EP1021665A1

EP1021665A1 - Method and device for controlling the supply of an automatic transmission hydraulic actuators

Info

Publication number: EP1021665A1
Application number: EP98949039A
Authority: EP
Inventors: François LEORAT; Daniel Valentin
Original assignee: Renault SAS
Current assignee: Renault SAS
Priority date: 1997-10-10
Filing date: 1998-10-12
Publication date: 2000-07-26
Also published as: FR2769677A1; FR2769677B1; WO1999019644A1

Abstract

The invention concerns a method for controlling the supply of an automatic transmission with staged gear ratio, whereby each ratio upshift or downshift is obtained by draining a first actuator and filling a second actuator. The invention is characterised in that each actuator involved in a ratio shift can be in one of the following situations: empty or to be drained without any particular precaution; in active control phase to be filled in upshifting under a first pressure level PL; or in active control phase to be drained in upshifting or to be filled in downshifting under a second pressure level P2.

Description

PRQCEDE AND DEVICE FOR MONITORING

RECEPTOR FEEDING

HYDRAULICS OF A TRANSMISSION

AUTOMATIC

The present invention relates to the control of automatic transmissions with torque-shift stage ratios comprising at least one epicyclic gear train controlled by several hydraulic receivers according to information concerning the running of the vehicle equipped with the transmission.

It relates to an automatic transmission in which each change in up or down ratio is obtained by emptying a first receiver and filling a second receiver, provided for this purpose with a hydraulic distributor capable of selectively supplying the various receivers according to the principles of kinematic closed loop control.

Kinematic closed-loop control of gear changes in an automatic transmission can be implemented by directly supplying each receiver in the transmission with a high-flow modulating solenoid valve, allowing the entire filling or emptying flow of each receiver to pass through. . High-flow electrovalves are, however, relatively expensive control devices and bulky, so that their possibilities of integration into a hydraulic distributor are limited.

It has therefore been proposed to replace these solenoid valves with low flow solenoid valves, driving hydraulic amplifier drawers, each supplying a hydraulic receiver. The latter are less expensive than the previous ones, but their combination with hydraulic amplifiers poses the same problem of weight and bulk as the latter.

However, their systematic use is in particular hardly compatible with automatic gearboxes with a transverse front architecture with five forward gears, requiring the control of at least seven hydraulic receivers.

The present invention aims to reduce the number of low-flow modulating valves involved in controlling the filling and emptying of receivers in an automatic transmission.

It relates to a method of controlling the power supply to the receivers of an automatic transmission with stage reports, according to which each change in up or down ratio is obtained by emptying a first receiver and by filling a second receiver. According to this process, each receiver affected by a gear change can be in one of the following situations:

- empty or empty without special precautions,

- in active control phase for filling upstream passage under a first pressure PL, OR

- in active control phase for emptying in upward passage or filling in downward passage under a second pressure P2.

The measures proposed make it possible, in particular, to control in kinematic closed loop all changes of up and down gears in an automatic five-speed gearbox by limiting the number of modulating low-flow valves of the hydraulic distributor to two.

In accordance with the invention, the emptying and filling pressures of the hydraulic receivers which are swapped during a passage are controlled independently of one another.

Preferably, the pressures PL and P2 satisfy the following relationships:

pmini ξ P _{L and} 0 <P ₂ ^ PL

The invention also relates to a device for controlling the supply to the hydraulic receivers of an automatic transmission with stage ratios with torque shifting comprising at least one epicyclic gear train controlled by several hydraulic receivers according to information concerning the running of the vehicle. equipped with transmission.

This device is characterized in that at least two of the receivers are supplied through a first drawer with two positions, one of which unconditionally puts the receiver concerned in the cover, and the other connects it either at a first press PL, or at a second pressure P ₂ , depending on the position of a second drawer with two positions.

Other characteristics and advantages of the invention will appear clearly on reading the following description of an example of preferred, but not limiting, application thereof in the case of an automatic transmission with five forward gears, illustrated by the accompanying drawings, in which:

- Figures 1 and 2 represent the functional diagram and the RAVIGNEAUX diagram of the transmission in question, FIG. 2bis presents the switching table for this in steady state and for all transient states,

FIG. 3 shows in a simplified and nonlimiting manner a hydraulic distributor in accordance with the invention, and

- Figure 4 relates to the means for regulating the second modulated pressure P2 used in such a distributor.

The automatic transmission, the architecture of which is illustrated in FIG. 1, has on its input shaft 1 a simple double planetary gear 2, 3, the output of which attacks the input.

6 of an additional reduction gear 7. This five-speed gearbox actually consists of a basic four-speed gearbox 8, of the type with two clutches Ei, E2, and three brakes FI, F2, F3 , whose output 4 drives a simple reduction gear 7, active on the first three gears, and blocked on the fourth and fifth forward gears. The additional train 7 is controlled by a third clutch E3, a fourth brake F, and a free wheel RL, mounted in parallel with the brake F4, to simplify certain passages. The diagram in FIG. 2 illustrates the operation of this gearbox and the staging of the ratios, while the switching table in FIG. 2bis highlights the situation of all the hydraulic receivers Ei, E2 E3, Fi F2, F3, F , of the freewheel RL and of the flow absorber Abs in each stable state, N (neutral), 1 to 5 (forward gears), R (reverse) and in each transient state of the gearbox, Db ( with clutch disengaged), R / N, N / l, 1/2, 2/3, 3/4, 4/5, 5/3, 4/2, 3/1, 5/4, 4/3 , 3/2, 2/1, 1 / N, and N / R. In this table, X means that the receiver is active, but that its state does not change during the transition considered, the sign + means that the receiver is in the filling phase, and the sign - signifies that it is in the filling phase emptying.

As an example, we see that during the passage 1/2, Ei is in the emptying phase, E2 is in the filling phase, and F3 and F remaining filled (the X in the column RL indicating that the freewheel cooperates with non-preeminent way with brake F). Finally, it should be noted that the clutch E3 and the brake Fi are filled in parallel with the flow absorber during passages 3/4 and 4/5.

According to the known state of the art, it is known that to effect a 1/2 shift in accordance with this table, it is necessary to start by filling the clutch E2, then, at the appropriate time, drain the clutch Ei. More precisely, when the torque transmitted by E2 increases, the torque transmitted by Ei must decrease in the same proportion, until it vanishes at the point said "Freewheeling point". This point corresponds, with very little difference, to the maximum of the turbine speed reached during the passage. Consequently, it is advantageous to control the pressure drop in Ei as a function of the pressure rise in E ₂ to accompany the drop in the torque to be transmitted by El, as the pressure in E ₂ rises, and to cancel the pressure sent into Ei at the instant of the freewheeling point (identified by the maximum of the turbine speed), to completely release

To make a 2/1 shift, in accordance with the same table, on the contrary, it is necessary to drain the clutch E ₂ and fill the clutch Ei to tighten it just when the turbine reaches the new synchronism speed on the first gear, so that the torque can then be transmitted by Ei without slippage. It is therefore advantageous to pre-fill the clutch Ei in the docking configuration by means of reduced pressure during the acceleration phase of the turbine, so as to preposition the clutch in the docking position, then, at the instant of detection of synchronism on the first gear, to very quickly raise the pressure sent to Ei, so as to allow it to transmit the entire torque which falls to it.

In general, we can consider that a hydraulic receiver is either empty, or to be drained without special precautions, or in active control phase (controlled draining for an ascending passage, controlled filling for an ascending or descending passage).

On the switching table of FIG. 2bis, it can be seen that the receivers E ₂ , E3, Fi, are emptied only during descending passages, and filled only during ascending passages. Conversely, the receivers F ₂ and F ₄ are emptied only during ascending passages and filled only during descending passages.

It can also be seen that the receiver F3 is filled both during an ascending passage ((N / l), and during descending passages (4/2, 3/1, 3/2), and emptied both at the during an ascending passage (2/3) and a descending passage (1 / N), and that the Ei receiver is drained at the same time during ascending passages (declutching stopped, 1/2, 4 / 5) and descending passages (4/2, 3/2), and filled both during an ascending passage 2/3, and during descending passages 2/1, 5/3, 5/4.

As indicated above, the operation of the box illustrated in the figures assumes that each receiver can be placed in the following states: empty, emptying without special precautions, controlled emptying for a rising passage, or controlled filling for a passage descending. So that all the receivers in the box can meet these conditions, and in particular that the receivers Ei and F3 can meet the conditions imposed by all the situations described in the table, the invention provides that the hydraulic distributor delivers, depending on the circumstances, two pressures PL and P ₂ , which can be modulated independently of one another.

In accordance with the invention, these two pressures are directed to the receivers Ei and F3 in the following manner: controlled filling during rising passages under the first pressure PL, and controlled emptying during rising passages or filling during descending passages under the second pressure P ₂ .

This arrangement allows the receivers Ei and F3 to satisfy the state conditions mentioned above, as shown by the sequences marked with an arrow in the table in FIG. 2bis, where they must be supplied by the second pressure P, while that it is the first PL pressure which is involved in the other sequences in which these receptors are involved.

With reference to the above, the invention also provides that the two modulated pressures PL and P ₂ generated by the hydraulic system of the gearbox are defined by the following relationships:

- P ^mini -≤ P _L P ^max (i)

- 0 <P ₂ <P (ϋ) For ascending passages N / N + l (N = 1 to 4), the pressure in the receiver which is in the emptying phase is pressure P ₂ , except for passages for which the freewheel is active.

For the passage N / l, it is the pressure P ₂ , which ensures the filling of the clutch Ei.

For the upward passages N / N + 1 (N = 1 to 4), it is by the pressure PL that the receiver concerned is filled, alone or in parallel with the flow absorber or accumulator.

Finally, for N / Nl descending passages, the receiver which transmits the torque at the end of the passage, at the instant of synchronism, is supplied by the pressure P ₂ .

The pressure PL, OR line pressure, is a direct image of the turbine torque. Its variation can in particular be managed as indicated in publication EP 0 187 051, by a modulating solenoid valve, which establishes a modulated pressure on the differential section of a pressure regulating valve.

To establish the second pressure P ₂ , the means illustrated in FIG. 4 can be used without limitation, comprising a modulating solenoid valve 9, supplied by a constant pressure P3, and delivering a modulated pressure P _m2 , the value of which is determined in real time by the automatic transmission computer (not shown). The pressure P _m2 is directed to the large diameter end 11 of a regulating slide 12. The pressure PL is directed to a first chamber 13 associated with the slide 12, so that the second bearing 14 of the latter forms with a second chamber 16 a regulating lip 17, making it possible to create the second pressure P ₂ : in fact, the second chamber 16 is placed in communication with a third chamber 18, into which opens the small diameter end 19 of the drawer 2. In a fourth chamber 21, a spring 22 cooperates with the thrust exerted by the pressure P on the end of small diameter 19.

According to the invention, the relation (ii) is verified for example by choosing

To representing the tare in place of the spring 9, and S / s the ratio of the end sections of the drawer 2. We then have:

There are thus two pressures PL and P _{2 which} can be modulated at will independently of one another: this particularity allows the draining and filling pressures of the hydraulic receivers to be controlled independently of one another which are swapped during a shift, a necessary condition for making all gear changes in kinematic closed loop.

Referring again to passages 1/2 and 2/1, it can be noted that the invention provides for the pressure P ₂ in Ei to drop in a controlled manner to the maximum turbine speed during passage 1/2. For the passage 2/1, it plans on the contrary to pre-fill the clutch Ei with a low value of P ₂ and then to very quickly raise the pressure P ₂ to the value PL, when the point of synchronism of the first gear is reached.

As shown in Figure 4, each receiver Ei and F3 is supplied through a two-position receiver drawer B and D. The drawer B is actuated by an all-or-nothing solenoid valve (not shown). According to the invention, one of the two positions of the drawers B and D connects the receiver concerned to the cover (emptying position without any special precautions), while its other position connects the receiver concerned to the outlet of another drawer Q with two positions, the output in question being connected, depending on the position of the drawer Q (also actuated by an all-or-nothing solenoid valve) either at pressure PL or at pressure P ₂ . In conclusion, we see that:

- by generating two modulated pressures, PL and P ₂ , as defined by relations (i) and (ii), and

- by supplying certain receivers through a drawer with two positions, one of which unconditionally puts the receiver in the tank, and the other connects it, either to the pressure PL, or to the pressure P2, depending on the position d '' a second drawer with two positions,

it is possible to make all the gear changes of an automatic gearbox, according to the principle of kinematic closed loop control.

The control method proposed by the invention is applicable to any type of automatic gearbox, whatever the kinematics of its planetary gear. Its implementation simply assumes compliance with the principle of the arrangement of distribution drawers illustrated with the aid of FIG. 3, with reference to a gearbox with five forward gears. We have seen, in fact, that the measures specific to this process only concern the receivers El and F3 of this box, because they are the only ones to have to receive, depending on the circumstances, one or the other of the pressures PL and P, the other receptors (for example E ₂ or F in the example described) not requiring respect for themselves of such a arrangement, because they are caused to receive only one or the other of these two pressures.

Finally, it should be remembered that the invention finds a particularly advantageous application in a gearbox having a declutching function when stationary, according to which a clutch is slid in a controlled manner in the position of first gear to achieve declutching at stopping, since it then suffices to supply this clutch with the second pressure P.

Claims

[1] Method for controlling the supply of the receivers of an automatic transmission with step ratios, according to which each change of up or down gear is obtained by emptying a first receiver and filling a second receiver, characterized in that two distinct modulated pressures PL and P ₂ are generated and in that each receiver affected by a change of gear can find itself in one of the following situations:

- empty or to be drained without special precautions,

- in the active control phase for filling in the rising passage under the first pressure PL, OR - in the active control phase for emptying in the rising passage or filling in the descending passage under the second pressure P ₂ .

[2] Control method according to claim 1, characterized in that the draining and filling pressures of the hydraulic receivers which are swapped during a passage, are controlled independently of each other.

[3] Control method according to claim 1 or 2, characterized in that the two pressures PL and P ₂ satisfy the following relationships: pmini < p _L <pmaxi _{) and}

[4] Control method according to claim 1, 2 or 3, characterized in that the first pressure PL is a line pressure, the value of which depends directly on the turbine torque, while the second pressure P ₂ is obtained by directing the first pressure PL through a controlled regulation drawer.

[5] Control method according to one of the preceding claims, characterized in that for the upward passages N/N+l, the pressure in the drained receiver is the second pressure P ₂ , except for the passages for which the freewheel is activated.

[6] Control method according to one of the preceding claims, characterized in that for the passage N/l, the filling of the receiver concerned is ensured by the second pressure P ₂ .

[7] Control method according to one of the preceding claims, characterized in that the filling of the receiver concerned for the rising passages N/N+l, on the first four gears of the transmission, the filling of the receiver concerned is ensured by the first pressure PL.

[8] Control method according to one of the preceding claims, characterized in that for the passages descendants N/Nl filling of the receiver concerned is ensured by the second pressure P.

[9] Control method according to one of the preceding claims, characterized in that the clutch which it is desired to slide into the first gear position to disengage when the transmission stops, is powered by the second pressure P ₂ .

[10] Device for controlling the supply of the hydraulic receivers of an automatic transmission with step-by-step ratios under torque comprising a hydraulic distributor and at least one epicyclic gear train controlled by several hydraulic receivers according to information concerning the operation of the vehicle equipped with the transmission, characterized in that the distributor delivers two distinct modulated pressures, and in that at least two of the receivers are supplied through a first drawer with two positions, one of which unconditionally places the receiver concerned to the tarpaulin, and the other connects it either to the first pressure

PL, or at the second pressure P, depending on the position of a second two-position drawer.

[11] Control device according to claim 9, characterized in that the first two-position drawer and/or the second two-position drawer are actuated by on-off solenoid valves.