FR2837889A1 - METHOD FOR CONTROLLING THE ENGINE TORQUE DURING A VEHICLE SPEED CHANGE - Google Patents

Abstract

A method of controlling engine torque during a gear change of a motor vehicle having a transmission system, an automatic transmission system, or an automatic gear change system in which a gearbox multiple ratio (12) is coupled to a motor (10) by means of a friction clutch (14); and an electric machine (100) drivenly connected to the motor (10); said method comprising controlling the torque applied to the motor (10) by means of the electric machine (100), in order to control the motor torque during a gear change.

Description

The present invention relates to transmission systems for

  vehicle and in particular transmission systems, automatic transmission systems or automatic gear change systems provided with an automatically controlled friction clutch and a combined starter / alternator or a similar electric machine connected

directly to the engine.

  With automatic transmission systems with a multi-speed gearbox coupled to a motor by means of a friction clutch,

  for example as described in GB- documents

  2,088,007; GB-2,079,888; GB-2,130,329; GB-2,229,244;

  GB-2,225,821; GB-2,225,822; GB-2,211,577; GB

  2,233,053; GB-2,250,075; GB-2,265,958; GB

  2,245,036; GB-2,292,593; GB-2,292,594; GB-2,299,643;

  GB-2,296,046; GB-2,301,408; GB-2,316,454; GB

  2,324,584; GB-2,338,528; GB-2,339,249; GB-2,354,297;

  GB-2,353,835; GB-2,354,296; GB-2,356,438; GB-O

  105 186.1; GB-O 026 423.4; GB-O 025 848.3; GB

  025 847.5; GB-O 029 454.6; GB-O 025 000.1; GB

  02424 999.5; GB-O 026 178.4; GB-O 027 640.2; GB

  0 028 310.1; GB-O 031 624.0; GB-O 103 312.5; GB

  0 109 222.0, the content of which is expressly incorporated

  in the content of the description of this

  request, in order to avoid the exchanging of the engine when the clutch is disengaged for a gear change, it is necessary to check the clutch torque so that it follows the engine torque. Conventionally, the engine torque is controlled by means of an engine management control system or by means of the throttle valve, when the latter is motorized. The response time of the motor on a torque request is typically of the order of 100 to 200 ms. Therefore, there is a delay of 100 to 200 ms from the moment the driver initiates the gear change until there is a noticeable change in the engine or in the clutch torque. This delay is

  perceived by the driver as a slow change.

  When an electric machine such as the combined starter / alternator is connected directly to the engine, it is possible to quickly and precisely control the engine torque available for transmission by means of the clutch by modifying the torque applied by the electric machine, by the appropriate setting of the inductor winding current of the machine. Consequently, the delay in disengaging the clutch can be considerably reduced, the heating of the engine being controlled by means of the torque applied by the electric machine. In addition, the electric machine can be used to synchronize the speed of the engine with the speed of the input shaft of the gearbox, after the clutch has been disengaged and also to control the restoration of the engine torque. after a new gear

has been engaged.

  According to one aspect of the present invention, a method for controlling the engine torque during a gear change of a motor vehicle provided with a transmission system, an automatic transmission system or a gear change system automatic in which a multiple-ratio gearbox is coupled to a motor by means of a friction clutch; and an electric machine connected by drive to the motor; characterized in that said method comprises controlling the torque applied to the motor by the electric machine, in order to control the motor torque during a gear change. According to a preferred embodiment of the invention, a method for controlling the engine torque during a gear change comprises the steps consisting in, following the initiation of a gear change, sending a torque request signal to the system engine management control; trigger clutch release in a controlled manner and change the torque applied to the engine by the machine

  electric to control the engine overheating.

  According to another embodiment of the invention, after the clutch is released, the torque applied to the engine by the electric machine is modified to synchronize the speed of the engine with the speed of the corresponding clutch disc. at speed

target.

  The torque applied to the motor by the electric machine can be controlled by adjusting the inductor winding current at the machine. This is preferably achieved by means of a circuit

closed loop control.

  According to another aspect of the invention, the torque applied to the engine by the electric machine can further be controlled to control the engine torque during the increase in torque when the clutch is again engaged after the selection of a

new speed.

  The invention will now be described, by way of example only, with reference to the accompanying drawings in which: FIG. 1 schematically represents an automatic transmission system according to the present invention. Figures 2a to 2c schematically illustrate the alternative arrangements for the kinematic chain of the transmission system illustrated in Figure 1; FIG. 3 is a plot representing the engine torque and the speed and the clutch torque and the speed of the engine disc for a typical clutch representing the effect of disengaging the clutch independently of the engine torque; FIG. 4 is a plot showing the engine torque and speed and the clutch torque and the speed of the engine disc for a typical clutch showing torque control using conventional techniques; and FIG. 5 is a plot representing an engine torque and the speed and the clutch torque and the speed of the engine disk illustrating the control of the torque using a combined starter / alternator

according to the present invention.

  FIG. 1 of the accompanying drawings represents a motor 10 with a starter and an associated starter circuit 10a which is coupled by the main drive friction clutch 14 to a gearbox of the synchronized secondary shaft type with pneumatic relay 12 , via a gearbox input shank 15. The fuel is supplied to the engine by a throttle valve 16 which includes an acceleration pressure valve 18, controlled by the accelerator pedal 19. The invention can also apply to petrol or diesel injection engines

  electronic or mechanical fuel.

  The clutch 14 is actuated by a declutching fork 20 which is controlled by a hydraulic clutch receiving cylinder 22, under the control

  clutch actuator control means 38.

  A speed selector lever 24 operates in a sector 50 provided with two members 51 and 52 assembled by a transverse track 53 extending between the end of the member 52 and halfway between the ends of the member 51. The sector 50 defines five

  positions: "R" at the end of member 52; "N" at mid-

  distance from the ends of the transverse track 53; "S" at the junction of member 51 with the transverse route 53; and "+" and "-" at the ends of the member 51. In the member 51, the lever 24 is biased towards the central position "S". The "N" position of the selector lever 24 corresponds to neutral; "R" corresponds to the selection of the reverse gear; "S" corresponds to the selection of a forward drive mode; the momentary movement of the lever to the "+" position provides a command to force the gearbox to shift up one gear; and the momentary movement of the gear lever 24 towards the "-" position offers a command to force the

  gearbox down a gear.

  The positions of the lever 24 are sensed by a series of sensors, for example micro-switches

  or optical sensors, positioned around sector 50.

  The signals from the sensors are supplied to an electronic control unit 36. An output from the control unit 36 controls a gear engagement mechanism 25, which engages the gear ratios of the gearbox 12 , according to the movement of the selector lever 24 by the driver of the vehicle. In addition to the signals coming from the speed selector lever 24, the control unit 36 receives the signals from: sensor 19a which indicates the degree of depression of the accelerator pedal 19; sensor 30 which indicates the degree of opening of the acceleration control valve 18; sensor 26 which indicates the speed of the motor; sensor 42 which indicates the speed of the clutch motor disc; and sensor 34 which indicates the position of the clutch slave cylinder. The control unit 36 uses the signals coming from these sensors to control the actuation of the clutch 14 during the engagement from the support and the speed changes, for example, as described in the patent memories EP0038113, EP0043660, EP0059035 , EP0101220 and WO92 / 13208, the content of which is expressly incorporated into the content of the

  description of this application.

  In addition to the sensors mentioned above, the control unit 36 also receives signals from a vehicle speed sensor 57, an ignition switch 54 and a stop light switch 56 associated with the braking system

  main, for example the vehicle's foot brake 58.

  A buzzer 55 is connected to the control unit 36 to warn / indicate to the driver of the vehicle when certain control conditions occur. In addition to or in place of the buzzer 55, a flashing indicator light or other means of indication can be used. A speedometer 60 is also provided to indicate the gear

selected speed.

  As shown in FIG. 2a, a combined starter / alternator 100 can be connected in a driven manner to the crankshaft 102 of the engine 10, between the engine 10 and the clutch 14. The combined starter / alternator 100 can be connected in a driving way to the crankshaft in any suitable manner, for example, a gear 104 on the combined starter / alternator 100 engaging a gear ring 106 on the flywheel of the engine 10. Alternatively, a belt or chain may be used to connect the starter / alternator

combined 100 with crankshaft 102.

  In the embodiment illustrated in FIG. 2b, a starter / alternator 100 is connected in a driven manner to the crankshaft 102 of the engine 10, but at the end of the latter opposite to the clutch 14. A pulley 110 on the starter / combined alternator, is connected in a driven manner to a pulley 112 on the

  crankshaft 102 by a belt 114.

  In the embodiment illustrated in FIG. 2c, a rotor 202 of a combined alternator starter 200 is mounted directly on a drive bar 204 connecting the engine 10 to the clutch 14. A stator 206 of the combined starter / alternator 200 surrounds the rotor 202 and is fixed to a non-rotating transmission housing. As shown in Figure 3, when the vehicle moves smoothly with the clutch engaged, the clutch torque illustrated by the line

  300 exceeds the engine torque illustrated by line 302.

  Following the engagement of a gear change at the instant to, the control unit 36 requests a reduction in the engine torque illustrated by line 304. This can be obtained by means of the engine management control system. or direct order

  of the throttle valve 19, when the latter is motorized.

  However, there is a time delay t of 100 to 200 ms in the motor 10 to respond to the request concerning the reduction of the torque. If, consequently, the clutch 10 is released following the engagement of the gear change, then the clutch torque drops considerably below the engine torque, as shown in FIG. 3. This forces the engine speed illustrated by the line 306 to increase rapidly, which results in

engine overheating.

  Up to now, in order to avoid overheating of the engine, following the engagement of a gear change, the clutch torque is reduced to the engine torque, the clutch disengagement being then controlled, so that the clutch torque follows the engine torque, as illustrated in FIG. 4. Consequently, there is a time delay at of 100 to ms from the moment when the driver engages the gear change, until any perceptible change is felt, this being perceived by the

  driver like a slow change.

  According to the present invention, following the initiation of a speed change at the instant to, the control unit 36 requests a reduction in the engine torque and at the same time begins the disengagement of the clutch 14 in a controlled manner. In addition, the control unit 36 controls the torque applied to the engine 10 by the combined starter / alternator 100, 200, to bring the available engine torque down to the clutch torque, as shown in FIG. 5. The torque applied to the engine 10 by the combined starter / alternator 100, 200, as shown by line 308, can be quickly controlled by varying the inductive winding current of the starter / generator 100, 200. The time delay t clutch 14 can therefore be considerably reduced, by proposing

faster change.

  Preferably, the torque applied by the starter / alternator 100, 200 can be controlled by a closed loop control circuit, the difference between the engine speed and the speed of the clutch drive disc as shown by line 310 being monitored and the winding current

  inductor being increased or reduced, depending on the difference.

  The engine speed can also be controlled by means of the controlled starter / alternator 100, 200 in the same manner as that described above, when the clutch 14 is disengaged, in order to synchronize the engine speed with the speed of the disk

  clutch motor corresponding to the target speed.

  Furthermore, after the clutch has been brought back into gear when the target speed has been selected, the torque restoration is controlled by means of

  the clutch 14 to provide a smooth grip.

  The motor torque is controlled in order to reduce the selected speed to zero, and at the same time guarantee that the motor speed and the speed of the input shaft of the gearbox have the same acceleration when the sliding speed is zero. Given the offsets, this is achieved using an open loop control system. The combined starter / alternator 100, 200 can still be used to compensate for errors in the engine torque control and to reduce deviations that the open loop control strategy cannot

provide.

  While the invention has been described with reference to a transmission system for a semi-automatic motor vehicle, it should be noted that the invention can be applied to any vehicle transmission system or any transmission system. automatic gear change including an automatically controlled friction clutch 14. Furthermore, instead of the combined starter / alternator, any suitable electric machine, for example a hybrid electric drive, can be used to control the

engine couple.

  The patent claims submitted with the

  request are formulations proposed without prejudice to obtaining additional patent protection The requester reserves the right to submit

  claims to combinations of features

  additional, only described previously in the

description and / or drawings.

  References used in the sub

  claims relate to development

  additional to the subject of the main claim by the features of the respective sub-claim; they should not be understood as a waiver from obtaining independent object protection for the combination of features in the sub

claims concerned.

  Since the subject of the sub-claims

  may form separate and independent inventions in reference to the prior art on the priority date, the applicant reserves the right to be the subject of

  independent claims or demands

  Divisional. In addition, they may also contain independent inventions that demonstrate a design that is independent of one of the objects

  of the previous claims.

  The embodiments should not be considered a restriction of the invention. On the contrary, a wide variety of amendments and modifications is possible within the limits of the

  scope of the current description, particularly these

  variations, elements and combinations and / or materials that, for example, the expert can learn by combining

  individual items with those in the description and

  general embodiments in addition to the features and / or elements or steps of the

  process described in the claims and contained on

  drawings with the aim of solving a task, thus leading to a new object or to new process steps or sequences of process steps via the combinable characteristics, even when they relate to manufacturing, tests and processes

of work.

Claims (8)

R E V E N D I C A T I O N S   1. Method for controlling the engine torque during a gear change of a motor vehicle equipped with a transmission system, an automatic transmission system or an automatic gear change system in which a gearbox multiple ratio is coupled to a motor (10) by means of a friction clutch; and an electric machine (100; 200) drively connected to the motor; characterized in that the method includes controlling the torque applied to the engine by the electric machine to control the engine torque during a change of speed.   2. Method according to claim 1 characterized in that, following the engagement of a gear change: a torque request signal is generated to control the torque produced by the motor (10); the clutch release (14) is triggered in a controlled manner; and the torque applied to the engine by the electric machine is controlled to match the torque available for transmission through the clutch to the torque transmitted by the clutch, avoiding thus overheating the engine.   3. Method according to claim 1 characterized in that at the time of a gear change, when the clutch (14) is disengaged, the torque applied to the engine (10) by the electric machine is modified to synchronize the speed of the motor with the speed of a clutch motor disk which corresponds to the target speed.   4. Method according to claim 1, characterized in that at the moment ol 'clutch is engaged after the selection of a new speed, the torque applied to the engine (10) by the electric machine (100;) is modified so to control the engine torque available for transmission through the clutch, in order to obtain a smooth drive. 5. Method according to any one of   claims 2 to 4, characterized in that the torque   applied to the engine by the electric machine is changed according to the difference between the engine speed and the speed of a clutch drive disk, an input shaft (15) of the gearbox (12) or any what other driven component of the transmission. 6. Method according to claim 5 characterized in that the torque applied to the motor (10) by the electric machine (100; 200) is controlled by means of a closed-loop servo circuit which monitors the speed of the motor and the speed of a clutch drive disc, a gearbox input shaft or any other driven component of the transmission.   7. Method according to any one of   claims 1 to 6 characterized in that the couple   applied to the motor (10) by the electric machine (100; 200) is controlled by changing the winding current   electric machine inductor.   8. Method according to any of the   previous claims characterized in that the   electric machine (100; 200) is a combined starter / alternator or drive