CONTROL OF TRIGGERING MOTIONS FOR A CRAWL MOTION BY THE INTERNAL COMBUSTION ENGINE AND NON-INTERNAL COMBUSTION DRIVE OF A HYBRID VEHICLE

Description

[0001] The invention relates to hybrid vehicles which include a thermal engine and a non-thermal drive machine consuming respectively fuel and energy (or power) stored in at least one energy storage means to provide torque, together or separately, for at least one train.

[0002] It should be noted that the invention relates to both electrical energy storage methods and hydraulic or pneumatic energy storage methods. Furthermore, the invention relates to both the case in which the internal combustion engine and the non-thermal drive provide two torques for the same train and the case in which the internal combustion engine and the non-thermal drive provide two torques for two separate trains.

[0003] Some hybrid vehicles, of the type defined above, have a "creeping" function that allows them to continue moving smoothly at low speeds (typically 5 to 12 km / h on flat ground or inclines) by providing variable torque as soon as their speed drops below a certain threshold and the driver releases the brake and accelerator pedals. This mode of movement (or creeping) allows the driver to maneuver the vehicle more easily, needing only to control the steering wheel and temporarily apply the brake pedal. A hybrid vehicle with a creeping function is described in patent document EP 2195185.

[0004] Creep was initially inherent to vehicles with torque converter automatic transmissions, and has since been implemented in many other automated vehicles. In fact, when the transmission is automatic, creep is a result of the torque converter's operation, which transforms the speed difference between the input shaft of the automatic transmission (connected to the internal combustion engine running at a non-zero speed) and the output shaft of the same automatic transmission (coupled to the drive wheels). For other types of automatic transmissions, creep can be achieved through the control of components designed to approximate the behavior of an automatic transmission.

[0005] We also know of patent document GB-A-2 527 515 disclosing the preamble of claim 1.

[0006] As experts know, creep is a useful driving mode, but it introduces several drawbacks in a hybrid drivetrain, notably different response times and performance levels depending on whether the creep function is performed using torque supplied by the internal combustion engine or the non-thermal drive unit. Indeed, if the state of charge of the energy storage system associated with the non-thermal drive unit is below a predefined threshold, the internal combustion engine is used to perform the creep function, and if this state of charge is above this predefined threshold, the non-thermal drive unit is used to perform the creep function. These different response times and performance levels, resulting from the different performance of the internal combustion engine and the non-thermal drive unit, can cause inconvenience for the driver and passengers of a hybrid vehicle.

[0007] The invention is therefore intended, in particular, to improve the situation in hybrid vehicles.

[0008] In particular, it proposes a control device intended to equip a vehicle comprising a brake pedal coupled to a braking circuit in which there is ongoing pressure, an accelerator pedal, at least one means of energy storage having an ongoing state of charge, and a thermal engine and a non-thermal motive machine providing torques respectively for at least one train by consuming respectively fuel and energy stored in the means of energy storage.

[0009] This control device is characterized by the fact that it includes control means which, when the vehicle is moving with its brake and accelerator pedals not depressed, trigger either an early operation of the internal combustion engine to provide at a predetermined instant a predetermined torque to ensure a so-called creeping function when the current pressure (in the braking circuit) becomes less than a predetermined pressure threshold, or a delayed operation of the non-thermal drive machine for a predetermined time interval after the current pressure (in the braking circuit) has become equal to a predetermined value, strictly less than the predetermined pressure threshold, to provide at that predetermined instant this predetermined torque to ensure this creeping function, depending on whether the current load state is less than or greater than a predetermined state threshold.

[0010] Thus, we are now certain that at the predetermined instant the predetermined torque (of creep) will be supplied to the drive wheels, whatever its source (thermal engine or driving machine).

[0011] The control device according to the invention may include other features which may be taken separately or in combination, and in particular: Its control means can trigger the operation of the internal combustion engine, which is advanced by a predefined duration relative to a reference instant when the current pressure becomes equal to the predefined value. In this case, this predefined duration is a function of the time required for the internal combustion engine to provide the predefined (creep) torque from the generation of an initial torque setpoint dedicated to the creep function and equal to this predefined torque; its control methods can use a predefined duration which is between -20 ms and -100 ms; Its control means can use a predefined duration that has been previously learned for the vehicle; its control means can trigger the operation of the non-thermal drive unit, which is delayed by a predefined time interval relative to a reference instant when the current pressure becomes equal to the predefined value. In this case, this predefined time interval is a function of the time required for the non-thermal drive unit to provide the predefined torque from the generation of a second torque setpoint dedicated to the creep function and equal to the predefined torque; its control means can use a predefined time interval between +20 ms and +100 ms; Its control means can use a predefined time interval that has been previously learned for the vehicle.

[0012] The invention also proposes a vehicle, possibly of the automobile type, comprising a brake pedal coupled to a braking circuit in which there is ongoing pressure, an accelerator pedal, at least one means of energy storage having an ongoing state of charge, a thermal engine and a non-thermal motive machine providing torques respectively for at least one train by consuming respectively fuel and energy stored in the means of energy storage, and a control device of the type of that presented above.

[0013] For example, the non-thermal powertrain of this vehicle could be electric. In this case, the energy storage system stores electrical energy.

[0014] The invention also proposes a control method intended to be implemented in a vehicle comprising a brake pedal coupled to a braking circuit in which there is ongoing pressure, an accelerator pedal, at least one energy storage means having an ongoing state of charge, and a thermal engine and a non-thermal drive machine respectively providing torques for at least one train by respectively consuming fuel and energy stored in the energy storage means.

[0015] This control method is characterized by the fact that it includes a step in which, when the vehicle is moving with its brake and accelerator pedals not depressed, either an early operation of the internal combustion engine is triggered to provide at a predetermined instant a predetermined torque to ensure a creeping function when the current pressure (in the braking circuit) becomes less than a predetermined pressure threshold, or a delayed operation of the non-thermal drive machine for a predetermined time interval after the current pressure (in the braking circuit) has become equal to a predetermined value, strictly less than the predetermined pressure threshold, to provide at that predetermined instant this predetermined torque to ensure this creeping function.

[0016] Other features and advantages of the invention will become apparent upon examination of the detailed description below, and the accompanying drawings, in which: there figure 1 schematically and functionally illustrates a vehicle comprising a hybrid transmission system and a supervisory computer equipped with a control device according to the invention, and the figure 2 illustrates schematically, within a diagram, an example of time evolution curves of the pressure in the master cylinder of a braking circuit of a hybrid vehicle (c1), of a first advanced creep torque setpoint for the internal combustion engine of this hybrid vehicle (c2), of a creep torque actually supplied by the internal combustion engine during the creep phase to satisfy the first creep torque setpoint (c3), of a second delayed creep torque setpoint for the non-thermal drive machine of this hybrid vehicle (c4), and of a creep torque actually supplied by the non-thermal drive machine during the creep phase to satisfy the second creep torque setpoint (c5).

[0017] The invention aims in particular to provide a DC control device for equipping a vehicle V, comprising a hybrid transmission chain including at least one thermal engine MT and a non-thermal drive machine MM, in order to control the triggering times of a creeping (or creeping) function respectively by this thermal engine MT and this drive machine MM.

[0018] In what follows, vehicle V is considered, by way of non-limiting example, to be an automobile. For example, a car. However, the invention is not limited to this type of vehicle. It relates to any type of hybrid land vehicle comprising at least one internal combustion engine and one non-thermal drive unit, each providing torque to at least one set of wheels (or similar components) while consuming fuel and energy (or power) stored in at least one energy storage device.

[0019] Here, a "non-thermal power machine" refers to a machine designed to provide or recover torque to move a vehicle, either alone or in conjunction with a thermal engine. Examples include an electric machine (or motor), a hydraulic machine, or a pneumatic (or compressed air) machine.

[0020] Furthermore, here we mean a "thermal engine" which is a machine or engine that consumes fuel to produce torque to move a vehicle.

[0021] On the figure 1 schematically illustrated is a vehicle V comprising a hybrid transmission chain, a CS supervisory computer for supervising (or managing) the operation of the transmission chain, a brake pedal PF coupled to a (hydraulic) braking circuit CF in which there is a current pressure p mc, an accelerator pedal PA, and a control device DC according to the invention.

[0022] The hybrid transmission chain here includes, in particular, a thermal engine MT, a drive shaft AM, a clutch EM, a non-thermal drive machine MM, gear-changing means BV, a first energy storage means MS1 and a transmission shaft AT.

[0023] The internal combustion engine includes a crankshaft (not shown) which is fixedly attached to the drive shaft AM in order to rotate the latter (AM). It is intended to provide torque to at least one set of wheels T1, via the clutch EM, the (non-internal combustion) drive machine MM, and the gear-shifting means BV. However, in an alternative embodiment, it could provide torque to at least one set of wheels via the clutch EM and the gear-shifting means BV.

[0024] For example, the first axle T1 is located at the front of the vehicle V, and coupled to the AT driveshaft, preferably, and as illustrated, via a differential (here front) D1. But in a variant this first axle T1 could be located at the rear of the vehicle V.

[0025] The EM clutch is responsible for coupling / decoupling the drive shaft AM (coupled to the internal combustion engine MT) to / from the drive machine MM, as instructed by the supervisory control unit CS, in order to transmit the torque it produces. This EM clutch can be of any type as long as it can assume at least a first state (coupled) in which it ensures the coupling between the internal combustion engine MT and the drive machine MM, and a second state (decoupled) in which it decouples the internal combustion engine MT from the drive machine MM.

[0026] The drive machine MM is coupled to the first energy storage unit MS1 in order to be supplied with energy or to supply energy to the latter (MS1). It is also coupled to the output of the clutch EM and to the primary shaft AP of the gear-changing unit BV.

[0027] In what follows, we consider, by way of non-limiting example, that the drive machine MM is of the electric type. However, the invention is not limited to this type of non-thermal drive machine. Thus, it also relates, in particular, to hydraulic machines (or motors) and pneumatic (or compressed air) machines (or motors).

[0028] Since the drive machine MM is considered to be of the electric type, the first energy storage device MS1 that supplies it with energy is designed to store electrical energy, for example at low voltage (typically 220 V as an illustration). The current state of charge (or SOC) of this first energy storage device MS1 is known to the supervisory computer CS.

[0029] The gear-changing means BV can, for example, be arranged in the form of a gearbox, possibly automated. They include the primary shaft AP, which is designed to receive torque from the drive unit MM, and a secondary shaft designed to receive this torque via the primary shaft AP in order to transmit it to the transmission shaft AT, to which it is coupled and which is indirectly coupled to the drive wheels (here, the front wheels) of the vehicle V via the differential D1. However, in an alternative embodiment, the gear-changing means BV could, for example, include at least one epicyclic gear train comprising one, two, or three synchronizers.

[0030] It should be noted, as illustrated (but not limited to) on the figure 1 The transmission chain may also include a starter or a starter-alternator AD coupled to the internal combustion engine MT and responsible for starting the latter (MT) to enable it to start. This starting is achieved using electrical energy which is, for example and as illustrated without limitation, stored in a second storage means MS2. This second storage means MS2 can be configured as a very low voltage battery (for example, 12 V, 24 V, or 48 V). This battery (MS2) can, for example, power an on-board electrical system to which the vehicle's electrical equipment V is connected. Furthermore, this second storage means MS2 can, as illustrated without limitation, be coupled to the first energy storage means MS1 and to the drive machine MM via a DC / DC converter CV, in order to be recharged.

[0031] The operation of at least the internal combustion engine MT, the drive unit MM, and the clutch EM, as well as possibly the gear-changing means BV, can be controlled by the CS supervisory control unit. Furthermore, the CS supervisory control unit is constantly informed of the percentage of brake pedal depressment PF, the current pressure pmc in the braking circuit CF (and more specifically in its master cylinder (CF)), and the percentage of accelerator pedal depressment PA.

[0032] It should be noted that the transmission chain could also include another non-thermal drive unit in addition to its primary drive unit MM. In this case, this other non-thermal drive unit is responsible for providing torque to a second train T2 of the vehicle V, for example located at the rear, using energy stored in the first energy storage unit MS1. It then operates either alone or in conjunction with the internal combustion engine MT and / or the primary drive unit MM, depending on the commands provided by the supervisory computer CS.

[0033] As previously stated, the invention proposes a DC control device intended to equip the vehicle V in order to control the triggering times of a creeping (or creeping) function respectively by the internal combustion engine MT and the drive machine MM.

[0034] It is recalled that the creep function is intended, when activated by the supervisor CS, to move the vehicle V at low speed (typically between 5 km / h and 12 km / h) by supplying a variable torque produced by its internal combustion engine MT or its driving machine MM without its driver acting on its brake pedals PF and accelerator pedals PA.

[0035] In the non-limiting example illustrated on the figure 1 The DC control device is part of the CS supervisory computer. However, this is not mandatory. This DC control device could be a separate piece of equipment coupled to the CS supervisory computer, either directly or indirectly. Therefore, the DC control device can be implemented as software modules, or as a combination of electronic circuits (or hardware) and software modules.

[0036] A DC control device, according to the invention, comprises control means MC which are responsible for intervening whenever the vehicle V is moving forward or backward and at a speed below a speed threshold, with its brake pedal PF and accelerator pedal PA not depressed. This speed threshold is, for example, equal to 10 km / h.

[0037] Each time the aforementioned life situation occurs, the MC control means trigger either an early operation of the thermal engine MT, or a delayed operation of the (non-thermal) drive machine MM, depending on whether the current state of charge ec of the first energy storage means MS1 is below or above a predefined state threshold s2.

[0038] The early operation of the MT thermal engine is triggered to provide at a predefined instant ip (or t5) a predefined torque cp to ensure the creeping function when the current pressure p mc in the master cylinder of the CF braking circuit becomes less than a predefined pressure threshold s1.

[0039] The delayed operation of the drive machine MM is triggered a predefined time interval it after the current pressure p mc in the master cylinder of the braking circuit CF has become equal to a predefined value vp, strictly less than the predefined pressure threshold s1, to provide at that predefined instant ip (or t5) that predefined torque cp to ensure the creeping function.

[0040] In other words, if vehicle V is traveling at a speed below the speed threshold with its brake pedal PF and accelerator pedal PA not depressed, and if ec is less than s2, then the control means MC trigger an early operation of the internal combustion engine MT when p mc becomes less than s1. Now, if vehicle V is traveling at a speed below the speed threshold with its brake pedal PF and accelerator pedal PA not depressed, and if ec is greater than s2, then the control means MC trigger a delayed operation of the drive machine MM for a predefined time interval it after p mc has become equal to vp.

[0041] This predefined value vp can, for example, be zero.

[0042] Thanks to this strategy of controlling the activation times of the creep function by the internal combustion engine MT and the drive machine MM respectively, it is now certain that at the predefined time ip, the predefined creep torque cp will be supplied to the drive wheels, regardless of its source (MT or MM). Thus, the response times and performance of the internal combustion engine MT and the drive machine MM appear virtually identical, which avoids any inconvenience for the driver and passengers of vehicle V during a creep phase.

[0043] For example, the MC control means can trigger the operation of the advanced MT thermal engine for a predefined duration dp relative to a reference instant ir (or t3) where the current pressure becomes equal to the predefined value vp (see figure 2 ). In this case, this predefined duration dp is a function of the time tn1 required for the internal combustion engine MT to supply the predefined torque cp from the generation of an initial torque setpoint dedicated to the creeping function and equal to the predefined torque cp (see figure 2 ).

[0044] The predefined duration dp, which is used by the MC control means, can, for example, be between -20 ms and -100 ms. As an example, the MC control means can use a predefined duration dp of -50 ms.

[0045] It should be noted that the MC control means can use a predefined duration dp which has been previously learned for the vehicle V during factory or road tests.

[0046] Also, for example, the MC control means can trigger the operation of the drive machine MM delayed by the predefined time interval it relative to the reference instant ir (or t3) where the current pressure p mc in the master cylinder of the brake circuit CF becomes equal to the predefined value vp (see figure 2 ). In this case, this predefined time interval it is a function of the time tn2 required for the drive machine MM to supply the predefined torque cp from the generation of a second torque setpoint dedicated to the creeping function and equal to the predefined torque cp (see figure 2 ).

[0047] The predefined time interval it, which is used by the MC control means, can, for example, be between +20 ms and +100 ms. As an example, the MC control means can use a predefined time interval it of +50 ms.

[0048] It should be noted that the MC control means can use a predefined time interval it which has been previously learned for the vehicle V during factory or road tests.

[0049] It should also be noted that if the moment (t2) at which the first torque command for the internal combustion engine MT is generated is anticipated too early (and therefore if a predefined duration dp is used that is too long), there is a risk of triggering the creep phase with a pressure threshold s1 that is too high, and therefore incorrectly. Conversely, if the moment (t4) at which the second torque command for the drive machine MM is generated is delayed too long (and therefore if a predefined time interval it is used that is too long), there is a risk of degrading the driver's experience because they will think that the creep function has not been triggered.

[0050] This has been schematically illustrated within the diagrams of the figure 2an example of a vehicle life situation V in which a creeping phase occurs resulting in the supply of the predefined torque cp at the predefined instant ip (or t5) either by the internal combustion engine MT (central diagram), or by the drive machine MM (bottom diagram).

[0051] In these diagrams: a first curve c1 represents an example of the time evolution (t) of the pressure p mc in the master cylinder of the CF braking circuit, a second curve c2 represents an example of the time evolution (t) of the first creep torque setpoint generated for the internal combustion engine MT before and during a creep phase when the current state of charge ec of the first energy storage means MS1 is below the predefined state threshold s2, a third curve c3 represents an example of the time evolution (t) of the creep torque actually supplied by the internal combustion engine MT during the creep phase to satisfy the first creep torque setpoint,A fourth curve, c4, represents an example of the time evolution (t) of the second creep torque setpoint generated for the drive machine MM before and during a creep phase when the current load state ec of the first energy storage means MS1 is greater than the predefined state threshold s2, and a fifth curve, c5, represents an example of the time evolution (t) of the creep torque actually supplied by the drive machine MM during the creep phase to satisfy the second creep torque setpoint.

[0052] In this example, we can observe on curve c1 that from a certain instant t1, the pressure p mc (in the master cylinder of the braking circuit CF) begins to decrease sharply, which is characteristic of the fact that the driver has just released the brake pedal PF. We assume here that the vehicle V is moving forward or backward at a speed below the speed threshold, with its accelerator pedal PA also released.

[0053] From time t2, the current pressure pmc (c1) falls below the pressure threshold s1. If the control systems MC detect that the current load state ec is below the state threshold s2, they immediately trigger early operation of the MT internal combustion engine at time t2. To do this, and as illustrated in the central diagram by curve c2, they generate, for the MT internal combustion engine, at time t2 shifted from the reference time t3 (or ir) by the predefined duration dp, an initial creep torque setpoint equal to the predefined torque cp. It can be observed on curve c3 that slightly after time t2, the actual creep torque supplied by the MT internal combustion engine increases during the creep phase until it reaches the value of the predefined torque cp at time t5 (equal to the predefined time ip).

[0054] Conversely, if at time t2 the control means MC detect that the current load state ec is above the state threshold s2, then they trigger a delayed operation of the internal combustion engine MT. To do this, and as illustrated in the lower diagram by curve c4, they generate for the drive machine MM, at a time t4 offset from the reference time t3 (or ir) by a duration equal to the predefined time interval it, a second creep torque command equal to the predefined torque cp. We can observe on curve c5 that slightly after time t4, the creep torque actually supplied by the drive machine MM increases during the creep phase until it reaches the value of the predefined torque cp at time t5 (equal to the predefined time ip), as in the case of curve c3.

[0055] It is also important to note that the invention can also be considered from the perspective of a control method, which can be implemented, in particular, by means of a DC control device of the type described above. Since the functionalities offered by the implementation of the method according to the invention are identical to those offered by the DC control device described above, only the combination of main functionalities offered by the method is presented below.

[0056] This control method includes a step in which, when the vehicle V is moving with its brake pedal PF and accelerator pedal PA not depressed, the vehicle V's DC control device either triggers an early operation of the internal combustion engine MT to provide at a predefined instant ip a predefined torque cp to ensure a creeping function when the current pressure p mc becomes less than a predefined pressure threshold s1, or a delayed operation of the drive machine MM for a predefined time interval it after the current pressure p mc has become equal to a predefined value vp, strictly less than the predefined pressure threshold s1, to provide at that predefined instant ip this predefined torque cp to ensure the creeping function, depending on whether the current state of charge ec of the energy storage means MS1 is less than or greater than a predefined state threshold s2.

[0057] The invention makes it possible to guarantee a homogeneous performance of the creep phase regardless of the torque source (thermal or non-thermal) used.

Claims

1. Control device (DC) for a vehicle (V) comprising i) a brake pedal (PF) coupled to a braking circuit (CF) in which a current pressure prevails, ii) an accelerator pedal (PA), iii) at least one energy storage means (MS1) having a current state of charge, and iv) a heat engine (MT) and a non-thermal drive machine (MM) respectively providing torques for at least a train (T1) by consuming respectively fuel and energy stored in said energy storage means (MS1), characterized in that it comprises control means (MC) triggering, when said vehicle (V) rolls with said brake pedal (PF) and accelerator pedal (PA) not depressed, an anticipated operation of said heat engine (MT) to provide at a predefined moment a predefined torque to ensure a so-called crawling function when said pressure in progress becomes below a predefined pressure threshold, a function of said non-thermal prime mover (MM) by a predefined time interval after said current pressure has become equal to a predefined value, strictly less than said predefined pressure threshold, to provide said predefined moment at said predefined torque for performing said crawling function, depending on whether said current state of charge is lower or higher than a predefined state threshold.

2. Device according to claim 1, characterized in that said control means (MC) trigger said operation of the heat engine (MT) advanced by a predetermined time relative to a reference time when said current pressure becomes equal to said value predefined, this predetermined time being a function of the time required for said heat engine (MT) to provide said preset torque from generating a first torque set dedicated to said function of walking crawled and equal to said predefined torque.

3. Device according to Claim 2, characterized in that the said control means (MC) use a predefined duration of between - 20 ms and - 100 ms.

4. Device according to claim 2 or 3, characterized in that said control means (MC) using a predefined duration previously learned for said vehicle (V).

5. Device according to one of claims 1 to 4, characterized in that said control means (MC) trigger said operation of the non-thermal engine (MM) delayed from said predefined time interval with respect to a reference time when said current pressure becomes equal to said predefined value, this predefined time interval being the time needed for the said prime mover nonthermal (MM) to provide the said preset torque from generating a second torque setpoint dedicated to said crawling function and equal to said predefined torque.

6. Device according to claim 5, characterized in that the said control means (MC) use a predefined time interval of between + 20 ms and + 100 ms.

7. Device according to claim 5 or 6, characterized in that said control means (MC) using a predefined time interval learned beforehand for said vehicle (V).

8. Vehicle (V) comprising i) a brake pedal (PF) coupled to a braking circuit (CF) in which current pressure prevails, ii) an accelerator pedal (PA), iii) at least one storage means energy (MS1) having a state of charge in progress, and iv) a heat engine (MT) and a non-heat engine (MM) respectively providing torques for at least one train (T1) by consuming fuel respectively and energy stored in said energy storage means (MS1), characterized in that it further comprises a control device (DC) according to one of the preceding claims.

9. Vehicle according to Claim 8, characterized in that the said non-thermal driving machine (MM) is of the electrical type, and the said energy storage means (MS1) stores electrical energy.

10. Control process (DC) for a vehicle (V) comprising i) a brake pedal (PF) coupled to a braking circuit (CF) in which a current pressure prevails, ii) an accelerator pedal (PA)), iii) at least one energy storage means (MS1) having a current state of charge, and iv) a heat engine (MT) and a non-thermal drive machine (MM) respectively providing torques for at least a train (T1) by consuming respectively fuel and energy stored in said energy storage means (MS1), characterized in that it comprises a step in which, when said vehicle (V) is running with said pedal brake (PF) and accelerator pedal (PA) not depressed, either an anticipated operation of said heat engine (MT) is triggered to provide at a predefined moment a predefined torque to ensure a so-called crawling function when said pressure in progress falls below a predefined pressure threshold, operation delayed of said non-thermal prime mover (MM) by a predefined time interval after said current pressure has become equal to a predefined value, strictly lower than said predefined pressure threshold, to provide at said predefined instant said predefined torque to ensure said crawling function, depending on whether said current state of charge is below or above a predefined state threshold.