JP2012042015A - Control device of continuously variable transmission for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a continuously variable transmission for a vehicle, which can suppress air suction of an oil pump while reducing oil storing amount as much as possible.SOLUTION: The control device of the continuously variable transmission for the vehicle includes: a transmission rate increasing speed control means 78 which sets a duty ratio Rof a second transmission control solenoid valve DS2 so that a transmission rate increasing speed is slower than that when braking force is applied to a vehicle during travelling on a flat road, when the braking force is applied to the vehicle during travelling on a downhill road; and a transmission control means 74 which makes the transmission rate increasing speed slower than that during travelling on the flat road when the braking force is applied to the vehicle during travelling on a downhill road by controlling the second transmission control solenoid valve DS2 based on the duty ratio R.

Description

  The present invention relates to a control device for a continuously variable transmission for a vehicle that includes an oil pump and increases a gear ratio as the vehicle speed decreases, and particularly relates to a technique for suppressing air suction of the oil pump.

  2. Description of the Related Art There is known a control device for a continuously variable transmission for a vehicle that includes an oil pump that is driven by a vehicle drive source and that increases a gear ratio as the vehicle speed decreases. For example, it is described in Patent Document 1. As shown in FIG. 4, the continuously variable transmission for a vehicle of Patent Document 1 is controlled so that the gear ratio increases as the vehicle speed decreases as long as the accelerator opening (required output-related value) is the same. . For example, when braking force is applied to a running vehicle, the gear ratio of the continuously variable transmission is increased as the vehicle speed decreases, and the gear ratio of the continuously variable transmission is set to the maximum gear ratio when the vehicle is stopped. Shift control is performed. As described above, since the gear ratio of the continuously variable transmission when the vehicle is stopped is set to the maximum gear ratio, it is possible to sufficiently secure the driving force when the vehicle starts.

  Further, Patent Document 2 includes an oil pump that is driven by an electric motor different from the drive source of the vehicle, estimates the amount of air mixed in the hydraulic oil stored in the reservoir, and determines the amount of air mixed in the vehicle. A control device for a continuously variable transmission for a vehicle that controls an oil pump based on a posture is described. According to this, it is supposed that it can suppress that the amount of mixed air increases due to the attitude of the vehicle and the line pressure decreases.

  Further, Patent Document 3 discloses a differential chamber that houses a differential gear device, an oil chamber that stores lubricating oil, a communication passage that communicates the differential chamber and the oil chamber, and the above-mentioned when the vehicle is tilted and the vehicle is accelerated. A vehicle power transmission device including a transaxle case having an opening and closing mechanism for closing a communication path is described. According to this, it is said that so-called air sucking in which the oil pump sucks air when the vehicle is tilted or the vehicle is accelerated can be suppressed.

  Patent Document 4 describes a vehicle transmission including a baffle plate that restricts the movement of oil away from an oil suction port of an oil pump. According to this, it is said that the air suction of the oil pump can be suppressed.

  Patent Document 5 discloses a control of a continuously variable transmission for a vehicle that can improve a climbing performance and appropriately obtain an engine brake when descending a slope by appropriately setting a target gear ratio according to a road gradient. An apparatus is described.

  Further, in Patent Document 6, when the road surface gradient exceeds a preset threshold value, the target vehicle speed is set based on the vehicle speed at the time when the threshold value is exceeded, and the vehicle speed is changed so that the vehicle speed becomes the target vehicle speed. A control device for a vehicle automatic transmission for controlling the ratio is described. According to this, it is supposed that an appropriate engine brake can be obtained automatically while traveling downhill.

JP 2008-51317 A JP 2004-144233 A JP 2009-103202 A JP 2006-307986 A JP-A-8-338520 Japanese Patent Laid-Open No. 9-242853

  By the way, in the above conventional control device for a continuously variable transmission for a vehicle, when braking force is applied to a vehicle traveling on a downhill road, a deceleration is applied to the vehicle in a forward leaning posture. The hydraulic oil stored in the oil storage part in the machine is shifted to the front side of the vehicle. For this reason, the oil suction port of the oil pump is not immersed in the hydraulic oil in the oil reservoir and is exposed to the air outside the hydraulic oil, so that so-called air suction that sucks air from the oil suction port is likely to occur. . The deviation of the hydraulic oil toward the front side of the vehicle becomes more conspicuous as the rapid deceleration is performed.

  On the other hand, it is conceivable to solve the above problem by increasing the oil level by increasing the amount of hydraulic oil stored in the oil reservoir, but according to this, the weight increase of the continuously variable transmission, the cost increase, and The disadvantage of increased oil agitation loss occurs.

  The present invention has been made against the background of the above circumstances. The object of the present invention is to provide a continuously variable for a vehicle that can suppress air suction of an oil pump while reducing the amount of oil stored as much as possible. An object of the present invention is to provide a transmission control device.

  The gist of the invention according to claim 1 for achieving this object is as follows: (a) a control device for a continuously variable transmission for a vehicle that includes an oil pump and increases the gear ratio as the vehicle speed decreases; (b) When a braking force is applied to the vehicle traveling on a downhill road, a transmission speed control is performed to make the speed ratio increase speed slower than when a braking force is applied to the vehicle traveling on a flat road. There is.

  A gist of the invention according to claim 2 is that, in the invention according to claim 1, in the speed change control, the speed change ratio increasing speed is made slower as the slope of the downhill road is larger.

  The gist of the invention according to claim 3 is that, in the invention according to claim 1 or 2, in the speed change speed control, the greater the braking force is, the slower the speed change ratio increase speed is.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the temperature of the hydraulic oil in the continuously variable transmission for a vehicle is equal to or lower than a predetermined value set in advance. Sometimes the speed change control is performed.

  The gist of the invention according to claim 5 is that, in the invention according to any one of claims 1 to 4, the continuously variable transmission for a vehicle includes an input shaft and an output shaft provided in parallel to each other. And a pair of variable groove width pulleys fixed to the input shaft and the output shaft, and transmission belts wound around the V grooves of the pair of variable groove width pulleys, respectively, and changing the groove width of the V grooves. The belt-type continuously variable transmission in which the gear ratio is continuously changed by changing the engagement diameter of the transmission belt.

  The gist of the invention according to claim 6 is that, in the invention according to any one of claims 1 to 5, the oil pump is driven by a drive source of a vehicle.

  According to the control device for a continuously variable transmission for a vehicle according to the first aspect, when a braking force is applied to a vehicle traveling on a downhill road, the braking force is applied to a vehicle traveling on a flat road. Since speed change control is performed to make the speed ratio increase speed slower than when traveling on a downhill road, an increase in the rotational speed of the vehicle drive source due to a decrease in the vehicle speed during braking is suppressed compared to when traveling on a flat road. Since the amount of oil sucked into the pump is reduced and the decrease in oil level is suppressed, the air suction of the oil pump can be suppressed while reducing the amount of oil stored as much as possible.

  According to the control device for a continuously variable transmission for a vehicle according to a second aspect of the present invention, in the shift speed control, the greater the gradient of the descending slope, the slower the speed ratio increasing speed. The oil intake amount of the oil pump is reduced and the oil level decreases as the slope becomes larger and the vehicle leans forward and the hydraulic oil stored in the oil reservoir in the continuously variable transmission is shifted further toward the front of the vehicle. Therefore, the air suction of the oil pump can be suitably suppressed while reducing the oil storage amount as much as possible.

  According to the control device for a continuously variable transmission for a vehicle according to a third aspect of the present invention, in the shift speed control, the greater the braking force is, the slower the speed ratio increase speed is. As the vehicle deceleration increases and the hydraulic oil stored in the oil reservoir in the continuously variable transmission shifts further toward the front of the vehicle, the oil suction amount of the oil pump is reduced and the oil level is prevented from lowering. Therefore, it is possible to suitably suppress the air suction of the oil pump while reducing the oil storage amount as much as possible. Therefore, it is possible to suitably suppress the air suction of the oil pump even during a sudden stop while traveling on a downhill road.

  According to the control device for a continuously variable transmission for a vehicle according to a fourth aspect of the present invention, the shift speed control is performed when the temperature of the hydraulic oil in the continuously variable transmission for the vehicle is equal to or lower than a predetermined value. Therefore, in the state where the viscosity of the hydraulic oil circulating to the oil storage part of the continuously variable transmission is high and the hydraulic oil supplied to each lubricating part is difficult to return to the oil storage part, the oil suction amount of the oil pump is reduced. Therefore, the oil level can be prevented from lowering, and the oil suction of the oil pump can be suitably suppressed while reducing the oil storage amount as much as possible.

  According to the control device for a continuously variable transmission for a vehicle according to a fifth aspect of the present invention, the continuously variable transmission for a vehicle includes an input shaft and an output shaft provided in parallel to each other, and an input shaft and an output shaft thereof. A pair of groove width variable pulleys fixed to the belt, and transmission belts wound around the V grooves of the pair of groove width variable pulleys, respectively. Since it is a belt type continuously variable transmission that continuously changes the gear ratio by changing the diameter, the vehicle drive source is associated with a decrease in vehicle speed during braking compared to traveling on a flat road when traveling downhill. The increase in the rotation of the oil pump is suppressed, the oil suction amount of the oil pump is reduced, and the decrease in the oil level is suppressed, so that the air suction of the oil pump can be suppressed while reducing the oil storage amount as much as possible. .

  According to the control device for a continuously variable transmission for a vehicle of the invention according to claim 6, since the oil pump is driven by a drive source of the vehicle, the gear ratio of the continuously variable transmission is reduced as the vehicle speed decreases. Even when traveling on downhill roads, the increase in rotational speed of the drive source of the vehicle due to a decrease in vehicle speed during braking is suppressed and the oil intake amount of the oil pump is reduced when traveling downhill. Since the decrease in the oil level is suppressed, it is possible to suppress the air suction of the oil pump while reducing the oil storage amount as much as possible.

1 is a schematic diagram of a vehicle power transmission device according to an embodiment of the present invention. It is sectional drawing which shows the II-II arrow part of FIG. It is a block diagram explaining the control system for controlling the continuously variable transmission of FIG. It is a functional block diagram for demonstrating the principal part of the control function with which the electronic control apparatus of FIG. 3 was equipped. It is a figure which shows the shift map used in shift control. It is a figure which shows the target secondary oil pressure value map used in belt clamping pressure control. It is a figure which shows the correction coefficient map (M _RATIO map) used in gear ratio increase speed control. It is a flowchart explaining the principal part of the control action performed by the signal processing of the electronic controller of FIG. It is a time chart for comparing and explaining the control action of the electronic control unit of Example 1 and the control action of the conventional electronic control unit. It is sectional drawing of a continuously variable transmission which shows a mode that the hydraulic fluid in a continuously variable transmission deviates to the vehicle front side by adding deceleration to the vehicle of a forward leaning attitude in a downhill road. It is a flowchart explaining a part of control action performed by the signal processing of the electronic control apparatus of the other Example of this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a skeleton diagram of a vehicle power transmission device 10 according to an embodiment of the present invention. In FIG. 1, a vehicle power transmission device 10 is suitably employed in a FF (front engine / front drive) type vehicle, and is connected to an engine 12 as a drive source of the vehicle. The vehicle power transmission device 10 includes a torque converter 14 connected to the engine 12, a forward / reverse switching device 16 that switches a rotational direction of an output from the torque converter 14 between forward travel and reverse travel of the vehicle, The belt-type continuously variable transmission 18 that changes the output from the forward / reverse switching device 16, the reduction gear device 20 that reduces the output from the continuously variable transmission 18, and the output from the reduction gear device 20 is left and right. And a differential gear device 24 that transmits the rotation difference between the pair of drive wheels 22 to the drive wheels 22 while allowing the difference in rotation. The torque converter 14, the forward / reverse switching device 16, the continuously variable transmission 18, the reduction gear device 20, and the differential gear device 24 are accommodated in a transaxle case 26.

  The torque converter 14 is connected to the crankshaft of the engine 12 and is driven to rotate by the engine 12 to generate a fluid flow due to the flow of hydraulic oil in the torque converter 14, and the output of the torque converter 14. The fluid transmission device includes a turbine impeller 32 that is connected to a turbine shaft 30 as a member and is rotated by receiving the fluid flow.

  The forward / reverse switching device 16 is composed of a double pinion type planetary gear device including a sun gear S, a carrier CA, and a ring gear R. The sun gear S is connected to the turbine shaft 30 of the torque converter 14, and the carrier CA is connected to the input shaft 34 of the continuously variable transmission 18. When the forward clutch 36 disposed between the sun gear S and the carrier CA is engaged, the turbine shaft 30 and the input shaft 34 are directly connected, and the output from the torque converter 14 is the same as the engine rotation. It is transmitted to the continuously variable transmission 18 in the rotational direction. When the reverse brake 38 disposed between the ring gear R and the transaxle case 26 is engaged, the input shaft 34 is rotated in the reverse direction with respect to the turbine shaft 30, and the torque converter 14 is transmitted to the continuously variable transmission 18 in the direction opposite to the engine rotation.

  Between the torque converter 14 and the forward / reverse switching device 16, there is an oil pump 40 that is rotationally driven by the engine 12 and that feeds hydraulic oil to various hydraulic devices and lubricating parts of the vehicle power transmission device 10. Is provided. The rotor of the oil pump 40 is connected to the pump impeller 28 of the torque converter 14 and is driven to rotate by the engine 12. FIG. 2 is a cross-sectional view showing the II-II arrow portion of FIG. As shown in FIG. 2, an oil pan 42 is fixed to an opening formed in the lower part of the transaxle case 26. Hydraulic oil is stored in a lower portion of an oil-tight internal space formed by the oil pan 42 and the transaxle case 26. The oil pump 40 in FIG. 1 sucks the hydraulic oil stored in the oil storage portion in the lower part of the internal space shown in FIG. 2 through a strainer 44 that opens toward the bottom surface of the oil pan 42. The strainer 44 is formed of a mesh member made of resin or metal, for example. The hydraulic oil stored in the oil pan 42 is sucked into the strainer 44 through the plurality of meshes of the mesh member. The plurality of meshes function as an oil inlet. Note that the oil suction port is formed in the entire strainer 44 that is elongated in the longitudinal direction of the vehicle. As shown in FIG. 10 to be described later, the hydraulic oil is moved to the front side of the vehicle under the influence of the deceleration of the vehicle. In the case of deviating, a part of the oil suction port, that is, a part on the vehicle rear side is close to the oil level.

  The continuously variable transmission 18 includes an input shaft 34 and an output shaft 46 that are provided in parallel to each other and rotatable about each axis, a primary pulley (groove width variable pulley) 48 fixed to the input shaft 34, A secondary pulley (groove width variable pulley) 50 fixed to the output shaft 46 and an endless annular transmission belt 52 wound around the V grooves of the pulleys 48 and 50 are provided. The primary pulley 48 includes a fixed sheave 48a fixed to the input shaft 34, a movable sheave 48b provided so as to be capable of approaching and separating in the axial direction with respect to the fixed sheave 48a, and moving the movable sheave 48b in the axial direction. The hydraulic cylinder 48c is configured to change the groove width of the V groove between the fixed sheave 48a and the movable sheave 48b. The secondary pulley 50 includes a fixed sheave 50a fixed to the output shaft 46, a movable sheave 50b provided so as to be able to approach and separate in the axial direction from the fixed sheave 50a, and the movable sheave 50b. A hydraulic cylinder 50c that applies a clamping force in the width direction to the transmission belt 52 by being pressed toward 50a is provided.

In the continuously variable transmission 18 configured as described above, the flow rate of hydraulic pressure into the hydraulic cylinder 48c is controlled or the flow rate of hydraulic pressure from the hydraulic cylinder 48c is controlled, so that the V of each pulley 48, 50 is controlled. When the groove width of the groove is changed, the engagement diameters of the transmission belt 52 at the pulleys 48 and 50 are respectively changed, and the transmission gear ratio γ (= input shaft rotational speed N _IN / output shaft rotational speed N _OUT ) is increased. It can be changed continuously and continuously. Then, by adjusting the hydraulic pressure to the hydraulic cylinder 50c, the belt clamping pressure of the pulleys 48 and 50 is adjusted, and the slippage of the transmission belt 52 is suppressed. Note that when the engagement diameter of the primary pulley 48 of the transmission belt 52 is relatively small and the engagement diameter of the secondary pulley 50 is relatively large, the gear ratio γ is relatively small. When the engagement diameter of the transmission belt 52 at the primary pulley 48 is relatively large and the engagement diameter at the secondary pulley 50 is relatively small, the speed ratio γ is relatively large.

  FIG. 3 is a block diagram illustrating a control system for controlling the continuously variable transmission 18. In FIG. 3, the electronic control unit 54 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like, and the CPU stores in advance in the ROM while using a temporary storage function of the RAM. By performing signal processing in accordance with the program, shift control of the continuously variable transmission 18 is executed. The electronic control unit 54 functions as a control unit for the continuously variable transmission 18.

The electronic control unit 54 is supplied with various input signals detected by each sensor provided in the vehicle. The aforementioned input signals, for example, rotational speed or signal representing the input shaft speed N _IN of the primary pulley 48 detected by the primary pulley rotation speed sensor 56, rotation of the secondary pulley 50 detected by the secondary pulley rotation speed sensor 58 speed or signal representing the output shaft speed N _{OUT (corresponding} to the vehicle speed V), the hydraulic oil of the continuously variable within transmission 18 detected by the signal, an oil temperature sensor 62 representative of the line pressure P _L which is detected by the oil pressure sensor 60 is detected in the signal representing the oil temperature T _oIL, the signal representing the throttle opening degree θth detected by the throttle opening sensor 64, a signal representing the accelerator opening Acc detected by the accelerator opening sensor 66, a brake switch 68 A signal indicating whether or not the foot brake is operated, which is detected by the brake pedal force sensor 70 Signal representative of the depression force F _B of the foot brake pedal that, and the signal or the like representing the acceleration G of the vehicle detected by the acceleration sensor 72.

Further, the electronic control device 54 supplies various output signals to each device provided in the vehicle. The aforementioned output signal, for example, signals supplied to the first shift control solenoid valve DS1 that controls the inflow rate of the line pressure P _L to the hydraulic cylinder 48c of the primary pulley 48 in accordance with the vehicle speed V and the accelerator opening Acc , the secondary pulley 50 in response to the second signal is supplied to the shift control solenoid valve DS2, and the input shaft torque T _iN for controlling the outflow rate of the working oil from the hydraulic cylinder 48c in accordance with the vehicle speed V and the accelerator opening Acc There is a signal supplied to the belt clamping pressure control solenoid valve SLS for regulating the pressure of the hydraulic pressure to the hydraulic cylinder 50c. Incidentally, the line pressure P _L is the hydraulic pressure to pressure regulated as a source pressure oil from the oil pump 40. Further, a the first duty solenoid valve shift control solenoid valve DS1 is known well, it is to increase the inflow rate of the line pressure P _L to the hydraulic cylinder 48c as the duty ratio R _DUTY1 is increased. Further, the second shift control solenoid valve DS2 is a well-known duty solenoid valve, and increases the outflow rate of hydraulic oil from the hydraulic cylinder 50c as the duty ratio R _DUTY2 increases. Further, the belt clamping pressure control solenoid valve SLS is a well-known linear solenoid valve, and controls the excitation current to the solenoid to regulate the hydraulic pressure to the hydraulic cylinder 50c.

FIG. 4 is a functional block diagram for explaining the main part of the control function provided in the electronic control unit 54. In FIG. 4, the shift control means 74 uses a target input shaft rotation speed from a shift map in which the relationship between the vehicle speed V and the target input shaft rotation speed N _INT is predetermined for each accelerator opening Acc, as shown in FIG. 5, for example. N _INT is calculated, and shift control of the continuously variable transmission 18 is performed so that the input shaft rotational speed N _IN matches the target input shaft rotational speed N _INT . The shift map in FIG. 5 corresponds to the shift conditions, and the target input shaft rotational speed N _INT is determined in advance so that the gear ratio γ increases as the vehicle speed V decreases as long as the accelerator opening degree Acc is the same. The shift control means 74 performs shift control for increasing the speed ratio γ of the continuously variable transmission 18 as the vehicle speed V decreases according to the shift map.

For example, the gear ratio of the continuously variable transmission 18 reduces the gamma (reduced) when the inflow of the line pressure P _L to the hydraulic cylinder 48c by controlling the duty ratio R _DUTY1 of the first shift control solenoid valve DS1 By increasing the flow rate, the groove width of the primary pulley 48 is reduced while the groove width of the secondary pulley 50 is increased, and the engagement diameter of the transmission belt 52 at the primary pulley 48 is increased while the transmission belt 52 at the secondary pulley 50 is increased. Reduce the hook diameter. The shift control means 74 functions as a shift speed control device that controls the speed ratio reduction speed. For example, the speed change control means 74 makes the duty ratio R _DUTY1 of the first speed change control solenoid valve DS1 relatively small, thereby reducing the speed (gear ratio) of the speed ratio γ compared to when the duty ratio R _DUTY1 is relatively large. Shift speed control is performed to slow down (decrease speed).

When the transmission gear ratio γ of the continuously variable transmission 18 is increased (increased), the duty ratio R _DUTY2 of the second transmission control solenoid valve DS2 is controlled to _reduce the flow rate of hydraulic oil from the hydraulic cylinder 50c. By increasing the groove width of the primary pulley 48, the groove width of the secondary pulley 50 is reduced, and the engagement diameter of the transmission belt 52 at the primary pulley 48 is reduced, while the engagement of the transmission belt 52 at the secondary pulley 50 is increased. Increase the diameter. The shift control means 74 functions as a shift speed control device that controls the speed ratio increasing speed. For example, the speed change control means 74 _reduces the duty ratio R _DUTY2 of the second speed change control solenoid valve DS2 to be relatively small, thereby increasing the speed ratio γ (speed ratio) as compared with the case where the duty ratio R _DUTY1 is relatively large. Shift speed control is performed to slow down (increase speed).

The speed change control means 74 determines that the speed change ratio increase speed control means 78 (described later) determines that the vehicle is traveling on a downhill road and that a braking force is applied to the vehicle. By controlling the second speed change control solenoid valve DS2 based on the duty ratio R _DUTY2 calculated by the ratio increasing speed control means 78, the speed change ratio is higher than when a braking force is applied to a vehicle running on a flat road. The increase speed (the increase speed of the gear ratio γ) is slowed down. The speed ratio γ of the continuously variable transmission 18 is not instantaneously matched with the target speed ratio γ _T corresponding to the target input shaft rotational speed N _INT by slowing down the speed ratio increasing speed as described above. , It is made to follow so as to coincide with a predetermined time delay.

The belt clamping pressure control means 76, for example, the relationship between the speed ratio γ and the target secondary hydraulic pressure value P _SECT 6 is predetermined target secondary for each accelerator opening Acc corresponding to the input shaft torque T _IN A target secondary hydraulic pressure value P _SECT that does not cause belt slippage is calculated from the hydraulic pressure value map, and each pulley 48 is set by matching the hydraulic pressure value of the hydraulic cylinder 50c, that is, the secondary hydraulic pressure value P _SEC with the target secondary hydraulic pressure value P _SECT. , 50, belt clamping pressure control of the continuously variable transmission 18 is performed so that belt slip does not occur. Specifically, the belt clamping pressure control unit 76 controls the secondary hydraulic pressure value P _SEC corresponding to the belt clamping pressure by controlling the excitation current to the belt clamping pressure control solenoid valve SLS.

The transmission ratio increasing speed control means (transmission speed control means) 78 is more effective when a braking force is applied to a vehicle traveling on a downhill road than when a braking force is applied to a vehicle traveling on a flat road. The duty ratio R _DUTY2 of the second transmission control solenoid valve DS2 is set so that the increase speed (increase speed of the speed ratio γ) becomes slow.

The speed ratio increasing speed control means 78 calculates the actual acceleration of the vehicle, that is, the actual acceleration G _ACT based on the rate of change of the output shaft rotational speed N _OUT corresponding to the vehicle speed V. Further, the gear ratio increasing speed control means 78 calculates the reference acceleration G _OPT from a predetermined relationship based on the vehicle state, that is, the throttle opening θth (output related value), the gear ratio γ, the vehicle speed V, and the like. The reference acceleration G _OPT is a value corresponding to the acceleration G of the vehicle when traveling on a flat road in the vehicle state. Further, the gear ratio increase speed control means 78 determines whether or not the difference _ΔG between the actual acceleration G _ACT and the reference acceleration G _OPT is greater than zero. If the determination is affirmative, it is determined that the vehicle is traveling on a downhill road. If the determination is negative, it is determined that the vehicle is not traveling on a downhill road, that is, the vehicle is traveling on an uphill road. The gear ratio increase speed control means 78 has downhill road determination means.

Further, the gear ratio increase speed control means 78 determines whether or not the foot brake is operated in order to apply a braking force to the vehicle. Further, the gear ratio increases the speed control means 78 detects a depression force F _B or the braking oil pressure of the foot brake pedal corresponding to the brake force of the vehicle. The gear ratio increase speed control means 78 has a braking force determination means.

Further, for example, as shown in FIG. 7, the gear ratio increasing speed control means 78 uses the pedaling force F _B and acceleration difference ΔG (= G _ACT −G _OPT ) as parameters, and the pedaling force F _B and acceleration difference ΔG. A correction coefficient M _RATIO is calculated from a correction coefficient map (M _RATIO map) in which a relationship with the correction coefficient M _RATIO of the duty ratio R _DUTY2 of the second shift control solenoid valve DS2 corresponding to the speed ratio increasing speed is predetermined. . Based on the correction coefficient M _RATIO , the duty ratio R _DUTY2 of the second shift control solenoid valve DS2 is calculated. The correction coefficient M _RATIO is set in advance so that when a braking force is applied to a vehicle traveling on a downhill road, the speed ratio increasing speed is slower than when a braking force is applied to a vehicle traveling on a flat road. Required and determined experimentally. Specifically, the correction factor M _RATIO, as shown in FIG. 7, if the braking force is the same depression force F _B is applied to the same i.e. vehicle, downhill slope θ is large i.e. acceleration difference △ G is It is determined in advance so that the larger the ratio is, the slower the speed ratio increase speed becomes. Further, as shown in FIG. 7, descending if the same slope of the gradient θ is the same i.e. acceleration difference △ G, as the gear ratio increases speed is greater braking force applied to the large ie vehicle pedal force F _B is delayed Is determined in advance.

  FIG. 8 is a flowchart for explaining the main part of the control operation executed by the signal processing of the electronic control unit 54. This flowchart is for explaining a control operation for downhill gear ratio increase speed control (downhill road determination, speed ratio increase speed correction coefficient calculation) in the control operation by the electronic control unit 54. It is repeatedly executed with a very short cycle time of about several milliseconds to several tens of milliseconds.

In FIG. 8, first, in a step (hereinafter, “step” is omitted) S1 corresponding to the gear ratio increase speed control means 78, the vehicle is determined based on the rate of change of the output shaft rotational speed N _OUT corresponding to the vehicle speed V. The actual acceleration, that is, the actual acceleration _GACT is calculated.

Subsequent to S1, in S2 corresponding to the gear ratio increasing speed control means 78, the reference acceleration G _OPT is determined based on the vehicle state, that is, the throttle opening θth, the gear ratio γ, the vehicle speed V, and the like from a predetermined relationship. Calculated.

Subsequent to S2, in S3 corresponding to the gear ratio increasing speed control means 78, it is determined whether or not the acceleration difference _ΔG between the actual acceleration _GACT and the reference acceleration _GOPT is greater than zero.

  If it is determined that the vehicle is not traveling on a downhill road because the determination in S3 is negative, this routine is terminated. If the determination in S3 is negative and it is determined that the vehicle is traveling on a downhill road, in S4 corresponding to the gear ratio increase speed control means 78, a signal STP indicating whether or not the foot brake is operated is displayed. Based on this, it is determined whether or not the foot brake is operated (STP = ON) in order to apply the braking force to the vehicle.

When it is determined that the braking force is not applied to the vehicle as a result of the determination in S4 being negative, this routine is terminated. If the determination in S4 is negative, it is determined that the braking force is applied to the vehicle. In S5 corresponding to the gear ratio increase speed control means 78, the foot corresponding to the braking force of the vehicle. depression force F _B of the brake pedal is detected.

Subsequent to S5, in S6 corresponding to the gear ratio increase speed control means 78, a correction coefficient map (M _RATIO map) as shown in FIG. 7 is read. This correction coefficient map uses the pedaling force F _B and acceleration difference ΔG (= G _ACT −G _OPT ) as parameters, and the second shift control solenoid valve corresponding to the pedaling force F _B and acceleration difference ΔG and the gear ratio increase speed. The relationship between the DS2 duty ratio R _{DUTY2 and} the correction coefficient M _RATIO is predetermined.

Following the S6, in S7 corresponding to the speed ratio increase rate control means 78, from the read correction coefficient map, the correction coefficient M _RATIO is calculated on the basis of the depression force F _B and the acceleration difference △ G. As shown in FIG. 7, the correction coefficient M _RATIO is such that if the pedaling force F _B is the same, that is, the braking force applied to the vehicle is the same, the gear ratio increases as the slope of the downhill road increases, that is, the acceleration difference ΔG increases. It is determined in advance so as to reduce the speed. Further, as shown in FIG. 7, if the slope of the downhill road is the same, that is, the acceleration difference ΔG is the same, the gear ratio increase speed becomes slower as the pedaling force F _B is larger, that is, the braking force applied to the vehicle is larger. Is predetermined.

Subsequent to S7, in S8 corresponding to the gear ratio increase speed control means 78, the duty ratio R _{DUTY2 of} the second gear shift control solenoid valve DS2 is calculated based on the calculated correction coefficient M _RATIO . Then, this routine is terminated.

  FIG. 9 is a time chart for comparing and explaining the control operation of the electronic control device 54 of the present embodiment and the control operation of the conventional electronic control device, and the brake operation is performed at time t1 during traveling on the downhill road. It is the case where is made. In FIG. 9, the control operation of the conventional electronic control device is indicated by a two-dot chain line, and the control operation of the electronic control device 54 of the present embodiment is indicated by a solid line. It should be noted that only the solid line indicates that there is no difference between the present embodiment and the prior art. Note that the conventional electronic control unit is configured not to change the speed ratio increasing speed even when traveling on a downhill road or on a flat road. In addition, the conventional electronic control device is configured such that the speed increase ratio increases as the vehicle deceleration increases.

  As shown in FIG. 9, the acceleration G of the vehicle starts to decrease to the minus side immediately after time t1, that is, the deceleration of the vehicle starts to increase. Then, the vehicle speed V begins to gradually decrease, and the gear ratio γ of the continuously variable transmission 18 is increased accordingly. The conventional electronic control device is configured not to change the speed ratio increase speed even when traveling on a downhill road or on a flat road, whereas the electronic control device 54 of this embodiment is During traveling on a downhill road, the speed ratio increasing speed is made slower than when traveling on a flat road. Therefore, in this embodiment, the gear ratio γ is increased relatively later than in the prior art. As a result, in this embodiment, the rotation of the engine 12 is made relatively smaller than in the prior art, and the intake amount of hydraulic oil in the oil pump is relatively reduced.

As shown in FIG. 10 showing a cross section of the continuously variable transmission 18 at time t2 in FIG. 9, when deceleration is applied to a vehicle in a forward leaning posture on a downhill road with a gradient θ, the hydraulic oil in the continuously variable transmission 18 is moved forward of the vehicle. Gently lean to the side. In FIG. 10, the conventional oil level is indicated by a two-dot chain line, and the oil level of the present embodiment is indicated by a solid line. As shown in FIG. 10, in the prior art in which the amount of hydraulic oil suctioned by the oil pump is relatively increased as compared with the present embodiment, a part of the oil suction port of the strainer 44 is operated by relatively reducing the oil level. There is a problem that air sucking occurs in which air is sucked from a part of the oil suction port because the oil does not soak in the oil. This air sucking, pulsation in the line pressure P _L as shown by the two-dot chain line occurs, shift control and control belt clamping pressure there is a problem that can not be accurately performed in FIG. Furthermore, there has been a problem that the operating sound of the oil pump increases as the rotational speed of the oil pump increases.

On the other hand, in this embodiment, as shown in FIG. 10, even if deceleration is applied to the vehicle leaning forward and the hydraulic oil in the continuously variable transmission 18 largely deviates toward the front side of the vehicle, The oil level is maintained at a relatively high level by reducing the amount of hydraulic oil sucked by the oil pump. Therefore, suck air is hardly generated in the oil pump 42, the line pressure P _L as shown by the solid line is stabilized in Fig. When the vehicle stops on a downhill road, the start performance does not deteriorate as in the case of a flat road even if the gear ratio γ does not reach the maximum gear ratio γmax as shown in FIG.

According to the electronic control unit 54 serving as the control unit for the belt-type continuously variable transmission 18 according to the present embodiment, when braking force is applied to a vehicle traveling on a downhill road, the braking force is applied to the vehicle traveling on a flat road. The gear ratio increasing speed control means 78 for setting the duty ratio R _DUTY2 of the second speed control solenoid valve DS2 so that the speed ratio increasing speed (the speed of increasing the speed ratio γ) is slower than the case where is given. By controlling the second speed change control solenoid valve DS2 based on the duty ratio R _DUTY2 , when the braking force is applied to the vehicle running on the downhill road, the speed change rate increasing speed is higher than that on the flat road running. Since the speed change control means 74 for delaying the vehicle is provided, the increase in the rotation of the engine 12 due to the decrease in the vehicle speed V during braking is suppressed when traveling on a downhill road, compared with when traveling on a flat road, and the oil pump 40. Since the oil intake amount is reduced and the oil level is prevented from lowering, the air suction of the oil pump 40 can be suppressed while reducing the oil storage amount as much as possible.

Further, according to the electronic control device 54 of the present embodiment, in the downhill when the speed ratio increasing speed control, downhill slope is greater i.e. acceleration difference slope _{△ G (= G ACT -G OPT} ) gear ratio increases with greater Since the duty ratio R _DUTY2 of the second speed change control solenoid valve DS2 is set so as to slow down the speed, the slope of the downhill road is large and the vehicle is in a forward leaning posture, so that the hydraulic oil in the continuously variable transmission 18 Since the oil intake amount of the oil pump 40 is reduced and the decrease in the oil level is suppressed as the position of the oil is further to the front side of the vehicle, the air of the oil pump 40 is preferably reduced while reducing the oil storage amount as much as possible. Suction can be suppressed.

Further, according to the electronic control device 54 of the present embodiment, in the downhill when the gear ratio increases the speed control, the speed ratio increasing rate larger the larger depression force F _B i.e. braking force applied to the vehicle is slow When the duty ratio R _{DUTY2 of} the second shift control solenoid valve DS2 is set, the braking force is large and the deceleration of the vehicle is larger, so that the hydraulic oil in the continuously variable transmission 18 is more biased toward the vehicle front side. As the oil suction amount of the oil pump 40 is reduced and the decrease in the oil level is suppressed, the air suction of the oil pump 40 can be suitably suppressed while reducing the oil storage amount as much as possible. Therefore, it is possible to suitably suppress the air suction of the oil pump 40 even during a sudden stop while traveling on a downhill road.

  Next, another embodiment of the present invention will be described. In the following description of the embodiments, portions that overlap each other are denoted by the same reference numerals and description thereof is omitted.

In an electronic control unit 80 according to another embodiment of the present invention shown in FIG. 4, the gear ratio increasing speed control means (shift speed control means) 82 is preset with the oil temperature T _OIL of the hydraulic oil in the continuously variable transmission 18. When the braking force is applied to the vehicle traveling on the downhill road, which is equal to or less than the predetermined value T _OIL 1, the speed change ratio increasing speed (when the braking force is applied to the vehicle traveling on the flat road ( The duty ratio R _DUTY2 of the second speed change control solenoid valve DS2 is set so that the speed of increase of the speed ratio γ becomes slower. The predetermined value T _OIL 1 is experimentally obtained in advance as an upper limit value of the oil temperature T _OIL that requires speed ratio increase speed control. The speed change control means 84 is such that the oil temperature T _OIL of the hydraulic oil in the continuously variable transmission 18 in the speed ratio increase speed control means 82 is equal to or lower than a predetermined value T _OIL 1 and the vehicle is traveling on a downhill road. And it is determined that the braking force is applied to the vehicle, the second speed control solenoid valve DS2 is set based on the duty ratio R _DUTY2 calculated by the speed ratio increasing speed control means 82. By controlling, the speed ratio increasing speed (speed increasing of speed ratio γ) is made slower than when braking force is applied to a vehicle traveling on a flat road.

  FIG. 11 is a flowchart for explaining a main part of the control operation executed by the signal processing of the electronic control unit 80. The control operation of the electronic control device 80 is the same as the control operation of the electronic control device 54 of the first embodiment except that S11 of FIG. 11 is performed before S1 of FIG.

In FIG. 11, in S11 corresponding to the gear ratio increase speed control means 82, it is determined whether or not the oil temperature T _OIL of the hydraulic oil in the continuously variable transmission 18 is equal to or lower than a predetermined value T _OIL 1 set in advance. The

  When the determination at S11 is negative, this routine is terminated. If the determination in S11 is affirmative, S1 and subsequent steps in FIG. 8 are performed.

According to the electronic control unit 80 as the control unit for the belt-type continuously variable transmission 18 according to the present embodiment, when braking force is applied to a vehicle traveling on a downhill road, the braking force is applied to the vehicle traveling on a flat road. The gear ratio increasing speed control means 82 for setting the duty ratio R _DUTY2 of the second speed control solenoid valve DS2 so that the speed ratio increasing speed (the increasing speed of the speed ratio γ) is slower than when the speed ratio is given, and Shift control means 84 for controlling the second shift control solenoid valve DS2 on the basis of the duty ratio R _{DUTY2 so as} to make the speed ratio increase speed slower than when braking force is applied to a vehicle running on a flat road; Therefore, when the vehicle is traveling on a downhill road, an increase in the rotation of the engine 12 due to a decrease in the vehicle speed V during braking is suppressed as compared to when traveling on a flat road, and the oil suction amount of the oil pump 40 is reduced. As a result, the oil level is prevented from lowering, and as in the first embodiment, the air suction of the oil pump 40 can be suppressed while the oil storage amount is reduced as much as possible.

Further, according to the electronic control unit 80 of the present embodiment, the speed change control means 84 is the predetermined value T in which the oil temperature T _OIL of the hydraulic oil in the continuously variable transmission 18 is preset in the speed ratio increase speed control means 82. _When it is determined that it is _OIL 1 or less, the transmission ratio increase speed (increase speed of the transmission ratio γ) is made slower than when braking force is applied to a vehicle traveling on a flat road. In a state where the viscosity of the hydraulic oil circulating to the 18 oil reservoirs is high and the hydraulic oil supplied to each lubrication unit is difficult to return to the oil reservoirs, the oil suction amount of the oil pump 40 is reduced and the oil level is lowered. Therefore, the air suction of the oil pump 40 can be suitably suppressed while reducing the oil storage amount as much as possible.

  As mentioned above, although one Example of this invention was described in detail with reference to drawings, this invention is not limited to this Example, It can implement in another aspect.

  For example, the first shift control solenoid valve DS1 and the second shift control solenoid valve DS2 may be other valves such as a linear solenoid valve.

  The belt clamping pressure control solenoid valve SLS may be another valve such as a duty solenoid valve.

Further, the gear ratio increase speed control means 78 may calculate the actual acceleration _GACT based on a signal from the acceleration sensor 72, for example.

Further, although the gear ratio increasing speed control means 78 calculates the correction coefficient M _RATIO from the correction coefficient map as shown in FIG. 7, it may be calculated by, for example, a calculation formula.

Further, the correction coefficient M _RATIO is determined in advance so that the speed ratio increasing speed becomes slower as the slope θ of the downhill road becomes larger, and the speed ratio increasing speed becomes slower as the braking force applied to the vehicle becomes larger. However, it is not limited to this. For example, the correction coefficient M _RATIO may be set so that the speed ratio increasing speed becomes slower as the slope θ of the downhill road becomes larger, or the speed ratio increasing speed becomes slower as the braking force applied to the vehicle becomes larger. Alternatively, it may be set to a predetermined constant value so that the speed ratio increase speed becomes slow regardless of the slope θ of the downhill road and the braking force applied to the vehicle.

  In addition to the belt-type continuously variable transmission 18, for example, another continuously variable transmission such as a toroidal type may be provided.

  Further, the vehicle power transmission device 10 is not limited to the one used for the FF type vehicle, and may be used for other driving type vehicles.

  The oil pump 40 is driven by the engine 12, but may be an electric pump driven by a motor or an electromagnetic pump driven by a solenoid.

  It should be noted that the above description is merely an embodiment, and other examples are not illustrated. However, the present invention is implemented in variously modified and improved modes based on the knowledge of those skilled in the art without departing from the gist of the present invention. Can do.

12: Engine (drive source)
18: Vehicle continuously variable transmission 34: input shaft 40: oil pump 46: output shaft 48: primary pulley (variable groove width pulley)
54, 80: Electronic control unit 50: Secondary pulley (variable groove width pulley)
52: Transmission belt T _OIL : Hydraulic oil temperature T _OIL 1: Predetermined value V: Vehicle speed γ: Gear ratio θ: Downhill slope

Claims (6)

A control device for a continuously variable transmission for a vehicle that includes an oil pump and increases a gear ratio as the vehicle speed decreases.
When a braking force is applied to the vehicle traveling on a downhill road, a shift speed control is performed to make the speed ratio increase speed slower than when a braking force is applied to the vehicle traveling on a flat road. A control device for a continuously variable transmission for a vehicle.   2. The control device for a continuously variable transmission for a vehicle according to claim 1, wherein, in the shift speed control, the speed ratio increase speed is decreased as the gradient of the downhill road increases.   3. The control device for a continuously variable transmission for a vehicle according to claim 1 or 2, wherein in the shift speed control, the speed ratio increasing speed is decreased as the braking force increases.   The vehicle continuously variable transmission according to any one of claims 1 to 3, wherein the shift speed control is performed when a temperature of hydraulic oil in the continuously variable transmission for the vehicle is equal to or lower than a predetermined value set in advance. Control device.   The continuously variable transmission for a vehicle includes an input shaft and an output shaft provided in parallel to each other, a pair of groove width variable pulleys fixed to the input shaft and the output shaft, and V of the pair of groove width variable pulleys. A belt-type continuously variable transmission that includes a transmission belt wound around each of the grooves and continuously changes the speed ratio by changing a groove width of the transmission belt by changing a groove width of the V-groove. 5. The control device for a continuously variable transmission for a vehicle according to any one of claims 1 to 4.   The control device for a continuously variable transmission for a vehicle according to any one of claims 1 to 5, wherein the oil pump is driven by a drive source of the vehicle.

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