JPS6252268A - Shift-down control for v belt type continuously variable transmission - Google Patents

Abstract

PURPOSE:To enable a smooth shift-down to be carried out by providing a power connect/disconnect clutch in an output shaft system, and disconnecting the clutch if the pulley ratio is on the higher side than the allowable pulley ratio when a vehicle is stopped. CONSTITUTION:Since the restarting is impossible when the pulley ratio i is smaller (on the high side) than the allowable pulley ratio i', the 2nd solenoid valve 61 is turned ON, and a clutch 16 is disconnected, while at the same time the 1st solenoid value 60 is turned ON, and the effective diameter of a driven side pulley 12 is shifted to the larger diameter side. Since the clutch 16 is disconnected at this time. The V-belt transmission 6 is caused to perform an idle running by an engine, and is shifted to a low pulley ratio. Thus, prompt shift into a lower side can be enabled without applying an excessive side pressure to the V-belt.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a downshift control method for a V-belt continuously variable transmission, particularly a method for shifting the pulley ratio of a V-belt continuously variable transmission to the low side when the vehicle is stopped. This relates to a control method.

Conventional technology and its problems Conventionally, hydraulic chambers were provided for each of the driving pulley and the driven pulley, line pressure was introduced into one hydraulic chamber, and hydraulic pressure controlled by a hydraulic control valve was introduced into the other hydraulic chamber. A V-belt type continuously variable transmission capable of steplessly changing the pulley ratio (speed ratio) by changing the effective diameter of both pulleys is disclosed, for example, in JP-A-58-42862. .

In the case of this type of V-belt continuously variable transmission, the pulley ratio is hydraulically controlled to be in a high state during high-speed running, and when decelerating slowly from this state, the predetermined input rotation speed is maintained. The ratio shifts from the high side to the low side, and when the vehicle is stopped, it returns to a low ratio that allows it to restart.

However, when the vehicle suddenly decelerates from high-speed driving,
The return of the pulley ratio to the low side is delayed compared to the decrease in vehicle speed, and when the vehicle comes to a stop, the pulley ratio does not return to the low pulley ratio and there is a risk that the vehicle will not be able to restart.

Purpose of the Invention The present invention has been made in view of such conventional problems.
The purpose of this is to make it possible to easily shift to a low pulley ratio without applying excessive pulley thrust if the pulley ratio has not returned to a low pulley ratio that allows restart when stopped.
An object of the present invention is to provide a downshift control method for a belt type continuously variable transmission.

Structure of the Invention In order to achieve the above object, the present invention has an input shaft connected to a primary shaft of a V-belt transmission, and a secondary shaft of the V-belt transmission connected to an output shaft via a power intermittent clutch. V
In a belt type continuously variable transmission, when the output shaft is in a stopped state and the pulley ratio of the V-belt transmission is higher than the allowable pulley ratio, the power intermittent clutch is disengaged and the V
The pulley ratio is shifted to the low side while the belt transmission is idling.

In other words, when the vehicle is stopped and unable to restart,
By disengaging the power intermittent clutch to cut off the power transmission from the output shaft system of the V-belt transmission, and shifting the pulley ratio to the low side while the V-belt transmission is idling, ■Easy transmission without applying excessive thrust to the belt. It is possible to shift to a low pulley ratio that allows restarting.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows an example of a V-belt type continuously variable transmission according to the present invention, in which the power of an engine 1 is transmitted to an input shaft 3 via a fluid coupling 2.
This input shaft 3 is connected to a primary shaft 7 of a V-belt transmission 6 via a reduction gear 4.5.

The V-belt transmission device 6 includes a drive-side pulley 8 provided on the secondary shaft 7, a driven-side pulley 12 provided on the secondary shaft 11, and a V-belt 14 wound between both pulleys. The drive pulley 8 has a fixed sheave 8a and a movable sheave 8b,
A thrust force commensurate with the input torque is applied to the movable sheave 8b by a thrust generating torque cam 9 and a torsion spring 10 provided behind the movable sheave 8b. on the other hand,
Similarly to the driving pulley 8, the driven pulley 12 also has a fixed sheave 12a and a movable sheave 12b.
A hydraulic chamber 13 that operates the movable sheave 12b in the axial direction by hydraulic pressure is provided behind the movable sheave 12b. This hydraulic chamber 1
The hydraulic pressure to the pump 3 is controlled by a hydraulic control device which will be described later.

A driven shaft 15 is rotatably inserted around the outer periphery of the secondary shaft 11, and the secondary shaft 11 and the driven shaft 15 are connected to each other by a power intermittent clutch 16. The engagement and engagement of this clutch 16 is also controlled by a hydraulic control device, which will be described later. A forward gear 17 and a reverse gear 18 are rotatably fitted onto the driven shaft 15, and either the forward gear 17 or the reverse gear 18 is connected to the driven shaft 15 by a forward/reverse switching device 19. It has become.

The reverse idle shaft 20 is arranged parallel to the driven shaft 15, and a reverse idle gear 21 that meshes with the reverse gear 18 and another reverse idle gear 22 are fixed to this shaft 20.

The counter shaft 23 is also arranged parallel to the driven shaft 15,
A counter gear 24 that simultaneously meshes with the forward gear 17 and the reverse idle gear 22 and a final reduction gear 25 are fixed to the counter shaft 23.
meshes with the ring gear 27 of the differential device 26 to transmit power to the output shaft 28.

FIG. 2 shows the hydraulic control device during downshift control, where 30 is a pulley control valve, 40 is a shift town control valve, 50 is a clutch control valve, 60 is a first solenoid valve, 61 is a second solenoid valve, and 62 is a An oil path 70 is a control circuit such as a microcomputer, and a line pressure is introduced from a hydraulic source.

The pulley control valve 30 has a spool 32 biased leftward by a spring 31.
Hydraulic pressure (solenoid pressure) controlled by turning on and off the first solenoid valve 60 is in the right end chamber 33 that accommodates the
is working. A port 35 to which line pressure is introduced and a drain port 36 are formed on both sides of a port 34 communicating with the hydraulic chamber 13 of the driven pulley 12. The port 34 communicating with the hydraulic chamber 13 communicates with the left end chamber 37 via a communication hole 32a formed inside the spool 32, so that the hydraulic pressure in the hydraulic chamber 13 is controlled when the first solenoid valve 60 is turned off ( When the solenoid pressure is 0FF), the hydraulic pressure is controlled to be low enough to balance the spring force of the spring 31, and when the first solenoid valve 60 is turned ON (the solenoid pressure is ON), the hydraulic pressure is balanced with the sum of the spring force of the spring 31 and the solenoid pressure. Controlled by high oil pressure.

The downshift control valve 40 has a spool 42 biased leftward by a spring 41, and the left end chamber 4
Hydraulic pressure (solenoid pressure) controlled by turning ON and OFF the second solenoid HALPRO 1 is led to 3. The downshift control valve 40 includes a boat 44 communicating with the bow +-35 of the pulley control valve 30, a boat 45 to which line pressure is introduced, a boat 46 communicating with the clutch control valve 50, and a drain boat 47. When the second solenoid HALPRO 1 is OFF (solenoid pressure is OFF), the spool 42 is at the left end position, the boats 45 and 46 are communicated, the drain ports 1 and 47 are closed, and the line pressure is controlled by the clutch. valve 5
0. In addition, at this time, the pulley control valve 30
Communication between the boats 44 and 45 leading to the pump is cut off, but the line pressure is acting on the boat 35 of the pulley control valve 30 through the orifice 48, so the oil pressure in the hydraulic chamber 13 does not become zero. . On the other hand, when the second solenoid HALPRO 1 is turned on (the solenoid pressure is turned on), the spool 42 moves to the right as shown in the figure, and the boats 44 and 45
The line pressure is communicated with the boolean control valve 30.
while the boat 46 communicates with a drain boat 47 to drain hydraulic pressure to the clutch control valve 30.

The clutch control valve 50 has a boat 51 at the right end that communicates with the boat 46 of the downshift control valve 40,
The spool 52 moves to the left against the spring 53 due to the hydraulic pressure acting on the boat 51, and the boat 54 is connected to the boat 54 to which line pressure is supplied and the boat 55 is connected to the clutch 16.
and the drain boat 56 are selectively switched. That is, when hydraulic pressure is not applied to the rightmost boat 51, the spool 52 is at the rightmost position as shown in the figure, and the boat 54 is closed and the boat 55 is closed.
and the drain port 56 are connected to the communication hole 52a of the spool 52.
The hydraulic pressure of the clutch 16 is drained and the clutch 16 is disengaged. On the other hand, when hydraulic pressure is applied to the boat 51 on the right end, the spool 52 moves to the left and the boats 54 and 55 communicate with each other, and the hydraulic pressure is introduced to the clutch 16, so that the clutch 16 is connected. Therefore, the clutch 16 is disengaged only when the second solenoid valve 61 is turned on, as shown in FIG.

The control circuit 70 has an input rotation speed N3 of the negative secondary shaft 7 and an output rotation speed N of the secondary shaft 11. , vehicle speed V (or rotational speed of the output shaft 28), foot brake brake signal, etc. are input as electrical signals, and the first solenoid valve 60 and the second solenoid valve 61 are turned on and off depending on the driving condition.
let Note that the control circuit 70 has an input rotation speed and an output rotation speed.

In addition to the vehicle speed signal and the brake signal, a shift position signal, a throttle opening signal, and the like may be input to comprehensively judge the driving state. In addition, the first solenoid valve 60 is not limited to simple ON/OFF control, but can also provide a pulse signal with a constant cycle including ON time and OFF time, and change the ratio of ON time to the cycle (duty ratio). Thus, so-called duty control may be performed in which solenoid pressure is generated approximately proportional to the duty ratio.

Here, an example of the control of the present invention by the control circuit 70 will be explained in the third example.
This will be explained according to the diagram.

First, when the operation starts, the input rotation speed N is input (8
0), output rotation speed N. Input (81), input vehicle speed (
82) and inputting a brake signal (83) in sequence. Next, it is determined whether the vehicle speed V is 0, that is, the vehicle is in a stopped state (84), and if ■≠0, it is determined that the vehicle is running, and normal shift control is performed (85). In normal speed change control (85), the second solenoid valve 61 is OFF, so the clutch 16 maintains the engaged state. On the other hand, if V=O, the vehicle is in a stopped state, so it is determined whether the brake signal is ON (the foot brake is stepped on) at this time (86)L, and if the brake signal is OFF, the normal When the brake signal is ON, the actual pulley ratio i and the control circuit 70
and the allowable pulley ratio i' stored in (87).

The pulley ratio i is the input rotation speed N input above and the output rotation speed N. (i = Nt /No), and the allowable pulley ratio i' is set based on the minimum pulley ratio (the highest pulley ratio) that allows the vehicle to restart when it stops on an uphill slope, For example, the speed is set to be equivalent to the second speed of a general stepped transmission.

If the pulley ratio i is larger than the allowable pulley ratio i' (on the low side), it is possible to restart the vehicle without executing the downshift control of the present invention, so the normal shift control (85) is performed. Do not disengage clutch 16.

Also, the pulley ratio i is smaller than the allowable pulley ratio i' (high side)
Since restarting is not possible when
), a large hydraulic pressure is supplied to the hydraulic chamber 13 to forcibly shift the effective diameter of the driven pulley 12 to the large diameter side, that is, the pulley ratio to the low side. At this time, since the clutch 16 is disengaged, the V-belt transmission 6 remains in an unloaded state and the engine 1
This allows the V-belt 14 to idle and quickly shift to a low pulley ratio without applying excessive side pressure to the V-belt 14.

The reason why the V-belt transmission 6 is shifted to the low pulley ratio while idling as described above is as follows. For example, V
If the belt is a metal belt, there is an oil film between the pulley and the belt, so if a large amount of oil pressure is applied to the hydraulic chamber 13 while the V-belt transmission is stopped, it will shift to the low side. is possible, but it requires a very large amount of oil pressure and has the problem of slow transition to the low side. In addition, if the V-belt is a rubber or resin belt, the pulleys and the belt are in frictional contact, so even if a large amount of hydraulic pressure is applied to the hydraulic chamber 13 when the V-belt transmission is stopped, the low side It is impossible to make the transition to 1, and this is a serious problem because the belt is subjected to large lateral pressure, which impairs the service life of the belt. In the present invention, since hydraulic pressure is applied to the hydraulic chamber 13 while the V-belt transmission device 6 is idling,
The V-belt shifts to the low side while rolling on the pulley surface, and can quickly shift to the low-pulley ratio without applying excessive hydraulic pressure to the hydraulic chamber 13. Also, the side pressure applied to the V-belt can be reduced, so the V The life of the belt can be improved.

In the above embodiment, an example was shown in which the V-belt transmission 6 was provided with a mechanical thrust adding device such as a torque cam 9 on the driving pulley 8, and a hydraulic chamber 13 was provided on the driven pulley 12. Alternatively, as in the conventional case, hydraulic chambers are provided in both the driving pulley and the driven pulley, line pressure is applied to one hydraulic chamber, and the hydraulic pressure in the other hydraulic chamber is controlled. It may be possible to perform a step change.

Further, in the downshift control of the above embodiment, the ON/OFF determination of the brake signal was made for the following reasons. That is, if the vehicle stops on a slope without pressing the foot brake, there is a risk that the vehicle will start moving if the clutch 16 is disengaged. It is designed to perform control.

Effects of the Invention As is clear from the above explanation, according to the present invention, a power intermittent clutch is provided in the output shaft system of a V-belt type continuously variable transmission, and when the pulley ratio is higher than the allowable pulley ratio when the vehicle is stopped. Since the clutch is disengaged, the boolean ratio can be shifted to the low side while the V-belt transmission is idling, and it is possible to quickly shift the boolean ratio to the low side without applying excessive side pressure to the V-belt. can. Therefore, even if the vehicle suddenly decelerates and stops, it can always be kept in a state where it can restart.

[Brief explanation of the drawing]

Fig. 1 is a skeleton diagram of an example of a belt-type continuously variable transmission according to the present invention, Fig. 2 is a configuration diagram of the hydraulic control device during downshift control, and Fig. 3 is a flowchart showing the downshift control. be. 3...Input shaft, 6...V Hell I/Transmission device, 7...
・-Next axis, 8... Drive side pulley, 11... Secondary axis,
12... Driven pulley, 13... Hydraulic chamber, 16...
・Power intermittent clutch, 28... Output shaft, 30... Pulley control valve, 40... Shift down control valve,
50...Clutch control valve, 60.61...Solenoid valve, 70...Control circuit. Applicant Daihatsu Motor Co., Ltd. Agent Patent Attorney Hidetaka Tsutsui Figure 1 J55-

Claims (1)

[Claims] (1) The input shaft is connected to the primary shaft of the V-belt transmission,
In a V-belt continuously variable transmission in which the secondary shaft of the V-belt transmission is connected to the output shaft via a power intermittent clutch, the output shaft is in a stopped state and the pulley ratio of the V-belt transmission is within the allowable pulley ratio. A shift down control method for a V-belt type continuously variable transmission, characterized in that when the ratio is on the high side, the power intermittent clutch is disengaged and the pulley ratio is shifted to the low side while the V-belt transmission is idling.