JPS6328740A - Control method of continuously variable transmission associated with direct-coupled mechanism - Google Patents

Abstract

PURPOSE:To eliminate hunting phenomenon, by setting the width of hysteresis such that the engine rotation for switching from direct-coupled driving the continuously variable driving is lower than the engine rotation for switching from continuously variable driving to direct-coupled driving. CONSTITUTION:When the speed change ratio of a continuously variable speed change path reaches to a direct-coupled transmission ratio, a start clutch 20 is disengaged while a direct-coupled clutch 5 is engaged so as to switch to direct-coupled driving. During said direct-coupled driving, a continuously variable transmission 10 is controlled to the optimal speed change ratio at the lower speed ratio side than the highest speed ratio so as to idle the continuously variable transmission 10 turns reducing the loss torque. When it is switched from direct-coupled driving to continuously variable driving, a hysteresis width corresponding to the throttle opening is set below the target engine rotation and it is controlled such that the continuously variable transmission is not switched to the continuously variable speed change driving until the engine rotation drops below said hysteresis width. In such a manner, hunting phenomenon can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control method for a continuously variable transmission with a direct coupling mechanism, and particularly to a method for controlling switching between a direct coupling drive and a continuously variable transmission drive.

Conventional technology and its problems Conventionally, in a held-type continuously variable transmission, a continuously variable transmission has a directly coupled drive path with a fixed transmission ratio between the input and output shafts and a continuously variable transmission device to improve transmission efficiency during high-speed running. For example, the one provided in parallel with the speed change path is
It is stated in the No.

In the above case, the continuously variable transmission is stopped during direct drive,
This aims to reduce power loss and prevent deterioration of the heald.

However, the direct drive of this type of continuously variable transmission with a direct drive mechanism
, the following i1 are used to control the switching of the continuously variable speed drive.
There is an issue.

The first problem is the switching problem. As mentioned above, if the continuously variable transmission is stopped during direct drive, the continuously variable transmission will suddenly start when switching from direct drive to continuously variable drive, resulting in a large shock. This may also lead to problems such as held U&loss. In order to solve this problem, one idea is to cut off the connection between the continuously variable transmission during direct drive and the input shaft or output shaft, and keep the continuously variable transmission 1 at the direct drive transmission ratio (maximum speed ratio) and let it idle. It will be done. In this case, since the continuously variable transmission is always idling during direct drive, there is no shock even if there is a sudden switch from direct drive to continuously variable drive, and there is no risk of the heald being damaged.

The second problem is the tn loss of 1-lux during direct drive. In other words, when the continuously variable transmission is idled at the highest speed ratio during direct drive as described above, the direct drive time occupies most of the total travel time, so the tn of the continuously variable transmission during idle is
Lost torque becomes impossible to ignore, and fuel efficiency worsens. especially,
In a continuously variable transmission, like a general transmission, d) the i large torque tends to be the largest when the i is connected. This problem can be solved by controlling the continuously variable transmission to a lower speed ratio than the highest speed ratio, for example, an intermediate speed ratio (speed ratio -1), and causing it to idle during direct drive. However, in this case, when switching from direct drive to continuously variable speed drive, due to the difference in gear ratio between the direct drive path and the continuously variable speed path, engine braking suddenly occurs, causing the C-ring to drop by 1n. That's what happens.

The third problem is the instability of running during drive switching. In other words, if the engine speed when switching from direct drive to continuously variable 1818 drive is the same as the engine speed when switching from continuously variable speed drive to direct drive,
If the throttle opening degree is changed even slightly at this switching point, a problem arises in that a so-called hunting phenomenon occurs in which the direct coupling 'gAil+ and the continuously variable speed drive go back and forth, resulting in extremely unstable running.

Purpose of the Invention The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce torque loss during direct drive, and reduce engine braking during switching from direct drive to continuously variable speed drive. The object of the present invention is to provide a control method for a continuously variable transmission with a horizontally viscous machine that can achieve running stability during drive switching.

Structure of the Invention In order to achieve the above object, the present invention provides a direct drive path with a fixed transmission ratio and a continuously variable transmission path with a continuously variable transmission in parallel between the input and output shafts. In a continuously variable transmission with a direct-coupled gearbox that allows the continuously variable transmission to idle, during direct-coupling drive, the gear ratio of the continuously variable transmission is set to a lower speed proportional than the final gear ratio at the time of switching to direct-coupling drive. Control i
At the same time, the hysteresis width is set so that the engine speed when switching from direct drive to continuously variable speed drive is lower than the engine speed when switching from continuously variable speed drive to direct drive at the same throttle opening. , when the engine speed falls within the hysteresis range described in 1), change the gear ratio of the continuously variable transmission.)'-! This is to control 1311 the first speed ratio measurement.

That is, during direct drive, the continuously variable transmission is controlled from the highest speed ratio to the lowest speed ratio to avoid idling, so that tU lost torque can be reduced. In addition, the hysteresis width was set so that the engine speed when switching from target drive +h to continuously variable speed drive fIlj is lower than the engine speed when switching from continuously variable speed drive to direct drive J, so hunting phenomenon can be prevented. Since the continuously variable transmission is controlled in advance to the high speed ratio side when the hysteresis falls within the above hysteresis width, the difference in gear ratio when switching from direct drive to continuously variable speed drive is small, and the engine speed per rotation is small. Even if you immediately switch to continuously variable speed drive when the hysteresis width falls below, engine braking can be reduced.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows an example of a continuously variable transmission with a direct motion mechanism according to the present invention, in which a crankshaft 2 of an engine 1 is connected to an input shaft 4 via a damper mechanism 3. On the human power shaft 4, a direct clutch 5 consisting of a wet type multi-disc clutch and a rotatable direct drive gear t-6 are installed. ! 11! ; The driving gear 6 is connected to the input shaft 4. An outer I7i chaff is fixed to the end of the input shaft 4, and this outer I7i chaff is connected to the drive shaft II of the continuously variable transmission 10. It meshes with the determined internal gear 8, and drives the input shaft 4's 4th force to the inner gear 1 (triple).

The continuously variable transmission 10 is composed of a drive-side boot 2 provided on a drive shaft 11, a driven-side boo 4 provided on a driven shaft 13, and a heald 15 wound between both the boots. There is. The drive pulley 12 has a fixed sheave 12a and a movable sheave 12b.
A torque cam device 21G and a compression spring 17 are provided behind the movable sheave 12b.

The torque cam device 216 generates a thrust proportional to the input torque, and the compression spring 17 generates an initial thrust sufficient to prevent the heald 15 from loosening.
5 is given the belt tension necessary for torque transmission. On the other hand, similarly to the driving pulley 12, the driven pulley 14 has a fixed sheave 14a and a movable sheave 14b, and a hydraulic chamber 18 for speed ratio control is provided behind the movable sheave 14b. The oil pressure in this oil pressure chamber 18 is controlled by a pulley control valve 43, which will be described later.

A hollow shaft 19 is rotatably supported on the outer periphery of the driven shaft 13, and the driven shaft 13 and the hollow shaft 19 are connected to each other by a starting clutch 20 consisting of a wet multi-disc clutch. The hydraulic pressure to the starting clutch 20 is provided by a starting control valve 45, which will be described later.
controlled by A forward gear 21 and a reverse gear 22 are rotatably supported on the hollow shaft 19, and a forward/reverse switching dog clutch 23 connects either the forward gear 21 or the reverse gear 22 to the hollow shaft 19. It is designed to be connected. A reverse idler gear 25 that meshes with the reverse gear 22 and another reverse idler gear 26 are fixed to the reverse idler shaft 24. Further, a counter gear 28 that meshes with the forward gear 21 and the reverse idler gear 26 at the same time, and a final reduction gear 29 are fixed to the counter shaft 27, and the final reduction gear 29 meshes with the ring gear 31 of the differential device 30. , transmits power to the output shaft 32.

In the above continuously variable transmission, the direct coupling clutch 5, the direct coupling drive gear 6, the counter gear 28, the final reduction gear 29, and the differential device 30 constitute a direct coupling drive path, and the external gear 7
, internal gear 8, continuously variable transmission lO2 starting clutch 20,
Forward gear 21, counter gears 1 and 28, final reduction gear 2
9. The differential gear device 30 constitutes a continuously variable transmission path (when moving forward). And the direct transmission ratio between the input shaft 4 and the output shaft 32 in the direct drive path! . is the maximum speed ratio i o+ between the human power shaft 4 and the output shaft 32 in the continuously variable transmission path
The speed ratio is set to a slightly lower speed ratio than the in.

The pressure regulating valve 40 regulates the hydraulic pressure discharged from the oil reservoir 41 by the oil pump 42, and outputs it as line pressure to the pulley control valve 4.
31 Start control valve 45. It is output to the direct control valve 47.

The boolean control 7ffll valve 435, the start control valve 45, and the direct control valve 47 control the line pressure by solenoids 44, 46, and 48. 311L, which outputs control hydraulic pressure to the hydraulic chamber 18 of the driven pulley 14, the starting clutch 20, and the direct coupling clutch 5, respectively.

Signals such as engine speed, vehicle speed, throttle opening, brake signal, position switch signal, etc. are input to the control circuit 50, and by comparing and determining these signals with data recorded in advance, one turn is determined. Depending on the state, a control signal, for example, a duty control signal, is output to solenoid 4=L46.48.

Above: Ijl 1ff11 valve 43, 45.47 (7)
% Physical + Rm Ha, Example Eva No. 2 [2! It may be a combination of a spool valve 51 and a solenoid valve 52 as shown in I.
Alternatively, as shown in FIG. 3, it may be composed of a single three-point solenoid valve that selectively opens and closes the input port 54 and the drain port 55 with a ball-shaped valve body 53 and controls the output oil pressure of the output port 56. Good too. In either case, the control valves 43, 45
．． If the duty ratio of 47 is controlled, the control 311 oil pressure proportional to the duty ratio can be output, so the continuously variable transmission lO
This is suitable for controlling the transmission gear ratio of the starting clutch 20 and the transmission torque of the starting clutch 20.

In addition, since the direct coupling clutch 5 only performs intermittent control,
There is no need to perform duty control, and only 0N10FF control may be used.

Figure 1 shows a speed change diagram of the above-mentioned continuously variable transmission. To explain its operation, first of all, when starting with a constant throttle opening, the engine speed is set to the target value at the time of starting (point A).
The starting clutch 20 is disconnected until reaching G4, and after reaching point A, the starting clutch 20 is gradually engaged, and when reaching point B, the starting clutch 20 is maintained in a fully engaged state, and the starting control is changed to shift control. Move to 1all. In the variable speed control, the engine is first accelerated along the straight line of the minimum speed ratio (max), and when the engine speed reaches the target engine speed Nc (point C) corresponding to the throttle opening at that time,
The engine shifts to a shift region and shifts toward a high speed ratio while maintaining the target engine speed N. 1 [The gear ratio of the i-shift path is the direct transmission ratio l. (Point D), the starting clutch 20
At the same time, the direct coupling clutch 5 is engaged to switch to direct coupling drive), and thereafter the direct coupling transmission ratio is I. travel along a straight line.

During direct drive, the continuously variable transmission 10 continues idling with no load, but during idling the heald bending H1 loss is large at the highest and lowest speed ratios, and due to the balance between this bending fi loss and the gear ratio. As shown in FIG. 5, the in-lost torque of the continuously variable transmission 1O during idling is greatest at the highest speed ratio, and decreases as it moves toward lower speed ratios. Therefore,
During direct drive, the continuously variable transmission IO is idled at an optimum speed ratio lower than the highest speed ratio, for example, an intermediate speed ratio im (im-1), to reduce ti loss torque. Note that the gear ratio control of the continuously variable transmission 10 during idling may be performed by controlling the pulley control valve 13 with a duty ratio of 1311 L, as in the case of continuously variable transmission driving, but since it does not require much accumulation, 0N10FF control may also be used.

Furthermore, switching from continuously variable transmission drive to direct transmission drive can be achieved by simply switching the gear ratio of the continuously variable transmission path to 11.5, which matches the direct transmission ratio, while maintaining the target engine speed as described above. , if the transition from direct drive to continuously variable speed drive is when the engine speed matches the target engine speed, then
A slight change in throttle opening causes frequent switching between direct drive and continuously variable drive, causing the so-called λ-nching phenomenon. In order to eliminate this, a hysteresis width ΔF (according to the throttle opening) is set below the target engine speed N as shown in Figure 4, and direct connection is only made when the engine speed becomes lower than this hysteresis width. The control switches from drive to continuously variable speed drive to prevent hunting.As shown by the solid line in Figure 6, the hysteresis width Δ11 is large in the low throttle opening range and small in the high throttle opening range. It is set to be.

This is because the frequency of running at a low throttle opening is much higher than when driving at a high throttle opening, and moreover, the throttle opening is frequently changed in the low throttle opening range. Note that the setting of the hysteresis width is not limited to the case where it decreases continuously as the throttle opening degree increases, as shown by the solid line in FIG. 6, but may be changed stepwise as shown by the broken line in FIG.

By the way, even though it is possible to switch from direct drive to continuously variable transmission drive when the engine speed falls below the hysteresis width (NE - ΔH or below) as described above, the continuously variable transmission 1
0 is maintained at the intermediate gear ratio im, the direct transmission ratio i
. Due to the 1ffl difference between the intermediate gear ratio and the intermediate gear ratio, sudden engine braking is applied, which affects the driving feeling. In order to solve this problem, in the present invention, the direct drive T
During engine rotation, when the engine speed falls within the hysteresis width corresponding to the throttle opening at that time, the continuously variable transmission IO is changed from the intermediate gear ratio in to the high speed ratio in advance, and the speed becomes below the hysteresis width. Continuously variable speed drive υJ immediately at 11.5
Even when switching to the straight 1, 1, and transmission ratios, the difference in gear ratio is small, so the engine brake/yaw can be reduced when switching. As mentioned above, when the engine speed falls within the hysteresis range, the continuously variable transmission lO must be shifted from the intermediate gear ratio to the high speed ratio each time, but the continuously variable transmission lO is not in direct drive mode. Since it is idling, the gear shift is quick and there is no problem.

Here, specific switching control from the above-mentioned direct drive to continuously variable speed drive will be explained with reference to the flowchart of FIG. 7.

When control starts, first check whether direct drive is in progress by -Fl
Separate (60). Specifically, this determination can be made based on whether the direct coupling control valve 47 is ONL, the start control valve 45 is OFF, or whether the gear ratio is fixed to the direct coupling transmission ratio. If the direct drive is not in progress, it is then determined whether or not the gears are being shifted (61).

If you are not changing gears, you will have no idea that you are in the process of starting, so
Start control is performed (62). This starting control maintains the boolean control valve 43 in the ON state, and the starting side 1llllll valve, 15
This is done by controlling the duty. On the other hand, if the gear is being changed, perform the gear shift control 1fIll (63) and start north;
1 maintains the valves 11 and 15 in the ON state and performs duty control on the pulley control valve 43.

In addition, in the determination of (60), if direct drive is in progress,
Is the engine speed N at that time within the hysteresis width ΔH, that is, N, -ΔH≦N≦N?

It is determined whether or not (64). If it is NINE, the continuously variable transmission 10 is controlled to an intermediate gear ratio (65) because the direct drive is in a state where it should be continued. Also, N<N
, -ΔH, it is already in a state to switch to continuously variable speed drive, so the direct coupling clutch 5 is immediately disconnected and the starting clutch 20 is engaged to switch to continuously variable speed drive (66). Furthermore, N, −Δl (≦N≦NE
At this time, it is unstable whether to continue direct drive or to switch to continuously variable transmission drive. Therefore, in order to reduce the engine brake shock when switching to continuously variable transmission drive, the continuously variable transmission 10 is switched on. Control is performed in advance from the intermediate gear ratio to the high speed ratio side (67).

Incidentally, in the above embodiment, the description has been given of the held type continuously variable transmission; however, the present invention can be applied to a toroidal type continuously variable transmission or any other continuously variable transmission with a direct coupling mechanism.

Effects of the Invention As is clear from the above explanation, according to the present invention, direct connection UA
During operation, the continuously variable transmission is always controlled to a lower speed ratio than the highest speed ratio and idles, so lost torque can be reduced and efficient direct drive can be achieved.

In addition, the hysteresis width was set so that the engine speed when switching from direct drive to continuously variable speed drive was lower than the engine speed when switching from continuously variable speed drive to direct drive.
Hunting phenomenon can be eliminated and stable running can be achieved.

Furthermore, when the engine speed during direct drive is within the hysteresis range, the continuously variable transmission is controlled to the high speed ratio α in advance, so the difference in gear ratio when switching from direct drive to continuously variable drive is small. Even if the system immediately switches to continuously variable speed drive when the engine speed falls below the hysteresis width, engine braking noise can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an example of a continuously variable transmission with a direct coupling mechanism using the control method of the present invention, Figs. 2 and 3 are specific structural diagrams of the control valve, and Fig. 4 is a transmission diagram. FIG. 5 is a loss torque characteristic diagram of the continuously variable transmission, FIG. 6 is a relationship diagram between throttle opening and hysteresis width, and FIG. 7 is a flowchart of an example of the control method of the present invention. l...Engine, 4...Input shaft, 5...Direct coupling clutch, 6...Direct coupling drive gear, 10...Continuously variable transmission, 20...Starting clutch, 32... Output shaft, 43
...Pulley control valve, 45...Start control valve, 47...
- Directly connected control valve, 50... control circuit. Applicant Daihatsu Motor Co., Ltd. Agent Patent Attorney Hidetaka Tsutsukata Figure 1', ('+2 l'!,.31,
1 Figure 4 Figure 5 8.1 A; 6B+ ↑ S 0 ・Ll change rate Figure 7

Claims (1)

[Claims] (1) A direct drive path with a fixed transmission ratio and a continuously variable transmission path with a continuously variable transmission are provided in parallel between the input and output shafts, and the continuously variable transmission is idled during direct drive. In a continuously variable transmission with a mechanism, during direct drive, the gear ratio of the continuously variable transmission is controlled to a lower speed ratio than the final gear ratio at the time of switching to direct drive, and the gear ratio is changed from direct drive to continuously variable transmission with the same throttle opening. The hysteresis width is set so that the engine speed when switching to drive is lower than the engine speed when switching from continuously variable speed drive to direct drive, and when the engine speed falls within the above hysteresis width, the A control method for a continuously variable transmission with a direct coupling mechanism, characterized in that the gear ratio of the step-change transmission is controlled in advance to high-speed proportionality.