JP4367188B2 - Control device for belt type continuously variable transmission - Google Patents

Description

  The present invention relates to a continuously variable transmission that changes speed by changing the distance between a fixed flange and a movable flange, and in particular, a belt-type continuously variable transmission that does not degrade the durability of an endless metal belt wound around two flanges. The present invention relates to a control device.

  A vehicle may be equipped with a belt-type continuously variable transmission (CVT) that continuously adjusts the transmission gear ratio in accordance with the traveling state of the vehicle. This continuously variable transmission can efficiently extract the engine output, and is excellent in improving fuel consumption and running performance. As one of continuously variable transmissions that have been put into practical use, there is one that uses a metal belt and a pair of pulleys to change the effective diameter of the pulleys by hydraulic pressure, thereby realizing a continuously variable transmission. An endless metal belt is wound around an input side pulley attached to the input shaft and an output side pulley attached to the output shaft. The input side pulley and the output side pulley are each provided with a pair of sheaves whose groove width can be changed steplessly. By changing the groove width, the winding radius of the endless metal belt with respect to the input side pulley and the output side pulley changes, Thereby, the rotation speed ratio between the input shaft and the output shaft, that is, the gear ratio can be continuously changed continuously.

  In such a continuously variable transmission, the pulley width of the input shaft pulley is small (the pulley diameter is large), the pulley width of the output shaft pulley is large (the pulley diameter is small), and the rotation speed of the output shaft pulley is the input shaft pulley. When the rotation speed is higher than the rotation speed, the speed increase is called acceleration. The pulley width of the input shaft pulley is large (the pulley diameter is small), the pulley width of the output shaft pulley is small (the pulley diameter is large), and the rotation speed of the output shaft pulley is The case where the rotational speed of the input shaft pulley is lower is called deceleration.

  A vehicle having an automatic transmission including such a continuously variable transmission is provided with, for example, a slide-type shift lever operated by a driver, and a range, for example, a parking range, based on a slide operation of the shift lever. (P range), reverse travel range (R range), neutral range (N range), forward travel range (D range), forward travel range (S (2) range, L (1) ) Range) etc. are selected.

  In automatic transmissions including these continuously variable transmissions, in order to realize driving that is more suited to human sensitivity, the driver's intention is reflected in driving and the driving interests are taken into account. There is a case in which a manual transmission mode that enables intentional selection of the transmission gear is added.

  That is, a plurality of discrete gear ratios are set as the forward shift speed in the continuously variable transmission. A shift pattern (P range, R range, N range, D range, etc.) of the shift lever is provided with a manual shift range in which the plurality of forward shift stages can be up and down manually. For example, when the shift lever is operated to an up position or a down position determined on opposite sides of the manual shift range (M range), a plurality of forward shift stages set in the continuously variable transmission are up and down. It is like that. For example, the P range, the R range, and the N range are vehicles that are substantially perpendicular to the longitudinal direction of the vehicle in which the N range is provided directly beside the M range (vehicle width direction of the vehicle) and the up position and the down position are set. When the shift lever is moved in the width direction, it is operated to the N range so that the continuously variable transmission can be switched between a power transmission state and a power cutoff state. In some cases, the steering is provided with a switch for upshifting and downshifting in the manual shift mode.

  Japanese Patent Application Laid-Open No. 8-82354 (Patent Document 1) is not capable of performing a manual-feeling operation with a change in engine rotation and selecting a gear ratio according to the driver's intention. A transmission control device for a continuously variable transmission, which discloses a transmission control device for a continuously variable transmission, is a transmission control device for a continuously variable transmission that continuously controls a gear ratio by electronic control. When the normal mode / manual mode switching means is switched to the manual mode and the normal mode / manual mode switching means can be switched between the normal mode for controlling to the normal mode and the manual mode for controlling the gear ratio in a stepped manner. Gear ratio setting means capable of setting the gear ratio of the stage.

According to this transmission control device for a continuously variable transmission, first, the normal / manual mode switching means is switched to the manual mode. Next, a desired gear ratio is set by the gear ratio setting means. Thereby, it is possible to perform a manual and sporty operation with a change in engine rotation. When the normal / manual mode switching means is switched to the normal mode, normal shift control is performed in which the gear ratio is continuously controlled in accordance with the throttle opening, the vehicle speed, and the like.
JP-A-8-82354

  In the shift control device for a continuously variable transmission disclosed in Patent Document 1, when the manual shift mode is selected, the continuously variable transmission is controlled to be shifted stepwise according to an upshift operation and a downshift operation. In addition, when a downshift is required such that the engine speed exceeds the allowable range, the shift control based on the downshift operation is invalidated and the gear is shifted to the downshift side gear ratio close to the current gear ratio. ing.

  By the way, in the belt type continuously variable transmission, the closer to the maximum speed ratio, the smaller the diameter of the output shaft pulley, the smaller the belt hook diameter, and the greater the bending stress generated by the belt. The increase in the belt stress has a problem that the durability of the belt is lowered. In particular, when traveling at high speed, the centrifugal force increases, and the belt stress further increases. In addition, since the running resistance of the vehicle increases during high-speed running, the transmission torque increases, and the belt tension increases according to the transmission torque. For these reasons, in the automatic transmission mode of the belt-type continuously variable transmission, the transmission pattern is determined so that the transmission ratio does not become the maximum speed increase ratio during high-speed traveling.

  However, if the manual transmission mode disclosed in Patent Document 1 is selected and an attempt is made to change gears stepwise using a belt-type continuously variable transmission, it is necessary to set a gear ratio near the maximum speed increase ratio on the upshift side. As a result, there is a problem in that the durability of the belt is adversely affected as described above if the high speed running is performed in a state where the speed ratio near the maximum speed ratio is set when the manual speed change mode is selected.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to improve a belt-type continuously variable transmission having a manual transmission mode at a high speed without reducing the durability of the belt. To provide a control device for a belt type continuously variable transmission corresponding to a shift.

  The control device according to the present invention is used in a belt-type continuously variable transmission for a vehicle having an automatic transmission mode and a manual transmission mode, and is provided according to an upshift operation and a downshift operation when the manual transmission mode is selected. A belt-type continuously variable transmission for a vehicle that performs stepwise shifting is controlled. The control device includes a detection unit for detecting the vehicle speed, a determination unit for determining whether or not the vehicle speed is equal to or higher than a predetermined vehicle speed, and when the manual transmission mode is selected, the vehicle speed is And a prohibiting unit for prohibiting a shift based on a predetermined upshift operation when it is determined that the vehicle speed is equal to or higher than a predetermined vehicle speed.

  According to the present invention, the shift based on the upshift operation that uses the vicinity of the maximum speed increase ratio (upshift side) is prohibited by the prohibiting means when traveling at high speed. That is, when the manual transmission mode is selected, it is possible to avoid high-speed traveling in a state where a transmission ratio near the maximum speed increase ratio is set. In the vicinity of the maximum speed increase ratio, the belt-wound diameter of the output pulley is small and receives a large bending stress, and the centrifugal force applied to the belt is large and the belt tension is large during high speed running, resulting in a large stress on the belt. . Since the upshift is prohibited by the prohibiting means, it is possible to avoid the occurrence of such a large stress on the belt, and the durability of the belt is improved. Also, when driving at high speeds, the running resistance of the vehicle increases, and there is a possibility that a driving force shortage may occur at a gear ratio near the maximum speed increase. However, such a situation can be avoided and drivability deteriorates. Can be suppressed. As a result, in the belt-type continuously variable transmission having the manual transmission mode, it is possible to provide a control device for the belt-type continuously variable transmission that supports upshifting at high speed without reducing the durability of the belt.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 shows a cross-sectional view of a power train 1000 including a continuously variable transmission according to the present embodiment. As shown in FIG. 1, this power train 1000 includes an input shaft 1100 that transmits rotational torque from the engine to the power train 1000, and a torque with a lockup clutch that is a fluid coupling that controls torque transmission between the engine and the transmission. Converter 1200, oil pump 1300, forward / reverse switching mechanism 1400, primary pulley 1500, secondary pulley 1600, metal belt 1550 wound around primary pulley 1500 and secondary pulley 1600, and reduction gear 1800 as a reduction gear And a differential gear 1900. As indicated by the arrows in FIG. 1, engine torque is transmitted to the drive wheels.

  The primary pulley 1500 on the input side and the secondary pulley 1600 on the output side are each provided with a pair of sheaves whose groove width can be changed steplessly, and the groove width is changed by a hydraulic circuit controlled in accordance with the running state of the vehicle. As a result, the winding radius of the endless metal belt 1550 around the primary pulley 1500 and the secondary pulley 1600 changes, whereby the rotation speed ratio between the rotation shaft of the primary pulley 1500 and the rotation shaft of the secondary pulley 1600, that is, the gear ratio is changed. It can be changed continuously and continuously.

  In the metal belt 1550, a large number of elements 1700 are arranged in a ring shape in the plate thickness direction, and the elements 1700 are bound to the left and right saddle portions through hoops that are annular metal bands, thereby forming an endless metal as a whole. A belt 1550 is configured.

  A gear ratio is calculated by an ECT (Electronically Controlled Automatic Transmission) _ECU (Electronic Control Unit) that controls the continuously variable transmission, and a radius ratio between the primary pulley 1500 and the secondary pulley 1600 is determined so as to realize the gear ratio. The hydraulic circuit is controlled so that the respective pulley diameters (diameters around which the metal belt 1550 is wound) are obtained.

  In addition, a manual transmission mode is set for the continuously variable transmission. For example, in the shift pattern, the positions of the P range, R range, N range, and D range used in the automatic transmission mode and the manual shift range (M range) used in the manual transmission mode are set in the groove that is the shift gate. It is predetermined. By shifting the shift lever from the neutral position of the M range to the front side or the rear side of the vehicle, it can be upshifted or downshifted.

  A shift map stored in the ECT_ECU will be described with reference to FIG.

  As shown in FIG. 2, this shift map is such that the horizontal axis is the vehicle speed, the vertical axis is the engine speed (the input speed to the primary pulley 1500), and the gear ratio of the continuously variable transmission. Is a map that realizes a 7-speed stepped manual transmission mode in which is set discretely to 1st, 2nd, 3rd, 4th, 5th, 6th, and 7th. The 1st side is the speed reduction side and the speed ratio is large, the 7th side is the speed increasing side, and the speed ratio is small. By executing a program to be described later, the upshift operation in the manual shift mode is prohibited in the shaded area shown in FIG.

  With reference to FIG. 3, the relationship between the transmission ratio of the continuously variable transmission and the stress generated in the metal belt 1550 will be described.

  As shown in FIG. 3, when the horizontal axis is the transmission ratio and the vertical axis is the stress, the greater the transmission ratio, the greater the stress, and the smaller the transmission ratio, the greater the stress. In particular, when the gear ratio is small (accelerating side), the pulley width of the secondary pulley 1600 is large (the belt winding radius is small), and bending stress is generated. In addition, the gear ratio is small because the vehicle is traveling at high speed, the pulley has a high rotational speed and a large centrifugal force acts on the metal belt 1550. For this reason, as shown by the arrow in FIG. 3, the stress tends to further increase in the region where the gear ratio is small. During high-speed traveling, the traveling resistance of the vehicle is large, so that the transmission torque is large, and a hydraulic pressure having a magnitude corresponding to the transmission torque acts, so that the tensile tension of the belt is also large.

  Even when the gear ratio is large, the stress generated in the metal belt 1550 is large because the pulley width of the primary pulley 1500 is large (the belt winding radius is small), so that a large bending stress is generated.

  A control structure of a program executed by the ECT_ECU will be described with reference to FIG.

  In step (hereinafter step is abbreviated as S) 100, the ECT_ECU determines whether or not an upshift manual shift command has been detected. If an upshift manual shift command is detected (YES in S100), the process proceeds to S110. If not (NO in S100), the process returns to S100 and waits until an upshift manual shift command is detected.

  In S110, the ECT_ECU determines whether or not the shift is to the shift gear set with the upshift prohibition flag set. If the shift is to the shift gear set with the upshift prohibition flag set (YES in S110), the process proceeds to S120. If not (NO in S110), the process proceeds to S130.

  In S120, the ECT_ECU executes an upshift prohibition process.

  In S130, the ECT_ECU executes an upshift permission process.

  In S140, the ECT_ECU outputs a shift command signal. By this shift command signal, the hydraulic pressure of the continuously variable transmission is controlled so as to realize the set gear ratio.

  A control structure of another program executed by the ECT_ECU will be described with reference to FIG. This program is a subroutine program for setting an upshift prohibition flag.

  In S200, ECT_ECU determines whether or not the manual shift mode is set. If it is the manual shift mode (YES in S200), the process proceeds to S210. Otherwise (NO in S200), this process ends.

  In S210, the ECT_ECU detects the vehicle speed. At S220, ECT_ECU determines whether or not the detected vehicle speed is greater than a predetermined threshold value. If the detected vehicle speed is greater than a predetermined threshold value (YES in S220), the process proceeds to S230. If not (NO in S220), the process proceeds to S240.

  In S230, the ECT_ECU sets an upshift prohibition flag to the high speed gear stage. In S240, the ECT_ECU resets the upshift prohibition flag to the set high speed gear.

  The operation of the control device for the belt type continuously variable transmission according to the present embodiment based on the above-described structure and flowchart will be described.

  If it is the manual shift mode (YES in S200), the vehicle speed is detected (S210), and if the vehicle speed is greater than a predetermined threshold value (YES in S220), an upshift prohibition flag to the high-speed gear stage is determined. Is set (S230). At this time, the shaded area shown in FIG. 2 is an area where the upshift prohibition flag is set. The vehicle speed, which is a threshold value, is different for each gear position (4th, 5th, 6th, 7th). The 4th vehicle speed is higher than the 7th threshold, and the 7th vehicle speed is lower than the 4th.

  Therefore, in the shift map shown in FIG. 2, an upshift prohibition flag indicating that an upshift to 4th is prohibited, an upshift prohibition flag indicating that an upshift to 5th is prohibited, There are four flags: an upshift prohibition flag indicating that an upshift is prohibited and an upshift prohibition flag indicating that an upshift to 7th is prohibited.

  In the manual shift mode, when the driver tilts the shift lever to the up side, an upshift manual shift command is detected (YES in S100). If the shift is to the shift gear set with the upshift prohibition flag set based on the current shift gear and the upshift prohibition flag (YES in S110), an upshift prohibition process is executed (S120). ) Even if the driver performs an upshift operation, the upshift is not performed in the continuously variable transmission. At this time, as an upshift prohibition process, for example, a display indicating that the upshift prohibition has been executed may be performed on the indicator lamp.

  On the other hand, if the shift is to a shift gear stage in which the upshift prohibition flag is not set (NO in S110), an upshift permission process is executed (S130), and an upshift shift command signal to that shift stage is executed. The ECT_ECU outputs a shift command signal to the hydraulic control device of the continuously variable transmission (S140).

  As described above, according to the control device for the belt-type continuously variable transmission according to the present embodiment, when the manual transmission mode is selected in the belt-type continuously variable transmission having the manual transmission mode and the automatic transmission mode. In this case, the shift based on the upshift operation that uses the vicinity of the maximum speed ratio during high speed traveling is prohibited. When the manual transmission mode is selected, it is avoided that high-speed traveling is performed in a state where the transmission ratio in the vicinity of the maximum speed increase ratio is set. In the vicinity of the maximum speed increase ratio, the belt winding diameter of the secondary pulley is small and receives a large bending stress, and the centrifugal force applied to the belt is large, the transmission torque is large, and the belt tension is large during high speed traveling. For this reason, the stress which generate | occur | produces in a belt becomes large. Since such an upshift to the transmission gear stage is prohibited, it is possible to avoid the occurrence of such a large stress on the belt and to improve the durability of the belt. Further, during high-speed running, the running resistance of the vehicle increases, and there is a possibility that a driving force shortage may occur at a gear ratio near the maximum speed increase ratio. Such a situation can also be avoided.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a structural diagram of a power train including a continuously variable transmission that is a control target in a control device according to an embodiment of the present invention. It is a figure which shows the shift map memorize | stored in ECT_ECU. It is a figure which shows the relationship between the gear ratio of a belt-type continuously variable transmission, and the stress which generate | occur | produces in a metal belt. It is a flowchart (the 1) which shows the control structure of the program performed by ECT_ECU which implement | achieves the control apparatus which concerns on embodiment of this invention. It is a flowchart (the 2) which shows the control structure of the program performed by ECT_ECU which implement | achieves the control apparatus which concerns on embodiment of this invention.

Explanation of symbols

  1000 power train, 1100 input shaft, 1200 torque converter with lock-up clutch, 1300 oil pump, 1400 forward / reverse switching mechanism, 1500 primary pulley, 1550 metal belt, 1600 secondary pulley, 1700 element, 1800 reduction gear, 1900 differential gear.

Claims (1)

Used in a belt-type continuously variable transmission for a vehicle having an automatic transmission mode and a manual transmission mode. When the manual transmission mode is selected, a stepped transmission is performed according to an upshift operation and a downshift operation. A belt type continuously variable transmission control device for a vehicle,
Detection means for detecting the vehicle speed;
Determination means for determining whether the vehicle speed is equal to or higher than a predetermined vehicle speed;
And a prohibiting unit for prohibiting a shift based on a predetermined upshift operation when it is determined that the vehicle speed is equal to or higher than the predetermined vehicle speed when the manual shift mode is selected. ,Control device.

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