Very precise control of the minimum torque that the power train of a land vehicle can supply according to the state of a torque converter
Patent Information
- Application Number
- EP2024709138
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-03-23
- Filing Date
- 2024-02-07
- Publication Date
- 2026-01-28
AI Technical Summary
Current systems for determining the minimum torque achievable by a powertrain in land vehicles with a torque converter and automatic gearbox inaccurately account for the torque converter's state, leading to inconsistencies and passenger discomfort during autonomous driving due to overestimated torque and resulting jolts.
A control method that determines the minimum torque achievable by the powertrain based on the current reduction factor in the gearbox, the torque converter's state, loss torque, and inertial torque, ensuring precise torque calculation and reducing oscillations.
This method provides a precise determination of the minimum torque, improving passenger comfort by eliminating inconsistencies and reducing jolts during autonomous driving phases.
Smart Images
Figure FR2024050160_26092024_PF_FP
Abstract
Description
DESCRIPTION TITLE: HIGHLY ACCURATE CONTROL OF THE MINIMUM TORQUE ACHIEVABLE BY THE GMP OF A LAND VEHICLE, ACCORDING TO THE STATE OF A TORQUE CONVERTER The present invention claims priority from French application No. 2302727 filed on 03 / 23 / 2023, the content of which (text, drawings and claims) is incorporated herein by reference. Technical field of the invention
[0001] The invention relates to land vehicles comprising a powertrain (or GMP) with a thermal motor coupled to a torque converter associated with an automatic gearbox and coupled to drive wheels, and more precisely the determination of the minimum torque which can be achieved by such a GMP at the drive wheels. State of the art
[0002] Certain land vehicles, possibly of the automobile type, include a powertrain (or GMP) comprising a thermal motor having a drive shaft coupled to a torque converter, itself coupled to an automatic gearbox and coupled to at least one set of drive wheels.
[0003] When the land vehicle is in an autonomous driving phase controlled by a driving assistance function, the GMP supervision computer sends to this driving assistance function at least an estimate of the torque that is supplied to the drive wheels by the GMP and the minimum torque that can be achieved by the GMP at the drive wheels. It will be noted that unless the transmission chain including the GMP is “open”, the GMP cannot provide less than this minimum torque, because the latter corresponds to the idling torque of the thermal engine. For its part, the driving assistance function determines for the GMP supervision computer a torque setpoint that defines the torque that it wants the GMP to provide to the drive wheels and which cannot be less than the minimum torque achievable by the GMP.
[0004] As is known to those skilled in the art, the torque converter associated with an automatic gearbox can be either in a first state, sometimes called "bridged", in which it allows the transmission to the drive wheels of all the engine torque produced, taking into account the gear ratio of the gearbox, and a second state, sometimes called "unbridged", in which it allows only a portion of the engine torque produced to be transmitted to the drive wheels, taking into account the gear ratio of the gearbox. For example, the torque converter can be in an unbridged state when the vehicle is started (or taken off) or when the driver of the vehicle lifts his foot off the accelerator pedal.
[0005] Currently, the estimation of the torque provided by the GMP is made taking into account the state in which the torque converter is placed (the calculations are in fact different depending on whether the torque converter is in its bridged state or its unbridged state). On the other hand, the calculation of the minimum torque achievable by the GMP does not take into account the state in which the torque converter is placed (in fact the calculation is carried out as if the torque converter were permanently in its bridged state).
[0006] This difference in processing leads to inconsistencies, the consequences of which may be felt by the vehicle's passengers during autonomous driving phases. Indeed, the minimum torque achievable by the powertrain may be higher than the torque actually supplied to the drive wheels by the powertrain when this minimum torque is overestimated due to the torque converter being in its disengaged state. Each time this situation occurs, there is an inconsistency in the control carried out by the driving assistance function and therefore the torque setpoint that it transmits to the powertrain supervision computer is disturbed (occurrence of oscillations), which causes jolts in the vehicle, for example when following a lane or when starting (or taking off), which are felt by the passengers.
[0007] The invention therefore aims in particular to improve the situation. Presentation of the invention
[0008] To this end, it proposes in particular a control method intended to be implemented in a land vehicle comprising:
[0009] - a powertrain comprising a thermal engine capable of supplying a first torque to a torque converter having first and second states in which it delivers to a gearbox, automatic and coupled to drive wheels, a second torque equal respectively to the first torque and to a part of the first torque, and
[0010] - a driving assistance function capable of controlling the movements of the vehicle during an autonomous driving phase depending (in particular) on a first minimum torque achievable by the powertrain at the drive wheels.
[0011] This control method is characterized by the fact that it comprises a step in which, when the torque converter is in its second state, the first minimum torque is determined as a function of a current gear reduction factor in the gearbox, of a second minimum torque that the torque converter can provide, of a loss torque of the gearbox and of an inertial torque of the gearbox.
[0012] This consideration of the second minimum torque that the torque converter can provide, and which is variable, makes it possible to obtain a very precise first minimum torque, and therefore to significantly improve the passengers' feeling in terms of jolts.
[0013] The control method according to the invention may include other characteristics which may be taken separately or in combination, and in particular:
[0014] - in its step, when the torque converter is in its second state, the first minimum torque can be determined by multiplying the current gear reduction factor in the gearbox by a result of a subtraction between the second minimum torque that the torque converter can provide and a sum of the loss torque of the gearbox and the inertial torque of the gearbox;
[0015] - in the presence of the first option, in its step, it is possible to determine the second minimum torque that the torque converter can provide as a function of a minimum speed that the thermal motor machine can have, of an invariant of the torque converter and of a current torque ratio in the torque converter;
[0016] - in the presence of the last sub-option, in its step, we can determine the second minimum torque that the torque converter can provide by multiplying a result of a square of a ratio, between the minimum speed that the thermal motor can have and the invariant of the torque converter, by ten times the current torque ratio in the torque converter;
[0017] - also in the presence of the last sub-option, in its step, we can determine the invariant of the torque converter and the current torque ratio in the torque converter as a function of the minimum speed that the thermal motor machine can have and a current speed at the output of a turbine of the torque converter;
[0018] - in its step, when the torque converter is in its first state, the first minimum torque can be determined as a function of the current gear reduction factor in the gearbox, of a third minimum torque that can be supplied by the thermal engine, of the loss torque of the gearbox and of a cumulative inertial torque of the thermal engine and of the gearbox;
[0019] - in the presence of the last option, in its step, the first minimum torque can be determined by multiplying the current gear reduction factor in the gearbox by a result of a subtraction between the third minimum torque that the thermal motor can provide and a sum of the loss torque of the gearbox and the cumulative inertial torque of the thermal motor and the gearbox.
[0020] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a control method of the type of that presented above, in a land vehicle comprising, on the one hand, a powertrain comprising a thermal engine capable of supplying a first torque to a torque converter having first and second states in which it delivers to a gearbox, automatic and coupled to drive wheels, a second torque equal respectively to the first torque and to a part of the first torque, and, on the other hand, a driving assistance function capable of controlling movements of the vehicle during an autonomous driving phase as a function of a first minimum torque achievable by the powertrain at the drive wheels, to control a determination of the first minimum torque.
[0021] The invention also proposes a control device intended to equip a land vehicle comprising:
[0022] - a powertrain comprising a thermal engine capable of supplying a first torque to a torque converter having first and second states in which it delivers to a gearbox, automatic and coupled to drive wheels, a second torque equal respectively to the first torque and to a part of the first torque, and
[0023] - a driving assistance function capable of controlling the movements of the vehicle during an autonomous driving phase based on an initial minimum torque achievable by the powertrain at the drive wheels.
[0024] This control device is characterized by the fact that it comprises at least one processor and at least one memory arranged to carry out the operations consisting, when the torque converter is in its second state, in determining the first minimum torque as a function of a current gear reduction factor in the gearbox, of a second minimum torque that the torque converter can provide, of a loss torque of the gearbox and of an inertial torque of the gearbox.
[0025] The invention also provides a land vehicle comprising:
[0026] - a powertrain comprising a thermal engine capable of supplying a first torque to a torque converter having first and second states in which it delivers to a gearbox, automatic and coupled to drive wheels, a second torque equal respectively to the first torque and to a part of the first torque,
[0027] - a driving assistance function capable of controlling the movements of the vehicle during an autonomous driving phase based on a first minimum torque achievable by the powertrain at the drive wheels, and
[0028] - a control device of the type presented above.
[0029] For example, this vehicle may be of the automobile type. Brief description of the figures
[0030] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:
[0031] [Fig. 1] schematically and functionally illustrates an exemplary embodiment of a land vehicle comprising a GMP, thermal and torque converter associated with an automatic gearbox, a supervision computer, a driving assistance computer and a control device according to the invention,
[0032] [Fig. 2] schematically and functionally illustrates an exemplary embodiment of a supervision computer comprising an exemplary embodiment of a control device according to the invention, and
[0033] [Fig. 3] schematically illustrates an example of an algorithm implementing a control method according to the invention. Detailed description of the invention
[0034] The invention aims in particular to propose a control method, and an associated DC control device, intended to allow, in an autonomous driving phase of a land vehicle V controlled by a driving assistance function FAC, to control the precise determination of a first minimum torque d min which can be achieved by the GMP of this land vehicle V at the level of its driving wheels.
[0035] In the following, it is considered, by way of non-limiting example, that the land vehicle V is a motor vehicle. This is for example a car, as illustrated in Figure 1. But the invention is not limited to this type of land vehicle. It relates in fact to any type of land vehicle comprising, on the one hand, a powertrain (or GMP) comprising at least one thermal motor having a drive shaft coupled to a torque converter, itself coupled to an automatic gearbox and coupled to at least one set of drive wheels, and, on the other hand, a driving assistance function making it possible to control its movements during autonomous driving phases.
[0036] Figure 1 schematically shows a (land) vehicle V comprising a GMP transmission chain with a thermal engine MMT and a CC torque converter associated with an automatic gearbox BV, a supervision computer CS, a driving assistance computer CF, and a DC control device according to the invention.
[0037] It should be noted that the GMP could also be of the hybrid type (electric and thermal).
[0038] As shown, the drive train here also includes an AM drive shaft and an AT drive shaft.
[0039] The operation of the transmission chain (and therefore of the GMP) is supervised by the CS supervision computer.
[0040] The GMP being here purely thermal, as an illustrative example, it comprises a thermal motor MMT comprising a crankshaft (not shown) which is fixedly secured to the engine shaft AM in order to drive the latter (AM) in rotation. This thermal motor MMT is capable of operating according to a speed to provide a first torque c1, on order of the supervision computer CS. In addition, it (MMT) is capable of being coupled to the primary shaft AP of the gearbox BV via the torque converter CC. The latter (CC) is capable of delivering a second torque c2 from the first torque c1 produced by the thermal motor MMT, in particular for at least one train T1 of driving wheels.
[0041] This DC torque converter can be either in a first state, called "bridged", in which it allows to transmit to the drive wheels of the vehicle V a second torque c2 which is considered equal to the entirety of the first torque c1 produced taking into account the gear ratio of the gearbox BV, and a second state, called "unbridged", in which it allows to transmit to the drive wheels a second torque c2 which is equal to a part of the first torque c1 produced taking into account the gear ratio of the gearbox.
[0042] For example, the train T1 can be located in the front part PW of the vehicle V. It is preferably, and as illustrated, coupled to the transmission shaft AT via a differential (here front) DV. But in a variant this train T1 could be the one referenced T2 which is located in the rear part PRV of the vehicle V.
[0043] The driving assistance computer CF provides at least one driving assistance function FAC which makes it possible to control the movements of the vehicle V in autonomous driving phases. For example, this driving assistance function FAC may be responsible for regulating the speed of the vehicle V and the distance between vehicles (it is then often designated by the English acronym ACC ("Adaptive Cruise Control")).
[0044] In an autonomous driving phase controlled by the driving assistance function FAC, the supervision computer CS sends to this driving assistance function FAC at least one estimate ecr of the torque which is supplied to the drive wheels by the GMP and the first minimum torque c1 min which is achievable by (or which can supply) the GMP at the drive wheels. On receipt of these torque estimates ecr and first minimum torque cl min, the driving assistance function FAC determines for the supervision computer CS a torque setpoint ccg which defines the torque which it wants the GMP to supply to the drive wheels and which cannot be less than the first minimum torque cl min.
[0045] It will be noted that the driving assistance computer CF and the supervision computer CS can, for example, communicate via an internal communication network RC of the vehicle V, possibly multiplexed, as illustrated non-limitingly in figure 1.
[0046] As mentioned above, the invention proposes in particular a control method intended to enable the control of the precise determination of the first minimum torque c1 min which is achievable by (or which can be provided by) the GMP of the vehicle V at the level of its drive wheels.
[0047] This (control) method can be implemented at least partially by the DC control device (illustrated at least partially in Figures 1 and 2) which comprises for this purpose at least one processor PR1, for example a digital signal processor (or DSP ("Digital Signal Processor")), and at least one memory MD. This DC control device can therefore be implemented in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). For example, it can be a microcontroller.
[0048] The MD memory is RAM in order to store instructions for the implementation by the processor PR1 of at least part of the control method. The processor PR1 may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is understood to mean any type of device capable of carrying out at least one electrical or electronic operation.
[0049] In the example illustrated non-limitingly in Figures 1 and 2, the DC control device is part of the supervision computer CS. But this is not obligatory. Indeed, the DC control device could include its own dedicated computer, which is then coupled to the supervision computer CS, or could be part of another computer embedded in the vehicle V (here a vehicle) and providing at least one other function, for example.
[0050] As illustrated non-limitingly in Figure 3, the (control) method, according to the invention, comprises a step 10-50 which is implemented each time the supervision computer CS must transmit (in particular) a first minimum torque cl min determined to the driving assistance computer CF during an autonomous driving phase of the vehicle V.
[0051] Step 10-50 of the method comprises a sub-step 30 in which, when the DC torque converter is in its second state, one (for example the DC control device) determines the first minimum torque c1 min as a function of a current gear reduction factor fdb in the gearbox BV, of a second minimum torque c2min that the DC torque converter can provide, of a loss torque cpb of the gearbox BV and of an inertial torque ci 1 of the gearbox BV.
[0052] By taking into account the second minimum torque c2min that the torque converter CC can provide at the instant in question, and which is therefore variable, the first minimum torque c1 min determined is very precise, and therefore there is no longer any risk of inconsistency in the control carried out by the driving assistance function FAC. The torque setpoint ccg that the latter (FAC) will determine from, in particular, this first minimum torque cl min, then transmit to the supervision computer CS, is therefore no longer disturbed, and therefore the passengers' feeling in terms of jolts is significantly improved, in particular when following a lane or when starting (or taking off) the vehicle V.
[0053] For example, and as illustrated non-limitingly in Figure 3, the method may also comprise a sub-step 10 in which one (for example the DC control device) begins by determining the state (first or second) in which the DC torque converter is placed at the instant in question. If it is placed in its second state, one (for example the DC control device) will carry out in particular sub-step 30, while if it is placed in its first state, one (for example the DC control device) will carry out in particular a sub-step 50 to which one will return later.
[0054] Also for example, in sub-step 30 of step 10-50, and therefore when the DC torque converter is in its second state, we (e.g. DC control device) can determine the first minimum torque cl min by multiplying the current gear ratio fdb in the BV gearbox by the result of the subtraction between the second minimum torque c2min that can be provided by the DC torque converter and the sum of the loss torque cpb of the BV gearbox and the inertial torque cil of the BV gearbox. We then have the formula cl min = fdb*(c2min - (cpb + cil )).
[0055] Also for example, and as illustrated non-limitingly in Figure 3, the method can also comprise a sub-step 20 in which one (for example the DC control device) can determine the second minimum torque c2min that the DC torque converter can provide as a function of the minimum speed rtmin that the thermal motor MMT can have at the instant considered, of an invariant icc of the DC torque converter and of the current torque ratio rcc in the DC torque converter.
[0056] In this case, in sub-step 30 one (for example the DC control device) can, for example, determine the second minimum torque c2min that the DC torque converter can provide by multiplying the result of the squaring of a ratio, between the minimum speed rtmin that the thermal motor MMT can have at the instant considered and the invariant icc of the DC torque converter, by ten times the torque ratio rcc in progress in the DC torque converter. We then have the formula c2min = (rtmin / icc) 2 *10*rcc.
[0057] Also for example, in sub-step 30 of step 10-50, one (for example the DC control device) can, for example, determine the invariant icc of the DC torque converter and the current torque ratio rcc in the DC torque converter as a function of the minimum speed rtmin that the thermal motor MMT can have at the instant considered and the current speed rst at the output of the turbine of the DC torque converter. It is recalled that a hydraulic type torque converter generally comprises a hydraulic pump (possibly preceded by a clutch), followed by a receiving turbine comprising an inner part followed by an outer part.
[0058] It will be noted that the minimum speed rtmin can, for example, be determined by means of at least one sensor associated with the engine shaft AM, and the current speed rst can, for example, be determined by means of at least one sensor associated with the turbine of the torque converter CC.
[0059] It will also be noted, as illustrated non-limitingly in Figure 3 and as mentioned above, that the method can also comprise a sub-step 50 of step 10-50 in which, when the torque converter CC is in its first state (for example determined in sub-step 10), one (for example the control device DC) can determine the first minimum torque c1 min as a function of the current gear reduction factor fdb in the gearbox BV, of the third minimum torque c3min that the thermal motor MMT can provide, of the loss torque cpb of the gearbox BV at the instant in question and of a cumulative inertial torque ci2 of the thermal motor MMT and the gearbox BV at the instant in question. Here, the term "cumulative inertial torque ci2" means the sum of the inertial torque ci3 of the thermal motor MMT and the inertial torque ci1 of the gearbox BV, i.e. ci2 = ci3 + ci1.
[0060] For example, in sub-step 50 of step 10-50, and therefore when the DC torque converter is in its first state, one (for example the DC control device) can determine the first minimum torque cl min by multiplying the current gear reduction factor fdb in the gearbox BV by the result of the subtraction between the third minimum torque c3min that can be supplied by the thermal motor MMT and the sum of the loss torque cpb of the gearbox BV and the cumulative inertial torque ci2 of the thermal motor MMT and the gearbox BV. We then have the formula cl min = fdb*(c3min - (cpb + ci2)).
[0061] Also for example, and as illustrated non-limitingly in Figure 3, the method can also comprise a sub-step 40 in which, when the DC torque converter is in its first state, one (for example the DC control device) can begin by determining the third minimum torque c3min that the thermal motor MMT can provide.
[0062] It will also be noted, as illustrated non-limitingly in Figure 2, that the supervision computer CS (or the computer of the control device DC) can also include a mass memory MM1, in particular for storing the gear reduction factor fdb, the loss torque cpb, the inertial torque cil, the minimum speed rtmin, the invariant icc, the torque ratio rcc, the third minimum torque c3min and the cumulative inertial torque ci2, as well as any intermediate data involved in all its calculations and processing.Furthermore, this supervision computer CS (or the computer of the DC control device) can also comprise an input interface IE for receiving at least the gear ratio fdb, the loss torque cpb, the inertial torque cil, the minimum speed rtmin, the invariant icc, the torque ratio rcc, the third minimum torque c3min and the cumulative inertial torque ci2, possibly after having shaped and / or demodulated and / or amplified them, in a manner known per se, by means of a digital signal processor PR2. Furthermore, this supervision computer CS (or the computer of the DC control device) can also comprise an output interface IS, in particular for delivering each message containing the first minimum torque c1 min determined.
[0063] It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the control method described above to control the precise determination of the first minimum torque cl min which can be achieved by the GMP of the vehicle V at the level of its drive wheels.
Claims
CLAIMS
1. Control method for a land vehicle (V) comprising i) a powertrain comprising a thermal motor (MMT) capable of supplying a first torque to a torque converter (CC) having first and second states in which it delivers to a gearbox (BV), automatic and coupled to drive wheels, a second torque equal respectively to said first torque and to a part of said first torque, and ii) a driving assistance function capable of controlling movements of said vehicle (V) during an autonomous driving phase as a function of a first minimum torque achievable by said powertrain at said drive wheels, characterized in that it comprises a step (10-50) in which, when said torque converter (CC) is in said second state, said first minimum torque is determined as a function of a current gear reduction factor in said gearbox (BV),of a second minimum torque that can be provided by said torque converter (CC), of a loss torque of said gearbox (BV) and of an inertial torque of said gearbox (BV).,
2. Method according to claim 1, characterized in that in said step (10-50), when said torque converter (CC) is in said second state, said first minimum torque is determined by multiplying said current gear reduction factor in said gearbox (BV) by a result of a subtraction between said second minimum torque that can be provided by said torque converter (CC) and a sum of said loss torque of said gearbox (BV) and said inertial torque of said gearbox (BV).
3. Method according to claim 2, characterized in that in said step (10-50) said second minimum torque that said torque converter (CC) can provide is determined as a function of a minimum speed that said thermal motor (MMT) can have, of an invariant of said torque converter (CC) and of a current torque ratio in said torque converter (CC).
4. Method according to claim 3, characterized in that in said step (10-50) said second minimum torque that said torque converter (CC) can provide is determined by multiplying a result of a square of a ratio, between said minimum speed that said thermal motor (MMT) can have and said invariant of the torque converter (CC), by ten times said current torque ratio in said torque converter (CC).
5. Method according to claim 3 or 4, characterized in that in said step (10-50) said invariant of the torque converter (CC) and said current torque ratio in said torque converter (CC) are determined as a function of said minimum speed that said thermal motor (MMT) can have and of a current speed at the output of a turbine of said torque converter (CC).
6. Method according to one of claims 1 to 5, characterized in that in said step (10-50), when said torque converter (CC) is in said first state, said first minimum torque is determined as a function of said current gear reduction factor in said gearbox (BV), of a third minimum torque that said thermal motor (MMT) can provide, of said loss torque of said gearbox (BV) and of a cumulative inertial torque of said thermal motor (MMT) and of said gearbox (BV).
7. Method according to claim 6, characterized in that in said step (10-50) said first minimum torque is determined by multiplying said current gear reduction factor in said gearbox (BV) by a result of a subtraction between said third minimum torque that can be provided by said thermal motor (MMT) and a sum of said loss torque of said gearbox (BV) and said cumulative inertial torque of said thermal motor (MMT) and said gearbox (BV).
8. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the control method according to one of claims 1 to 7, in a land vehicle (V) comprising i) a powertrain comprising a thermal motor machine (MMT) capable of providing a first torque to a torque converter (CC) having first and second states in which it delivers to a gearbox (BV), automatic and coupled to driving wheels, a second torque equal respectively to said first torque and to a part of said first torque, and ii) a driving assistance function capable of controlling movements of said vehicle (V) during an autonomous driving phase as a function of a first minimum torque achievable by said powertrain at said driving wheels, to control a determination of said first minimum torque.
9. Control device (DC) for a land vehicle (V) comprising i) a powertrain comprising a thermal motor (MMT) capable of supplying a first torque to a torque converter (CC) having first and second states in which it delivers to a gearbox (BV), automatic and coupled to driving wheels, a second torque equal respectively to said first torque and to a part of said first torque, and ii) a driving assistance function capable of controlling movements of said vehicle (V) during an autonomous driving phase as a function of a first minimum torque achievable by said powertrain at said driving wheels, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting, when said torque converter (CC) is in said second state,determining said first minimum torque as a function of a current gear reduction factor in said gearbox (BV), of a second minimum torque that said torque converter (CC) can provide, of a loss torque of said gearbox (BV) and of an inertial torque of said gearbox (BV).,
10. Land vehicle (V) comprising i) a powertrain comprising a thermal motor (MMT) capable of supplying a first torque to a torque converter (CC) having first and second states in which it delivers to a gearbox (BV), automatic and coupled to drive wheels, a second torque equal respectively to said first torque and to a part of said first torque, and ii) a driving assistance function capable of controlling movements of said vehicle (V) during an autonomous driving phase as a function of a first minimum torque achievable by said powertrain at said drive wheels, characterized in that it further comprises a control device (DC) according to claim 9.