Patent Application
20080172170
The present invention concerns a method of controlling a rotary electrical machine for a motor vehicle, the said machine being intended to function in starter mode for starting a thermal engine of the said vehicle. It also concerns a device for implementing such a control method.
The control method makes it possible to implement, for the thermal engine, functioning with automatic cutoff and starting (including restarting) of the thermal engine, a function known by the English term “Stop and Go”. To this end, the control method controls the rotary electrical machine in order to automatically start the thermal engine after a stoppage of the thermal engine, the said machine then functioning in starter mode.
Such an electrical machine is coupled to the said thermal engine, by means of a belt for example, and in general comprises a stator and a rotor. A current applied to the stator of the machine causes the rotor to start to rotate, which then drives the shaft of the thermal engine.
A typical situation of functioning in “Stop and Go” mode is that of stopping at a red light. When the vehicle stops at the light, the thermal engine is automatically stopped and then, when the light changes to green, the engine is restarted in particular by means of the electrical machine following the detection of the pressing of the clutch pedal by the driver, this action being interpreted as a request to restart. The advantage of this functioning in “Stop and Go” mode will thus be understood in terms of energy savings and reduction in pollution, in particular in an urban environment.
However, this circumstance of implementation of functioning in “Stop and Go” mode remains very particular and does not cover all situations where restarting may be sought.
Thus a technical problem to be resolved by the object of the present invention is to propose a method of controlling a rotary electrical machine for a motor vehicle, the said machine being intended to function in starter mode for starting a thermal engine of the said vehicle, which makes it possible to define the conditions in which an instruction to start the thermal engine of the vehicle, initially stopped, is transmitted to the rotary electrical machine.
A solution to the technical problem posed consists, according to a first object of the present invention, of the control method comprising the steps of:
Thus the invention provides for two major categories of starting conditions, namely the said essential safety conditions that must be satisfied continuously at any time since they usually relate to reasons of safety of the vehicle, the driver or other persons, and the said conditions prior to starting that are satisfied only at the time of the starting request so as to ensure that nothing opposes the starting of the thermal engine.
According to non-limiting preferential embodiments, the present invention also has the following characteristics.
in the case of a negative test on the safety conditions, preventing or interrupting at any time an execution of the said starting phase, and
in the case of a negative test on the prior conditions, preventing execution of the starting phase.
Thus, even if the starting phase has begun, it is possible to stop it if a problem arises.
Moreover, the invention distinguishes two different types of starting: the first startups, that is to say conventional startups that can be made with the engine cold, and restarts, that is to say after a stop phase, at a red light for example.
The aim of the invention is therefore to define, according to the type of starting requested, the safety and prior conditions that must be satisfied and the way in which these conditions are managed by the control method according to the invention.
Thus, according to non-limiting preferential embodiments, the invention also comprises the following characteristics:
The invention also distinguishes two types of action for triggering a starting. One type of action coming from the vehicle driver, whether intentional or not, and one type of action not coming from the driver.
The invention also provides for a starting as a function of the air-conditioning system.
In addition the invention takes account of various embodiments of the air-conditioning system depending on whether it comprises a certain type of sensor.
In addition, the invention also concerns the execution of the starting instructions, and more especially the restartings of the thermal engine requested of the electrical machine.
In particular, provision is made by the invention for a restart instruction not to be executed if the thermal engine is already started. This arrangement has the advantage of preventing restarting of the electrical machine when the thermal engine has previously been started by another means. In this case, the said reversible machine is put in alternator mode, without passing through a starting phase. This situation applies in particular when the electrical machine is an alternator/starter and the other means is an additional conventional starter.
Finally, according to a preferred non-limiting embodiment of the invention, the control method comprises the additional steps of:
In addition, provision is made for two consecutive starting instructions to be separated by a given interval of time. Thus there is obtained in this way optimum management of successive restarts preventing any risk of overheating of the alternator/starter and electronic circuits.
In addition, the starting instruction is transmitted to the rotary electrical machine when the counter is below the excluded maximum value, and the starting instruction is transmitted to an additional starter when the counter has reached the maximum value. Thus in this way any risk of overheating is avoided. In addition, the starting of the rotary electrical machine is avoided if optimum conditions are not achieved or if the said machine has a problem.
According to a second object of the invention, the invention proposes a reversible rotary electrical machine comprising a device for implementing the control method according to any one of the above characteristics.
According to a third object of the invention, the invention proposes a device for controlling a rotary electrical machine for a motor vehicle, the said machine being intended to function in starter mode for starting a thermal engine of the said vehicle, characterised in that it comprises:
According to the said device, the first means are also suitable for preventing and interrupting at any time execution of the said starting phase in the case of a negative test of the safety conditions and the second means are also able to prevent execution of the starting phase in the case of a negative test of the prior conditions.
The description that follows with regard to the accompanying drawings, given by way of non-limiting examples, will give a good understanding of what the invention consists and how it can be implemented.
a is a timing diagram of the state of a prior condition of
b is a timing diagram of the state of a prior condition of
In the following description, the control method according to the invention is applied to a rotary electrical machine of a vehicle such as an alternator/starter. Naturally the control method can be applied to any other rotary electrical machine such as a conventional starter.
In
The control electronics 7 comprise:
power in starter and alternator modes
regulation in alternator mode
transition from starter mode to alternator mode.
The management unit 9 is for this purpose supplied by the voltage of the battery, referenced B, to which it is connected by means of a vehicle ignition switch 10.
It should be noted that, according to a non-limiting preferential embodiment, the starting strategy according to the control method is downloaded into a flash or EEPROM memory of a control device such as a microcontroller of the alternator/starter. The microcontroller is situated in the management unit 9 of the alternator/starter and communicates with a bus of the vehicle.
According to another non-limiting embodiment, this strategy can also be downloaded into a memory of the control device included in the engine control ECU.
As can be seen in
The second conditions, referred to as prior to starting, are tested only before a starting phase, that is to say before the sending of the starting instruction, and may prevent its execution in the case of a negative test, but no longer have any influence once the instruction has been given.
It should be noted that a starting phase is determined in the following manner:
Concerning the prior conditions, the invention proposes, according to a non-limiting embodiment, an advantageous provision according to which, after a first positive test, maintaining the validity of one or more of these conditions for a given period.
One advantage of this operating mode appears in the case where starting does not succeed as a result of poor control of the fuel injection or lack of torque supplied by the alternator/starter, or if the rotor is locked for example. Thus, for example, when a second starting instruction is implemented, this second instruction will be effected only if the prior conditions are still true, in accordance with the general provisions of the invention. There will therefore be two possibilities for each prior condition: ensuring that it is true for only a short instant (0.5 seconds), as shown by the diagram in
It should be noted that two types of starting are taken into consideration in the context of the invention: first starts, or conventional cold starts, and restarting after having run (engine hot) and after a stop phase following the implementation of the “Stop and Go” functioning or after having stalled.
The safety and prior conditions that have just been presented may of course vary depending on whether a first starting or a restarting is envisaged.
Thus, according to non-limiting embodiments, where it is a case of a first starting:
Still in the context of a first starting, a prior condition envisaged by the invention is a minimum duration of a starting request, for example a request by the driver using the ignition key in the starting position for at least 100 milliseconds. It is thus ensured that the driver actually wishes to start.
In the case of a hands-free starting, a prior condition envisaged is the fact that the driver presses on the starter button provided for this purpose.
In addition, according to non-limiting embodiments, for a restarting request:
a minimum period between two consecutive restart instructions, on the same terms as those disclosed above with reference to the first starts,
the closed position of the vehicle bonnet, in order to prevent restarting of the thermal engine carried out in an unwanted manner while a person is working on the engine, with the bonnet open. It should be noted that, preferentially, this second safety condition is however invalidated (it is no longer taken into account) if the driver actuates his ignition key (key in the starting position START) or uses his hands-free badge and presses the starter button provided for this purpose.
Naturally, in this case, it is also necessary for the on-board system to be powered in the same way as that disclosed above with reference to the first start.
Intentional actions of the driver are, according to non-limiting embodiments:
Unintentional actions of the driver are, according a non-limiting embodiment:
It should be noted that a stop phase is determined by:
It will be understood that unintentional action by the driver means an action by the driver by means of which the said driver does not explicitly wish to request starting (including restarting) of the thermal engine of his vehicle.
The prior restarting conditions involving no action by the driver are, according to non-limiting embodiments, taken separately or in combination:
A control diagram for the prior conditions relating to the air-conditioning system and a corresponding timing diagram are given in
In this example, a restart request is made if the driver switches on the air conditioning during the stop phase when it was switched off when stopped; it can in fact be thought that, if this action is performed, the driver wishes the air conditioning to be operational immediately.
If the air conditioning was switched off when stopped, any restart request sent by the air-conditioning system (independently therefore of any action by the driver) is inhibited for 15 seconds. This avoids surprising the user. This is because stopping and starting the thermal engine too quickly is avoided.
In addition, according to the type of air-conditioning system, the following specific prior restart conditions are provided in a non-limiting embodiment.
In the case of an air-conditioning system comprising a sensor disposed at the outlet from an evaporator of the air-conditioning system, the said evaporator making it possible to cool the air, and the said sensor making it possible to sense the air temperature blown outside the said evaporator, if the temperature of the said air is greater than a given value, preferably 7 degrees Celsius, a restart request is initiated.
In the case of an air-conditioning system comprising a car cabin sensor, if the temperature increases by more than 5 degrees Celsius with respect to the temperature T1 at the time of stopping, a restart request is initiated. As indicated in the example in
In addition, if the air conditioning was switched on before the stop phase, restarting is automatically requested, whatever the type of air conditioning system, at the end of a given stop period, one minute for example. Preferentially, the stop period is dependent on the external temperature, and the said period is thus applied according to a look-up table. It can in fact be assumed that the driver wishes to have access to air conditioning even if the temperature of the cabin or of the air blown out has not increased too much.
After having established the various starting conditions tested by the method of controlling the electrical machine according to the invention, it is necessary now to present the various operating modes of the alternator/starter at the time of a starting request, these operating modes also being managed by the control method that is the object of the invention.
Referring now to
From a stop phase “STOP mode”, the following steps are performed:
In a first step 1), all the safety and prior conditions are verified as disclosed above. If they are all verified, there is then a “starting request”.
In a second step 2), if there is no starting request, it is checked whether or not the thermal engine is rotating. The condition “the engine is rotating” is true if the thermal engine reaches a sufficient speed during a sufficient time; for example, if its speed has remained above 500 revolutions per minute for at least two seconds. The time of two seconds makes it possible to have no doubt about the starting. The starting request by the alternator/starter is then not executed.
This transition is necessary for managing the startings carried out without explicit instruction to the alternator/starter, for example starting by means of the traditional convention starter, or starting on a slope. In these cases, the thermal engine has started all alone without being managed by the alternator/starter. It should be noted that, when the engine rotates, “ALTERNATOR” mode is passed to as indicated at step 6), as if the alternator/starter had itself given the instruction to go into this mode.
In a third step 3), corresponding to the “STARTING” step: a starting instruction is initiated.
In the case of a first starting, in a non-limiting embodiment, the instruction is sent to the alternator/starter if the temperature of the thermal engine is above a given value, for example 0 degrees Celsius, and if the “Stop and Go” functionality is enabled by the driver by means of a knob provided for this purpose. In the contrary case, the instruction is sent to the additional conventional starter if available.
On the other hand, in the case of a restarting, the instruction is preferably always sent to the alternator/starter except in the case of a problem as described in detail below. At this moment, the rotor of the electrical machine is set in rotation, which will make it possible to start the thermal engine.
In a fourth step 4), a test is carried out to determine whether there is a cancellation of starting. A “cancellation of starting” is obtained, for example, if the clutch pedal is released before the engine has truly started or in the event of prevention of starting by the alternator/starter, as will be seen in detail below in the description on the occasion of the fitting of a counter CPT. If there is a cancellation of starting, the stop phase “STOP” is resumed.
In the contrary case, in a fifth step 5), it is checked whether or not the engine has started. The condition “engine started” is true if the thermal engine reaches a sufficient speed for a sufficient length of time; for example, if its speed has remained above 700 revolutions per minute for at least 200 milliseconds. It should be noted that the speed of the thermal engine is in general equal to one third of the speed of the alternator/starter.
It should also be noted that it is advantageous to monitor the speed of the thermal engine rather than that of the alternator/starter in order to be free of any possible failures of the belt connecting the thermal engine to the alternator/starter. This is because, if the belt breaks or slips, the thermal engine is no longer driven whilst the alternator starter could continue to rotate “in a vacuum”.
If the “motor started” condition is true, the sixth step 6) is passed to, and the alternator/starter is in ALTERNATOR mode again as indicated in
In the contrary case, if, after three seconds after the sending of a starting instruction, the “motor started” condition is not true, or if a fault is immediately detected (rotor locked, overheating of the electronics or of the alternator/starter, poor establishment of the current in the rotor, a system voltage too low or too high, etc), it is considered that the starting has failed and the third step 3) of “STARTING” is returned to in order once again to attempt to effect a restarting.
However, in order to avoid any risk of overheating of the electrical machine and in particular of its management unit 19, the control method according to the invention provides a mechanism for managing the number of starting instructions sent is provided according to a non-limiting embodiment.
After each starting (including a first starting), incorrect or not, a counter CPT is incremented. According to the value of this counter, the starting will not be managed in the same way: beyond a maximum value, any starting instruction by the alternator/starter is prevented. In the following example this maximum value is taken to be equal to 2.
Moreover, whatever the value of the counter, an interval of time is preferably waited, for example at least 1.5 seconds between two starting instructions, in order to avoid electronic overheating at the alternator/starter.
After the last instruction, any new starting instruction is prevented, namely the “cancellation of starting” condition of
Finally, according to a preferential embodiment, the counter CPT is routinely decremented by one unit per given interval of time, for example every 20 seconds (“cancellation of starting” condition false). It is thus possible to attempt a starting (including restarting) again after 20 seconds. Thus, for example, this may apply when a starting has failed by means of the conventional starter. In this case, at the end of 20 seconds after the last starting attempt (CPT=3) it is possible to reattempt starting with the starter and at the end of 40 seconds with the alternator/starter.
This mechanism is advantageous, in particular in the case of failed starting, in order to minimise the impact on the driver: as long as the starting request is present, that is to say for example as long as the air conditioning has sent a starting request and all the safety and prior conditions necessary are true, it is possible to concatenate the instructions automatically in a manner that is transparent for the driver.
In addition, in a non-limiting embodiment, in the case of three consecutive failures, and therefore a pause of at least 20 seconds before any other sending of a starting instruction, it can be envisaged that another instruction be possible only after an explicit request from the driver according to an intentional action as defined previously, for example by an action on the key or on one of the pedals, etc, so as to not start in an impromptu manner while the driver is not prepared for it, and this although there is a “starting request”, that is to say all the safety and prior conditions are true.
The timing diagram in
The pause having only been for 23 seconds, the counter has been decremented only once; it is therefore equal to 2 at the time of the last starting instruction, the said starting therefore being performed by means of the additional starter.
Finally, in a sixth step 6), when the engine is started, ALTERNATOR mode is passed to.
Naturally in the context of the invention, in order to have access to certain information such as the cabin temperature, the position of the clutch, brake and accelerator pedals, the gearbox position, the ignition key position, etc, sensors are used.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0410096 | Sep 2004 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR05/02352 | 9/22/2005 | WO | 00 | 10/17/2007 |
