JPH1182707A - Control device for continuously variable transmission for vehicles - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent a belt from slipping even during a sudden braking operation. SOLUTION: Drive and driven pulleys 21 and 22 are provided.
5, a belt 24 wound between these pulleys,
A drive-side hydraulic actuator 22, a driven-side actuator 26, an input torque detector for detecting an input torque to a drive pulley, a speed ratio detector for detecting a rotational speed ratio of both pulleys, and an input torque and a rotational speed ratio. Based on this, the hydraulic control devices 60 and 70 for controlling the pulley side pressures of the drive-side and driven-side actuators constitute a control device for a vehicle continuously variable transmission. The device further includes a sensor 6 for detecting the throttle opening of the engine.
3, the hydraulic pressure set by the hydraulic control device when the throttle opening is substantially fully closed is increased and corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a V-belt type continuously variable transmission used for a vehicle, and more particularly, to controlling a pulley side pressure applied for the purpose of applying tension to a belt in the transmission. To a device that

[0002]

2. Description of the Related Art A V-belt type continuously variable transmission is constructed by winding a metal V-belt between a drive and a driven pulley whose pulley width can be variably set, and variably controlling the pulley width of both pulleys. It is configured to perform stepless speed ratio control by changing the winding radius of the belt on each pulley. As such a continuously variable transmission, a hydraulic cylinder chamber (hydraulic actuator) for changing the pulley width is provided for each pulley, and the hydraulic pressure supplied to the hydraulic cylinder chamber is controlled (ie, the pulley side pressure is controlled) to change the speed. A configuration for performing control is conventionally known (for example, Japanese Patent Publication No. 5-64258).

Here, the pulley side pressure is used to change the speed ratio by variably setting the pulley width as described above, and to apply a predetermined tension to the belt so that the belt can efficiently move without slipping. Also used for power transmission. For this reason, in such a continuously variable transmission, the pulley side pressure, which is a low pressure among the pool side pressures supplied into the hydraulic cylinder chambers of the drive and driven pulleys, applies a predetermined tension to the belt and does not slip. The hydraulic pressure required for power transmission is set, and the pulley width is changed by the pulley-side pressure, which is high, so that the shift control is performed.

[0004]

In such a V-belt type continuously variable transmission, the pulley side pressure, which is the lower pressure, that is, a predetermined tension is applied to the belt to perform power transmission without slip. The pulley side pressure is set to a value that does not cause a slip according to the transmitted torque and the like, and is set to a minimum necessary value in consideration of fuel efficiency and the like. However, when power is transmitted through the belt-type continuously variable transmission and a vehicle equipped with the transmission is running and a sudden brake is actuated, the vehicle speed drops rapidly. In other words, because the wheel rotation is braked by the brake and the driven pulley rotation rapidly decreases, the pulley side pressure becomes insufficient and the belt slips,
There is a problem that the belt may be worn or durability may be reduced.

It is known that the pulley side pressure is increased from the time the brake is actuated to suppress the slip of the belt. However, in such a control, the response of the pulley side pressure rise is delayed, and the side pressure is reduced. However, there is a problem that the belt slips before the belt rises sufficiently.

The present invention has been made in view of such a problem.
To provide a control device for a continuously variable transmission for a vehicle configured to increase a pulley side pressure before a brake is actuated during traveling and to effectively prevent the occurrence of a belt slip when the brake is actuated. Aim.

[0007]

In order to achieve the above object, in the present invention, a drive and driven pulley of a variable pulley width, a belt wound between these pulleys, and a pulley side pressure applied to the drive pulley. A drive-side hydraulic actuator to be applied, a driven-side actuator to apply a pulley-side pressure to the driven pulley, an input torque detecting means for detecting an input torque to the drive pulley, and a speed ratio for detecting a rotation speed ratio between the drive pulley and the driven pulley. Detecting means for controlling the hydraulic pressure supplied to the drive-side and driven-side actuators based on the input torque detected by the input torque detecting means and the rotational speed ratio detected by the speed ratio detecting means; Hydraulic pressure control device that controls the side pressure applied to the belt from the A drive request detecting means for detecting a required level of the drive output of the prime mover, wherein the required level of the drive output detected by the drive request detecting means is equal to or less than a determination threshold. This control device is provided with correction means for increasing the hydraulic pressure set by the hydraulic control device at a certain time.

It is preferable that the prime mover is usually an engine, and the required level corresponds to the throttle opening of the engine, and the drive request detecting means detects the throttle opening of the engine.

In the control device having such a configuration, when the required level of the drive output, that is, the engine throttle opening is equal to or smaller than the determination threshold, the pulley side pressure is corrected to increase. Here, for example, when the brake pedal is depressed during traveling, the foot is released from the accelerator pedal to release the depression of the accelerator pedal, and the brake is depressed with the foot. That is, the depression of the accelerator pedal is released before the brake pedal is depressed, and the throttle opening becomes substantially zero, which is lower than the determination threshold value. Therefore, at this time, the hydraulic pressure which becomes the pulley side pressure is increased and corrected by the correction means, and thereafter, the brake pedal is depressed. For this reason, even when a sudden braking operation is performed, the pulley side pressure is increased before the braking operation, and the belt does not slip.

Since the deceleration rate of the vehicle speed with respect to the brake operation when the vehicle speed is high is smaller than the deceleration rate of the vehicle speed with respect to the brake operation when the vehicle speed is low, the correction means is larger than when the vehicle speed is low. It is preferable to set a correction amount. However, since the belt slip problem hardly occurs in a state where the vehicle speed is almost stopped, the correction amount of the hydraulic pressure may be zero when the vehicle speed is almost zero.

In a vehicle having an anti-lock brake system for preventing the wheels from being locked when the brake is operated, an abnormality detecting means for detecting an abnormal state of the anti-lock brake system is provided. When it is detected that there is, it is preferable to set a larger correction amount than in the normal case. If the anti-lock brake system is abnormal and does not work,
When a sudden brake is applied, the wheel rotation decreases rapidly.If the anti-lock brake system is abnormal, a larger correction amount than in the normal case is used so that belt slip does not occur even if such a rapid decrease occurs. Is set.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. First, FIG. 2 and FIG. 3 show a configuration of a V-belt type continuously variable transmission for a vehicle controlled by a control device according to the present invention. The continuously variable transmission has a V-belt type continuously variable transmission mechanism in a housing 1. This housing 1 has a joint surface 2 with the engine flywheel housing at the left end,
The transmission is mounted on the engine such that the joint surface 2 is joined to the engine flywheel. At this time, the first shaft S1 is located coaxially with the engine output shaft Es. In the following description, each rotation center axis of the transmission, such as a rotation shaft and a gear, is shown as a first axis S1 to a fourth axis S4, which means a center axis.

In this belt type continuously variable transmission, the torque converter 5 is mounted on the first shaft S1 in the housing 1.
(Comprising an impeller 5a, a turbine 5b and a stator 5c) and a forward / reverse switching mechanism 4 in parallel. The engine output shaft Es is the impeller 5 of the torque converter 5
The turbine 5b of the torque converter 5 is connected to a turbine shaft 6 (which is also an input shaft of the forward / reverse switching mechanism 4). Further, the torque converter 5 has a lock-up clutch 5d capable of directly connecting the engine output shaft Es and the turbine 5b (that is, connecting the engine output shaft Es and bypassing the power transmission unit by the torque converter).

The forward / reverse switching mechanism 4 has a double pinion type planetary gear train as shown in detail in FIG.
The sun gear 13 is connected to the turbine shaft 6 and to the clutch inner 8, and the carrier 11 is connected to the first shaft 23 via the clutch outer 7.
The ring gear 17 is supported on the inner circumference so as to be rotatable relative to the turbine shaft 6, and is driven by the reverse brake 12.
It can be fixedly held on the brake casing 3. The outer pinion gear 14 and the inner pinion gear 15 mesh with each other, and the outer pinion gear 14
7, and the inner pinion gear 15 meshes with the outer periphery of the sun gear 13. By selectively operating the forward clutch 11 and the reverse brake 12, the first shaft 23 can be rotated forward or backward with respect to the turbine shaft 6.

The first shaft 23 has a fixed pulley half 21a integrally formed therewith, and a movable pulley half 21b opposed thereto and disposed movably in the axial direction on the first shaft 23. Is provided. A second shaft 27 is rotatably provided on a second shaft S2 extending parallel to the first shaft S1 at a predetermined distance from the first shaft S1, and a fixed pulley half formed integrally with the second shaft 27. The driven pulley 2 comprises a body 25a and a movable pulley half 25b opposed to the body 25a and arranged on the second shaft 27 so as to be movable in the axial direction.
5 are configured.

Drive pulley 21 and driven pulley 25
A metal V-belt 24 is wound therearound to form a belt-type power transmission device, and the rotation of the drive pulley 21 is transmitted to the driven pulley 25 via the metal V-belt 24. At this time, the movable pulley 21 of the two pulleys 21 and 25
a, 25a is moved to adjust the pulley width, so that the winding radius of the belt between the pulleys 21 and 25 can be adjusted arbitrarily, and the speed ratio between the pulleys 21 and 25 is adjusted steplessly. can do. For such pulley width adjustment (that is, movable pulleys 21a, 2
5a), the drive side hydraulic cylinder 2
2 and a driven hydraulic cylinder 26 are provided.

In this case, both cylinders 22, 26
Is controlled not only for the reduction ratio control as described above, but also for the side pressure acting on the V-belt 24 from the pulleys 21 and 25, so that the V-belt 24 does not slip.
The lateral pressure required for efficient power transmission is set. Specifically, of the hydraulic pressures supplied to the two cylinders 22 and 26, a low-pressure hydraulic pressure is a hydraulic pressure for applying a lateral pressure necessary for transmitting power without causing the V-belt 24 to slip. Is the oil pressure for adjusting the gear ratio. Note that the control device according to the present invention controls the setting of the low-pressure hydraulic pressure, that is, the pulley-side pressure necessary to transmit power without causing the V-belt 24 to slip, which will be described later.

Left side of driven pulley 25 (engine side)
Is provided with a first gear 31 connected to the second shaft 27. A third shaft 34 is rotatably disposed on a third shaft S3 extending parallel to the predetermined distance from the second shaft S2, and the second gear 32 and the third gear 33 are integrally formed on the third shaft 34. Have been. The first gear 31 meshes with the second gear 32. Further, a differential mechanism 36 is disposed on a fourth axis S4 extending parallel to the third axis S3 at a predetermined distance from the third axis S3.
The fourth gear 35 connected to the sixth gear 6 meshes with the third gear 33. Thus, the first to fourth gears 31, 32, 33,
A power transmission gear train 30 is constituted by 35, and the rotation of the driven pulley 25 is transmitted to a differential mechanism 36 via the power transmission gear train. The left and right axle shafts 37, 38 are connected to the differential mechanism 36, and the power transmitted to the differential mechanism 36 is split here and divided into left and right axle shafts 37, 38.
The power is transmitted to the left and right wheels (not shown) via 38.

In the continuously variable transmission having the above configuration,
An input rotation sensor 51 that detects the rotation of the drive pulley 21 from the rotation of the casing of the forward / reverse switching mechanism 4, and an output rotation sensor 5 that detects the rotation of the driven pulley 25 from the rotation of a sensing gear 55 fixed to the second shaft 27.
2 are provided as shown.

Next, in the continuously variable transmission configured as described above, the drive side and driven side hydraulic cylinders 2
A hydraulic pressure control (ie, pulley side pressure control) device supplied to each of the pulleys 2 and 26 will be described with reference to FIG. These two hydraulic cylinders 22 and 26 have oil passages 75 and 76 respectively.
The control valve 70 is connected via the control valve 70, and the supply of the hydraulic oil from the hydraulic pump 71 is controlled by the control valve 70.
The two hydraulic cylinders 22 and 26 correspond to the drive-side and driven-side hydraulic actuators, respectively.

The operation of the control valve 70 is controlled by a control signal from the controller 60. The controller 60 includes an input rotation speed (drive pulley rotation speed) NI detected by the input rotation sensor 51, an output rotation sensor 5
2, the output rotation speed (driven pulley rotation speed) NO, the engine rotation speed NE detected by the engine rotation sensor 61, the engine intake negative pressure PB detected by the intake negative pressure sensor 62, and the throttle opening sensor 63 The detected throttle opening TH and signals from an ABS abnormality detector 65 for detecting the presence or absence of an abnormality in the antilock brake system ABS are input, and the operation of the control valve 70 is controlled based on these detection signals. The controller 60 corresponds to a hydraulic control device.

The pulley side pressure control is performed by controlling the operation of the control valve 70 by the controller 60 in this manner. The contents of this side pressure setting control will be described with reference to the flowchart of FIG. In this control, as shown in FIG. 4, first, the detection value of each sensor is read (Step S).
1), input torque TIN to drive pulley 21 is obtained (step S2). This calculation is based on the engine speed N
E, the engine output torque is obtained from the intake negative pressure PB and the throttle opening TH, the drive torque of the auxiliary machine is subtracted from the engine torque to obtain the input torque to the transmission side, and this is multiplied by the torque ratio of the torque converter 5. Then, the input torque TIN to the drive pulley 21 is obtained (this configuration corresponds to the input torque detecting means).

Next, the rotational speed ratio SR of the rotational speeds NI and NO of the drive pulley 21 and the driven pulley 25 is calculated (step S3) (this configuration corresponds to the speed ratio detecting means). Then, based on the input torque TIN and the rotational speed ratio SR, a basic pulley side pressure PSB necessary for causing the belt 24 to transmit torque efficiently without causing slip is calculated (step S4).

At this time, it is determined whether or not the current engine throttle opening TH is substantially zero, that is, whether or not the depression of the accelerator pedal is released and the throttle opening is substantially fully closed. (Step S5) (This configuration corresponds to the drive request detecting means). In this determination, specifically, a value at which the throttle opening is slightly opened is set as a determination threshold, and it is determined whether or not the actual throttle opening is smaller than this determination threshold. If the throttle opening TH is not substantially zero, that is, if the accelerator pedal is depressed, step S
The process proceeds to step 6 to set the correction value β = 0. On the other hand, when the throttle opening TH is substantially zero (fully closed state), the routine proceeds to step S.
7, the presence or absence of an abnormality detection signal from the ABS abnormality detector 65, that is, the anti-lock brake system ABS
Is determined to be abnormal (this configuration corresponds to the abnormality detecting means). When the antilock brake system ABS is normal, β1 is set as the correction value β (step S
8) If abnormal, β2 is set as the correction value β (this configuration corresponds to the correction means).

These correction values β1 and β2 are set in advance as shown in FIG. In this case, the correction value β1 becomes the correction value β
The correction value is set so as to be smaller than 2, that is, when the anti-lock brake system ABS is normal, and when it is abnormal. Further, these correction values are set in accordance with the vehicle speed V.
The correction value is set to be zero when the vehicle speed is almost zero. Therefore, in steps S9 and S8, the correction value β1 or β2 corresponding to the current vehicle speed V
Is set.

When the correction value β is set as described above,
The correction value β is added to the basic pulley side pressure PSB calculated in step S4 to determine the pulley side pressure PS (step S10), and the controller 60 controls the operation of the control valve 70 so as to obtain the pulley side pressure PS.

Thus, when the vehicle is running with the accelerator pedal depressed, the input torque TIN and the speed ratio S
The basic pulley side pressure capable of transmitting power without belt slip set based on R is used as it is, and efficient power transmission is performed without belt slip. And
When the foot is released from the accelerator pedal and the brake pedal is depressed, the pulley side pressure PS to which the correction value β has been added is used when the foot is released from the accelerator pedal and the throttle opening is almost fully closed. Be increased.
Therefore, when the brake pedal is depressed, the pulley side pressure increases, and the V-belt does not slip even if a sudden braking operation is performed.

The anti-lock brake system AB
In the case of having S, the brake operation control is performed so that the wheels are not locked even when the sudden brake operation is performed, but when the system ABS does not operate due to abnormality,
At the time of sudden braking, the wheels are locked, and the output rotation of the transmission rapidly decreases. For this reason, when the antilock brake system ABS is abnormal, the correction value β is set to a large value so that the slip of the V-belt does not occur in this case as well.

[0029]

As described above, according to the present invention,
A hydraulic control device that controls the hydraulic pressure supplied to the drive-side and driven-side actuators based on the input torque and the rotational speed ratio, and controls the belt tension (side pressure applied to the belt from the pulley); If the required drive output level (throttle opening) is equal to or smaller than the determination threshold value (when the throttle is almost fully closed), the hydraulic pressure set by the hydraulic control device is corrected to increase. When the brake pedal is depressed during running, the oil pressure that is the pulley side pressure is corrected to increase when the foot is released from the accelerator pedal, and thereafter, even if the brake pedal is depressed and sudden braking is performed, No belt slippage occurs.

Since the deceleration rate of the vehicle speed with respect to the brake operation when the vehicle speed is high is smaller than the deceleration rate of the vehicle speed with respect to the brake operation when the vehicle speed is low, a larger correction amount is set when the vehicle speed is low. You. However,
Since the belt slip problem hardly occurs in a state where the vehicle speed is almost stopped, the correction amount of the hydraulic pressure is set to zero when the vehicle speed is almost zero.

In a vehicle having an anti-lock brake system for preventing wheel lock during braking, when the anti-lock brake system is detected to be abnormal, a larger correction amount is set than when the anti-lock brake system is normal. You. If the anti-lock brake system is abnormal and does not work, the wheel rotation will decrease rapidly when sudden braking is applied, but if the anti-lock brake system is abnormal, a larger correction amount will be set than in the normal case. Therefore, even in this case, slip of the belt can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a control device configuration of a belt-type continuously variable transmission according to the present invention.

FIG. 2 is a sectional view showing the configuration of a V-belt type continuously variable transmission for a vehicle having a control device according to the present invention.

FIG. 3 is a skeleton diagram showing a configuration of a V-belt type continuously variable transmission for a vehicle having a control device according to the present invention.

FIG. 4 is a flowchart illustrating control of pulley side pressure by a control device according to the present invention.

FIG. 5 is a graph showing a correction value used for the shift control.

[Explanation of symbols]

 5 Torque converter 21 Drive pulley 24 Belt 26 Driven pulley 60 Controller 70 Control valve

Claims (5)

[Claims] A drive pulley of a variable pulley width that is driven to rotate by receiving a driving force from a prime mover; a driven pulley of a variable pulley width that is disposed in parallel with the drive pulley and is connected to a wheel side; A belt wound around a drive and a driven pulley, a drive-side hydraulic actuator that is operated under hydraulic pressure and applies a pulley-side pressure to the drive pulley, A driven-side actuator for applying torque, input torque detection means for detecting torque input from the prime mover to the drive pulley, speed ratio detection means for detecting a rotation speed ratio between the drive pulley and the driven pulley, Input torque detected by input torque detecting means and the speed ratio detecting means A control device for a continuously variable transmission for a vehicle, comprising: a hydraulic control device that controls a hydraulic pressure supplied to the drive-side and driven-side actuators based on the detected rotation speed ratio, and controls a tension of the belt. A drive request detecting means for detecting a required level of drive output of the prime mover; and a hydraulic drive control device configured to set the required level of drive output detected by the drive request detector when the required level is equal to or less than a determination threshold. And a correcting means for increasing and correcting the hydraulic pressure. 2. The engine according to claim 1, wherein the prime mover comprises an engine, the required level corresponds to a throttle opening of the engine, and the drive request detecting means detects a throttle opening of the engine. A control device for a continuously variable transmission for a vehicle as described in the above. 3. A vehicle speed detecting means for detecting a vehicle speed of a vehicle equipped with the vehicle continuously variable transmission, wherein the correcting means corrects the hydraulic pressure in accordance with the vehicle speed detected by the vehicle speed detecting means. 2. The control device for a continuously variable transmission for a vehicle according to claim 1, wherein the amount is set, and when the vehicle speed is low, a larger correction amount is set than when the vehicle speed is high. 4. The vehicleless vehicle according to claim 3, wherein the correction means sets the correction amount of the hydraulic pressure to zero when the vehicle speed detected by the vehicle speed detection means is substantially zero. Control device for step transmission. 5. An anti-lock brake system for controlling a brake operation so as to prevent locking of the wheels when a vehicle equipped with the vehicle continuously variable transmission is operated, and an abnormal state of the anti-lock brake system. Abnormality detecting means for detecting, wherein the correcting means sets a correction amount of the hydraulic pressure according to a detection result of the abnormality detecting means, and when the antilock brake system is detected to be abnormal, 2. The control device for a continuously variable transmission for a vehicle according to claim 1, wherein a larger correction amount is set than when it is not.