JPS6293562A - Switching control method of transmission - Google Patents

Abstract

PURPOSE:To perform stable switching, by increasing a hysteresis width, when a throttle opening is in a low degree, larger than that, when the throttle opening is in a high degree, and preventing hunting. CONSTITUTION:An input rotary speed Ni is compared with a switching reference value nE(NE-DELTAnE). When the compared value is in a relation where Ni>=NE-DELTAnE, no switching is performed by maintaining the third solenoid valve 103 to be placed in an on-condition because of possibility of generating hunting action. While if the compared value is in a relation where Ni<NE-DELTAnE, driving is switched to an ordinary speed change control of belt driving because no hunting is generated even for switching to the belt driving. Accordingly, stable switching can be performed.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a transmission switching control method, and more particularly, to a transmission switching control method.

The present invention relates to a control method for smoothly switching from direct drive to continuously variable speed drive in a transmission in which a direct drive path and a continuously variable speed path are provided in parallel between output shafts.

Conventional technology and its problems Various types of continuously variable transmissions have been known in the past, such as V-belt type continuously variable transmissions and toroidal type continuously variable transmissions.
In either case, there is a problem in that the power transmission efficiency during continuously variable speed driving is about 10 to 15% inferior to the transmission efficiency of gears, chains, etc. Therefore, as previously described in Japanese Patent Publication No. 57-23136, a direct drive path having a fixed transmission ratio between the input shaft and the output shaft and a continuously variable transmission path including a belt-type continuously variable transmission are arranged in parallel. In addition, a clutch is provided in each of the direct drive path and the continuously variable transmission path, and power is transmitted via the continuously variable transmission path in the low speed ratio range, and via the direct drive path in the high speed ratio range. Some proposals have been made to improve the power transmission efficiency in the high-speed ratio range.

By the way, as a control method for the continuously variable transmission, upper and lower limits having a predetermined control range above and below the target input rotation speed according to the throttle opening are set, and duty control is performed between the upper and lower limits. For example, Japanese Unexamined Patent Application Publication No. 59-62761 discloses a gear shift system that allows smooth gear shifting. Therefore, it is possible to apply this control method to switching control between direct drive and continuously variable speed drive.

For example, when switching from continuously variable speed drive to direct drive, the input rotation speed is set to the upper limit of the target input rotation speed N1 (N, +ΔN+
) and the lower limit value (N, = ΔNl), the gear is shifted to the high speed ratio side while controlling the duty, and when the gear ratio of the continuously variable transmission device matches the fixed transmission ratio of the direct drive path, the clutch of the continuously variable transmission path is activated. If the clutch of the direct drive path is shut off and the clutch of the direct drive path is engaged, it is possible to automatically switch to the direct drive.

On the other hand, when changing from direct drive to non-variable speed drive, for example, as shown in line B in Figure 6, the input rotation speed drops to the target input rotation speed N2 corresponding to the throttle opening at that time. One possible method is to switch at any point in time. However, with this method, there is a problem in that if the throttle opening is opened or closed even slightly near the switching point, a so-called hunting phenomenon occurs, making running extremely unstable. This problem occurs when the input rotation speed is lower than the target input rotation speed N2 (N2-ΔN).

) can occur any time within the above range.

Therefore, if you switch to continuously variable speed drive after the input rotation speed falls below a certain switching reference value that is lower than the above lower limit value,
It is possible to perform stable switching.

However, in general, 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. Therefore, the difference between the target input rotation speed and the switching reference value (
If the hysteresis width (hereinafter referred to as hysteresis width) is constant regardless of the throttle opening, the switching operation from direct drive to continuously variable speed drive at low throttle openings tends to become unstable.

Purpose of the Invention The present invention has been made in view of the above problems, and its purpose is to provide a transmission switching system that can stably switch from direct drive to continuously variable speed drive at low throttle openings. The objective is to provide a control method.

Structure of the Invention In order to achieve the above object, the present invention provides a direct drive path having a fixed transmission ratio between an input shaft and an output shaft and a continuously variable transmission path having a continuously variable transmission in parallel. A switching mechanism is provided to selectively drive either the direct drive path or the continuously variable transmission path, and the continuously variable transmission has a control range above and below the target input rotation speed according to the throttle opening. In a transmission equipped with a hydraulic control device that sets a lower limit value and duty-controls the gear ratio between the upper and lower limit values, the switching mechanism changes from direct drive to continuously variable speed drive when the input rotational speed increases. The switching is performed when the target input rotational speed becomes lower than the lower floor value corresponding to the throttle opening at that time, and the difference between the above target input rotational speed and the switching reference value is set to high throttle, 2 Torr. It is set so that it is larger when the throttle opening is low than when the throttle opening is wide.

In other words, by setting the hysteresis width between the target human rotation speed and the switching reference value to be larger at high throttle openings than at low throttle openings, direct connection is achieved in the low throttle opening range. When switching from drive to continuously variable speed drive, hunting can be prevented and stable switching can be performed even if the throttle opening is frequently opened and closed.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows an example of a transmission according to the present invention, in which a fluid coupling cover 2 is coupled to an end of a crankshaft 1 of an engine, and a fluid coupling is configured inside the fluid coupling cover 2. A pump 3, a turbine 4, and a centrifugal candlestick 5 are rotatably housed.

The input shaft 6 is coupled to the turbine 4 and the Ronoqua knob clutch 5, and a direct coupling drive gear 7 constituting a direct coupling drive path is rotatably inserted into the input shaft 6. and the input shaft 6 are selectively coupled by a dog clutch 8, which is an example of a direct coupling switching mechanism. The tongue clutch 8 is composed of a spline hub 6a fixed to the input shaft 6, spline teeth 7a integrally formed with the direct coupling drive gear 7, and a switching sleeve 8a that connects and disconnects these splines 6a and 7a. This switching sleeve 8a is actuated in the axial direction via the shift fork 32 by an actuator 90, which will be described later. A direct connection switch 35 is provided on the side of the shift fork 32, and the direct connection switch 35 is turned on when the shift fork 32 moves to the direct connection position.

An external gear 9 is fixed to the end of the input shaft 6, and this external gear 9 is connected to the drive shaft 11 of the Held type continuously variable transmission 10.
It meshes with an internal toothed gear '+12 fixed to the input shaft 12, thereby decelerating the driving force of the input shaft 6 and transmitting it to the drive shaft 11. ■The belt-type continuously variable transmission 10 includes a drive pulley 13 provided on the drive shaft 11, a driven pulley 15 provided on the driven shaft 14, and a heel (16) wound between both boars. The drive pulley 13 has a fixed sheave 13a and a movable sheave 13b, and a torque cam 33 for generating thrust and a torsion spring 34 provided behind the movable sheave 131) allows the movable sheave 13b to match the input torque. Adding thrust. On the other hand, the driven side boo 'J15 is also connected to the drive side pulley 1.
3, it has a fixed sheave 15a and a movable sheave 15b, and behind the movable sheave 15b is provided a hydraulic chamber 18 that operates the movable sheave 15b in the axial direction by hydraulic pressure. The hydraulic pressure to this hydraulic chamber 18 is controlled by a hydraulic control device described later.

A hollow fQil 19 is rotatably fitted around the outer periphery of the driven shaft 14, and the driven shaft 14 and the hollow shaft 19 are connected to each other by a wet clutch 20, which is an example of a power disconnection mechanism.

This clutch 20 is also actuated by a hydraulic control device to be described later, and connects the driven shaft 14 and the hollow shaft 9 during belt drive, and disconnects it during direct drive. A forward gear 21 and a reverse gear 22 are rotatably fitted onto the hollow shaft 19, and either the forward gear 21 or the reverse gear 22 is connected to the hollow shaft 9 by a forward/reverse switching sleeve 23. Ru. A reverse idle shaft 2 arranged parallel to the driven shaft 14
4, a reverse idle gear 25 that meshes with the reverse gear 22 and another reverse idle gear 26 are fixed. A counter shaft 27 is also arranged parallel to the driven shaft 14, and a counter gear 28 and a final reduction gear 29 are fixed to this counter shaft 27. The counter gear 28 meshes with the direct drive gear 7, the forward gear 21, and the reverse idle gear 26 at the same time, and also serves as a direct drive gear. The final reduction gear 29 meshes with a ring gear 31 of a differential device 30 and transmits power to an output shaft 32.

In the transmission having the above configuration, the dog clutch 8° direct connection drive gear 7, the counter gear 28. Final reduction gear 29. The differential device 30 forms a direct drive path, while the external gear 9. Internal gear 12. V-held continuously variable transmission section 10. Clutch 20, forward gear 21. Counter gear 28, final reduction gear 29. Differential device 3
0 forms a belt drive path. The direct gear ratio between the input shaft 6 and the output shaft 32 in the direct drive path is:
As shown in FIG. 3, compared to the maximum speed ratio between the input shaft 6 and the output shaft 32 in the held i-dynamic path, the speed ratio is set to be slightly lower.

Fig. 2 shows the hydraulic control device, 40 is a boolean control valve, 50 is a shift down control valve, 60 is a throttle valve, 70 is a throttle valve, 80 is a lock-up control valve, 90; actuator, 10
0 is a control circuit such as a fixed computer, 101
．． 102, 103 are the first, second . The third solenoid valve 104 is an oil passage through which line pressure is introduced from a hydraulic source.The six-pulley control valve 40 has a spool 42 biased leftward by a spring 41, and a 27 Hydraulic pressure (solenoid pressure) controlled by the first solenoid valve 101 is guided to the −1 end chamber 43 . A boat 45 to which line pressure is introduced and a drain boat 46 are formed on both sides of a boat 44 communicating with the hydraulic chamber 18 of the driven pulley 15. The boat 44 that communicates with the hydraulic chamber 18 communicates with the left end chamber 47 via a communication hole 42 a formed inside the spool 42 , so that the hydraulic pressure in the hydraulic chamber 18 is controlled by the solenoid pressure of the first solenoid valve 101 and the spring force of the spring 41.

The shift down control valve 50 has a spool 52 biased leftward by a spring 51, and a signal hydraulic pressure from a second solenoid valve 102 that is turned ON during kickdown and sudden deceleration is guided to the left end chamber 53. . The shift down control valve 50 includes a boat 54 communicating with the boat 45 of the pulley control valve 40, a boat 55 communicating with the lock-up control pulp 80, a boat 56 communicating with the clutch control valve 70, and a throttle valve 60.
When the first solenoid valve 101 is OFF (signal oil pressure is OFF), the spool 52 is at the left end position as shown in the figure, and the boats 55 and 56 are in communication with each other. pressure is applied to the clutch control valve 70. At this time, communication between the boats 54 and 55 leading to the pulley control valve 40 is cut off, but the line pressure is guided to the boat 45 of the pulley control valve 40 via the orifice 58. On the other hand, the second
When the solenoid valve 102 is turned on (signal hydraulic pressure is turned on), the spool 52 moves to the right, the boats 54 and 55 communicate with each other, and line pressure is supplied to the pulley control valve 40.
On the other hand, the connection between boats 55 and 56 is cut off.

The throttle valve 60 is linked to the accelerator pedal, and when the throttle opening is fully closed or close to fully closed, the spool 62 is moved by a spring 61 as shown by the dashed line.
is in the leftmost position, and the boat 63 leading to the downshift control valve 50 is closed. Furthermore, when the throttle opening is opened, the spool 62 moves to the right and the boats 63 and 64 communicate with each other, and the line pressure is reduced to the shift down control valve 5.
It leads to 0.

The clutch control valve 70 has a boat 71 at the right end that communicates with the boat 56 of the downshift control valve 50,
The spool 72 moves to the left against the spring 73 due to the hydraulic pressure acting on the boat 71, and a boat 74 to which line pressure is supplied and a boat 75 leading to the clutch 20 are moved.
and the drain boat 76 are selectively switched. That is, when no hydraulic pressure is applied to the rightmost boat 71, the spool 72 is at the rightmost position, the boat 74 is closed, the boats 75 and 76 are in communication, and the hydraulic pressure of the clutch 20 is drained and the clutch 20 is disengaged. . On the other hand, when hydraulic pressure acts on the boat 71 on the right end, the spool 72 moves to the left and the boats 74 and 75 communicate with each other, and the hydraulic pressure is guided to the clutch 20.
It is a system that connects.

The lock-up control pulp 80 is a valve that controls the actuator 90, and has a spool 82 biased to the left by a spring 81, and a left end chamber 83 is provided with a signal for a third solenoid valve 103 that is turned ON during direct drive. Hydraulic pressure is being guided. Five boats 84 to 88 are formed in the lock-up control valve 80, the rightmost boat 84 communicates with the left chamber 91 of the actuator 90, the line pressure is introduced to the boat 85, and the boat 86 controls downshifting. It communicates with the boat 55 of the valve 50, and the boat 87
communicates with the right chamber 92 of the actuator 90, and the leftmost boat 88 serves as a drain boat. When the third solenoid valve 103 is 0FF (signal oil pressure is 0FF), the spool 82 is at the left end position as shown in the figure, the boats 85, 86, 87 are in communication, and the line pressure is connected to the right chamber 92 of the actuator 90 for downshift control. It acts on the boat 55 of the valve 50. On the other hand, the third solenoid valve】0
3 is ON (signal oil pressure is ON), the spool 82 moves to the right, the boats 84 and 85 communicate to supply line pressure to the left chamber 91 of the actuator 90, and the spool 82 further moves to the right. Then, the spool 82 comes into contact with the shift fork 32 and moves together to the right, and the boat 86 is also drained.

The actuator 90 has a piston 93 that is movable by hydraulic pressure applied to the left and right chambers 91 and 92, and a rod 94 is connected to this piston 93, and the shift fork 32 of the dog clutch 8 is connected to the middle of the rod 94. ing. Further, a spring 95 is housed in the left chamber 92, and always urges the piston 93 to the left, that is, in the direction of non-direct connection. When the hydraulic pressure is introduced into the left chamber 91 at the time of switching to direct drive, the rod 94 is urged to the right, but when the dog clutch 8 is in the head butt state, the rod 94 does not move to the right and the shift fork 32 It also does not move to the right. Therefore, the spool 8 of the lock 7-tube control valve 80
2 cannot move to a position where it hits the shift fork 32 and drains the boat 86, and there is no risk that the clutch 20 will be disengaged.

In other words, the clutch 20
can maintain the connected state and prevent the engine from revving up.

The control circuit lOO has an input rotation speed N1 of the input shaft 6 and an output rotation speed N of the output shaft 31. (vehicle speed), brake signal,
A throttle opening signal, a position switch signal, etc. are input, and the first to third solenoid valves 101 to 103 are controlled depending on the driving state. In particular, the first solenoid valve 101 is simply ON, OF
Unlike F control, a pulse signal with a predetermined period including an ON time and an OFF time is given, and the ratio of the ON time to the period (
By changing the duty ratio), duty control is performed to generate solenoid pressure proportional to the duty ratio. Then, upper and lower limit values having a predetermined control width above and below are set for the target input rotation speed according to the throttle opening degree,
When the actual input rotation speed is outside the range of the upper and lower limit values, the first solenoid valve 101 is continuously turned ON or OFF so that the input rotation speed quickly falls within the range, and when it is within the range, the upper limit value and the actual The duty ratio is changed according to the difference from the input rotation speed.

Now, if the target input rotation speed is N, the control width is ΔN1, and the actual input rotation speed is N, then the duty ratio is as follows: When NI>NE+ΔN, D=O%(OFF)N, +Δ
When N, ≧N [≧N, -ΔN, 2×ΔN.

When N, <N, -ΔN, D=100% (ON) Also,
The control circuit 100 has a target input rotation speed Nε and a control width Δ.
In addition to N, a hysteresis width Δn is set according to the throttle opening as shown in FIG. This hysteresis width Δn[ is the difference between the switching reference value n, which is the reference for the input rotation speed NL when switching from direct drive to belt drive, and the target input rotation speed N (Δn2 wNl − n2 )
As shown by the solid line in FIG. 4, the throttle opening is gradually decreased from a low throttle opening to a high throttle opening. Since the hysteresis width Δn[ is larger than the duty control width ΔN, the switching reference value n is always lower than the lower limit value (N, -ΔN,).

Note that the hysteresis width Δn[ is not limited to decreasing linearly as the throttle opening increases as shown by the solid line in FIG. 4, but may be set stepwise as shown by the broken line in FIG.

Here, the general operation of the hydraulic control device is shown in Table 1 according to each running state.

Table 71 31 S2 S3 PI P2 P3 During normal shifting DXX △ ○ ○Kick down 2
Time ○ ○ × ○ ○ ○During sudden deceleration ○
○ × × ○ ×During direct drive × × O△
× ×In Table 1, S and ~S3 are the signals of the solenoid valves 101~103, respectively, P1~P1 are the oil pressures of the oil passages 1.05~107, respectively, D is the duty control, ○
indicates that the hydraulic pressure or solenoid valve is continuously ON, × indicates that the hydraulic pressure or solenoid valve is continuously OFF, and △ indicates that the hydraulic pressure is O.
This indicates a state that can be either N or OFF.

Next, control circuit 1. The switching control of the present invention using OO will be explained with reference to FIG. 5G.

In FIG. 5, when the operation starts, it is first determined whether or not the direct connection switch 35 is ONL (110), then ON.
If not: Since it is in the direct drive state, switch control (111) from the heald drive to the 1u coupling drive. Shift to the switching control (l 20) of -.

In the switching control (111) from heald drive to direct drive,
First, calculate the actual gear ratio i (=NL/NO) during belt drive from the input rotation speed N and the output rotation speed Nrl, and compare this gear ratio i with the direct gear ratio 1゛ of the direct drive path. (112). If i>lo (low speed ratio side), it means that the speed ratio i has not reached a state where it can be directly connected, so normal speed change control (113), that is, the first solenoid valve 101 is controlled by The third solenoid valve 103 is maintained in the OFF state.

If 1≦i' (high speed ratio side), it means that a state where direct connection is possible has been reached, so the third solenoid valve 103 is turned on (114), and the actuator 90 is biased in the direction of direct connection. Then, the speed ratio i and the direct gear ratio l'' are compared again (115), and if i>i' (low speed ratio side), the duty ratio of the first solenoid valve 101 is lowered L (116), and the oil pressure is The hydraulic pressure in the chamber 18 is lowered to shift to the high speed ratio side.When l≦i' (high speed ratio side), the duty ratio of the first solenoid valve 101 is increased (117), and the hydraulic pressure in the hydraulic chamber 18 is increased. Shift to low speed ratio side.

After performing the above two reciprocating controls, the direct connection switch 35 is turned OFF.
118), direct connection switch 35 to determine whether it is N or not.
If it is in the OFF state, it means that the switching of the dog clutch 8 to direct drive has not been completed, so the above-mentioned reciprocating control is repeated. If the direct coupling switch 35 turns ON, it means that the switching to direct coupling drive is completed, so the first
The solenoid valve 101 is turned off (119) to complete the reciprocating control. At the same time as switching of the tongue clutch 8 is completed, the boat 86 of the lock-up control valve 80 is drained, so the clutch 20 is disconnected, and only the belt-type continuously variable transmission 10 shifts to the high-speed ratio side and idles under no load. do.

In addition, switching control from direct drive to belt drive (1, 20
), the target input rotation speed N and hysteresis width Δn should be determined according to the throttle opening at that time.121>
, actual input rotation speed N1 and switching reference value + 1E (NF
Compare with An(). (122),, N1 ≧N
5-Δn, the state has not been reached where it is possible to switch to belt drive, or hunting may occur even if it switches to belt drive, so the 13th solenoid valve 103 is kept in the ON state and the switch is not performed. (123
). On the other hand, if N, <N, -ΔIIE, hunting will not occur even if the gear is switched to heald drive, so the third solenoid I1' valve 103 is switched to 0FFL and normal shift control for heald drive (113 ).

In addition, although the tongue clutch 8 was used as the direct coupling switching mechanism in the above embodiment, a wet type clutch may also be used. In the case of a wet clutch, control is simple because there is no need to reciprocate the gear ratio when switching from belt drive to direct drive as in the tongue clutch 8.

Further, the continuously variable transmission of the present invention is not limited to the belt type; for example, various types such as a conventionally known toroidal type continuously variable transmission (for example, see Japanese Patent Application Laid-Open No. 58-54262) can be used. Furthermore, the direct drive path is not limited to the gear train as in the above embodiment, but a chain or a toothed belt may also be used.

Effects of the Invention As is clear from the above explanation, according to the present invention, the hysteresis width is set so that the reference value for switching from direct drive to continuously variable speed drive is lower than the lower limit of the target input rotation speed. The hysteresis width at low throttle openings is larger than at high throttle openings, so even if the throttle opening is frequently opened and closed near the switching point at low throttle openings, there is no risk of hunting and stable switching is possible. It can be carried out.

[Brief explanation of drawings]

FIG. 1 is a Sugerton diagram of an example of a transmission according to the present invention;
Figure 2 is a circuit diagram of the hydraulic control device, Figure 3 is a shift diagram when switching from direct drive to belt drive, Figure 4 is a diagram showing the relationship between throttle opening and hysteresis width, and Figure 5 is a diagram showing the relationship between throttle opening and hysteresis width. FIG. 6, which is a flowchart showing the switching control method of the present invention, is a shift diagram that is the premise of the present invention. 6...Input shaft, 7...Direct drive gear, 8...Dog clutch, 10...■ Belt type continuously variable transmission, 2
0...Power I! fr continuation clutch...counter gear, 30...differential device, 32...
Output shaft, 40... Pulley control valve, 50... Shift down control pulse 7", 60... Throttle valve,
70...Clutch? Fdl control valve, 80... lockup control valve, 90... actuator, 1
00...Control circuit, 101-103...Solenoid valve. Publisher: Daihatsu Motor Co., Ltd. Representative: Patent Attorney Hidetaka Tsutsukata Figure 6 Figure 3 Figure 4

Claims (1)

[Claims] (1) A direct drive path having a fixed transmission ratio and a continuously variable transmission path having a continuously variable transmission are provided in parallel between the input shaft and the output shaft, and one of the direct drive path and the continuously variable transmission path is provided. A switching mechanism for selectively driving is provided, and upper and lower limit values having a predetermined control range above and below the target input rotation speed according to the throttle opening are set in the continuously variable transmission, and In a transmission equipped with a hydraulic control device that duty-controls the gear ratio between 1 and 2, the switching mechanism switches from direct drive to continuously variable speed drive at a target input rotation speed according to the throttle opening at that time. This is done when the switching reference value, which is lower than the lower limit, is reached, and the difference between the target input rotation speed and the switching reference value is set to be larger at low throttle openings than at high throttle openings. A transmission switching control method characterized by: