Further, since the hysteresis determination flags FlgUp and FlgDn change with a hysteresis characteristic depending on the values of the gradient setting values θA, θB, θC, and θD, switching between the load correspondence control in step S17 and the load correspondence control in step S18 is performed. It takes some time, and it is possible to prevent the control from being switched complicatedly.

  Next, the normal control subroutine executed in step S17 will be described with reference to FIGS.

  First, in step S101, the rotational speed command variable NDRCMD0 is subtracted from the target engine rotational speed NED to obtain a differential rotational speed SNDR. The rotational speed command variable NDRCMD0 is a command value for increasing or decreasing the engine rotational speed Ne by changing the gear ratio of the CVT 16, and during stable running, the rotational speed command variable NDRCMD0, the engine rotational speed Ne, and the target engine rotational speed NED are Match.

  Next, in step S102, the first change characteristic map 130 (see FIG. 6) recorded in the ROM 104 is referred to, and the value of the first shift speed DNDRDC is searched based on the differential rotation speed SNDR. The first speed change DNDRDC is a value indicating a temporal change characteristic when the speed change ratio of the CVT 16 changes, and specifically indicates the speed of change of the ratio that is the speed change ratio. The first shift speed DNDRDC is set substantially proportional to the differential rotation speed SNDR as indicated by the first shift characteristic line 130a.

  Next, in step S103, the first speed change DNDRDC is multiplied by a constant k to obtain a speed increment DNDRCMD.

  Further, in step S104, the speed increment DNDRCMD is added to the intermediate command variable NDRCMD. The intermediate command variable NDRCMD is a variable that prevents the rotational speed command variable NDRCMD0 from changing suddenly and causes the rotational speed command variable NDRCMD0 to change in a first-order lag based on the differential rotational speed SNDR.

  Next, in step S105, the intermediate command variable NDRCMD is substituted into the rotation speed command variable NDRCMD0.

  Further, in step S106, the control valves 56 and 58 are controlled based on the rotational speed command variable NDRCMD0 to change the gear ratio of the CVT 16.

  In this way, in the normal control, by continuously executing the processes of steps S101 to S106, the rotation speed command variable NDRCMD0 can be smoothly changed as shown in FIG. That is, when the throttle opening TH changes stepwise, the target engine speed NED changes stepwise so that the differential engine speed SNDR is generated based on this. Further, from the first change characteristic map 130, the first shift speed DNDRDC and the speed increment DNDRCMD are obtained as values that are substantially proportional to the differential rotation speed SNDR, and the speed increment DNDRCMD acts as a slope value of the change in the rotation speed command variable NDRCMD0.

  Accordingly, when the change in the throttle opening TH is large, the rotational speed command variable NDRCMD0 follows quickly and the response characteristics of the gear ratio and the vehicle speed V are good, and the engine 12 can be used in an efficient rotational speed region, and the fuel consumption performance is improved. It can be kept in a good state. Further, when the change in the throttle opening TH is small, the rotation speed command variable NDRCMD0 changes smoothly, and the gear ratio and the vehicle speed V follow gently, and the ride comfort is good.

  Further, since the rotational speed command variable NDRCMD0 changes in a first order lag, there is no shift shock even when the load corresponding control in step S18 is shifted to the normal control in step S17.

  Next, the load handling control subroutine executed in step S18 will be described with reference to FIGS.

  Step S201 in the load handling control is the same process as step S101.

  In step S202 in the load handling control, the second change characteristic map 132 (see FIG. 6) recorded in the ROM 104 is referred to, and the value of the second shift speed DNDRDD is searched based on the differential rotation speed SNDR. The second speed change speed DNDRDD is a value corresponding to the first speed change speed DNDRDC, and is a value indicating a temporal change characteristic when the speed change ratio of the CVT 16 changes during the load handling control. The second shift speed DNDRDD is set as a dead zone of “0” in a section where the absolute value of the differential rotation speed SNDR is smaller than X as indicated by the second shift characteristic line 132a, and the absolute value of the differential rotation speed SNDR. In a section where is greater than X, it is set approximately proportional to the differential rotation speed SNDR. Further, in a section where the absolute value of the differential rotation speed SNDR is sufficiently large, the second shift speed DNDRDD is set as a value that substantially matches the first shift speed DNDRDC.

  Note that the first change characteristic map 130 and the second change characteristic map 132 are different maps, but in FIG. 6, they are shown in an overlapped state so as to be easily compared.

  Next, in step S203, the speed increment DNDRCMD is obtained by multiplying the second shift speed DNDRDD by a constant k.

  In step S204 and subsequent steps S206, the rotational speed command variable NDRCMD0 is obtained in the same manner as in steps S104 to S106, and the gear ratio of the CVT 16 is changed based on the rotational speed command variable NDRCMD0.

  As described above, in the load corresponding control, the processing of steps S201 to S206 is continuously executed, and as shown in FIG. 9, when the throttle opening TH changes stepwise, the target engine speed The NED changes in small steps so as to follow, and based on this, the differential rotation speed SNDR becomes a small value. At this time, if the differential rotation speed SNDR has an absolute value smaller than the value X on the second change characteristic map 132 shown in FIG. 6, the second shift speed DNDRDD and the speed increment DNDRCMD are calculated from the first change characteristic map 130. “0”, and the transmission ratio of the CVT 16 is fixed.

  In other words, in a place where the absolute value of the gradient value θ is large and the driving conditions are severe, the transmission ratio of the CVT 16 can be fixed even if the throttle opening TH changes slightly, and the vehicle can run more stably. Can do.

  Further, when the differential rotation speed SNDR is slightly larger than the value X on the second change characteristic map 132 shown in FIG. 6, the rotation speed command variable NDRCMD0 changes smoothly and gently, and the gear ratio and the vehicle speed are changed. V will follow slowly and is comfortable to ride.

  Further, when the change in the throttle opening TH is sufficiently large, it can be determined that the driver clearly shows the intention of acceleration / deceleration. In this case, the rotational speed difference SNDR becomes sufficiently large, and in the first change characteristic map 130 and the second change characteristic map 132, the second speed change speed DNDRDD is a value that substantially matches the first speed change speed DNDRDC. The control also has substantially the same effect as the normal control, and the speed ratio and the response characteristics of the vehicle speed V are good.

  In the above embodiment, either the normal control or the load corresponding control is executed according to the result of comparing the gradient set values θA, θB, θC and θD with the gradient value θ, and the first change characteristic map 130 or Although it has been described that the control is performed based on the second change characteristic map 132, more change characteristic maps may be set to branch the processing more finely according to the gradient value θ. The second change characteristic map 132 is a three-dimensional map that searches for the second shift speed DNDRDD based on the differential rotation speed SNDR and the gradient value θ, and sets the value of the gradient value θ as the second shift speed. It may be reflected directly in DNDRDD.

  The normal control in step S17 and the load-corresponding control in step S18 have been described as switching based on the gradient value θ. However, the reference parameter for switching is not limited to the gradient value θ, and in the process of calculating the gradient value θ. sin θ may be used as a reference value as it is, or running resistance R may be used as a reference value. That is, control may be switched based on a parameter related to a load applied to the vehicle among parameters indicating a traveling state when the vehicle is traveling.

  The load handling control for controlling the gear ratio of the CVT 16 is not limited to the method described as the step S18, and the methods described in Patent Documents 1, 2, and 3 may be used.

  Furthermore, the auto-cruise function is not limited to a simple constant-speed control function, but has a follow-up control function that automatically accelerates or decelerates so as to secure a clearance between the vehicle and other vehicles ahead. There may be. Furthermore, the CVT 16 is not limited to the belt type using the metal belt 42 but may be a so-called toroidal type or the like.

  A plurality of target engine speed maps 120 (see FIG. 3) may be prepared, and one map may be selected based on the road gradient value θ. In this case, the absolute values of the gradient setting values θA and θC may be set to values (flat values) smaller than a threshold value for switching the target engine speed map 120. By setting in this way, drivability is not impaired even when the target engine speed map 120 is switched.

  Of course, the continuously variable transmission control device according to the present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

It is a schematic block diagram of the drive mechanism of a vehicle provided with the continuously variable transmission control apparatus which concerns on this Embodiment. It is a block diagram of a CVT control part. It is a graph which shows the contents of a target engine speed map. It is a flowchart which shows the processing content of a CVT control part. It is a flowchart which shows the content in normal control among the processing content of a CVT control part. It is a graph which shows the contents of the 1st change characteristic map and the 2nd change characteristic map. It is a time chart which shows the change of each parameter in normal control. It is a flowchart which shows the content in load corresponding | compatible control among the processing content of a CVT control part. 6 is a time chart showing fluctuations of each parameter when a change in throttle opening is small in load handling control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Continuously variable transmission control device 14 ... Wheel axle 12 ... Engine 16 ... CVT
DESCRIPTION OF SYMBOLS 20 ... Main controller 22 ... CVT control part 32 ... Torque converter 34 ... Torcon shaft 36 ... Planetary gear type forward / reverse switching mechanism 40 ... Drive pulley 42 ... Metal belt 44 ... Driven pulley 46 ... Intermediate shaft 56, 58 ... Control valve 60 ... Differential gear 64 ... Drive wheel 70 ... Throttle opening sensor 78, 80, 84 ... Speed sensor 82 ... Vehicle speed sensor 120 ... Target engine speed map 130 ... First change characteristic map 132 ... Second change characteristic map DNDRCMD ... Speed increment DNDRDC ... first shift speed DNDRDD ... second shift speed NDRCMD ... intermediate command variable NDRCMD0 ... speed command variable Ne ... engine speed NED ... target engine speed SNDR ... differential speed

Claims (3)

In a continuously variable transmission control device for controlling a continuously variable transmission that continuously changes the output shaft rotational speed of an engine in a vehicle and transmits it to a wheel shaft,
Traveling control means for automatically controlling the vehicle speed of the vehicle;
Throttle opening detection means for detecting the throttle opening of the engine;
Vehicle speed detection means for detecting the vehicle speed;
Gear ratio control means for controlling a gear ratio of the continuously variable transmission based on the throttle opening and the vehicle speed;
Traveling state detection means for detecting a traveling state value corresponding to a load applied to the vehicle;
Have
The gear ratio control means, when the vehicle is automatically controlled by the travel control means, when the absolute value of the travel state value is larger than a predetermined threshold ,
The speed at which the speed ratio changes is changed to be smaller than when the vehicle is not automatically speed controlled ,
Furthermore, a dead zone is provided in which the speed at which the speed ratio changes becomes zero when the differential rotational speed between the rotational speed command from the travel control means and the output shaft rotational speed is smaller than a predetermined differential rotational threshold, and the differential rotational speed is provided. When the vehicle speed is greater than or equal to a threshold value, the speed at which the speed ratio changes is changed so as to approach a value when the vehicle is not automatically controlled in accordance with an excess width from the differential rotation threshold value. Step transmission control device. The continuously variable transmission control device according to claim 1,
The running state value is a slope value of the road surface,
The continuously variable transmission control device, wherein the speed ratio control means changes a change characteristic of the speed ratio based on the gradient value when the vehicle is automatically controlled by the travel control means. The continuously variable transmission control device according to claim 1,
The running state value is a running resistance value,
The continuously variable transmission control device, wherein the speed ratio control means changes a change characteristic of the speed ratio based on the travel resistance value when the vehicle is automatically controlled by the travel control means. .

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