FR2769677A1 - Feed control of hydraulic operators in vehicle automatic transmission - Google Patents

Abstract

The hydraulic feed for changing up or changing down gears is obtained by emptying the first operator and filling a second operator which control the clutches (E1,E2,E3) or the band brakes (F1,F2,F3,F4). The gear change can be found in one of the following conditions: a) emptying or empty without any particular control, b) in phase with active control for its filling in changing up under the pressure PL, c) in phase with active control for its emptying in changing up or refilling in changing down under a second pressure P2.

Description

METHOD AND DEVICE FOR CONTROLLING
RECEPTOR FEEDING
HYDRAULICS OF AN AUTOMATIC TRANSMISSION
The present invention relates to the control of automatic transmissions with stepped torque-shift reports 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 solenoid valves are however relatively expensive and bulky control devices, 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 stepped 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 method, 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 in
rising passage under a first pressure PL, OR
- in active control phase for emptying in transit
amount or filling in passage descending 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

The invention also relates to a device for controlling the supply to the hydraulic receivers of an automatic transmission with stepped torque-shifted reports 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 P2, as a function of 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 show the block diagram and
the RAVIGNEAUX diagram of the transmission in
question,
- Figure 2bis shows the switching table of that
here in steady state and for all schemes
transient,
- Figure 3 shows in a simplified way and not
limiting a hydraulic distributor conforming to
the invention, and
- Figure 4 relates to the means for regulating the
second modulated pressure P2 implemented 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 4 of which attacks the input 6 of an additional reduction gear 7. This gearbox five-speed gearbox is actually made up of a basic four-speed gearbox 8, of the type with two clutches E1,
E2, and three brakes F1, F2, F3, the output of which 4 drives a single reduction gear 7, active on the first three gears, and locked on the fourth and fifth forward gears. The additional train 7 is controlled by a third clutch E3, a fourth brake F4, 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 reports, while the switching table in FIG. 2bis highlights the situation of all the hydraulic receivers E1, E2 E3, F1-F2,
F3, F4, 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 (clutch disengaged when stopped), R / N, N / 1, 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, E1 is in the emptying phase, E2 is in the filling phase, and F3 and F4 remaining filled (the X in the column RL indicating that the freewheel cooperates with non-preeminent way with the brake
F4). Finally, it should be noted that the clutch E3 and the brake F1 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 E1. More precisely, when the torque transmitted by E2 increases, the torque transmitted by E1 must decrease in the same proportion, until it vanishes at the point known as the 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 E1 as a function of the pressure rise in E2 to accompany the fall in the torque to be transmitted by El, as the pressure rises in E2, and d '' cancel the pressure sent to
E1 at the instant of the freewheeling point (identified by the maximum turbine speed), to completely release
E1.

To carry out a 2/1 shift, in accordance with the same table, on the contrary, it is necessary to drain the clutch E2 and fill the clutch E1 to tighten it just when the turbine reaches the new synchronism speed on the first gear, so to then be able to transmit the torque by E1 without sliding. It is therefore advantageous to pre-fill the clutch E1 in the docking configuration by means of a reduced pressure during the acceleration phase of the turbine, so as to preposition the clutch in the docking position, then, at the instant of synchronism detection on the first gear, to very quickly increase the pressure sent to E1, so as to allow it to transmit the entire torque which falls to it.

In general, it can be considered that a hydraulic receiver is either empty or to be drained without special precautions, or in the 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 E2, E3, F1, are emptied only during descending passages, and filled only during ascending passages. Conversely, the receivers F2 and F4 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 / 1), 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 receiver E1 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 E1 and F3 can meet the conditions imposed by all the situations described in the table, the invention provides that the hydraulic distributor delivers according to the circumstances two pressures PL and P2 adjustable independently of one another.

In accordance with the invention, these two pressures are directed to the receivers E1 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 P2.

This arrangement allows the receivers E1 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 P2, 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 P2 generated by the hydraulic system of the gearbox are defined by the following relationships

For the upstream passages N / N + 1 (N = 1 to 4), the pressure in the receiver which is in the emptying phase is the pressure
P2, except for passages where the freewheel is active.

For the passage N / 1, it is the pressure P2, which ensures the filling of the clutch E1.

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 / N-1 descending passages, the receiver which transmits the torque at the end of the passage, at the instant of synchronism, is supplied by pressure P2.

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 P2, 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 Pin2, the value of which is determined in real time by the automatic transmission computer (not shown). The pressure Pm2 is directed to the large-diameter end 11 of a regulation drawer 12. The pressure PL is directed to a first chamber 13 associated with the drawer 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 P2: in fact, the second chamber 16 is placed in communication with a third chamber 18, into which the small diameter end 19 of the drawer 2 opens. In a fourth chamber 21, a spring 22 cooperates with the thrust exerted by the pressure P2 on the end of small diameter 19.

To représentant la tare en place du ressort 9, et S/s le rapport des sections extrêmes du tiroir 2. On a alors

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 P2 which can be modulated at will independently of one another: this feature makes it possible to control independently the draining and filling pressures of the hydraulic receivers which are swapped during one shift, a necessary condition for making all gear changes in a kinematic closed loop.

Referring again to passages 1/2 and 2/1, it can be noted that the invention provides for the pressure P2 in E1 to drop in a controlled manner to the maximum turbine speed during passage 1/2. For the 2/1 shift, it plans on the contrary to pre-fill the clutch E1 with a low value of P2 and then to raise the pressure P2 very quickly to the value PL, when the point of synchronism of the first gear is reached.

As shown in Figure 4, each receiver E1 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 P2.

In conclusion, we see that:
- by generating two modulated pressures, PL and P2, such
as defined by relations (i) and (ii), and
- by supplying certain receivers through a drawer
two positions, one of which unconditionally puts the
receiver to the tarp, and the other connects it, either to the
pressure PL, or at pressure P2, depending on the
position of 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 P2 the other receivers (for example E2 or F2 in the example described) not requiring for themselves the respect of such an arrangement, because they are only led to receive one or the other of these two pressures .

Finally, it must be rei-enir 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 the declutching when stationary, since it then suffices to supply this clutch with the second pressure P2

Claims (1)

 CLAIMS [1] Receiver power control method  an automatic transmission with stepped reports, according to  which each amount shift or  descending is obtained by emptying a first  receiver and filling a second receiver,  characterized in that each receiver affected by a  gear change can be found in one of  following situations  - empty or empty without special precautions,  - in active control phase for filling in  rising passage under a first pressure PL, OR  - in active control phase for emptying in transit  amount or filling in passage descending under  a second pressure P2. [2] Control method according to claim 1, characterized  in that the discharge 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 P2  satisfy the following relationships

   [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 P2 is  obtained by directing the first pressure PL through  a controlled regulation drawer. [5] Control method according to one of claims  previous, characterized in that for passages  amounts N / N + 1, the pressure in the drained receiver  is the second pressure P2, except for the passages for  which the freewheel is active. [6] Control method according to one of claims  above, characterized in that for passage N / 1,  filling of the receiver concerned is ensured by the  second pressure P2. [7] Control method according to one of claims  previous, characterized in that the filling of the  receiver concerned for upward passages N / N + 1,  on the first four reports of the transmission, the  filling of the receiver concerned is ensured by the  first press PL. [8] Control method according to one of claims  previous, characterized in that for passages  descendants N / N-1 filling the receiver concerned  is ensured by the second pressure P2. [9] Control method according to one of claims  previous, characterized in that the clutch which  wish to drag to first gear position  to disengage when the transmission stops,  is supplied by the second pressure P2. [10] Receiver power control device  hydraulics from an automatic transmission to  stepped reports with passage under torque comprising at  minus a planetary gear train controlled by  several hydraulic receivers according to  information concerning the running of the equipped vehicle  transmission, characterized in that at least two  receivers are powered through a first  drawer with two positions, one of which  unconditionally the receiver concerned with the tarpaulin,  and the other connects it either to a first pressure PL,  either at a second pressure P2, depending on the position  a second drawer with two positions. [11] Control device according to claim 9,  characterized in that the first two-position drawer  and / or the second two-position drawer are operated by  all or nothing solenoid valves.