JP2002181177A - Variable speed controller for belt-type continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission controller capable of preventing both the slipping of a belt of a belt-type continuously variable transmission, and the impairing of the driving force. SOLUTION: This gear change controller having a belt wound over a driving- side pulley of a variable groove width and a driven-side pulley, changes speed by changing the groove width of the driving-side pulley by a hydraulic actuator. A most reduced speed determining means for determining whether a change gear ratio is in a most reduced speed condition or not (step S3), and a control means for controlling the hydraulic fluid supplied to and discharged from the hydraulic actuator of the driving-side pulley to produce a slow speed up-shift when the change ratio is judged to be not in the most reduced speed condition under a low speed condition of less than a predetermined car speed, and controlling the hydraulic fluid thereof to keep the change speed ratio in the most reduced speed condition when the change ratio in the maximum decelerating condition is judged, in the above low speed condition (step S6, S7).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling a speed change in a belt-type continuously variable transmission capable of continuously changing a speed ratio, and more particularly to a device for controlling a speed change at a low vehicle speed. It concerns the device.

[0002]

2. Description of the Related Art In a belt-type continuously variable transmission, a belt is wound around an input pulley and an output pulley provided with a V-shaped pulley groove, and the width of the pulley groove of one pulley is enlarged while the other is simultaneously enlarged. By reducing the width of the pulley groove of the pulley,
The speed ratio is set steplessly by continuously changing the winding radius (effective diameter) of the belt with respect to each pulley. The torque transmitted in the belt-type continuously variable transmission is a torque corresponding to a load acting in a direction in which the belt and the pulley are brought into contact with each other, and therefore, the belt is pinched by the pulley so as to apply tension to the belt. I have.

Further, as described above, the speed change is performed by enlarging / reducing the width of the pulley groove. Specifically, each pulley is constituted by a fixed sheave and a movable sheave. The shift is performed by moving the movable sheave back and forth in the axial direction by a hydraulic actuator provided on the back side thereof.

As described above, in the belt-type continuously variable transmission, the belt is pinched by the pulley to apply tension to the belt, and the state of pinching of the belt by the pulley is changed to execute the shift. Therefore, conventionally, as described in, for example, JP-A-10-259865, a hydraulic pressure corresponding to a required torque represented by an engine load or the like is supplied to a hydraulic actuator on the output pulley side to perform necessary transmission. The torque capacity is ensured, and a hydraulic pressure for shifting is supplied to the hydraulic actuator on the input pulley side so that the groove width of the input pulley is changed and at the same time the groove width of the output pulley is changed.

[0005] Shifting for changing the belt wrapping position with respect to each pulley is executed in a state where each pulley is rotating and the belt is running. However, in a state where the pulley and the belt are stopped, the speed of the belt is changed. It is not possible to change the belt wrapping position without slipping, that is, to perform gear shifting. Therefore, in the case of a continuously variable transmission mounted on a vehicle, if the vehicle suddenly stops, the continuously variable transmission stops due to the stop of the vehicle. In some cases, the continuously variable transmission stops before changing to the belt wrapping state that sets the gear ratio in the maximum deceleration state, and the speed ratio remains lower than the gear ratio set at the start. The so-called belt return is defective.

When the vehicle is started in such a state in which the belt returns poorly, the gear ratio to be set is in the maximum deceleration state. Therefore, the gear ratio is rapidly changed to the maximum deceleration state by feedback control of the gear ratio. Occurs. this is,
In the continuously variable transmission having the above-described configuration, the speed is performed by rapidly increasing the groove width of the input pulley, so that the belt may be loosened, which may cause slippage between the belt and the pulley. is there.

On the other hand, in the continuously variable transmission described in the above-mentioned publication, hydraulic oil is supplied to a hydraulic actuator on the input pulley side for executing a gear shift while increasing the speed to a predetermined vehicle speed, thereby reducing the speed. Control is performed so that an upshift occurs.
This is to prevent a time required for the oil to be filled from the hydraulic actuator on the input pulley side with oil during a subsequent upshift, resulting in a shift delay. If such a slow upshift control in the low vehicle speed state is performed in the state of the so-called belt return failure, a rapid downshift at the time of starting due to the feedback control of the gear ratio does not occur.
It is possible to prevent loosening of the belt and slippage caused by the loosening.

[0008]

However, since the control for causing the above-described slow upshift is continued while the vehicle speed increases to the predetermined vehicle speed, the control is not performed at a low vehicle speed below the predetermined vehicle speed. When the vehicle travels for a long time, the speed ratio gradually decreases due to the slow upshift control during that time.
As a result, there is a possibility that the upshift amount as a whole becomes large and the driving torque is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above technical problem, and provides a transmission control device capable of preventing a belt from slipping and a reduction in driving force in a belt-type continuously variable transmission. It is intended to do so.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for controlling a slow upshift in a low vehicle speed state in a state in which a substantial downshift occurs. It is characterized in that it is configured to be executed or not to be executed. Specifically, the invention according to claim 1 is configured such that a belt is wound around a driving pulley and a driven pulley which can change a groove width of a belt winding groove by a hydraulic actuator, and the groove width of the driving pulley is reduced by the hydraulic pressure. In a shift control device for a belt-type continuously variable transmission that changes gears by changing an actuator, a maximum deceleration determining unit that determines whether a gear ratio is in a maximum deceleration state, and a low vehicle speed state that is equal to or less than a predetermined vehicle speed. When the speed ratio is not in the maximum deceleration state by the maximum deceleration determining means, control the hydraulic oil supplied to and discharged from the hydraulic actuator of the driving pulley so that a slow upshift occurs. When the speed reduction ratio is determined to be in the maximum deceleration state in the low vehicle speed state by the maximum deceleration determining means, the driving pulley is maintained so as to maintain the speed ratio in the maximum deceleration state. It is the shift control device according to claim which includes a control means for controlling the hydraulic oil supply and discharge to the hydraulic actuator.

Therefore, in the first aspect of the present invention, when it is determined that the speed ratio is not at the maximum deceleration state in the low vehicle speed state, the shift control is performed so that a slow upshift occurs. Therefore, even at a vehicle speed as low as the maximum deceleration state is set, no downshift occurs, that is, the effective diameter of the driving pulley does not decrease, so that belt slippage is avoided. Further, when it is determined that the vehicle is in the maximum deceleration state in the low vehicle speed state, the speed is controlled so as to maintain the maximum deceleration state, and the gear ratio does not decrease. Accordingly, no slippage of the belt occurs, and no upshift control for reducing the speed ratio is performed, so that a reduction in the speed ratio and a resulting reduction in driving force are avoided.

Further, according to a second aspect of the present invention, in the first aspect of the present invention, there is further provided a rotational speed detecting means for detecting a rotational speed of the driving pulley, wherein the control means is detected by the rotational speed detecting means. Further, when the rotation speed of the drive pulley is a low speed equal to or lower than a predetermined rotation speed, even if the speed reduction ratio is determined to be in the maximum deceleration state by the maximum deceleration determining means, A shift control device configured to control hydraulic oil supplied to and discharged from a hydraulic actuator of the drive pulley so that an upshift occurs.

Therefore, according to the second aspect of the present invention, if the operating oil in the hydraulic actuator of the driving pulley for executing the shift is easily discharged due to the low rotation speed of the driving pulley, the operating speed is increased slowly. The hydraulic oil is controlled so that a shift occurs. Specifically, hydraulic oil is supplied to the hydraulic actuator of the driving pulley. As a result, oil remains in the hydraulic actuator of the driving pulley, so that a delay in upshifting when hydraulic oil is supplied to the hydraulic actuator of the driving pulley for upshifting can be prevented or suppressed, and operability is improved.

Further, according to a third aspect of the present invention, in the second aspect of the present invention, there is further provided an input torque determining means for determining a magnitude of an input torque to the continuously variable transmission, and the control means is configured to determine that the speed ratio is the highest. If the input torque determining unit determines that the input torque is large when the maximum deceleration determining unit determines that the vehicle is in a deceleration state, the transmission gear ratio is determined regardless of the rotation speed of the driving pulley. A shift control device configured to control hydraulic oil supplied to and discharged from a hydraulic actuator of the drive-side pulley so as to maintain a maximum deceleration state.

Therefore, according to the third aspect of the present invention, when the input torque to the continuously variable transmission is large, the shift control is performed so that the speed ratio is in the maximum deceleration state. If each pulley rotates slightly due to the low rotation speed of the driving pulley, only a very small speed change will occur.However, if rotation occurs due to twisting of the power transmission system due to large input torque, etc. A shift may occur due to a change in the position at which the belt is engaged. However, since the shift control is a control for maintaining the maximum deceleration state, an upshift and a reduction in the gear ratio accompanying the shift are prevented.

[0016] Further, the invention of claim 4 is the invention of claim 1
The control means in any one of (3) to (3) controls the hydraulic oil supplied / discharged to / from the hydraulic actuator of the drive pulley so as to maintain the speed ratio in the maximum deceleration state so that a slow downshift occurs. A shift control device configured to be executed by feedforward control.

Therefore, according to the fourth aspect of the present invention, the downshift control is executed in a state where the gear ratio is in the maximum deceleration state, so that the gear ratio does not further increase. It is possible to reliably prevent the reduction and the reduction of the driving force due to the reduction.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the vehicle further comprises deceleration determining means for determining a deceleration, wherein the control means controls the speed change by the maximum deceleration determining means. When it is determined that the ratio is not in the maximum deceleration state, hydraulic oil is supplied / discharged to / from the hydraulic actuator of the drive pulley so that a slow upshift occurs at a vehicle speed equal to or lower than a predetermined reference vehicle speed. A shift control device for performing control and setting a reference vehicle speed to a higher vehicle speed when the deceleration determined by the deceleration determining means is higher than when the deceleration is lower.

Therefore, according to the fifth aspect of the present invention, the shift control is performed such that when the deceleration is large, the slow upshift occurs at a higher vehicle speed than when the deceleration is small. The greater the deceleration, the faster the downshift occurs, and the more likely the belt slips. Further, the lower the vehicle speed, the more easily the belt slips. Therefore, when the deceleration is large, the speed ratio is maintained at a speed lower than the most decelerated state while the vehicle speed is relatively high, or the speed ratio is shifted up slowly from the speed ratio. As a result, the belt slippage is prevented beforehand, and in a state where the deceleration is small and the belt slippage is unlikely to occur, the control in which a slow upshift is performed to a relatively low vehicle speed is not started. As a result, the return of the belt becomes good.

Further, the invention of claim 6 is the invention of claim 1
In any one of the above inventions, the speed reduction ratio determined from the rotation speed corresponding to the rotation speed of the driving pulley and the rotation speed corresponding to the rotation speed of the driven pulley may be a predetermined speed ratio. And the shift control is configured to determine that the speed ratio has reached the maximum deceleration state when the state in which the downshift speed is equal to or higher than the predetermined speed continues for a predetermined time period. Device.

Therefore, in the sixth aspect of the present invention, when the speed change ratio is greater than a predetermined value and the downshift control is continued at a certain speed or more and a predetermined time or more from that state, the maximum deceleration state is set. Is determined. For this reason, instead of detecting the maximum deceleration state by calculation that easily causes errors due to rotation speed detection errors and individual differences between products,
The maximum deceleration state can be accurately determined.

Still further, according to the invention of claim 7, the invention of claim 6
The invention according to claim 1, further comprising an input rotation speed sensor that outputs a pulse signal according to the rotation speed of the driving pulley, and an output rotation speed sensor that outputs a pulse signal according to the rotation speed of the driven pulley, The deceleration determining means calculates the number of pulses used to calculate the rotation speed corresponding to the rotation speed of the driving pulley and the rotation speed corresponding to the rotation speed of the driven pulley when calculating the speed change ratio. And the number of pulses to be used in accordance with the gear ratio.

Therefore, in the present invention, a rotation speed corresponding to the rotation speed of the driving pulley and a rotation speed corresponding to the rotation speed of the driven pulley are calculated based on the pulse signal. As the gear ratio increases, the rotation speed corresponding to the rotation speed of the driving pulley becomes faster than the rotation speed corresponding to the rotation speed of the driven pulley. Conversely, if the gear ratio is small, the rotation speed of the driving pulley decreases. The corresponding rotation speed is
The rotation speed is lower than the rotation speed corresponding to the rotation speed of the driven pulley. As described above, since the relative rotational speeds of the drive side and the driven side greatly differ depending on the gear ratio, if the number of pulses used for calculating the gear ratio is the same, the responsiveness of the rotational speed detection will be lower than the drive side. And the driven side will be different. According to the seventh aspect of the present invention, the number of pulses used for calculating the number of revolutions is changed in accordance with the gear ratio to approximate or equalize the responsiveness of detecting the number of revolutions on the drive side and the driven side. And the gear ratio can be determined with high accuracy.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on specific examples. First, an example of a power transmission system of a vehicle equipped with a transmission according to the present invention will be described. In FIG. 5, a power source 1 is connected to a transmission mechanism 2 and an output shaft 3 of the transmission mechanism 2 is connected to a differential 4. Are connected to the left and right drive wheels 5 through the rim. Here, the power source 1 includes various power sources that can be used for a vehicle, such as an internal combustion engine such as a gasoline engine or a diesel engine, or an electric motor such as a motor, or a device combining the internal combustion engine and the electric motor. In the following description, a so-called direct-injection gasoline engine capable of performing homogeneous combustion or stratified combustion by controlling the amount and timing of injection of fuel directly as a power source 1, An example in which a gasoline engine equipped with an electronic throttle valve that can be freely controlled will be described.

The engine 1 is configured to be electrically controllable, and is provided with an electronic control unit (E-ECU) 6 mainly composed of a microcomputer for the control. The electronic control unit 6 is configured to control at least the output of the engine 1, and the output shaft speed (engine speed) as data for the control.
NE and the required output amount such as the accelerator opening PA are input.

The required output is a signal for increasing / decreasing the output of the engine 1. The required output is a signal representing an operation amount of an acceleration / deceleration operation device 7 such as an accelerator pedal operated by a driver or an operation amount thereof. A signal obtained by electronically processing can be adopted, and in addition to that, an output demand signal from a cruise control system (not shown) for maintaining the vehicle speed at a set vehicle speed is included.

The transmission mechanism 2 includes a fluid transmission mechanism 8,
It comprises a forward / reverse switching mechanism 9 and a continuously variable transmission (CVT) 10. The fluid transmission mechanism 8 is a device configured to transmit torque between an input-side member and an output-side member via a fluid such as oil, and as an example, a general vehicle And the torque converter employed in the above. In addition, the fluid transmission mechanism 8
Has a direct connection clutch 11. That is, the direct connection clutch 11 is a clutch configured to directly connect the input side member and the output side member by mechanical means such as a friction plate, and is formed of an elastic body such as a coil spring for buffering. The damper 12 is provided.

A hydraulic pump, which is rotated by the engine 1 as a power source and whose discharge pressure increases in accordance with the number of revolutions, is provided at a position close to the fluid transmission mechanism 8. Specifically, it is disposed between the fluid transmission mechanism 8 and the forward / reverse switching mechanism 9. When the fluid transmission mechanism 8 is provided to keep the engine 1 running even when the vehicle is stopped, the automatic clutch that is automatically switched on and off based on the state of the vehicle is provided with the above-described automatic clutch. Can be used in place of the fluid transmission mechanism 8 described above.

The input member of the fluid transmission mechanism 8 is connected to the output member of the engine 1, and the output member of the fluid transmission mechanism 8 is connected to the input member of the forward / reverse switching mechanism 9. The forward / reverse switching mechanism 9 is constituted by, for example, a double pinion type planetary gear mechanism. Although not particularly shown, one of a sun gear and a carrier is used as an input element, and the other is used as an output element, and a ring gear is used. Brake means for selectively fixing, and clutch means for selectively connecting any two of the three elements of the sun gear, the carrier, and the link gear to integrate the entire planetary gear mechanism are provided. . That is, a forward state is set by engaging the clutch means, and a reverse state is set by engaging the brake means.

The continuously variable transmission 10 shown in FIG. 5 continuously (continuously) changes the ratio of the number of rotations of the input side member to the number of rotations of the output side member, that is, the gear ratio. It is a belt-type continuously variable transmission that can be used. An example of the belt type continuously variable transmission 10 will be briefly described with reference to FIG.
A driving pulley (primary pulley) 20, a driven pulley (secondary pulley) 21, and these pulleys 2
0, 21 and a belt 22 wound therearound.
Each of these pulleys 20 and 21 is provided with a fixed sheave 2
Approaching the fixed sheaves 23, 24
Hydraulic actuators 27 and 28 are provided, which are separated from the movable sheaves 25 and 26 and press the movable sheaves 25 and 26 in a direction approaching the fixed sheaves 23 and 24. These sheaves 23, 24, 25, 26 form a V-shaped belt winding groove (pulley groove) for winding the belt 22.

The drive pulley 20 is mounted on an input shaft 29, and a driven pulley 21 is mounted on an output shaft 30 arranged parallel to the input shaft 29. Then, the hydraulic actuator 28 in the driven pulley 21
Is supplied with a hydraulic pressure corresponding to a required driving force obtained based on an output request represented by the accelerator pedal opening PA, and presses the movable sheave 26 toward the fixed sheave 24 to pinch the belt 22, thereby reducing the torque. Is applied to the belt 22 to transmit the tension. Hydraulic oil is supplied to and discharged from the hydraulic actuator 27 of the drive pulley 20 so that the speed ratio of the input shaft 29 matches the target input speed. That is, by changing the groove width (the distance between the fixed sheaves 23, 24 and the movable sheaves 25, 26) in each of the pulleys 20, 21, the winding radius of the belt 22 around each of the pulleys 20, 21 changes to be large or small. A shift is performed. More specifically, the driving pulley 20 is controlled based on a rotational speed deviation (control deviation) between the actual input rotational speed and the target input rotational speed.
The shift is executed by feedback-controlling the hydraulic oil of the second gear. Therefore, the greater the control deviation, the faster the shift speed.

The supply and discharge of the working oil to and from the drive pulley 20 are performed by flow rate control. The valve mechanism for that is configured as shown in FIG. That is,
A first flow control valve 31 for supplying the line pressure PL and a second flow control valve 32 connected to the drain are connected to the hydraulic actuator 27 of the driving pulley 20. The first flow control valve 31 is a valve for executing an upshift, and is an input port 3 to which the line pressure PL is supplied.
A passage between the output port 3 and the output port 34 connected to the hydraulic actuator 27 is opened and closed by a spool 35. A spring 36 is disposed at one end of the spool 35 and the spool 35
A first signal pressure port 37 for applying a signal pressure is formed at the end opposite to the spring 36 with the. In addition, a second signal pressure port 38 for applying a signal pressure is formed at the one end where the spring 36 is disposed.

A first solenoid valve 39 whose output pressure increases according to the duty ratio is connected to the first signal pressure port 37, and the output pressure increases according to the duty ratio to the second signal pressure port 38. The second solenoid valve 40 is connected, and the signal pressure output from these solenoid valves 39 and 40 is applied to each signal pressure port 37 and 38. That is, the hydraulic pressure applied to the first signal pressure port 37 is increased,
Is opened, hydraulic oil is supplied from the output port 34 to the hydraulic actuator 27 of the driving pulley 20, and the groove width of the driving pulley 20 is reduced, and as a result, the gear ratio is reduced. That is, it is upshifted. Further, by increasing the supply flow rate of the working oil at that time, the shift speed is increased.

The second flow control valve 32 is a valve for executing a downshift. The second flow control valve 32 controls the first port 41 connected to the hydraulic actuator 27 of the drive side pulley 20 to the original pressure of the line pressure PL. The second port 42 and the drain port 43 to which the adjusted hydraulic pressure is supplied are selectively connected by a spool 44. A spring 45 is disposed at one end of the spool 44, and a first signal pressure port 46 for applying a signal pressure is formed at one end thereof. At the end opposite to the spring 45 across the spool 44,
A second signal pressure port 47 for applying a signal pressure is formed.

The first signal pressure port 46 is connected to the first signal pressure port 46.
The solenoid valve 39 is connected, and the second signal pressure port 47 is connected to the second solenoid valve 40. The signal pressure output from these solenoid valves 39, 40 is applied to each signal pressure port 46, 47. It is supposed to be. That is, by increasing the hydraulic pressure applied to the second signal pressure port 47 to make the first port 41 communicate with the drain port 43, the hydraulic oil is discharged from the hydraulic actuator 27 of the drive side pulley 20 and the drive side pulley 20 Are widened, and as a result, the gear ratio is increased. That is, it is downshifted. Further, by increasing the discharge flow rate of the working oil at that time, the speed change speed is increased.

Further, a pressure regulating valve 48 is connected to the second port 42 of the second flow control valve 32. This pressure regulating valve 4
An input port 51 to which the line pressure PL is supplied is formed on the front side of the piston 50 pressed by the spring 49, and an output port 52 communicating with the front side and the back side of the piston 50 is formed. The output port 52 of which is connected to the second port 42 of the second flow control valve 32. The input port 51 is supplied with a line pressure PL via a double orifice 53 having a small opening area. In other words, the pressure regulating valve 48 has an output port 52, that is, the second flow control valve 3 having a pressure equal to the line pressure PL reduced by the elastic force of the spring 49.
2 is formed at the second port 42.

More specifically, when the first port 41 and the second port 42 of the second flow control valve 32 are communicated with the input port 33 of the first flow control valve 31 closed, Hydraulic oil adjusted by the pressure adjusting valve 48 is supplied to the second port 4
2 through the hydraulic actuator 27 of the drive pulley 20
Supplied to The flow rate in that case is double orifice 53
Is a very small amount. As a result, the hydraulic pressure of the hydraulic actuator 27 increases, but since the hydraulic pressure of the hydraulic actuator 27 acts on the back side of the piston 50 in the pressure regulating valve 48, the pressure reduces the elastic force of the spring 49 from the line pressure PL. When pressure is reached, the piston 50
Is pressed to the input port 51 side to close the input port 51 and prevent the supply of the hydraulic oil any more. Therefore, in a so-called closed state in which hydraulic oil is not supplied from the first flow control port 31 to the hydraulic actuator 27 and is not discharged from the second flow control valve 32, the hydraulic pressure of the hydraulic actuator 27 of the driving pulley 20 is reduced. , Hydraulic pressure regulated by pressure regulating valve 48 (pressure lower than line pressure PL)
Is to be maintained.

Such a state of maintaining the hydraulic pressure is the same when an unavoidable oil leak occurs during the closing control. Oil leaks from a hydraulic circuit or a hydraulic control device, and the hydraulic actuator 27 When the hydraulic pressure of the pressure control valve 48 decreases, hydraulic oil is supplied little by little to the hydraulic actuator 27 from the input port 51 of the pressure control valve 48, and the pressure control value by the pressure control valve 48 is maintained. As a result, the state of the gear shift is a slight upshift tendency, and the gear ratio is a slow upshift in which the gear ratio gradually decreases.

The belt type continuously variable transmission 10 shown in FIG.
In this case, the winding radius of the belt 22 around the driving pulley 20 is the smallest and the belt 22 around the driven pulley 21
When the winding radius of the belt 22 is maximum, the speed ratio (maximum speed ratio) γmax on the lowest speed side is set. On the contrary, the winding radius of the belt 22 around the driving pulley 20 is maximum and The speed ratio (minimum speed ratio) γmin on the highest speed side is set in a state where the winding radius of the belt 22 around the pulley 21 is minimum.

The direct coupling clutch 1 in the above-described transmission mechanism 2
Basically, control of each state of engagement / disengagement and half-engagement involving slipping, switching of forward / reverse by the forward / reverse switching mechanism 9 and control of the speed ratio by the continuously variable transmission 10 are basically performed by the vehicle. Is controlled based on the running state of the vehicle.
For the control, an electronic control unit (T-ECU) 13 mainly composed of a microcomputer is provided.

The electronic control unit 13 is communicably connected to the electronic control unit 6 for the engine described above, while the vehicle speed SPD and the speed change mechanism 2 are used as control data.
, Such as the input rotation speed Nin and the output rotation speed Nout. The rotation speed sensor 60 is used to control the speed of the continuously variable transmission 10 so that the drive-side pulley 20 is controlled.
And a sensor for detecting the rotational speed of the driven pulley 21 and the like. As an example, when the teeth (each not shown) of the pulse gear pass through the tip side of the electromagnetic pickup,
A pulse signal is generated in the electromagnetic pickup, and the input rotation speed Nin and the output rotation speed Nout are obtained based on the interval and pulse width of the pulse signal. In such a type of rotational speed sensor 60, the minimum detectable rotational speed is several tens of rpm.

Further, the transmission mechanism 2 is stopped (parking position: P), and the reverse movement state (reverse position: P).
R), a neutral state (neutral position: N), an automatic forward state in which the gear ratio is automatically set in accordance with the running state of the vehicle to perform normal running (drive position:
D), a shift for selecting each state (position) of a state in which the pumping loss of the engine 1 is used as a braking force (brake position: B) and a state in which setting of a speed ratio on the high-speed side equal to or more than a predetermined value is prohibited (SD position) A device 14 is provided, which is electrically connected to the electronic control unit 13.

Also in the above-described continuously variable transmission 10, if the vehicle is suddenly stopped in a state where the vehicle is traveling with a relatively high vehicle speed ratio set, the continuously variable transmission 1 will be moved before the speed ratio returns to the maximum speed ratio.
The rotation of zero may stop. In this state,
Since the groove width of the driving pulley 20 is not widened to the maximum, when the hydraulic oil is discharged from the hydraulic actuator 27 in the driving pulley 20 in order to set the maximum speed ratio (the maximum deceleration state) at the time of starting, the driving pulley 20 Since the winding radius of the belt 22 with respect to the belt 22 becomes small, the belt 22 may loosen and slip.

The control device according to the present invention for the above-described belt-type continuously variable transmission 10 has the following functions in a low vehicle speed state equal to or lower than a predetermined vehicle speed Va in order to prevent slippage of the belt and a decrease in driving force. The shift control described in FIG. FIG. 1 is a flowchart showing an example of the control. First, it is determined whether or not the maximum deceleration command has been output (step S1). The gear ratio set by the continuously variable transmission 10 is basically determined based on the running state of the vehicle, such as the vehicle speed and the accelerator opening, or the required output, and the like. Since it is necessary to maintain the above, in a low vehicle speed state below a predetermined vehicle speed, a shift command is output so as to uniformly set the maximum deceleration state (largest gear ratio). Therefore, step S1 can be replaced with a step of determining whether the vehicle speed is equal to or lower than a predetermined vehicle speed. Also, this judgment
The determination can be made based on the output state of the shift signal from the electronic control unit 13 for the transmission mechanism 2 described above.

If a negative determination is made in step S1, normal control is executed as shift control (step S2). That is, the gear ratio is feedback-controlled based on the rotational speed deviation between the target input rotational speed and the actual input rotational speed.

Conversely, if the determination in step S1 is affirmative, that is, if the maximum deceleration command has been output, it is determined whether the gear ratio is in the maximum deceleration state (step S1). S3). That is, it is determined whether the position where the belt 22 is engaged with the pulleys 20 and 21 is the maximum deceleration position.

The speed ratio set by the continuously variable transmission 10 is basically determined by detecting the rotation speed of the driving pulley 20 and the rotation speed of the driven pulley 21 by the above-described rotation speed sensor 60. Although it is obtained by calculation based on the result, in a state where the number of rotations is low, the detection accuracy of the number of rotations by the rotation number sensor 60 is low. An error may occur in the calculation. Therefore, the control device according to the present invention determines the maximum deceleration state as described below.

FIG. 2 shows an example of the control flowchart. First, it is determined whether or not the speed ratio calculated from the detected rotational speed is larger than a predetermined speed ratio γ1 (step S1). S201). The speed ratio γ1 serving as the reference for this determination is a speed ratio slightly smaller than the speed ratio in the most decelerated state.

If the determination in step S201 is affirmative, it is determined whether a command signal for downshifting has been output (step S202). If the determination in step S202 is affirmative, it is determined whether or not the shift speed command value indicating the shift speed of the downshift is greater than a predetermined reference value Δγ0 (step S203).

If the determination in step S203 is affirmative, whether or not the elapsed time from the time when the speed ratio becomes larger than the speed ratio γ1 determined in step S201 exceeds a predetermined reference time τ0. Is determined (step S204). The reference time τ0 is set in advance based on the time from the gear ratio γ1 to reach the maximum deceleration state when the shift speed is a downshift greater than the reference value Δγ0. Therefore, its reference time τ0
Is determined, it is determined that the speed ratio has reached the maximum deceleration state (step S205).

Each of the above determination steps S201, S20
If a negative determination is made in any of steps S2, S203, and S204, it is not determined that the vehicle is in the maximum deceleration state (step S2).
206).

Therefore, when the determination of the maximum deceleration state shown in FIG. 2 is performed, the maximum deceleration state is determined not only by the calculation based on the detected rotational speed including the error but also by taking the situation of the downshift into account. Therefore, the maximum deceleration state can be accurately determined.

In step S201, the speed ratio calculated from the detected rotation speed (rotation speed) is used. Since the rotation speed is detected based on the pulse signal as described above, the driving pulley 20 or In order to improve the detection accuracy by matching the detection response of the rotation speed corresponding to this and the detection response of the rotation speed of the driven pulley 21, the control device according to the present invention rotates the rotation as shown in FIG. Calculate the number.

The example shown in FIG. 3 is an example in which the number of pulse signals used for calculating the rotational speed is changed in accordance with the speed ratio. It is determined whether the ratio is greater than a predetermined first reference speed ratio γ10 (step S301). If a negative determination is made in step S301, the speed ratio calculated from the rotational speed at that time is the second reference speed ratio γ11 smaller than the first reference speed ratio γ10.
(<Γ10) is determined (step S)
302). That is, the gear ratio is greater than the first reference gear ratio γ10, a gear ratio between the first reference gear ratio γ10 and the second reference gear ratio γ11, or the second reference gear ratio γ11
A determination is made as to whether the gear ratio is smaller.

Since the gear ratio is large, step S3 is executed.
01, the driving pulley 20
A predetermined number Np1 of pulse signals is used as a pulse number used to calculate an input rotation speed Nin corresponding to the rotation speed of the driven pulley 21, and an output rotation speed Nout corresponding to the rotation speed of the driven pulley 21 is calculated. A predetermined number Np2 (<Np1) of pulse signals is used as the number of pulses to be used (step S303).

Further, when the speed ratio is set to the above-mentioned reference speed ratio γ10,
If the answer is affirmative in step S302 due to being within γ11, a predetermined number Np3 of pulse signals is used as the number of pulses used to calculate the input rotation speed Nin corresponding to the rotation speed of the driving pulley 20. Is used, and a predetermined number Np4 of pulse signals is used as the number of pulses used to calculate the output rotation speed Nout corresponding to the rotation speed of the driven pulley 21 (step S304). here,
If Np1 = Np3, Np2 <Np4 is set, or if Np1> Np3, Np2 = Np4 or Np2 <Np4.

Further, when the speed ratio is small and the result of the determination in step S302 is negative, the predetermined number of pulses used for calculating the input rotation speed Nin corresponding to the rotation speed of the driving pulley 20 is set. The pulse signal of the number Np5 is used, and the pulse signal of the predetermined number Np6 is used as the pulse number used for calculating the output rotation speed Nout corresponding to the rotation speed of the driven pulley 21 (step S305). Here, Np5 is set equal to or smaller than Np3 in step S304, and Np6 is set equal to or larger than Np4 in step S304.

After all, according to the method of calculating the rotation speed shown in FIG. 3, when the gear ratio is large, that is, when the rotation speed on the input side is relatively large with respect to the rotation speed on the output side, the rotation speed on the input side is increased. The number of pulses used to calculate the speed is set to a relatively large number with respect to the number of pulses used to calculate the rotation speed on the output side. As a result, the detection time of the pulse signal on the input side and the detection time of the pulse signal on the output side are approximated to each other, and the difference in the response of the detection of the rotational speed is eliminated or suppressed. improves.

The gear ratio and the maximum deceleration state are determined as described above. As a result, if a positive determination is made in step S3 shown in FIG. 1, it is determined whether the input rotation speed Nin is lower than a predetermined reference rotation speed N0 (rpm) (step S4). The reference rotation speed N0 is a considerably low rotation speed in the range of the rotation speed that can be detected by the rotation speed sensor 60 described above.

If the input rotation speed Nin is a low rotation speed, the drive pulley 20 integrated with the input shaft 29 and the hydraulic actuator 27 rotate at a low rotation speed. The acting centrifugal force is reduced, and the oil is easily discharged. Therefore, if the determination is affirmative in step S4, it is determined whether the accelerator opening, which is an example of the engine load, is greater than a predetermined reference opening PA0 (%) (step S4).
5). If the accelerator opening is large, the throttle opening of the engine 1 is large, and the output torque of the engine 1, that is, the input torque of the continuously variable transmission 10 is large. Therefore, in step S5, is the input torque of the continuously variable transmission 10 large? It is determined whether or not.

Since the accelerator opening is large and therefore the input torque of the continuously variable transmission 10 is large, step S5 is performed.
If the answer is affirmative, the speed ratio is feedforward controlled so that a slow downshift occurs (step S6). Specifically, the hydraulic oil is discharged little by little from the hydraulic actuator 27 of the driving pulley 20 by the hydraulic control device shown in FIG. Therefore engine 1
Even if the power transmission system (drive system) generates torsional deformation or the like and the rotation of the continuously variable transmission 10 exceeds a predetermined level due to the large output torque of the power transmission system (drive system), an upshift that reduces the speed ratio does not occur.

On the other hand, if the result of the determination in step S5 is negative due to the small accelerator opening, the shift is restricted (step S7). This is the so-called closing (filling) control described above, in which hydraulic oil slightly exceeding oil leakage in the hydraulic system is supplied to the drive-side pulley 20.
Is supplied to the hydraulic actuator 27 in a slow upshift state. In this state, since the input torque is relatively small, it is unlikely that rotation due to torsion or the like and a shift resulting therefrom will occur. Therefore, even if such a shift limitation is performed, a substantial upshift does not occur. Further, since the hydraulic actuator 27 for performing a shift can be filled with oil, a shift delay at the time of an upshift that occurs afterward can be prevented or suppressed.

If the rotation speed of the driving pulley 20 or the input rotation speed Nin corresponding thereto is a high rotation speed and a negative determination is made in step S4, the process immediately proceeds to step S6. Progressively, a gentle downshift control by the feedforward control is executed. In this case, while the centrifugal force acting on the hydraulic actuator 27 of the driving pulley 20 is large and the oil inside the hydraulic actuator 27 is difficult to escape, if the closing control as in step S7 is executed, an upshift occurs. It is because.

On the other hand, if the determination is negative in step S3 because the vehicle is not in the maximum deceleration state, it is determined whether the deceleration at that time (negative acceleration) is greater than a predetermined reference deceleration α. It is determined whether or not the vehicle has been decelerated more than the reference deceleration α (step S8). If a positive determination is made in step S8 because the deceleration is large, the commanded downshift speed is high and the belt 22
Is likely to occur, and in this case, it is determined whether the vehicle speed is lower than a predetermined first reference vehicle speed V1 (step S9). Here, the vehicle speed is determined because the slip of the belt 22 is more likely to occur as the vehicle speed becomes lower. Therefore, if the determination in step S9 is negative, the vehicle speed is relatively high and the slip of the belt 22 is relatively high. Since it is hardly generated, the process proceeds to step S2 to execute the above-described normal control, that is, the gear ratio control by the feedback control.

On the other hand, if the determination in step S9 is affirmative, the slip of the belt 22 is likely to occur due to the relatively low vehicle speed. Therefore, in this case, the process proceeds to step S7 described above. Then, the shift is limited by the closing control. That is, since the hydraulic oil is controlled so that a slow upshift occurs, the groove width of the drive-side pulley 20 is maintained or gradually narrowed, so that the belt 22 becomes loose and the belt 22 slips due to the loosening. Is prevented.

Further, when the deceleration is equal to or less than the reference deceleration α and the determination in step S8 is negative, the commanded downshift speed is low, so that the belt 22 is less likely to slip. I have. Therefore, in this case, it is determined whether or not the vehicle speed is lower than the second reference vehicle speed V2 having a value lower than the first reference vehicle speed V1 (step S10). If a negative determination is made in step S10, that is, if the vehicle speed has not decreased to the second reference vehicle speed V2, the process proceeds to step S2, and the normal gear ratio control by feedback control is executed. . In this case, the feedback control of the gear ratio is performed at a vehicle speed lower than the first reference vehicle speed V1 and at a vehicle speed equal to or higher than the second reference vehicle speed V2, but the deceleration is relatively small and the commanded downshift speed is low. Therefore, slippage of the belt 22 can be prevented or suppressed.

On the contrary, when the vehicle speed is equal to the second reference vehicle speed V2
When the vehicle speed is lower, and the determination in step S10 is affirmative, the process proceeds to step S7 to execute the shift restriction by the closing control. That is, the hydraulic oil is controlled so that a slow upshift occurs. Even if the commanded downshift is slow, the vehicle speed is considerably reduced, so that the belt 22 tends to slip,
In this state, the control in which the slow upshift is performed by the closing control is executed, so that the slip of the belt 22 is reliably prevented or suppressed.

In the case of executing the control according to the flowchart of FIG. 1 described above, the area of the gentle downshift, the area of the shift restriction, and the area of the normal control are indicated by the vehicle speed and the accelerator opening as parameters. (A) and (B). FIG. 4A shows a step S3.
, Each region when the determination of the maximum deceleration state is established, and the region of the gentle downshift by the feedforward control is set as a region below the predetermined vehicle speed Va. FIG. 4B shows each area when the determination of the maximum deceleration state is not established in step S3. In FIG. 4B, in a range between the first reference vehicle speed V1 and the second reference vehicle speed V2 and in a region where the accelerator opening is as low as the idle opening, the normal control is performed in accordance with the deceleration. Shift restriction control is selected and executed.

Here, the relationship between the above specific example and the present invention will be briefly described. The functional means of step S3 shown in FIG. 1 and the specific control contents of steps S201 to S205 shown in FIG. The functional means corresponds to the maximum deceleration determining means in the present invention. FIG.
The functional means of steps S3 to S10 shown in FIG. 1 correspond to the control means of the present invention. Further, the functional means in step S4 of FIG. 1 corresponds to the rotational speed detecting means in claim 2, and the functional means in step S5 corresponds to the input torque determining means in claim 3. Further, the functional means of step S8 shown in FIG. 1 corresponds to the deceleration determining means in claim 5. On the other hand, the rotation speed sensor 60 shown in FIG. 5 corresponds to the input rotation speed sensor and the output rotation speed sensor in claim 7, and the step S shown in FIG.
The functional units 301 to S305 correspond to the maximum deceleration determining unit in claim 7.

The present invention is not limited to the specific example described above, but is applied to a control device for a belt-type continuously variable transmission that is connected to a power source without passing through a fluid transmission mechanism 8 such as a torque converter. be able to. Further, the present invention can be applied to a control device for controlling a continuously variable transmission of a vehicle using a motor as a power source. Therefore, the forward / reverse switching mechanism 9 shown in FIG. 5 may not be provided. Further, the hydraulic control device for controlling the tension and the gear ratio of the belt 22 includes:
The invention is not limited to the one provided with the hydraulic circuit having the configuration shown in FIG.

[0071]

As described above, according to the first aspect of the present invention, when it is determined that the vehicle is in the low vehicle speed state and the speed ratio is not in the maximum deceleration state, a slow upshift is performed. Since shift control is performed, even at a vehicle speed as low as the maximum deceleration state is set, downshifting does not occur, that is, the effective diameter of the driving pulley does not decrease, so that belt slippage is prevented or suppressed beforehand. Can also
When it is determined that the vehicle is in the maximum deceleration state in the low vehicle speed state, the speed is controlled so as to maintain the maximum deceleration state, and the speed ratio does not decrease, so that belt slippage can be prevented or suppressed, and Since the upshift control for reducing the speed ratio is not performed, it is possible to avoid a reduction in the speed ratio and a reduction in the driving force due to the reduction.

According to the second aspect of the present invention, if the operating oil in the hydraulic actuator of the driving pulley for executing the shift is easily discharged due to the low rotation speed of the driving pulley, the operating oil is slowly released. Hydraulic oil is supplied so that a speed upshift occurs, and oil remains in the hydraulic actuator of the driving pulley, so that the upshift when supplying hydraulic oil to the hydraulic actuator of the driving pulley to upshift is delayed. Can be prevented or suppressed,
As a result, drivability can be improved.

Further, according to the third aspect of the present invention, when there is a possibility that rotation may occur due to torsion of the power transmission system due to a large input torque, control is performed so as to maintain the maximum deceleration state. Therefore, an upshift can be reliably prevented.

Further, according to the fourth aspect of the present invention, the downshift control is executed in a state where the gear ratio is in the maximum deceleration state, so that the gear ratio does not increase any more. In addition, it is possible to reliably prevent a reduction in the gear ratio and a reduction in the driving force caused by the reduction.

According to the fifth aspect of the invention, when the deceleration is large, the vehicle speed is maintained at a relatively high speed, and the speed ratio is maintained at a speed lower than the most decelerated state. Upshifting at a slow speed makes it possible to prevent or suppress belt slippage beforehand,
Also, in a state where the deceleration is small and the belt does not easily slip, the control for generating a slow upshift is not started until the vehicle speed becomes relatively low, so that the speed ratio becomes large and the belt returns well.

According to the sixth aspect of the present invention, when the speed ratio is greater than a predetermined value and the downshift control is continued at a certain speed or more and for a predetermined time or more from that state, the maximum deceleration state is changed. Because it is determined that the setting has been made, instead of detecting the maximum deceleration state by calculation that is likely to cause an error due to the detection error of the number of revolutions and individual differences of products,
The maximum deceleration state can be accurately determined.

According to the seventh aspect of the present invention, the number of pulses used for calculating the number of revolutions is changed in accordance with the gear ratio to improve the responsiveness of detecting the number of revolutions on the driving side and the driven side. Since the speed ratio is approximated or made the same, the gear ratio can be obtained with high accuracy.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a control example executed by a shift control device according to the present invention.

FIG. 2 is a diagram illustrating an example of a flowchart for determining a maximum deceleration state.

FIG. 3 is a diagram showing an example of a flowchart for changing the number of pulses used to calculate the number of revolutions in accordance with the gear ratio.

FIG. 4 is a diagram schematically showing a control area by the control device of the present invention.

FIG. 5 is a block diagram schematically showing a drive system and a control system of a vehicle to which the present invention is applied.

FIG. 6 is a diagram schematically showing an example of the continuously variable transmission.

FIG. 7 is a hydraulic circuit diagram showing a part of a hydraulic circuit for shift control in a continuously variable transmission according to the present invention.

[Description of References] 1 ... engine, 2 ... transmission mechanism, 6 ... electronic control device,
DESCRIPTION OF SYMBOLS 10 ... Continuously variable transmission, 13 ... Electronic control device, 20 ... Driving pulley, 21 ... Driving pulley, 22 ... Belt
27: hydraulic actuator, 31: first flow control valve, 32: second flow control valve, 39: first solenoid valve, 40: second solenoid valve, 60: rotation speed sensor.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F16H 59:70 F16H 59:70 63:06 63:06 (72) Inventor Hideki Yasue 1st Toyota Town, Toyota City, Aichi Prefecture Toyota (72) Inventor Katsumi Kono 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Tadashi Tamura 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Ryoji Habuchi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Koji Taniguchi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Kenji Matsuo Toyota, Aichi Prefecture 1 Toyota Town, Toyota Motor Corporation F-term (reference) 3J552 MA07 NA01 PA15 PA54 RB07 SA36 SA54 SB09 SB10 TA06 TB01 TB18 VA32W VA34W VA37W VA74W VB04W

Claims (7)

[Claims] A belt is wound around a driving pulley and a driven pulley, the width of which is variable by a hydraulic actuator, and the groove width of the driving pulley is changed by the hydraulic actuator. A speed reduction control means for determining whether or not the speed ratio is in a maximum deceleration state; and a maximum speed reduction in a low vehicle speed state equal to or lower than a predetermined vehicle speed. When it is determined by the maximum deceleration determining means that the vehicle is not in the state, the hydraulic oil supplied to and discharged from the hydraulic actuator of the driving pulley is controlled so that a slow upshift occurs. When it is determined by the maximum deceleration determining means that the gear ratio is in the maximum deceleration state, the hydraulic actuator of the driving pulley is operated so as to maintain the gear ratio in the maximum deceleration state. Shift control device for a belt type continuously variable transmission, characterized in that it comprises a control means for controlling the hydraulic oil supply and discharge to the other. 2. The apparatus according to claim 1, further comprising: a rotation speed detection unit configured to detect a rotation speed of the driving pulley, wherein the control unit determines that the rotation speed of the driving pulley detected by the rotation speed detection unit is a predetermined rotation speed. In the case of the following low speeds, the hydraulic actuator of the driving pulley is configured to generate a slow upshift even when the speed reduction ratio is determined to be in the maximum deceleration state by the maximum deceleration determining unit. The shift control device for a belt-type continuously variable transmission according to claim 1, wherein the shift control device is configured to control hydraulic oil supplied to and discharged from the transmission. 3. An input torque determining means for determining a magnitude of an input torque to the continuously variable transmission, wherein the control means determines that the speed ratio is in a maximum deceleration state by the maximum deceleration determining means. When the input torque is determined to be large when the input torque is determined by the input torque determining means, the drive pulley of the drive pulley is maintained so as to maintain the gear ratio in the maximum deceleration state regardless of the rotation speed of the drive pulley. The shift control device for a belt-type continuously variable transmission according to claim 2, wherein the shift control device is configured to control hydraulic oil supplied to and discharged from the hydraulic actuator. 4. The control means controls hydraulic oil supplied to and discharged from a hydraulic actuator of the drive pulley so as to maintain the speed ratio in the most decelerated state so that a slow downshift occurs. The shift control device for a belt-type continuously variable transmission according to any one of claims 1 to 3, wherein the shift control device is configured to be executed by feedforward control. 5. The vehicle further comprising deceleration determining means for determining deceleration, wherein the control means determines a predetermined reference when the speed reduction ratio is determined not to be in the maximum deceleration state by the maximum deceleration determining means. At a vehicle speed equal to or lower than the vehicle speed, control is performed to supply and discharge hydraulic oil to and from the hydraulic actuator of the driving pulley so that a slow upshift occurs, and the reference vehicle speed is determined by the deceleration determining means. The shift control device for a belt-type continuously variable transmission according to any one of claims 1 to 4, wherein the vehicle speed is set to be higher when the deceleration is large than when the deceleration is small. 6. The apparatus according to claim 6, wherein the maximum speed reduction determining means determines that a speed ratio determined from a rotation speed corresponding to the rotation speed of the driving pulley and a rotation speed corresponding to the rotation speed of the driven pulley becomes a predetermined speed ratio. 6. The apparatus according to claim 1, wherein when the state in which the downshift speed is equal to or higher than the predetermined speed continues for a predetermined time or longer, it is determined that the speed ratio has reached the maximum deceleration state. A shift control device for a belt-type continuously variable transmission according to any one of the preceding claims. 7. An input rotation speed sensor that outputs a pulse signal according to a rotation speed of the driving pulley, and an output rotation speed sensor that outputs a pulse signal according to a rotation speed of the driven pulley, The maximum deceleration determining means, when calculating the gear ratio,
The number of pulses used to calculate the rotation speed corresponding to the rotation speed of the driving pulley and the number of pulses used to calculate the rotation speed corresponding to the rotation speed of the driven pulley are changed according to the gear ratio. The shift control device for a belt-type continuously variable transmission according to claim 6, wherein the shift control device is configured to perform the following.