JPS62275847A - Starting clutch controlling method for automatic transmission - Google Patents

Abstract

PURPOSE:To simplify starting control by moving in parallel and using a transmission characteristic in a starting process as it is for a regular transmission torque after the engine speed at that time, in a device having a slide type starting clutch. CONSTITUTION:A V-belt type continuously variable transmission 10 can vary the effective diameter of a pulley by controlling the supply of hydraulic pressure to a hydraulic pressure chamber 18 provided at the back of the movable sheave 14b of a driven pulley 14, to carry out continuous variation. And, a wet multiple disk starting clutch 20 is coaxially provided with the driven pulley 14 on a driven shaft 13 on which the pulley 14 is provided and, by controlling this starting clutch 20, transmission torque can be optionally controlled. In this case, the transmission torque of the starting clutch 20 at the time of idling is controlled so as to be nearly equal to the transmission torque at the time of regular idling engine speed. And, a transmission torque characteristic in a starting process is moved in parallel as it is and used for a regular transmission torque characteristic after the engine speed at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a starting clutch control method for an automatic transmission, and particularly to a starting clutch control method from an idle-up state.

Conventional technology and its problems Traditionally, automatic clutches such as fluid couplings and centrifugal clutches have been widely used as starting clutches in automatic transmissions, but fluid couplings have large transmission losses during normal driving.
Furthermore, in the case of a centrifugal clutch, the transmission torque characteristics depend only on the engine speed, so a complete neutral state cannot be obtained.

Therefore, by using an electromagnetic powder clutch or a wet multi-disc clutch and electronically controlling the transmission torque, we are able to achieve smooth starting performance similar to an automatic clutch, reduce transmission loss, and further expand the degree of freedom in control. A similar method has also been proposed.

By the way, when an electromagnetic powder clutch or a wet multi-disc clutch as described above is used as a starting clutch, the fluid coupling is used during idling in order to improve responsiveness during starting and to reduce stiffness when the clutch is engaged. It is thought that a similar leap (drag) phenomenon can be caused. In this case, when idling normally, the engine speed is low (and the creep force is small, so it is not a problem, but if you use an air conditioner or increase the idle with a choke in cold weather), the creep force will increase and you will not be able to press the accelerator pedal. There is a risk that the vehicle will suddenly start off.
When starting from an idle up state, the engine speed is higher than normal, so it is impossible to start with the normal starting characteristics, and it is necessary to perform start control specifically for when the idle is up. The problem is that it becomes more complicated.

OBJECT OF THE INVENTION The present invention has been made in view of the above problems, and its purpose is to provide a starting clutch control for an automatic transmission that prevents sudden starting when the idle is up and also simplifies starting control from the idle up state. The purpose is to provide a method.

Structure of the Invention In order to achieve the above-mentioned object, the present invention provides an automatic transmission equipped with a slip-type starting clutch capable of arbitrarily controlling transmission torque, and in which the starting clutch generates a creep state during idling. The transmission torque of the starting clutch is controlled so that it is almost equal to the transmission torque at normal idling speed, regardless of the engine speed at that time, and the transmission torque characteristics during the starting process are controlled to be equal to the transmission torque at the normal idling speed, regardless of the engine speed at that time. This is to use the normal transmission torque characteristics of , which are directly translated in parallel.

In other words, by controlling the transmission torque of the starting clutch to be approximately equal to that during normal idling when the engine is idling up, a sudden start during idling up can be prevented, and when starting from an idling up state, the normal starting characteristics can be utilized. This simplifies control.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows a V-belt continuously variable transmission which is an example of an automatic transmission 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. . A wet type direct coupling clutch 5 and a rotatable direct coupling drive gear 7 are provided on the input shaft 4, and the direct coupling clutch 5 connects the direct coupling drive gear 7 to the input shaft 4 during direct coupling drive by a hydraulic control device to be described later. It is supposed to be done.

An external gear 8 is fixed to the end of the input shaft 4, and this external gear 8 meshes with an internal gear 9 fixed to the drive shaft 11 of the continuously variable transmission 10 to transfer the power of the input shaft 4. The speed is decelerated and transmitted to the drive shaft 11.

The continuously variable transmission 10 is composed of a driving side boot 2 provided on a drive shaft 11, a driven pulley 14 provided on a driven shaft 13, and a V-belt 15 wound between both the boots. The drive pulley 12 has a fixed sheave 12a and a movable sheave 12b.
A torque cam device 16 and a compression spring 17 are provided behind the movable sheave 12b.

The torque cam device 16 generates a thrust proportional to the input torque, and the compression spring 17 generates an initial thrust sufficient to prevent the V-belt 15 from loosening.
5 is given the belt tension necessary for torque transmission. On the other hand, similarly to the drive side pulley 14, 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. There is. The hydraulic pressure to this hydraulic chamber 18 is controlled by the hydraulic control device described below.

A hollow shaft 19 is rotatably fitted around the outer periphery of the driven shaft 13, and the driven shaft 13 and the hollow shaft 19 are connected and connected by a starting clutch 20 consisting of a wet multi-disc clutch. The starting clutch 20 also serves as a power intermittent clutch, and is engaged by a hydraulic control device to be described later during belt drive (continuously variable speed drive), disconnected during direct drive, and duty-controlled during start. The hollow shaft 19 has a forward gear 2.
1 and a reverse gear 22 are rotatably supported, and either the forward gear 21 or the reverse gear 22 is connected to the hollow shaft 19 by a forward/reverse switching sleeve 23. The idler shaft 24 for reverse movement is the driven shaft 13
This shaft 24 has a reverse gear 2.
A reverse idler gear 25 meshing with the reverse idler gear 26 and another reverse idler gear 26 are fixed. A counter shaft 27 is also arranged parallel to the driven shaft 13.
7 includes 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, and the final reduction gear 29 meshes with the ring gear 31 of the differential device 30 to transmit power to the output shaft 32.

In the transmission having the above configuration, a direct coupling clutch 5°, a direct coupling drive gear 7, a counter gear 28. The final reduction gear 29 and the differential device 30 constitute a direct drive path, and the external gear 8. Internal gear9. Continuously variable transmission 10, starting clutch 2
0. Forward gear 21. Counter gear 28. Final reduction gear 2
9 and the differential device 30 constitute a belt drive path. Then, the input shaft 4 in the direct drive path
The direct transmission ratio between the input shaft 4 and the output shaft 32 is set to be approximately the same as the maximum speed ratio between the input shaft 4 and the output shaft 32 in the belt drive path.

FIG. 2 shows a hydraulic control device that controls the hydraulic pressure of the hydraulic chamber 18, the starting clutch 20, and the direct coupling clutch 5, where 40 is a solenoid valve for speed change control, 50 is a solenoid valve for starting control, and 60 is a solenoid valve for direct coupling control. , 70
is a control circuit such as a microcomputer.

The solenoid valve 40 for speed change control has the structure shown in FIG.
An output boat 43 that outputs u'r and a drain boat 44
is formed. A magnetic ball 46 that selectively opens and closes the input boat 42 and the drain boat 44 is movably housed in the central valve chamber 45 . This ball 46 normally closes the input boat 42 by a spring 47, and when an excitation current flows through the coil 4, the ball 46
moves to the right in FIG. 3 to open the input boat 42 and close the drain boat 44.

The solenoid valve 50 for start control and the solenoid valve 60 for direct connection control have exactly the same structure as the solenoid valve 40 for speed change control, and are also denoted by the reference numerals corresponding to those in FIG. 3. That is, 51.61 is the valve body, 5
2.62 is an input boat leading to the hydraulic power source, 53.63 is an output boat leading to the starting clutch 20 and direct coupling clutch 5, respectively, 54.64 is a drain boat, 55.65 is a valve chamber, 56.66 is a ball, 57. 67 is a spring, 5
8 and 68 are coils.

The control circuit 70 receives the engine rotation speed, output rotation speed of the output shaft 32 (or vehicle speed), throttle opening θ, brake signal, position switch signal, etc. from a sensor (not shown), and controls the solenoid valve according to the operating state. 40,5
0.60 is controlled by the deutei.

Now, assuming that the duty ratio of the control signal output from the control circuit 70 to the solenoid pulps 40, 50, 60 is D, the output oil pressure of the solenoid pulps 40, 50, and 60 is P.

is given by pHlIr; PL -D, and since PL (line pressure) is a constant value, the output oil pressure pHlIT is controlled only by the duty ratio. Therefore, the transmission ratio of the continuously variable transmission 10 and the transmission torque of the starting clutch 20 and the direct coupling clutch 5 are controlled by the control circuit 7.
It can be freely controlled by the duty ratio output from 0 to each solenoid pulp 40, 50, and 60. Note that the duty ratio of each solenoid pulp 40, 50, 60 in the operating state is stored in the control circuit 70 as, for example, a data map.

The overall operation of the hydraulic control system having the above configuration will be explained with reference to the shift diagram shown in FIG. 4.

First, during normal starting, the starting clutch 20 is gradually engaged from point A, and when reaching point B, the starting clutch 20 is maintained in the engaged state and the starting control is shifted to shift control. In shift control, first, acceleration is performed along the straight line of the lowest speed ratio, and when the input rotation speed N reaches the target input rotation speed NE corresponding to the throttle opening at that time, the shift region is entered, and the target input rotation speed N, Shift to the high speed ratio side while maintaining . When the gear ratio reaches the maximum speed ratio, that is, the direct coupling transmission ratio (point D), the starting clutch 20 is disconnected and the direct coupling clutch 5 is engaged, thereby shifting to direct coupling drive. Hydraulic chamber 1 in direct drive
Since the hydraulic pressure of 8 is drained, the continuously variable transmission 10 is maintained at the highest speed ratio and continues to idle. In addition, in order to reduce torque loss during idling, the idling medium heat stage transmission 10 may be shifted to an intermediate pulley ratio.

In addition, if an abnormal situation occurs such as damage to the belt 15 or failure of the starting clutch 20 itself or the starting control solenoid valve 50, it is impossible to start using the continuously variable transmission path as described above. Make an emergency start depending on the route. In this case, as shown by the broken line in FIG. 4, the starting clutch 2o is maintained in a disengaged state, and the direct coupling clutch 5 is gradually engaged while moving from point A to point B° to perform emergency starting control. After reaching point B°, the direct coupling clutch 5 is maintained in the engaged state, and the vehicle accelerates along the straight line of the direct coupling transmission ratio.

As shown by the solid line in Figure 5, the transmission torque characteristic of the starting clutch 20 is almost proportional to the square of the engine speed, similar to a fluid coupling or a centrifugal clutch, and is designed to provide smooth starting performance. There is.

In addition, in the low rotation range near the idle rotation speed N1, low oil pressure is introduced so that the starting clutch 2o generates a low transmission torque T, with the aim of improving responsiveness during starting and preventing shock when the clutch is engaged. It has been adjusted to produce a creep phenomenon. Note that the neutral range (P,
In the N range), no hydraulic pressure is introduced to the starting clutch 20, and the starting clutch 20 is in a completely disconnected state.

By the way, at the time of idling up, the idling speed increases to, for example, N2, so if the transmission torque T2 corresponding to N2 is generated, there is a problem of sudden start. Therefore, in the present invention, even when the idle speed is as high as N2, the starting clutch 20 is configured to generate the same low transmission torque T as during normal idling, as shown at point E in FIG. It's in control. Therefore, when switching from the neutral range to the power range, starting is always started from a low transmission torque T, and sudden starting can be prevented.
The transmission torque characteristics from when the starting clutch 20 starts to engage until it is fully engaged are controlled to the characteristics from point E to point F as shown by the broken line in Figure 5, and this characteristic is similar to that during normal starting. Of the transmission torque characteristics (solid line in FIG. 5), the curve from the 0 point to the H point corresponding to the idle rotation speed N2 is directly translated downward. therefore,
Since the data map shown in the solid line in Figure 5 can be used as is,
There is no need to set a separate data map for idle up in the control circuit 70, and the engagement point (F point)
Since there is almost no difference between the engine speed at the normal engagement point (H point) and the normal engagement point (H point), it is possible to prevent an excessive increase in the engine speed and the accompanying wear and tear of the starting clutch 20.

Next, an example of a method of controlling the starting clutch 20 according to the present invention will be explained with reference to FIG.

When the control starts, first the shift position goes up, then the L
, R etc. 80)
, if it is not in the power range, return it as is,
If it is in the power range, then it is determined whether the throttle opening is fully closed (81).

When fully closed, the next step is to determine whether the vehicle speed is below the minute value V1 (82), and if it is below 1, it is in the idling state, so read the idle rotation speed Nl at that time (83).
Regardless of the idle speed N, the starting clutch 20 outputs a duty ratio for generating the normal transmission torque T to the starting control solenoid valve 50 (84), while the vehicle speed When is larger than ■1, it means that the vehicle is decelerating or coasting, so the shift control is performed (85) and the starting flange 20 is maintained in the engaged state. In addition, if the throttle opening is not fully closed when determining (81), then compare the vehicle speed with the set value ■2 (for example, V2 = 5 km/b and V2 > v, 86), and then compare the vehicle speed with the set value V2. If it is larger, it means that the start has been completed and the acceleration is running, so (85
), the starting clutch 20 is maintained in the Eso gauge state and shift control is started. Also, if the vehicle speed is less than the set value V, it means that it is in the process of starting, so (83
) is the idle speed N read in.

is read out (87), a duty ratio corresponding to this idle rotation speed N1 is calculated using the following equation, and outputted to the start control solenoid valve 50 (88).

D-Da-A In the above equation, D is the normal duty ratio for generating the transmission torque along the solid line in FIG. 5, and A is given by the following equation.

A=a (N(2N)") a; Quadratic coefficient N1 of the curve shown by the solid line in Figure 5: Normal idle rotation speed In other words, the transmission torque characteristic at idle up is as shown by the broken line in Figure 5. Since the regular transmission torque characteristics (point G to point H) are used as they are, for example, when the idle rotation speed N, = N, A, = 0, and the duty ratio output to the solenoid valve 50 for start control. D”D
a, and the vehicle starts according to the transmission torque characteristics shown by the solid line in Figure 5. Also, when the idle speed N, = N2, A =
Since a (N22-N,'), A>0,
The duty ratio output to the start control solenoid valve 50 is a value A lower than the normal duty ratio D2, and the vehicle starts according to the transmission torque characteristic shown by the broken line in FIG.

In the above embodiment, the gear ratio of the continuously variable transmission 10, the transmission torque of the starting clutch 20 and the direct coupling clutch 5 are determined by the solenoid valves 40, 50, 601! With your body? Although we have shown an example in which the control is controlled by a spool valve, it is not fixed to this, and may be controlled by a combination of a solenoid valve and a spool valve. In this case, the solenoid valve is connected to the input boat and the drain boat by a pole-shaped valve body. In addition to the method of selectively opening and closing the valve, a needle type solenoid valve may also be used.

Further, as the starting clutch 20, an electromagnetic powder clutch can be used instead of a wet multi-disc clutch, and in this case, the transmission torque can be directly controlled by an electric signal, so the configuration can be simplified.

Further, in the present invention, the transmission is not limited to a continuously variable transmission such as a V-belt type continuously variable transmission or a toroidal type continuously variable transmission, but also a general idling gear type automatic transmission can be used.

Effects of the Invention As is clear from the above explanation, according to the present invention, the transmission torque of the starting clutch in the creep state is always controlled to the transmission torque at the normal idle speed, regardless of whether it is normal or idle up. , the creep force is controlled to be almost constant, which solves the problem of sudden acceleration even when the accelerator pedal is not pressed when idling up. In addition, i! l Since the normal starting characteristics are shifted in parallel and used, there is no need to perform special starting control during idle amplifier, simplifying the control, and adjusting the engine speed at the starting clutch engagement point to normal engagement. Since the engine speed can be made so that there is almost no difference from the engine speed at the point, the engine speed does not rise needlessly, and wear and tear of the starting clutch can be prevented.

[Brief explanation of drawings]

Figure 1 is a skeleton diagram of an example of a V-belt continuously variable transmission to which the present invention can be applied, Figure 2 is a circuit diagram of a hydraulic control device, Figure 3 is a structural diagram of a solenoid valve, and Figure 4 is a shift line. figure,
FIG. 5 is a transmission torque characteristic diagram of the starting clutch, and FIG. 6 is a flowchart of an example of a starting clutch control method. DESCRIPTION OF SYMBOLS 1... Engine, 4... Input shaft, 10... Continuously variable transmission, 15... V-belt, 18... Hydraulic chamber, 20
...Starting clutch, 32...Output shaft 1.50...
Solenoid valve for starting control, 70...control circuit. Applicant: Daihatsu Motor Co., Ltd. Representative: Patent Attorney Hidetaka Tsutsui Figure 3 Vehicle speed engine cape 1, EN Figure 6

Claims (1)

[Claims] (1) In an automatic transmission equipped with a slip-type starting clutch that can arbitrarily control the transmission torque, and in which the starting clutch generates a creep state during idling, the transmission torque of the starting clutch during idling is calculated from the engine at that time. Regardless of the engine speed, the transmission torque is controlled so that it is almost equal to the transmission torque at the normal idling speed, and the transmission torque characteristics during the starting process are shifted in parallel with the normal transmission torque characteristics after the engine speed at that time. A starting clutch control method for an automatic transmission, characterized in that the method is used.