JP3510399B2 - Speed change control device for continuously variable transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a case where a continuously variable transmission represented by a V-belt type continuously variable transmission or a toroidal type continuously variable transmission shifts to a new gear ratio with a change in running conditions. In the above, the present invention relates to a shift speed control device for a continuously variable transmission that controls at what speed the new gear ratio is reached.

[0002]

2. Description of the Related Art A continuously variable transmission is capable of continuously selecting a gear ratio. For example, in January 1992, the applicant of the present application, Nissan Motor Co., Ltd. (K-11) "(C-11), as seen in the V-belt type continuously variable transmission, a shift map preset for each range selected by the driver in accordance with a desired traveling mode. Based on the above, a target gear ratio corresponding to the traveling condition is obtained, and the gear is continuously changed so as to attain this target gear ratio.

[0003]

However, in the conventional continuously variable transmission, the speed at which the gear shift is performed from the current gear ratio to the above target gear ratio, that is, the gear shift speed As shown by the broken line in FIG. 5, the gear ratio change amount d per unit time with respect to the gear ratio deviation e _ip between the current gear ratio and the target gear ratio is not controlled.
_The rate of change in _ip (speed change ratio) was constant.

By the way, in the continuously variable transmission, since the gear ratio is changed steplessly, the change in the running condition causes the gear change immediately, and if the gear change speed can be controlled, this gear change speed control is performed. Through this, the driving feeling of the vehicle can be freely controlled for each traveling condition.

Now, a suitable shift speed for each change in running conditions will be considered on the general shift diagram of the continuously variable transmission shown in FIG. FIG. 4 shows the vehicle speed V for each throttle opening TVO.
The shift pattern is shown as a diagram of the transmission target input speed N _t ^* with respect to SP. The arrow indicates an auto upshift that occurs when the vehicle speed VSP increases while traveling while keeping the throttle opening TVO constant, and the arrow indicates
While traveling with the throttle opening TVO kept constant, the vehicle speed V
The respective coast downshift shifts caused by a decrease in SP are shown, and the arrow indicates a depression downshift shift caused by increasing the accelerator pedal depression TVO, and the arrow indicates a throttle opening shift by returning the accelerator pedal. The foot-up upshifts resulting from reduced TVO are shown respectively. Further, the arrow indicates a select downshift shift to the engine brake line E / B which occurs when the driver manually operates the manual valve to the corresponding range in a desire of engine braking.

By the way, in the automatic upshift shift and the coast downshift according to the change of the vehicle speed VSP, the shift speed is changed in the meaning of improving the trace performance of the shift line shown in FIG. It is better to let the driver feel that the speed is fast, and conversely, in the down-shifting downshift, the upshift shifting without foot release, and the downshifting with select downshift, each one considers the drivability of the vehicle and operates with a slow shift speed. It is better to make people feel it.

However, in the conventional continuously variable transmission,
5, the gear ratio deviation e _ipUnit time for
Change ratio d per hit_ipThe change rate of is constant
From the above, regardless of the type of driving conditions that involve gear shifting.
The speed change rate always felt the same,
Unable to meet the requirements for gear shifting speed
It was

According to the present invention, as is apparent from the time chart shown in FIG. 7, the gear ratio deviation e _ip is different from the gear shift caused by the change in vehicle speed of the former two and the shift caused by change in the driving operation of the latter three. it is considerably larger in time, based on the fact recognition that it is possible to determine the shift of both the speed ratio deviation e _ip, speed per unit time for the gear ratio deviation e _ip according to the gear ratio deviation e _ip It is an object of the present invention to make the change rate of the ratio change amount d _ip different so that the above-mentioned request regarding the shift speed can be realized.

[0009]

For this purpose, a speed change control device according to a first aspect of the present invention is a continuously variable transmission in which an actual speed ratio is changed toward a target speed ratio set steplessly according to running conditions. In the above, the gear ratio deviation calculating means for calculating the deviation between the target gear ratio and the actual gear ratio, and the absolute value of the gear ratio deviation according to the gear ratio deviation calculated by the means are gear changes accompanying vehicle speed changes. When the absolute value of the gear ratio deviation is a small value less than the set value, the change of the gear ratio deviation is larger than when the absolute value of the gear ratio deviation is a large value equal to or larger than the set value that represents a gear change accompanying a driving operation change. It is characterized by a configuration including a gear ratio change speed changing means for increasing a change ratio of the gear ratio change speed with respect to the amount.

In the structure of the first aspect of the invention, the continuously variable transmission is continuously variable geared toward the target gear ratio set steplessly according to the running condition.

Here, the gear ratio change speed changing means changes the absolute value of the gear ratio deviation according to the vehicle speed change in accordance with the gear ratio deviation between the target gear ratio calculated by the gear ratio deviation calculating means and the actual gear ratio. When the absolute value of the gear ratio deviation is larger than the set value indicating that the gear change is accompanied by a change in driving operation, the gear ratio is smaller than the set value indicating that The change ratio of the speed change ratio change speed with respect to the change amount of the deviation is increased.

According to the structure of the first aspect of the invention, when the absolute value of the gear ratio deviation is small below the set value, that is, in the automatic upshift gearshift and the coast downshift gearshift associated with the change in vehicle speed, the gear ratio deviation of The change ratio of the gear ratio change speed with respect to the change amount is relatively high, and it is better to make the driver feel that the gear change speed is fast in consideration of the trackability of the shift line during the gear change as described above. Meet the demand for good. On the contrary, when the absolute value of the gear ratio deviation is larger than the above set value, that is, when the pedal is downshifted due to a change in driving operation, foot release upshift, or select downshift, the gear ratio deviation changes. The rate of change of the gear ratio change speed relative to the amount is relatively low, and during such a gear change, it is better to make the driver feel that the gear change speed is slow in consideration of the drivability of the vehicle as described above. Meets the demand for.

Therefore, according to the first aspect of the present invention, it is possible to realize both of the above-mentioned demands regarding the shift speed for the shift due to the change in the vehicle speed and the shift due to the change in the driving operation.

In the second aspect of the invention, the gear ratio deviation calculating means uses the previous value of the command gear ratio for each gear shift control cycle as the actual gear ratio.

According to the structure of the second aspect of the invention, it is not necessary to calculate the actual gear ratio from the detected value of the input / output rotational speed, and the sensor for detecting the input / output rotational speed is not necessary. Therefore, there is a great cost advantage.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 3 show an example in which a shift speed control device according to an embodiment of the present invention is applied to a V-belt type continuously variable transmission.

FIG. 1 shows a transmission system of the same V-belt type continuously variable transmission. This transmission system inputs the rotation from an engine 1 which is a prime mover through a torque converter 2 which is a fluid transmission means. 3, a forward / reverse switching mechanism 4, a V-belt transmission mechanism 5, and a differential gear device 6. The torque converter 2 has a lockup clutch 2a.
When the clutch is engaged, the fluid transmission state (converter state) is switched to the direct connection transmission state (lock-up state) in which the input / output elements are directly connected. The forward / reverse switching mechanism 4 is provided with a double pinion type planetary gear set 7, the rotation of the input shaft 3 can be transmitted to the V-belt transmission mechanism 5 as it is by the engagement of the forward clutch 8, and the input by the engagement of the reverse brake 9. The rotation of the shaft 3 can be reversed and transmitted to the V-belt transmission mechanism 5.

The V-belt transmission mechanism 5 is a primary pulley 1 on the drive side to which the rotation from the forward / reverse switching mechanism 4 is input.
0, a secondary pulley 11 on the driven side, and a V-belt 12 spanned between the pulleys 10 and 11.
Here, the primary pulley 10 and the secondary pulley 1
1 rotates one flange 10a, 11a together with the other flange, but is a movable flange that can be displaced in the axial direction, and the positions of these movable flanges 10a, 11a can be controlled by the pressure in the cylinder chambers 10b, 11b. To do.

The V-belt transmission mechanism 5 sequentially transmits the rotation of the primary pulley 10 to the secondary pulley 11 and the output shaft 13 via the V-belt 12. During this transmission, which will be described in detail later with reference to FIG. 2, a line pressure corresponding to the transmission input torque is supplied to the secondary pulley cylinder chamber 11b, and the primary pulley cylinder chamber 10b uses this line pressure as a source pressure for gear shift control. The shift control pressure (primary pulley pressure) determined by the valve is supplied, and the positions of the movable flanges 10a and 11a are determined by the ratio of the primary pulley pressure in the primary pulley cylinder chamber 10b to the line pressure in the secondary pulley cylinder chamber 11b. The winding arc diameter of the V-belt 12 with respect to the pulleys 10 and 11, that is, the transmission ratio (gear ratio) between the pulleys is determined.

Therefore, the V-belt transmission mechanism 5 can perform a speed change by continuously increasing the speed change ratio from the lowest speed change ratio to the high speed side change ratio by increasing the primary pulley pressure. By reducing the primary pulley pressure, it is possible to perform a speed change in which the speed change ratio is continuously changed continuously toward the lowest speed speed change ratio.

The rotation from the V-belt transmission mechanism 5 to the output shaft 13 is input to the differential gear device 6 via the parallel shaft gear set 14, and the differential gear device 6 differentially operates the left and right drive wheels of a vehicle (not shown). Drive down.

FIG. 2 shows the primary pulley cylinder chamber 10
2 shows a shift control system for determining the pressures on the secondary pulley cylinder chamber 11b and the secondary pulley cylinder chamber 11b to perform the above continuously variable shift control. This speed change control system includes a speed change control valve 2
1, a step motor 22 as a shift actuator for controlling the stroke thereof, and a gear ratio feedback member 23 for feeding back an axial position of the primary pulley movable flange 10a, that is, an actual gear ratio to the shift control valve 21. .

The shift control valve 21 continues to supply the line pressure P _L from the circuit 24 to the secondary pulley cylinder chamber 11b as the secondary pulley pressure (output pulley pressure) P _sec , while the stroke of the spool 21a causes the primary pulley cylinder to move. The circuit 26 communicating with the chamber 10b is communicated with the line pressure circuit 24 or the drain port 27 to determine the primary pulley pressure (input pulley pressure) _Ppri to the primary pulley cylinder chamber 10b, that is, the shift control pressure.

The gear shift control valve spool 21a is connected to the center of the gear shift link 28 by a pin 29. One end of the gear shift link is a pin 30 for a rack 31 and the other end is a gear ratio feedback member 23 for a pin 32. Connect with. Rack 31
The pinion 22a on the output shaft of the step motor 22 is meshed with the step motor 22 to determine the stroke position of the rack 31. As for the stroke of the rack 31, the shift link 28 is rotated in the corresponding direction around the pin 32, and the shift control valve spool 21a is stroked in the same direction as the rack 31.

When the shift control valve spool 21a moves to the left in the figure in response to the rack 31 being displaced in the high speed side gear ratio direction (Hi direction) by the step motor 22, the shift control valve 21 operates in the primary pulley pressure circuit. 26 to the line pressure circuit 24 to increase the primary pulley pressure (shift control pressure) P _pri to the primary pulley cylinder chamber 10b.
At this time, the primary pulley movable flange 1 in FIG.
0a approaches the fixed flange, and the gear ratio is continuously changed to the high speed side by the amount of increase in the primary pulley pressure _Ppri .

The amount of movement of the primary pulley movable flange 10a toward the fixed flange is fed back to the gear ratio feedback member 23 in the direction indicated by the arrow Hi, and the gear shift control valve spool 21a is stroked in the returning direction.
When the gear ratio corresponding to the displacement of the rack 31 in the Hi direction is achieved, the gear shift control valve spool 21a returns to the original position shown and the gear shift is completed.

When the gear shift control valve spool 21a moves to the right in the drawing in response to the rack 31 being displaced in the low speed side gear ratio direction (Lo direction) by the step motor 22, the gear shift control valve 21 uses the primary pulley pressure circuit. 26 through the drain port 27 to reduce the primary pulley pressure (shift control pressure) P _pri to the primary pulley cylinder chamber 10b.
At this time, the primary pulley movable flange 1 in FIG.
0a moves away from the fixed flange, and the gear ratio is continuously changed to the low speed side by the amount corresponding to the decrease in the primary pulley pressure _Ppri .

The amount of movement of the primary pulley movable flange 10a moving away from the fixed flange is fed back to the gear ratio feedback member 23 in the direction indicated by the arrow Lo, and the gear shift control valve spool 21a is stroked in the returning direction to move the Lo of the rack 31 to Lo. When the gear ratio corresponding to the directional displacement is achieved, the gear shift control valve spool 21a returns to the original position shown and the gear shift is completed.

The gear ratio command to the step motor 22 is based on the rotational position (initial position) of the step motor 22 corresponding to the stroke position of the rack 31 at which the lowest speed gear ratio is achieved, and the number of steps (step motor Operation amount) Give as Step. Here, the step motor operation amount Step is determined by the controller 41. Therefore, the controller 41 is informed of the vehicle speed VS.
A signal from a vehicle speed sensor 42 that detects P, a signal from a throttle opening sensor 43 that detects an engine throttle opening TVO, and a signal from an ignition switch 44 of the engine 1 (see FIG. 1) are input.

The shift control including the shift speed control performed by the controller 41 will now be described.
Reference numeral 1 denotes a speed change control and a speed change control continuously while the ignition switch 44 is ON, at a constant calculation cycle, by the processing shown in the functional block diagram of FIG. 3, or by executing a corresponding program. And

The target input rotation speed calculation unit 51 uses the vehicle speed VSP detected by the sensors 42 and 43 and the throttle opening TVO based on the planned shift map illustrated in FIG. The input rotation speed N _t ^* (which may be the target engine rotation speed) is calculated. Then, the output speed calculation unit 52 calculates the transmission output speed N _o by multiplying the vehicle speed VSP by a constant k, and the target speed ratio calculation unit 53 calculates the target input speed N _t ^* obtained as described above ^. _Is divided by the transmission output speed N _o to calculate the target speed ratio i _p0 = N _t ^* / N _o .

The gear ratio deviation calculating section 54 corresponds to the gear ratio deviation calculating means in the present invention, and calculates the gear ratio deviation e _ip between the target gear ratio _ip0 and the actual gear ratio. , The previous commanded gear ratio i _p (OLD) stored in the commanded gear ratio storage unit 55 is used as the actual gear ratio.
To use. Here the last command gear ratio i _p (OLD) is
It has already been achieved by the shift control one cycle before, and can be regarded as the actual gear ratio. Accordingly, the gear ratio deviation e _ip in the present embodiment is represented by _{e ip = i p0 -i p (} OLD).

The gear ratio change speed determining unit 56 corresponds to the gear ratio change speed changing means in the present invention, and based on a predetermined characteristic map as illustrated by the solid line in FIG. 5, the above gear ratio deviation e. _{From ip} , the gear ratio change amount d _ip (gear ratio change speed) per one calculation cycle (gear control cycle) is determined. The change characteristic of the gear ratio change amount d _ip per operation cycle shown by the solid line in FIG. 5 is that the gear ratio deviation e _ip is the set value ± e _S
The change ratio of the gear ratio change amount d _ip per one calculation cycle with respect to the change amount of the gear ratio deviation e _ip is higher when the value is smaller within the range than when the value is outside the range. .

Here, the set value e _S includes an automatic upshift gearshift and a coast downshift gearshift that accompany a change in vehicle speed, and a depression downshift gearshift, a foot release upshift gearshift, and a select downshift gearshift that accompany a change in driving operation. Use a value that can be distinguished.

[0035] In command gear ratio calculating section 57, command gear ratio i _p of the previous cycle in the memory unit 55 (OLD) as a reference, to which is added the speed ratio variation amount d _ip per the one calculation cycle, command gear ratio i _p = i _p (OLD) for calculating a + d _ip. The point command gear ratio storage unit 55, the storing the current command gear ratio i _p as i _p (OLD), subjected to processing in the arithmetic unit 54, 57 in the next calculation cycle. At step motor operation amount calculating unit 58, the step motor operation amount S for achieving the command gear ratio i _p from the calculating unit 57
rep is obtained, and this is used as the step motor 22 in FIG.
Output to.

The step motor 22 drives the shift control valve 21 to a position corresponding to the operation amount Srep,
It can be achieved command gear ratio i _p by the shift control operation of the.

Here, the command gear ratio i_pOf the time series of
As shown in FIG. 6, the throttle opening TVO is instant t.₁To step
Increase in a lump-like manner and instant t₂Return to accelerator pedal operation
As a result, the target gear ratio i_p0Is stepped as shown by the broken line
In the following, the command gear ratio i_pIs
D determined by the gear ratio change speed calculation unit 56 of FIG. _ip
At the speed corresponding to, that is, the response shown by the solid line in FIG.
Occurs. By the way, with the operation of the accelerator pedal
Depressing downshift during gear shifting and foot release upshift
Change ratio d per calculation cycle during gear shifting_ip
However, as shown by the solid line in FIG._ipAgainst
Since it is set to change relatively slowly,
The tumbler may feel that the speed of shifting is slow.
Therefore, the above-mentioned request regarding the shift speed at the time of the shift is
Can be realized.

On the other hand, although not shown in the operation time chart, the gear ratio change amount d _ip per one operation cycle is shown in FIG. 5 at the time of automatic upshift shift and coast downshift shift due to the change in vehicle speed. As shown by the solid line, since it is determined that the gear ratio deviation e _ip changes relatively steeply, the driver feels that the gear change speed at the time of the gear change is rapid, and the gear change also occurs during such gear change. The above requirements for speed can be fulfilled.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a transmission system of a V-belt type continuously variable transmission equipped with a shift speed control device according to an embodiment of the present invention.

FIG. 2 is a system diagram showing a shift control device of the same V-belt type continuously variable transmission.

FIG. 3 is a flow chart showing a program of speed change control and speed change control executed by a controller in the speed change control device.

FIG. 4 is a shift map diagram of a V-belt type continuously variable transmission.

FIG. 5 is a diagram showing a control characteristic of a gear ratio change amount per calculation cycle.

FIG. 6 is an operation time chart of shift speed control in the example.

FIG. 7 is an explanatory diagram showing a difference in appearance of a gear ratio deviation between a target gear ratio and an actual gear ratio at the time of gear shift due to a change in vehicle speed and at the time of gear shift due to a change in driving operation.

[Explanation of symbols]

1 engine 2 Torque converter 3 input axes 4 Forward / reverse switching mechanism 5 V belt transmission mechanism 6 Differential gear device 10 primary pulley 10a movable flange 10b Primary pulley cylinder chamber 11 Secondary pulley 11a Movable flange 11b Secondary pulley cylinder chamber 12 V belt 13 Output shaft 21 Shift control valve 22 step motor 23 Gear ratio feedback member 28 speed change link 31 racks 41 Controller 42 Vehicle speed sensor 43 Throttle opening sensor 44 Ignition switch

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-280628 (JP, A) JP-A-63-53129 (JP, A) JP-A-1-275944 (JP, A) JP-A-8- 74958 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16H 61/00-61/24

Claims (2)

(57) [Claims] 1. A continuously variable transmission in which an actual gear ratio is changed toward a target gear ratio set steplessly according to a running condition, wherein a gear ratio for calculating a deviation between the target gear ratio and the actual gear ratio. When the absolute value of the gear ratio deviation is a small value less than a set value indicating that the gear change is accompanied by a change in vehicle speed, the absolute value of the gear ratio deviation is calculated according to the deviation calculating means and the gear ratio deviation calculated by the means. The gear ratio change speed changing means for increasing the change ratio of the gear ratio change speed with respect to the change amount of the gear ratio deviation than when the value is a large value equal to or larger than the set value indicating that the gear change is accompanied by a change in driving operation. A shift speed control device for a continuously variable transmission, comprising: 2. The gear shift speed control device for a continuously variable transmission according to claim 1, wherein the gear ratio deviation calculation means uses a previous value of a command gear ratio for each gear shift control cycle as the actual gear ratio. .