FR2638402A1 - Improved device for controlling a hydraulic automatic gearbox, particularly for a motor vehicle - Google Patents

Abstract

This device is characterised in that it includes means 1, 2, 3 for selecting the position of the gearbox, namely the main operating mode of this gearbox P, R, N, D, and the authorised ratios in forward gear "3", "2", "1", connected to a central unit 6 for processing data and controlling means 7 for displaying the selected position of the gearbox, that is to say of the main operating mode and/or of the maximum authorised ratio in forward gear and of an electric motor 8 with two directions of rotation for positioning a slide valve for selecting the position of the gearbox.

Description

 The present invention relates to an automatic gearbox control device, in particular for a motor vehicle.

The control devices known in the prior art comprise selection levers extending, for example, from the vehicle floor, and making it possible to choose the operating mode of the transmission. These levers allow you to select different positions. namely for example for a four-speed gearbox
- a parking position P. in which the transmission is disengaged and mechanically blocked so as to have a parking brake.

 - a reverse position R.

- a neutral N position in which the transmission is disengaged,
- a forward position D in which the four gears are authorized.

- a forward position 3. in which the fourth forward gear is prohibited,
- a forward position 2 in which the third and fourth forward gear ratios are prohibited, and
- a forward position 1 in which the first gear is imposed.

 It is therefore understandable that the lever must be able to be moved into these positions, which poses a certain number of handling problems.

 In order to overcome these difficulties in manipulating the lever, car manufacturers often use devices such as the use of lateral or vertical baffles with an esca motable lock, in order to improve the ease and speed of manipulation of these levers, various devices are sometimes supplemented by mechanical and / or light repeaters placed in a position such that they are easily perceptible by the driver.

 Furthermore, the connection between the lever and the gearbox is carried out using an expensive cable and requiring extremely precise adjustment.

 In fact, this cable is connected at one of its ends to the lever and at the other of the ends to a set of gears actuating a drawer for selecting the position of the gearbox.

 It is therefore understandable that the various devices of the state of the art have a relatively complex structure which is difficult to implement.

 The object of the invention is therefore to solve these problems and take advantage of the functional independence between the main modes of operation of the gearbox, namely the parking positions.

reverse, neutral and forward on the one hand, and the selection of authorized gears in forward on the other. so as to offer a simpler solution than those currently used.

 Another object of the invention is to propose an electromechanical system for controlling the gearbox which is simple. reliable. a low cost price which replaces the selection lever.

to the cable and to the set of gears described above for the actuation of the gearbox position selection drawer.

 To this end, the invention relates to a device for controlling an automatic hydraulic gearbox. especially for a motor vehicle.

characterized in that it comprises means for selecting the position of the gearbox. namely the main mode of operation thereof, parking. reverse. neutral and forward. and reports authorized in forward gear, connected to a central unit for processing information and controlling means for displaying the selected position of the gearbox, that is to say the main operating mode and / or of the maximum authorized ratio in forward and of a two-direction electric motor of rotation of positioning of a drawer for selecting the position of the gearbox,
Advantageously. the electric motor has an output shaft connected by a rack and pinion system to the gearbox position selection drawer.

The invention will be better understood with the aid of the description which follows, given solely by way of example and made with reference to the appended drawings, in which
- Fig.1 shows a block diagram of an automatic gearbox control device. according to the invention,
- Fig.2 shows a diagram illustrating the connection between an electric motor forming part of a device according to 1 invention and a gearbox,
- Fig.3 shows a sectional view of means for copying the position of the gearbox,
- Fig.4,5,6 and 7 show side views in section of different tracks forming part of the copying means described with regard to Fig.3.

- Fig.8 shows an electrical diagram for supplying an electric motor forming part of a device according to the invention. and
- Fig.9 shows a flowchart illustrating the operation of a device according to 1 invention.

 As can be seen from our Fiv. 1, an automatic gearbox control device, in particular for a motor vehicle, according to the invention, comprises means 1 for selecting the position of the gearbox, namely the mode main operating thereof and reports authorized in forward.

So for example. these selection means 1 include a keyboard 2 for selecting the main mode of operation of the gearbox, namely parking P, reverse R, neutral N or forward
D.

 The selection means 1 also comprise means 3 for selecting the reports authorized in forward direction D, these means being constituted for example by a selector * with three positions, for incrementing or decrementing the reports authorized in forward direction. This selector advantageously comprises a control lever 5 so as to form what is called a stick ".

 The operation of these means will be described in more detail below.

 These means for selecting the position of the gearbox, namely the means for selecting the main mode of operation thereof and the means for selecting the ratios authorized in forward gear, are connected to a central processing unit for information 6 whose function will be described in more detail below and comprising, for example, a microprocessor assembly of the appropriate type. This central unit 6 is connected to display means 7 of the selected position of the box, say of the main operating mode P, R, N or D and / or of the maximum gear authorized in forward gear "3", "2" or "1" in the case of a four-speed gearbox, These display means are constituted for example by an alphanumeric liquid crystal display, which can display the indication in full, or a network of light-emitting diodes, each of which corresponds to a position of the box, etc.

 The central unit 6 is also connected to means 8 for controlling the operation of the automatic gearbox, these means being constituted for example by a two-direction electric motor for positioning rotation of a drawer for selecting the position of the gearbox.

 According to one embodiment, shown in FIG. 2, the output shaft of the electric motor 8 comprises a pinion 9 associated with a rack 10.

 itself connected to the gearbox position selection drawer 11.

 The electric motor 8 is advantageously a direct current electric motor.

 This motor can also be constituted by any other type of motor, such as for example a stepping motor, or a motor associated with means 12 (Fig.t) for copying the position of the gearbox, connected to the central information processing unit 6 to ensure adequate control of the motor and therefore correct positioning of the box.

These copying means will be described in more detail below.

 The central information processing unit 6 is also connected to means for controlling the supply of the reversing lights 13 of the vehicle, so as to control 1 supply of these when the position R of reverse gear is selected. This makes it possible to dispense with the reversing light switch usually mounted on the gearbox or on the selector lever, which further simplifies the mounting of the gearbox.

 The central unit 6 is also connected to starting prohibition means 14 comprising for example a relay which authorizes the starting of the vehicle only if the gearbox is in position P or N. These means 14 can also be combined to light and / or audible means for warning the driver. This central unit is also connected to means for indicating faults 6a.

The central unit 6 is also connected for example to the brake light switch 15 of the vehicle so as not to allow passage from the parking position
P or neutral N, when driving forwards D or when reversing R, only if the vehicle's brake pedal is depressed.

 In fact, this increases safety on board the vehicle by preventing any untimely shifting of speed, for example by an animal or a child.

 The central unit 6 can also be linked to a computer 16 of automatic gearbox in the case where this gearbox is controlled by computer.

 The position information of the box position selection drawer is then directly delivered by the engine control computer instead of being delivered by a contactor.

 The central unit 6 also receives information on the speed of the vehicle by means of determining the speed 17 so as, as will be seen below, to ensure correct operation thereof and more particularly to prevent any change in main operating mode of the gearbox above a predetermined vehicle speed which is for example of the order of 4 km / hour.

The copying means 12 of the position of the gearbox therefore ensure the copying of this position for controlling the position of the motor,
These means 12 can be constituted for example by a mechanical, optical contactor with a potentiometer. with Hall effect probe, etc ...

 If we now refer to FIG. 3 which represents an embodiment of position copying means. it can be seen that these means include an insulating plastic case 18 in which is rotatably mounted a drum 19 made of electrically conductive material, connected to a drive shaft 20 itself driven by the electric motor.

 This drum 19 has tracks for example four in number. referenced respectively 21, 22, 23 and 2 & each comprising successively conductive and insulating portions of electricity, and adapted to cooperate with wipers, for example 25, 26, 27 and 28, fixed on the housing of the copying means and connected to an output connector 29 to determine the position of the drum and consequently of the gearbox position selection drawer. A fifth wiper 19a connects this drum to the vehicle supply.

 Indeed. as can be seen more carefully from Fig. 4 to 7, which respectively represent the tracks 21, 22, 23 and 2i, these comprise successively conductive and insulating portions, angularly offset so that the wipers of the housing deliver signals' defining different positions of the gearbox, It is thus possible to control the position of the electric motor by processing the output signals from these wipers, in the central information processing unit 6 described above.

 It can also be noted that the position copying means described comprising four tracks can code sixteen states using a GRAY code as a function of the successively conducting or insulating portions of the tracks, and thus make it possible to determine seven stable states, c ' is to say seven positions, corresponding to the positions "P", "R", "N", * D "," 3 "," 2 "," 1 "of the gearbox and eight intermediate states, giving thus in total fifteen possible binary codes.

It goes without saying that the copying means can be constituted by any other suitable coding means making it possible to determine a position and thus to control the electric motor in position,
This control is for example achieved by the diagram shown in Fig, 8. this circuit receiving three information signals from the central information processing unit 6 described above, namely a first signal A for controlling the speed of the motor using a variable duty cycle, a second signal B for controlling the forward gear and a third reverse gear signal C. Signals B and C control relay supply circuits 30 and 31, respectively 32 and 33, with three-position switches 34 and 35 supplying the motor 8 in one direction or another to determine the direction of rotation thereof, with a power determined by a circuit 36 controlled by the signal A.

 The structures of circuits 30, 31 and 36 being conventional. we will not describe them in more detail.

 The electric motor is controlled at the start, when the position is changed, at maximum power, and as soon as the copying means determine that the motor and therefore the selector for selecting the position of the box are in a correct selection position, the motor supply is cut off. However, the inertia of the motor causes it to exceed this position and the central unit then controls the supply of the motor in the opposite direction, at reduced power, by means of a modification of the duty cycle of signal A to stop the motor in the correct position.

 Another solution is to use a stepping motor which stops directly in the commanded position.

 In Fig.9, there is shown a flowchart illustrating the operation of a device according to the invention.

 This flowchart begins with an initialization phase at 37 followed by a vehicle speed acquisition phase, for example every 8 ms, at 38.

 Then, a step of detecting the presence of different faults is ensured at 39 and. depending on the result of this detection, the gearbox is set to "1", the tests are stopped and the fault indication means 6a are activated at 40 or we go to step 41 to determine whether the forward gear means for selecting the position of the gearbox is pressed. If so, the central information processing unit reads, at 42, means for incrementing or decrementing the authorized reports in forward gear and in 43, it is determined whether the initial position is the parking position P or neutral N and if the requested position is reverse R or forward D, while in 44, it is determined whether the driver has actuated the pedal brake or not, before authorizing at 45 the control of the positioning motor of the gearbox position selection drawer. depending on the position requested with as explained above. a variable duty cycle. This ratio is 100X before arriving at the requested position and then, each time it is exceeded, this ratio is reduced until the engine stops completely in position.

 In 46, a step of controlling the peripheral circuits of the central unit is provided. For example, if the gearbox is in the reverse position R, the central unit controls the switching on of the reversing lights. If the gearbox is in a park position P or neutral N, start is authorized by deactivating the start prohibition means and in all cases, the gearbox position is sent to the gearbox control computer automatic speed control if this is electronically controlled.

 In 4 ?, there is a re-testing of possible faults of the position copying means and in 48, a command of the means for displaying the requested position.

If one returns to step 41 in the case where the forward button D is not pressed, a test takes place at 49 to determine whether the neutral button
N is pressed. If this is the case, at 50 a test step is provided to determine if the vehicle speed is less than 4 km / hour. If yes. we refer to step 43; if not, nothing happens and it is carried over to step 38 for acquiring the vehicle speed.

 If the neutral key N is not pressed, a step 51 of determining an actuation of the reverse key R is provided. If this is the case, at 52, a step is provided to determine whether the gearbox is positioned in reverse R or not. If the response to this test is negative, a test takes place at 53 to determine whether the vehicle speed is less than 4 km / h or not in order to authorize or not carry over to step 43.

 If the reverse button R is not pressed, a step 54 is provided to determine whether the parking button P is pressed. If yes, it is determined at 55 if the speed of the vehicle is less than 4 km / h to authorize the postponement to step 43 and therefore the control of the gearbox. If the speed is greater than 4 km / h. we are carried back to step 38.

 In the case where the parking key P is not pressed, the determination takes place at 56 of a defect in the selection means insofar as none of the keys is actuated. A servo-control on the previous position and an activation of the means for indicating faults are also ensured.

 It is therefore understandable that the device according to the invention has a certain number of advantages insofar as when it is fitted to an automatic gearbox, it makes it possible to eliminate the start-inhibiting contactor, as well as the contactor for supply of the reversing lights, because it is the central information processing unit which issues the control orders for these various peripheral organs.

 Furthermore, it also eliminates the cable connecting in the devices of the prior art the selection lever to the positioning drawer of the gearbox.

 In the case where the gearbox is an electronically controlled gearbox, it makes it possible to remove the switch at the foot of the lever or on the gearbox insofar as it is the copying means which inform the control computer of the automatic gearbox. Otherwise. the actuator control electronics can be integrated into the gearbox control unit.

Claims (9)

 1. Hydraulic automatic gearbox control device, in particular for a motor vehicle. characterized in that it comprises means (1.2, 3) for selecting the position of the gearbox, namely the main mode of operation of the latter (P, R, ND), and authorized reports in operation front ("3". "2". "1"), connected to a central unit (6) for processing information and controlling display means (7) of the selected position of the gearbox, c '' is to say the main mode of operation and / or the maximum authorized ratio in forward gear and an electric motor (8) with two directions of rotation for positioning a drawer for selecting the position of the gearbox,  2. Device according to claim 1, characterized in that the motor (8) is a direct current motor.  3. Device according to claim 1, characterized in that the motor is a stepping motor.  4, Device according to any one of the preceding claims, characterized in that the output shaft of the electric motor (8) is connected by a rack and pinion system (9,10) to the drawer for selecting the position of the gearbox.  5. Device according to any one of the preceding claims, characterized in that it includes copying means (12) of the position of the gearbox,  6. Device according to claim 5 characterized in that the copying means (12) comprise a housing (18) in which is disposed a drum (19) of electrically conductive material, connected to a power supply by a wiper (19ai , this drum being driven in rotation by the electric motor and carrying at its periphery at least one friction track (21 to 24) having successively conductive and insulating portions of the electricity, adapted to cooperate with a wiper 125 28) fixed on the box (18) of the copying means, to determine the position of the drum 119) and therefore of the drawer for selecting the position of the gearbox,  7. Device according to claim 6. characterized in that the drum carries four parallel tracks 121 to Z41, the successively conductive and insulating portions of which are angularly offset so that the wipers deliver different signals corresponding to the different positions of the gearbox.  8. Device according to any one of the preceding claims ,. characterized in that the central information processing unit (6) is connected to control means tut3) of the vehicle reversing lights so as to control the supply thereof when the reverse position (R ) is selected.  9. Device according to any one of the preceding claims, characterized in that the central information processing unit (6) is connected to means (14) for starting prohibition to activate these when the position of parking (P) is selected.  fO. Device according to any one of the preceding claims, characterized in that the central information processing unit (6) is connected to means (17) for determining the speed of the vehicle to prevent any change in the main operating mode. of the gearbox (P, R, N, D), above a predetermined vehicle speed.  11. Device according to claim 10, characterized in that said predetermined speed is approximately 4 km / h.  12. Device according to any one of the preceding claims, characterized in that the central information processing unit (6) is connected to a brake light switch (15) of the vehicle to authorize the selection of the forward positions. (D) and reverse (R) when the vehicle brakes are applied.