FR2724693A1 - Two-stage pre-heating cycle for diesel engine cylinders - Google Patents

Abstract

The engine (14) pre-heaters (16) are supplied from the vehicle battery via a controller, energised by the normal start key (12) through a diode (13), but when the driver directs his transmitter (1) at the remote-locking (2) receiver (4), the decoding microprocessor (5,6), releasing the locks, also (10), through a relay (11), energises the controller (3). The controller microprocessor (8), using starter switch position (16), battery voltage and engine coolant temperature sensors, and memory storage (9), implements a first stage pre-heating strategy. Pre-heaters are energised and de-energised on a cycle based on branch type-testing, and the on-board data. Cycles are repeated several times if the car is not immediately driven off. Second stage pre-heating, beginning when the driver starts up (12), may overtake the first.

Description

PROCESS DB COXMAMDM DIS BOUGIE8 DB PRBCEAUFFING UM MOTEURUR DIBSIL
The present invention relates to a method for controlling the glow plugs of a diesel engine with internal combustion and & BR <compression ignition, equipping a motor vehicle.

 The invention relates more particularly to a method for controlling the power supply of the glow plugs of a diesel engine of a motor vehicle incorporating an anticipated preheating phase, triggered as soon as the vehicle doors are unlocked and intended to reduce the waiting time for the driver to start the engine.

 To start a diesel engine, it is necessary to have driven it to a speed of rotation sufficient for the temperature reached during compression of the fuel mixture contained in the combustion chambers to allow spontaneous ignition. The speed of rotation of the engine required and this auto-ignition quickly becomes important when the external temperature of the engine is low, especially for the engines & BR <prechamber of turbulence which comprise a maximum of thermal leaks.

 Also to allow starting regardless of the conditions of use without resorting to overpowered starters, use is conventionally made of auxiliary starting devices such as combustion air preheating devices using suitable electric candles that create a point hot.

 These preheating devices are usually implemented by the driver of the vehicle before launching the starter when powering the engine, by turning the ignition key in the + APC position which then activates an electronic boltier controlling the power supply. electric candles, in particular adjusting its duration according to predetermined strategies, depending on engine parameters such as the water temperature.

 The driver of a motor vehicle equipped with a diesel engine is therefore compelled to wait a longer or shorter time depending on the value of the outside temperature before starting the engine and thus move his vehicle. This poor starting ability compared in particular to engines & BR <spark ignition, devalues the diesel engines.

 A number of devices have been developed to reduce this glow time and make the starting of a comparable diesel engine comparable to that of a gasoline engine. This is how so-called "fast" glow plugs have been developed to reduce the preheating time to a few seconds. However, such systems still have the disadvantage of a very high surge compared to conventional systems and a certain lack of reliability.

 The Applicant has developed a glow plug control device, described in the patent application FR-A-2,692,319, which tends to overcome these disadvantages by substantially improving the starting ability of diesel engines.

 This control device of a preheating system relates to a vehicle & engine & BR <internal combustion & compression ignition with a system for preheating the intake air and a device for locking and unlocking the doors of the vehicle & BR <remote control. I1 is characterized in that the unlocking of the doors simultaneously triggers the implementation of the preheating system.

 Thus, even before the driver is mounted in the vehicle, the preheating system is activated so that when the driver turns the ignition key, the preheating period is over or about to be completed. The driver's perception of the warm-up time is thus greatly reduced: in most cases, his driving installation time will be longer than the preheating time and he will be able to start quickly.

 The object of the present invention is to improve such a device by proposing a control method for optimizing the service offered particularly from the point of view of power consumption.

 The method according to the invention for controlling glow plugs relates to a diesel engine fitted to a motor vehicle of the type comprising remote control means for locking and unlocking the doors cooperating with electronic means for controlling the electric power supply of the glow plugs.

 According to the invention, the method of controlling the glow plugs is characterized in that on the one hand, the supply of spark plugs before starting the engine is provided in at least two distinct phases, a first phase that starts with the unlocking doors by the remote-controlled means and a second phase which starts at BR <the instant of ignition of the engine and that secondly, the duration of the second phase is adjusted according to the course of the first phase and has a predetermined minimum value.

 According to another characteristic of the control method of the glow plugs object of the invention, the first phase of the preheating extends over a given duration that can not exceed a predetermined maximum value.

 According to another characteristic of the control method of the glow plugs object of the invention, during the first phase of preheating, the power supply of the candles is operated discontinuously in a succession of periods of supply and cut-off periods feeding times adjusted.

 According to another characteristic of the control method of the glow plugs according to the invention, the duration of the second phase of the preheating is a function of a value representative of the temperature reached by the spark plugs & the instant of ignition of the engine , this representative value being developed taking into account the effective periods of supply and non-power glow plugs.

 According to another characteristic of the control method of the glow plugs object of the invention, the development of the representative value also takes into account the values of engine parameters such as the coolant temperature, the atmospheric pressure or the voltage of the engine. drums.

According to another characteristic of the control method of the glow plugs object of the invention, the latter comprises the following steps
- when unlocking the doors by remote control means, switch on the electronic control bolt and start the first preheating phase
- Development of said value representative of the evolution of the temperature of the candles taking into account the actual periods of supply and non-power to which the glow plugs are subjected
and then, when the engine is switched on, launching the second phase of the preheating for a period of time enslaved to the value representative of the evolution of the temperature of the spark plugs attained at the instant of the engine being brought into contact.

 According to another characteristic of the control method of the glow plugs according to the invention, the development of the value representative of the temperature reached by the candles is operated from a gradually incremented meter during candle feeding periods. then gradually decremented during periods of non-feeding candles.

 According to another characteristic of the control method of the glow plugs according to the invention, the implementation of the first preheating phase is suspended after recognition of a given number of consecutive unlocking doors by the remote control means not followed by a contacting of the engine.

 According to another characteristic of the method for controlling the glow plugs according to the invention, a counter is incremented each unlocking of the doors by the remote control means and decremented each time the engine is put into contact, the first phase then being put into operation. only if the value of the counter is less than a given threshold value.

The aims, aspects and advantages of the present invention will be better understood from the following description of an embodiment of the invention, given by way of non-limiting example, with reference to the drawings, in which: which
Figure 1 is a schematic view of a device for implementing the method of the invention;
FIG. 2 is an operating diagram illustrating the progress of the method according to the invention.

 As shown in FIG. 1, only the elements necessary for understanding the invention have been represented.

 Thus, there has been a diesel engine & BR <four cylinders in line, referenced 14, equipped with four electric glow plugs 15, one per cylinder, this engine being mounted on a motor vehicle which has not been shown .

 The control device according to the invention of these glow plugs comprises an electronic box 3 powered from the unillustrated electric battery of the vehicle via a switch 12 actuated by the ignition key. This boltier comprises a microprocessor 8 with which associated live memories 9 and integrated or not and the latter and various input and output interfaces.

 The microprocessor 8 controls power relays also not shown to direct the power from the battery to the candles 15. The microprocessor 8 also controls an indicator light not shown on the dashboard, intended to inform the driver of the progress of preheating.

 The microprocessor 8 therefore controls the power supply of the spark plugs 15 according to predefined strategies, detailed below, according to a certain number of parameters, such as the power-on information of the engine or the + APC position of the ignition key. contact (obtained in particular through an electrical connection 16 and a diode 13), the temperature information of the cooling water delivered by a thermocontact, the atmospheric pressure information, the battery voltage information or the system information motor rotation.

 In addition to the previous parameters used to control the preheating, the unlocking information of the doors of the vehicle is also provided by means of remote control.

 These means consist of a portable transmitter box 1 and a receiver box 2 housed in the vehicle. The transmitter box 1 conventionally comprises a push button whose actuation drives a code generator such as a light emitting diode to cause the emission of a predetermined sequence of infrared pulses.

 The receiver box 2, permanently energized, comprises receiving means 4 pulses, formed by an infrared diode or a phototransistor. It also comprises a programmable microprocessor 5 associated with a memory 6, intended to operate the control of the opening / closing mechanisms of the doors.

 In accordance with the invention, the microprocessor 5 of the receiver box 2 is also able to power up the control box 3 of the spark plugs 15 under predefined conditions, thanks to a controlled relay 11 bypassing the switch 12 actuated by the ignition key .

An electrical connection 7 further allows the microprocessor 5 to receive the necessary information from the microprocessor 8 of the control cabinet 3.

 The control method of the glow plugs implemented from the device which has just been described will now be specified in accordance with the examples of FIG.

 The method of controlling the supply of spark plugs according to the invention is characterized in that, when the doors of the vehicle are unlocked from the infrared remote control, preheating effected before starting is split into at least two distinct phases.

 Start-up procedures following the opening of the doors by the key, or restart, consecutively for example & stalling, thus without unlocking the doors, as well as the procedures for supplying the candles after startup (post-heating, etc. ...) are not modified in relation to the existing one by the present invention and will therefore not be described.

 The preheating according to the invention therefore comprises a first phase F1, called preheating anticipated, which starts immediately after unlocking the doors, and a second phase F2, called normal preheating, which begins at the moment of ignition of the engine .

 However, it is also possible to consider other glow plug power phases preceding the start of the engine, such as a phase of maintaining the power glow plugs for a certain period after they have reached a temperature sufficient to ensure the engine start.

 The different steps of the control method then take place as follows.

 As soon as an order to unlock the doors of the vehicle is received by decoding the infrared pulses emitted by the housing 1, the microprocessor 5 of the receiver box increments a counter NB, the role of which will be specified below, by one unit and then compares the new value at a predetermined threshold value NBmax. If the value of the counter NB is lower than the threshold value NBmax, the microprocessor 5 operates the power of the box 3 to trigger the first phase F1 preheating anticipated, otherwise the microprocessor 5 does not trigger this first phase. In all cases, the microprocessor 5 then monitors the state of the link 7 to take into account any transmitted information.

 To trigger the first phase F1, the microprocessor 5 thus closes the relay 11 which operates the power of the box 3 and the microprocessor 8. The microprocessor 8 then tests the state of the switch 12 via the link 16 and triggers, if the latter is not closed (position + APC of the ignition key), the unfolding of the first phase F1 by controlling the supply of the candles 15 during a first period.

In parallel with the supply of the candles 15, the microprocessor 8 prepares and until the end of the phase F2, a value representative of the temperature of the candles for controlling the duration of the preheating in the form of a counter
CPT taking into account the duration of supply and non - supply of candles 15.

To do this, CPT counter, automatically initialized when powering the microprocessor 8, is then gradually incremented during the supply of candles and decremented when not power. The laws of incrementation and decrementation of the counter
CPT as a function of time, respectively characteristics of the rise in temperature of the candles 15 and their cooling, are thus previously calibrated for a given motor test bench and then stored in the memories of the microprocessors 8. These laws can be chosen constant or still depend in the form of maps of the value of engine parameters such as the water temperature.

 The first F1 power supply phase of the spark plugs 15 is then operated, in accordance with the example 1 of FIG. 2, for a programmed time t1 defined by a threshold value tlmax for the counter CPT. The first phase F1 thus ends as soon as the counter CPT has reached the threshold value tlmax, the power supply of the candles 15 then being immediately interrupted.

 The control of the duration of the anticipated preheating phase makes it possible to avoid excessive heating of the candles or excessive electrical consumption. The value tlmax can be constant or depend on engine parameters such as the water temperature.

 This solution offers a good compromise by offering both a significant reduction in the waiting time of the driver before starting, which is effective since some of the preheating has already been done before it is turned the key contact, and the limitation of the power consumption operated on the battery in all cases or the unlocking of the doors is not followed by the starting of the engine.

 The power supply of the spark plugs during this preheating phase can be adapted according to the engines. It is possible to simultaneously supply all the candles 15 or feed them alternately one after the other or in groups.

 It is also possible to operate the power supply candles 15 discontinuously in a given succession of feeding periods to maintain the temperature of the candles over a relatively long period without generating significant power consumption. According to the example 2 of FIG. 2, it is possible to operate the first phase of the preheating F1 in several distinct periods of power supply, the power supply stopping when the counter CPT reaches the value tl'max and taking again when the CPT counter has come down to a value tl'min.

 Thus, if the duration between the unlocking of the doors and the engine start exceeds a certain value (for example if the doors have been unlocked without intention to start the vehicle, as in a loading / unloading operation of the vehicle), the anticipated preheating is interrupted, then resumed (in order to reduce the driver's waiting time for a possible subsequent start), up to a maximum number of times allowing the backup of the battery and the preheating system.

 After the end of the anticipated preheating phase F1 and the stopping of the power supply of the candles 15, the update of the counter CPT continues in the form of a gradual decrementation.

 The second phase F2 of the preheating is triggered immediately after the closing of the switch 12, that is to say as soon as the ignition key in + APC position. Recognition of the closing of the switch 12 therefore initiates the second phase F2 preheating, possibly interrupting the first phase F1 if it was not finished. Only this second phase of the preheating F2 is accompanied by the lighting of the indicator corresponding to the dashboard of the vehicle.

The second phase F2 for supplying the candles 15 is then operated according to the invention for a determined programmed duration t2 defined by a threshold value t2max for the counter CPT whose update continues. The second phase
F2 therefore ends as soon as the counter CPT has reached the threshold value t2max after which the supply of the candles 15 is maintained for a certain programmable duration before being interrupted.

 The value t2max, which can be constant or depend on engine parameters such as the water temperature, is determined so that at this moment the spark plugs have reached a temperature such that ignition of the fuel mixture is possible at the start of the engine. .

 The use of the CPT counter to control the duration t2 of the second phase of the preheating perfectly adjusts the latter to the needs of the engine by taking into account the temperature already reached by the candles 15 at the moment of putting into contact motor and therefore avoid unnecessary power consumption.

Of course, if the preheating phase F1 anticipated did not take place before the closing of the switch 12 (NB higher than
NBmax), the phase F2 takes into account it through the counter CPT which is initialized automatically when the microprocessor 8 is turned on.

 Regardless of the value of the CPT counter when the engine is switched on, however, the duration of the second preheating phase is delayed so as not to be less than a predetermined minimum duration t2min. This minimum duration, which does not significantly affect the good startability allowed by the anticipated preheating phase F1, reduces the duration of the latter accordingly, which saves battery energy during unlocking / locking without starting the engine, and also allows to ensure the ignition of the preheating indicator on the dashboard informing the driver of the progress of the preheating.

 Furthermore, the information closing switch 12 is transmitted by the microprocessor 8 to the microprocessor 5 of the receiver box 2 by the link 7. The recognition of this information operated by the microprocessor 7 causes the reset of the counter NB or its decrementation a certain programmable value and the opening of the relay 11 (if it is closed) the supply of the housing 3 by the relay 12 having no reason to be.

 The counter NB thus makes it possible to suspend the implementation of the first phase F1 of the preheating after identification of a given number, NBmax, of consecutive unlocking of the doors by the remote control means not followed by an ignition of the motor, the first F1 phase of the preheating being restarted during subsequent unlocking occurring after powering up the engine.

 Thus, according to this characteristic of the method that is the subject of the invention, the anticipated preheating following the reception of an unlocking frame is only allowed under certain conditions, this making it possible to guard against possible cases of operation that may be harmful to the preheating device or the vehicle battery, for example.

 This makes it possible to protect the battery and the preheating system against inadvertent use of the infrared remote control, or simply of a normal but repeated use of the infrared remote control, such as consecutive door openings / closures without starting the engine, when vehicle loading or unloading operations, for example. The values of the parameters conditioning the anticipated preheating authorization are easily modifiable during the development of the vehicle, being defined in the device in the form of values stored in memory.

 For reasons of operational safety of the method according to the invention, it can also be provided to associate the closure of the relay 11 by the microprocessor 5 with a certain predetermined time delay beyond which the opening of the relay is controlled. Similarly, for security reasons, the information closing switch 12 communicated by the link 7 can be coded so that in case of failure of the microprocessor 8 the state of the link 7 is considered to indicate the closing of the switch 12 so as to prevent the closing of the relay 11.

 Of course, the invention is not limited to the described and illustrated embodiments which have been given only as examples.

 On the contrary, the invention comprises all the technical equivalents of the means described and their combinations if they are carried out according to its spirit.

 Thus, the counter NB can be updated not from the information closing the switch 12 but from the information "rotating motor" transmitted by the microprocessor 8 via the link 7, according to the motor has exceeded a certain rotational speed, the opening of the relay 11 by the microprocessor 5 remains however subject to the receipt of the information closing the switch 12, also transmitted via the link 7.

 The choice of this rotating engine criterion makes it possible to no longer authorize the anticipated preheating from a certain number of consecutive unlockings / interlocks without actually starting the engine and not simply by turning on the latter.

Claims (1)

 RHVIIDICATIOMS  t1] A method for controlling the glow plugs (15) for preheating a diesel engine (14) fitted to a motor vehicle of the type comprising remote-controlled means (1,2) for locking and unlocking the doors cooperating with electronic control means ( 3) of the power supply of the glow plugs (15), characterized in that on the one hand, the supply of the spark plugs (15) before starting the engine is provided in at least two distinct phases, a first phase ( F1) which starts with the unlocking of the doors by the remote control means (1,2) and a second phase (F2) which starts at the moment of ignition of the engine and that secondly, the duration (t2 ) of the second phase (F2) is adjusted according to the course of the first phase (F1) and has a predetermined minimum value (t2min). [2] A method of controlling the glow plugs of a diesel engine according to claim 1, characterized in that said first phase (F1) is operated for a given time (tl) can not exceed a predetermined maximum value (tlmax). [3] A method for controlling the glow plugs of a diesel engine according to any one of claims 1 & 2, characterized in that during said first phase (F1) the power supply of the candles (15) is operated from discontinuously in a succession of feeding periods and periods of cut-off of the supply of adjusted periods.  [4] A method for controlling the glow plugs of a diesel engine according to any one of claims 1 & 3, characterized in that the duration (t2) of the second phase (F2) is a function of a value (CPT ) representative of the temperature reached by the spark plugs (15) & BR <the moment of ignition of the engine (14), said representative value (CPT) being designed taking into account the actual duration of supply and non-power supply said glow plugs (15). [5] A method for controlling the glow plugs of a diesel engine according to claim 4, characterized in that the development of said representative value (CPT) also takes into account the values of engine parameters such as the temperature of the coolant, the atmospheric pressure or the battery voltage. [6] A method for controlling the glow plugs of a diesel engine according to any one of claims 4 & 5, characterized in that it comprises the following steps  - When unlocking the doors by the remote control means (1,2), powering the control unit (3) and launching said first phase (F1) supplying the glow plugs (15);  - development of said representative value (CPT) of the evolution of the temperature of the candles (15) taking into account the actual periods of supply and non-supply which are subject to said glow plugs (15)  and then, when the engine is switched on, launching the second candle supply phase (F2) for a period (t2) slaved to said representative value (CPT) reached at the time of putting the ignition on engine.  (7) A method for controlling the glow plugs (15) of preheating according to any one of claims 4 & 6, characterized in that the development of said value representative of the temperature reached by the glow plugs (15) is operated & from a counter (CPT) gradually incremented during the candle feeding periods (15) and then gradually decremented during periods of non-feeding of the candles (15). [8] A method of controlling the supply of glow plugs according to any one of claims 1 & 7, characterized in that the implementation of said first phase (F1) is suspended after recognition of a given number of consecutive unlocking of the doors by the remote control means (1,2) not followed by an ignition of the motor.  (9) A method for controlling the supply of glow plugs according to claim 8, characterized in that a counter (NB) is incremented each unlocking of the doors by the remote control means (1,2) and decremented & BR < each contacting of the motor (14) and in that said first phase (F1) is implemented only if the value of said counter (NB) is less than a given threshold value.