JPH08177998A - Continuously variable automatic transmission - Google Patents

Abstract

PURPOSE: To prevent the generation of vibration and noise accompanying a creep phenomenon in the stoppage of a continuously variable automatic transmission by controlling the change gear ratio lower than that of a low gear, and return the change gear ratio to that of the low gear in the start for ensuring the accelerating performance. CONSTITUTION: Springs 20c, 32c to energize variable pulleys 16, 26 at the drive and driven sides to positions of predetermined change gear ratio smaller than that of a low gear in the non-hydraulic operation are provided, while hydraulic pressure is supplied to the variable pulleys 16, 26 at the drive and driven sides in the stoppage after the start of an engine to maintain a predetermined change gear ratio, and a controller is constituted such that when the starting condition is detected the hydraulic pressure in the drive side pulley 15 is relatively reduced to increase the change gear ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an automatic transmission equipped with a continuously variable transmission.

[0002]

2. Description of the Related Art The output of an engine is transmitted to a drive shaft of a vehicle or the like via a fluid transmission such as a torque converter or a fluid coupling and a continuously variable transmission for continuously changing the output. There is known a continuously variable automatic transmission that is adapted to be transmitted. (For example, refer to Japanese Patent Application Laid-Open No. 61-105353 for a publicly known document.) In this type of automatic transmission, a hydraulic transmission is used except in the P range (parking range) or the N range (neutral range). Since the engine rotation is constantly transmitted via the vehicle, a so-called creep phenomenon occurs in which a slight driving force is transmitted to the wheels even when the idling is stopped.

The driving force due to the creep phenomenon can be sufficiently counteracted by operating a braking device of the vehicle such as a brake pedal or a parking brake, but the driving force due to the creep phenomenon is particularly generated immediately after the engine is started. This causes a problem that the vehicle vibration due to the engine rotation becomes noticeable with this braking, and an abnormal noise called a goo noise is generated to give an occupant an uncomfortable feeling.

As the fluid transmission of the continuously variable transmission described above, a continuously variable transmission to which an electromagnetic clutch using magnetic fluid as a torque transmission medium is applied is also considered. At times, even when the vehicle is stopped, the electromagnetic clutch is controlled so that some torque transmission is performed in consideration of the response after starting, and due to this so-called drag torque, the hydraulic power transmission device is set immediately after the engine is started. There is a possibility that the above-mentioned problem similar to the case of using is caused.

An object of the present invention is to provide a continuously variable automatic transmission that solves such problems.

[0006]

According to a first aspect of the present invention, there is provided a pair of variable pulleys, a driving side and a driven side, whose contact pulley width with a V belt is variably controlled based on hydraulic pressure. The engine output shaft is connected to the engine output shaft via the fluid transmission, and the driven variable pulley is connected to the drive system of the vehicle. The control means is provided for controlling the gear ratio by changing the hydraulic pressure according to the operating state of the vehicle. In the continuously variable automatic transmission, the control means supplies hydraulic pressure to the variable pulleys on the driving side and the driven side so as to maintain a predetermined gear ratio smaller than the low gear gear ratio when the vehicle is stopped after the engine is started. When the start condition is detected, the hydraulic pressure of the driving pulley is relatively reduced to increase the gear ratio.

According to a second aspect of the present invention, in the continuously variable transmission according to the first aspect of the invention, the variable pulleys on the driving side and the driven side are maintained at a position of a predetermined gear ratio smaller than the low gear gear ratio when hydraulic pressure is applied. It is assumed that the driven pulley is provided with a spring for urging so as to obtain it.

In the invention of claim 3, the control means of the invention of claim 1 or claim 2 detects the starting state from the release of the braking device of the vehicle.

According to a fourth aspect of the present invention, the control means of the first or second aspect of the invention similarly detects the starting state when the transmission is operated from the neutral range to the travel range.

According to a fifth aspect of the invention, in addition to the configuration of the fourth aspect of the invention, the control means is configured to increase the gear ratio after a lapse of a predetermined time after detecting an operation to the running range.

[0011]

In the invention of claim 1, the continuously variable transmission is controlled to a predetermined gear ratio smaller than the low gear gear ratio when the engine is started and the vehicle is stopped from idling.
The driving force associated with the creep phenomenon is reduced, and the occurrence of vibrations and noises peculiar to low gears can be avoided. Further, when the vehicle starts from this state, the hydraulic pressure to the drive pulley relatively decreases and the gear ratio increases to the low gear side, so that a large driving force necessary for starting is exerted.

According to the second aspect of the invention, since the continuously variable transmission maintains a predetermined gear ratio smaller than the low gear gear ratio even while the engine is stopped, the gear ratio of the continuously variable transmission is maintained immediately after the engine is started without a response delay. Is controlled to the predetermined gear ratio.

In the invention of claim 3 or 4, the starting state is detected in advance as the driver's intention by releasing the braking device or operating the traveling range. Therefore, prior to depression of the accelerator pedal at the time of starting, the low gear The increase of the gear ratio to the side is completed, and good starting performance is obtained.

According to the fifth aspect of the invention, the gear ratio is kept small during the response delay from the time when the vehicle is operated to the running range until the time when gear shifting is actually possible. Generation of sound is avoided.

[0015]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 shows a vertical sectional structure of a continuously variable automatic transmission to which the present invention can be applied. To explain this, the engine output shaft 10 has a torque converter 1 as a hydraulic transmission device.
Two are connected. A fluid coupling, an electromagnetic clutch, or the like may be used in place of the torque converter 12 as the fluid transmission.

The torque converter 12 is provided with a lock-up clutch 11, and by controlling the hydraulic pressures of the converter chamber 12c and the lock-up oil chamber 12d reciprocally, a pump impeller 12a on the input side and a turbine runner 12b on the output side are provided. Can be mechanically connected or disconnected.

The output side of the torque converter 12 is the rotary shaft 1
3, the rotary shaft 13 is connected to the forward / reverse switching mechanism 15. The forward / reverse switching mechanism 15 is the planetary gear mechanism 1.
9, a forward clutch 40, a reverse brake 50 and the like. The output side of the planetary gear mechanism 19 has a rotary shaft 13
Is connected to a drive shaft 14 which is coaxially fitted to the outside. A drive pulley 16 of a continuously variable transmission 17 is provided on the drive shaft 14.

The continuously variable transmission 17 is composed of the drive pulley 16, the driven pulley 26, a V belt 24 for transmitting the rotational force of the drive pulley 16 to the driven pulley 26, and the like.

The drive pulley 16 has a fixed conical plate 18 which rotates integrally with the drive shaft 14, and a hydraulic oil which is arranged to face the fixed conical plate 18 to form a V-shaped pulley groove and which acts on the drive pulley cylinder chamber 20. The movable conical plate 22 is movable in the axial direction of the drive shaft 14. In this case, the drive pulley cylinder chamber 20 includes the chamber 20a and the chamber 20.
It is composed of two chambers b, and has a larger pressure receiving area than a driven pulley cylinder chamber 32 described later.

The driven pulley 26 is provided on the driven shaft 28. The driven pulley 26 includes a fixed conical plate 30 that rotates integrally with the driven shaft 28, a V-shaped pulley groove that is disposed to face the fixed conical plate 30 to form a V-shaped pulley groove, and a hydraulic pressure that acts on the driven pulley cylinder chamber 32. And a movable conical plate 34 that is movable in the axial direction.

A drive gear 46 is fixed to the driven shaft 28, and the drive gear 46 meshes with an idler gear 48 on an idler shaft 52. The pinion gear 54 provided on the idler shaft 52 meshes with the final gear 44. The final gear 44 drives a propeller shaft or a drive shaft reaching a wheel (not shown) via a differential device 56.

The torque input from the engine output shaft 10 to the continuously variable automatic transmission as described above is converted into the torque converter 1.
2 is transmitted to the forward / reverse switching mechanism 15 via the rotary shaft 13, the forward clutch 40 is engaged, and the reverse brake 50 is released. The rotational force of the rotary shaft 13 is transmitted to the drive shaft 14 of the continuously variable transmission 17 while maintaining the same rotational direction, while the forward clutch 40 is released and the reverse brake 50 is engaged. Due to the action of the gear mechanism 19, the rotational force of the rotary shaft 13 is transmitted to the drive shaft 14 in a state where the rotating direction is reversed.

The rotational force of the drive shaft 14 is the drive pulley 16, V
Belt 24, driven pulley 26, driven shaft 28, drive gear 4
6, the idler gear 48, the idler shaft 52, the pinion gear 54, and the final gear 44 through the differential device 56.
Is transmitted to When both the forward clutch 40 and the reverse brake 50 are released, the power transmission mechanism is in a neutral state.

During the power transmission as described above, the movable conical plate 22 of the drive pulley 16 and the movable conical plate 34 of the driven pulley 26 are moved in the axial direction to change the contact position radius with the V belt 24. The rotation ratio between the drive pulley 16 and the driven pulley 26, that is, the gear ratio (reduction ratio) can be changed. For example, if the width of the V-shaped pulley groove of the drive pulley 16 is increased and the width of the V-shaped pulley groove of the driven pulley 26 is reduced, the V belt 2 on the drive pulley 16 side is reduced.
The contact position radius of No. 4 becomes smaller, and V on the driven pulley 26 side becomes smaller.
Since the V-belt contact position radius of the belt 24 becomes large, a large gear ratio can be obtained. Movable conical plate 2
If 2 and 34 are moved in the opposite direction, the gear ratio becomes smaller, contrary to the above.

The drive pulley 16 and the driven pulley 2 as described above
The control for changing the width of the V-shaped pulley groove 6 is performed by the drive pulley cylinder chamber 20 (20
a, 20b) or hydraulic control to the driven pulley cylinder chamber 32.

FIG. 2 shows an outline of a control system having a function of performing the basic gear ratio control of the continuously variable automatic transmission including the function of the control means of the present invention. Note that, in FIG. 2, the same reference numerals are given to the mechanical parts corresponding to those in FIG.

Hereinafter, this control system will be described focusing on the part related to the present invention. In FIG. 4, 101 is an electronic control unit including a microcomputer and the like, and 102 is a hydraulic control unit including various hydraulic control valves. In this control system, the control means of the continuously variable automatic transmission is mainly these electronic control units. It is configured by 101 and the hydraulic control unit 102.

The electronic control unit 101 performs a central processing unit 101A for performing control arithmetic processing, an input unit 101B for converting various operating state signals from the engine and the vehicle into a processable format and supplying the central operating unit 101A with the central processing unit 101A, and Central processing unit 1
The output unit 101C outputs various signals for hydraulic control and the like based on the control signal from 01A.

The input unit 101B has a water temperature signal S1, a throttle opening signal S2, an engine rotation signal S3, and an ABS which are used by a control module 103 for electronically controlling the fuel injection amount and ignition timing of the engine 100.
(Anti-lock brake system) ABS actuation signal S4 from the control device 104, braking signal S5 issued when the vehicle braking device is actuated, selector position signal S6 issued from the inhibitor switch as a signal indicating the operation position of the selector lever 105, drive pulley 16 rotation speed signals S
7, the rotation speed signal S8 of the driven pulley 26, etc. is input,
These signals are supplied to the central processing unit 101A as needed.

The central processing unit 101A includes a shift control unit 10
6, line pressure control unit 107, lockup control unit 108
The step motor drive circuit 109, the line pressure solenoid drive circuit 110, and the lockup solenoid drive circuit 11 which form the output unit 101C by calculating a control signal by using a necessary predetermined signal from the various signals.
By driving 1, the gear ratio of the continuously variable transmission 17, the line pressure, and the lockup clutch 11 are controlled.

More specifically, the shift control unit 106 controls the step motor drive circuit 109 so that the shift is performed according to a predetermined pattern according to the engine load represented by the throttle opening, the rotation speed, the vehicle speed, and the like. Output a signal. Based on this control signal, the step motor drive circuit 109 drives the step motor 113 connected to the shift control valve 112 of the hydraulic control unit 102.

That is, the step motor 113 drives the shift control valve 112 so that the gear ratio corresponds to the signal from the step motor drive circuit 109, and the drive pulley cylinder chamber 20 and the driven pulley cylinder chamber 32 (see FIG. 1) are driven. Reciprocally increase or decrease the supplied line pressure. Shift control valve 11
2, the displacement of the drive pulley 16, that is, the gear ratio is fed back to the step motor 113 via the link 114.
When the target gear ratio corresponding to the position is reached, the hydraulic pressure distribution to the pulley cylinder chambers 20 and 32 becomes constant, and the target gear ratio is stabilized.

On the other hand, when the transmission ratio of the continuously variable transmission 17 is controlled in this way, if the line pressure supplied to the pulleys 16 and 26 is too small, the pulleys 16 and 18 and the V belt 24 will be separated. The frictional force between
On the other hand, if the line pressure is excessive, the frictional force will unnecessarily increase, and in any case, the fuel efficiency and power performance of the vehicle will be adversely affected. Therefore, the line pressure control unit 10 is configured so that proper power transmission can be performed without excess or deficiency according to the gear ratio, the load, and the like.
7 controls the line pressure via the line pressure solenoid drive circuit 110.

That is, the line pressure solenoid drive circuit 1
Reference numeral 10 is a line pressure solenoid 115 of the hydraulic control unit 102.
Is controlled according to a control signal from the drive circuit 110, and the line pressure solenoid 115 responds to this by controlling a hydraulic pressure from a hydraulic pump (not shown) with a modifier (pressure control valve) 116 and a regulator (constant pressure valve). The desired line pressure is adjusted via 117 and supplied to the shift control valve 112 or the pulleys 16 and 26.

Further, the lockup control unit 108 performs hydraulic control so that the lockup clutch 11 is engaged, for example, when the vehicle speed becomes equal to or higher than a predetermined value and released when the vehicle speed becomes equal to or lower than the predetermined value. .

That is, the lockup control unit 108
Depending on the vehicle speed, the lockup solenoid 11 of the hydraulic control unit 102 is controlled via the lockup solenoid drive circuit 111.
8 is driven, and thereby the lockup control valve 119 is switch-controlled. In this case, the lockup control valve 119 is
Two systems: a system that supplies the hydraulic pressure from the hydraulic pump as an apply pressure to the converter chamber 12c of the torque converter 12 to connect the lockup clutch 11, and a system that similarly supplies a release pressure to the lockup oil chamber 12d as a release pressure. It is designed to perform reciprocal switching such as. That is, when the lock-up clutch 11 is connected, the apply pressure is supplied to the converter chamber 12c, the lock-up oil chamber 12d is opened, and the lock-up clutch 11 is opened.
When releasing, the release pressure is supplied to the lock-up oil chamber 12d and the converter chamber 12c is opened.

The above is an example of a continuously variable automatic transmission to which the present invention can be applied. In the present invention, in such a continuously variable automatic transmission, the transmission of the continuously variable transmission is a low gear when the vehicle is stopped. The gist is that the gear ratio is kept larger than the gear ratio and the low gear gear ratio is controlled again when the vehicle starts from that state.

This point will be explained in correspondence with the structure of the continuously variable automatic transmission. In the present invention, the initial gear ratio when the hydraulic pressure is not applied is smaller than the low gear gear ratio by, for example, about 20%. The positions of the drive pulley 16 and the driven pulley 26 are controlled so that the gear ratio can be obtained. For this reason, in this embodiment, as shown in FIG. 1, the movable conical plates 22 and 34 are set to the predetermined positions via the springs 20c and 32c respectively provided in the drive pulley cylinder chamber 20 and the driven pulley cylinder chamber 32. It is biased to a position that provides a gear ratio.

On the other hand, the control system controls the hydraulic pressure supplied to the cylinder chambers 20 and 32 so that the predetermined gear ratio is maintained when the vehicle is stopped after the engine is started, on the basis of various signals indicating the above-mentioned operating conditions. In this case, when the start condition is detected, the drive pulley cylinder chamber 20 is released to the drain in order to return the speed ratio to the low gear speed ratio and ensure the start performance. The start condition may be detected by depressing the accelerator pedal, but in that case, the gear ratio shifts to the low gear ratio only after the accelerator pedal is depressed, and the startability is somewhat low. Be damaged. Therefore, in this embodiment, the driver's brake operation or selector lever operation is used to predict the start of the vehicle and start shifting to the low gear transmission ratio. FIG. 3 is a flowchart showing details of such control, and FIGS. 4 and 5 are timing charts.

In this control, first, it is judged from the driven pulley rotation speed signal S8 whether or not the vehicle is in a stopped state after the engine is started after the key switch is turned on, and the vehicle speed is brought to a substantially stopped state in which the vehicle speed is less than the predetermined value Va. When it is determined that there is, hydraulic pressure is supplied to each of the drive pulley cylinder chamber 20 and the driven pulley cylinder chamber 32 so that the predetermined gear ratio initially set by the springs 20c and 32c is maintained.

From this stopped state, the selector lever 105
From P range or N range to driving range (D range)
When operated to, the forward clutch 40
Is connected and the engine rotational force from the torque converter 12 is transmitted to the drive system via the continuously variable transmission 17, a creep phenomenon occurs. At this time, however, the gear ratio is kept at a small value on the high speed side as described above. As a result, the occurrence of vibrations and noises peculiar to idling is suppressed.

On the other hand, when the braking device such as the foot brake is released from this state, the driving pulley cylinder chamber 20 is opened to the drain by detecting this by the braking signal S5. As a result, the pulley width is reduced based on the hydraulic pressure acting on the cylinder chamber 32 of the driven pulley 26, the pulley width of the drive pulley 16 is maximized, and the low gear transmission ratio is maximized (see FIG. 4). Therefore, when the accelerator pedal is depressed from this state, the vehicle starts with the original low gear speed ratio. Generally, in an automatic transmission, as a safety measure, the select operation from the P range to the D range side cannot be performed unless the brake pedal is depressed, that is, P
Braking is always applied during the operation from the range to the D range, and the vehicle is started by releasing the braking and depressing the accelerator pedal. Therefore, in this embodiment, the driver's intention to start is detected by releasing the braking device, and the gear ratio is returned to the low gear ratio before the accelerator pedal is actually depressed, whereby the desired start is achieved. I try to get acceleration.

On the other hand, since the braking operation is not compulsory for the operation from the N range to the D range, the selecting operation to the D range may be performed with the braking device being released. Therefore, when the braking device is not operating in this way, a select operation from the N range to the D range is detected based on the select position signal S6, and after a predetermined time T has elapsed from the operation, the drive pulley cylinder chamber 20 drains are performed (see FIG. 5). That is, when the braking device is not operating, the driver's intention to start is predicted by the select operation from the N range to the D range, and the shift to the low gear speed ratio prior to the accelerator pedal depression operation is performed. . The predetermined time T is set in consideration of the response delay of hydraulic control, and is usually about 0.5 to 0.8 seconds.

When the traveling in the D range is started in this manner, thereafter, the hydraulic control of the continuously variable transmission 17 is performed by a predetermined automatic transmission control so that the transmission ratio becomes a transmission ratio according to the traveling condition. When the vehicle speed is less than Va as a result of braking in this D range traveling,
The gear ratio is again controlled to a predetermined gear ratio larger than the low gear gear ratio. At this time, since the braking operation is being performed when the vehicle is stopped, the returning control to the low gear speed ratio is performed by the releasing operation at the time of starting thereafter.

As described above, when the vehicle is stopped, the gear ratio is maintained at a smaller gear ratio than the low gear gear ratio, so that vibration or abnormal noise is generated when the vehicle is stopped, which may cause a driver discomfort. On the other hand, when the vehicle starts, the gear ratio is returned to the low gear speed ratio prior to the driver's acceleration request to depress the accelerator pedal, so that the desired acceleration performance can be exhibited from the beginning of the start.

[0047]

As described above, according to the first aspect of the invention, the continuously variable transmission is controlled to a predetermined gear ratio smaller than the low gear gear ratio when the vehicle is stopped from engine stop to start and idling. Therefore, it is possible to reliably suppress the vibration and noise that tend to occur during idling operation due to the creep phenomenon. On the other hand, when starting from this state, the hydraulic pressure to the drive side pulley is reduced to shift the gear ratio to the low gear side, so a large driving force suitable for starting is exerted and good starting acceleration performance is achieved. Can be secured.

According to the second aspect of the present invention, since the continuously variable transmission maintains a predetermined gear ratio smaller than the low gear gear ratio even while the engine is stopped, the continuously variable transmission of the continuously variable transmission is maintained immediately after the engine is started without a response delay. The gear ratio can be controlled to the predetermined gear ratio.

According to the invention of claim 3 or 4,
Since the start state is predicted by releasing the braking device or operating to the running range and the shift to the low gear transmission ratio is performed in advance, better start acceleration performance can be obtained.

According to the fifth aspect of the present invention, since the shift to the low gear speed ratio is performed after a lapse of a predetermined time with respect to the operation to the traveling range, the actual operation after the operation to the traveling range is performed. It is possible to avoid the occurrence of vibration and abnormal noise even during the delay in the response until the gear shift becomes possible.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of a continuously variable automatic transmission to which the present invention can be applied.

FIG. 2 is a schematic diagram of a control system of the continuously variable automatic transmission.

FIG. 3 is a flowchart showing the control contents of the embodiment of the present invention.

FIG. 4 is a first timing chart showing a control state of the embodiment.

FIG. 5 is a second timing chart showing a control state of the embodiment.

[Explanation of symbols]

 10 Engine Output Shaft 11 Lockup Clutch 12 Torque Converter 12a Pump Impeller 12b Turbine Runner 12c Converter Chamber 12d Lockup Oil Chamber 13 Rotating Shaft 14 Drive Shaft 15 Forward / Reverse Switching Mechanism 16 Drive Pulley 17 Continuously Variable Transmission 18 Fixed Conical Plate 19 Planetary Gear mechanism 20 Drive pulley cylinder chamber 20c Spring 22 Movable conical plate 24 V belt 26 Driven pulley 28 Driven shaft 30 Fixed conical plate 32 Driven pulley cylinder chamber 32c Spring 34 Movable conical plate 40 Forward clutch 44 Final gear 46 Drive gear 48 Idler gear 50 Reverse brake 52 Idler shaft 54 Pinion gear 56 Differential device 101 Electronic control unit 101A Central processing unit 101B Input unit 101C Output unit 102 Hydraulic control unit 103 Engine controller Roll module 104 ABS control device 105 Selector lever 106 Gear shift control unit 107 Line pressure control unit 108 Lockup control unit 109 Step motor drive circuit 110 Line pressure solenoid drive circuit 111 Lockup solenoid drive circuit 112 Gearshift control valve 113 Step motor 114 Link 115 Line pressure solenoid 116 Modifier 117 Regulator 118 Lock-up solenoid 119 Lock-up control valve

Claims (5)

[Claims] 1. A pair of variable pulleys, a driving side and a driven side, whose contact pulley width with a V-belt is variably controlled based on hydraulic pressure, wherein the driving side variable pulley is connected to an engine output shaft via a hydraulic transmission. In the continuously variable automatic transmission, the driven-side variable pulley is connected to a drive system of a vehicle, and the control means is provided for controlling the gear ratio by changing the hydraulic pressure according to the operating state of the vehicle. Is supplied to the variable pulleys on the drive side and the driven side when the vehicle is stopped after the engine is started so as to maintain a predetermined gear ratio smaller than the low gear gear ratio, and when the start condition is detected, the drive side is driven. A continuously variable automatic transmission characterized in that the hydraulic pressure of the pulley is relatively lowered to increase the gear ratio. 2. The continuously variable transmission has a pulley on the driven side with a spring for urging the variable pulley on the driving side and the driven side so as to maintain the position at a predetermined gear ratio smaller than the low gear gear ratio when hydraulic pressure is applied. The continuously variable automatic transmission according to claim 1, further comprising: 3. The continuously variable automatic transmission according to claim 1, wherein the control means detects the start state from the release of the braking device of the vehicle. . 4. The control device according to claim 1, wherein the control means detects the start state from the fact that the transmission is operated from the neutral range to the travel range. Gear automatic transmission. 5. The continuously variable automatic transmission according to claim 4, wherein the control means is configured to increase the gear ratio after a lapse of a predetermined time after detecting the operation to the running range.