Control method for connecting a wheel axle and a drive machine in a hybrid vehicle

Abstract

The invention relates to a method designed to control the connection of a wheel axle in a traction chain of a vehicle to a drive machine (MM), the traction chain including an automatic transmission (BV) and a connection member (OC) for connection to the drive machine, and the method including providing a connection command (CC) for the connection member by a computer (CTRL) of the vehicle based on actuation of an accelerator pedal (PA) of the vehicle. According to the invention, the method includes: detecting an actuation of a predetermined type of the accelerator pedal, the actuation of the predetermined type possibly causing a change in at least one transmission ratio in the automatic transmission; and blocking (AC) the connection command when the actuation of the predetermined type is detected so as to prohibit torque transmission through the connection member.

Description

Technical field

[0001] This invention claims priority from French application N°2000172 filed on January 9, 2020, the content of which (text, drawings and claims) is incorporated herein by reference.

[0002] This invention generally relates to the control of the connection between the wheel axle and the drive machine in a land vehicle (such as a hybrid motor vehicle), but is not limited thereto. More specifically, this invention relates to a control method for controlling the connection between the wheel axle and the drive machine in a vehicle traction chain integrated with an automatic transmission. This invention is particularly applicable to, but not limited to, hybrid vehicles including at least two drive machines (of the thermal, electric and / or hydraulic type). Background art

[0003] The term "automatic transmission" needs to be interpreted broadly herein and in particular covers transmissions that are manually or automatically controlled and transmissions of the dual-clutch type, but is not limited thereto. Thus, depending on the type of transmission, the associated coupling member can be a dry clutch or a wet clutch.

[0004] Generally, in a vehicle equipped with an automatic transmission, a control computer (such as an engine management computer) manages the connection between the wheel axle associated with the automatic transmission and the drive machine, and in particular manages the transmission ratio to be engaged in the automatic transmission based on the position of the accelerator pedal. The position of the accelerator pedal represents the wheel torque requested by the driver of the vehicle.

[0005] In the control computer, different and independent first and second functions respectively determine the connection between the wheel axle and the drive machine and the transmission ratio to be engaged in the transmission.

[0006] Thus, when certain determined conditions are met, in particular when the wheel torque requested by the driver of the vehicle is greater than a predefined threshold, the first function mentioned above determines the connection between the wheel axle and the drive machine. This first function does not take into account the evolution of the transmission ratio to be engaged in the transmission in its decision, and the transmission ratio to be engaged itself is determined by the second function mentioned above.

[0007] The second function determines in particular the transmission ratio to be engaged in the transmission indirectly based on the position of the accelerator pedal. Generally, the more the accelerator pedal is depressed, the smaller the transmission ratio to be engaged in the transmission.

[0008] In the prior art, it is known to prohibit requests for gear ratio changes under special driving conditions. The prohibition of said gear ratio change is expressed by those skilled in the art as "dynamic correction", and this prohibition can intervene, in particular, in the case of a rapid lifting of the foot from the accelerator pedal, driving on a steep slope with the foot lifted, driving in a curve where the vehicle is subjected to a certain level of lateral acceleration, the intervention of a vehicle route control system (the so-called "ESP", i.e., "Electronic Stability Program"), the detection of excessive slipping of the drive wheels, and the gradual depression of the accelerator pedal until the accelerator pedal stabilizes.

[0009] In the situation where the driver gradually presses on the accelerator pedal, the inventive entity notices that events that are not conducive to driving pleasure may occur.

[0010] In fact, when gradually pressing on the accelerator pedal, the first function may determine the coupling of the wheel axle with the gear ratio determined by the second function therefrom. Subsequently, with the depression of the accelerator pedal, the second function may determine a change in the gear ratio, and this change is repeated several times until the accelerator pedal no longer changes.

[0011] Since the control computer responsible for implementing the gear ratio change and for the coupling of the wheel axle does not necessarily have the ability to interrupt the engaged action, the following events may occur, where, when the driver gradually presses on the accelerator pedal, one or more gear ratio changes intervene during or just after the coupling of the wheel axle with the drive machine. The gear ratio change that occurs just after the coupling of the wheel axle prolongs the arrangement time for arranging the torque desired by the driver and produces an acceleration of the vehicle at "multiple times", which affects driving pleasure. Summary of the Invention

[0012] It is desired to solve the above-mentioned disadvantages of the prior art by proposing an improved method for controlling the coupling of the wheel axle with the drive machine in the vehicle traction chain integrated with an automatic transmission.

[0013] According to a first aspect, the present invention relates to a control method for controlling the coupling of a wheel axle with a drive machine in a vehicle traction chain, the traction chain including an automatic transmission and a coupling member for coupling with the drive machine, the method including providing a coupling command for the coupling member by a computer of the vehicle according to the actuation of the accelerator pedal of the vehicle. According to the present invention, the method includes: detecting an actuation of a predetermined type of the accelerator pedal, the actuation of the predetermined type possibly prompting at least one gear ratio change in the automatic transmission; and, when detecting the actuation of the predetermined type, blocking the coupling command so as to prohibit the transmission of torque through the coupling member.

[0014] According to a particular feature, the actuation of the predetermined type is a gradual pressing on the accelerator pedal.

[0015] According to another particular feature, the detection includes: calculating a signed gradient of the position of the accelerator pedal; and comparing the amplitude of the signed gradient with a high threshold and a low threshold, and detecting the actuation of the predetermined type when the amplitude exceeds the high threshold.

[0016] Also according to another particular feature, the high threshold and the low threshold have values of adjustable parameters.

[0017] Also according to another particular feature, the detection further includes a confirmation duration which is required to cancel the block of the coupling command, and the cancellation occurs when the amplitude of the signed gradient does not exceed the low threshold for the confirmation duration.

[0018] Also according to another particular feature, the confirmation duration has a value of an adjustable parameter.

[0019] According to another aspect, the invention also relates to a computer which includes a memory storing program instructions for implementing the method briefly described above.

[0020] The invention also relates to a vehicle which is equipped with an automatic transmission and includes the computer described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other advantages and features of the invention will become more apparent by reading the detailed description of multiple embodiments and the drawings of the invention below. In the drawings:

[0022] Figure 1 is a schematic block diagram of a vehicle powertrain and a control computer in which a software module is housed for implementing a particular embodiment of the method according to the invention.

[0023] Figure 2 is a flowchart for describing the principle of the method according to the invention. DETAILED DESCRIPTION

[0024] Reference Figure 1, it is considered that the vehicle includes a powertrain GMP dedicated to the wheel axle of the vehicle. The powertrain GMP includes a drive machine MM and an automatic transmission BV. A coupling member OC (such as a dry clutch) ensures the coupling function for connecting the wheel axle to the drive machine MM. When the coupling member OC is in the closed state, the engine torque provided by the drive machine MM is transmitted towards the transmission BV and the wheel axle. The open state of the coupling member OC prohibits the transmission of the engine torque from the drive machine MM towards the transmission BV and the wheel axle.

[0025] In the vehicle, a computer CTRL ensures the control of the powertrain GMP by applying a control strategy capable of responding to different life situations of the vehicle. The computer CTRL implements the control strategy based on the actions of the driver on different control members (such as the accelerator pedal) of the vehicle and based on information from different sensors. Information from the sensors and from the components required by the control strategy is typically read by the computer CTRL on a vehicle data transfer network (such as a network of the "CAN" bus type).

[0026] The control of the coupling member OC according to the method of the present invention is implemented by a software module COC, which is housed and executed in the computer CTRL. The software module COC is installed in the memory MEM of the computer CTRL. The method of the present invention is implemented by the processor (not shown) of the computer CTRL executing the program code instructions of the software module COC.

[0027] As Figure 1 schematically shown above, the software module COC receives the position POS of the accelerator pedal PA of the vehicle as an input and sends a coupling command CC for the coupling member OC.

[0028] Figure 1 Other software modules different from the software module COC, not shown above, are also housed in the computer CTRL to control the transmission BV and the drive machine MM. In Figure 1 the above, a gear ratio change command CR and a drive machine command CM are shown. The gear ratio change command provides a set value of the gear ratio to be engaged to the transmission BV, and the drive machine command provides a speed / torque set value to the drive machine MM.

[0029] The coupling command CC is a valid actuation command for the coupling member OC and is determined according to the method of the present invention. The active logic state "1" and the non-active logic state "0" of the coupling command CC respectively determine the closed state and the open state of the coupling member OC.

[0030] As Figure 1 schematically shown above, in the method of the present invention, the coupling command CC is established by an "AND" logic function between a coupling request DC and a coupling authorization AC.

[0031] The connection request DC is determined in a known manner, as described above in the comments related to the prior art (see "First Function"). The logical state "1" and the logical state "0" respectively determine the activated connection request DC and the deactivated connection request DC.

[0032] In the method of the present invention, the set connection authorization AC is derived by calculating in consideration of the time evolution of the position POS of the accelerator pedal PA, so as to detect a gradual press on the accelerator pedal PA, which may cause a change in the transmission ratio after the closing of the connection member OC. The logical state "1" and the logical state "0" respectively determine the activated connection authorization AC and the deactivated connection authorization AC.

[0033] Now referring more specifically to Figure 2 , the method according to the present invention has been described in detail above, and this method is implemented to dynamically correct the connection command CC and prevent the occurrence of the drawbacks pointed out in the comments related to the prior art above.

[0034] In the present invention, in order to avoid multiple changes in the transmission ratio that may occur after the connection between the wheel axle and the drive machine MM, when a gradual press on the accelerator pedal PA is detected, the connection request CC is invalidated (AC = "0") until the accelerator pedal PA no longer evolves or hardly evolves. In other words, this is attributed to delaying the closing of the connection member OC during the gradual depression of the accelerator pedal PA, so that the said change in the transmission ratio occurs before the effective closing of the connection member OC. The gradual press on the accelerator pedal PA is detected by means of a marked gradient of the position POS of the accelerator pedal PA (hereinafter denoted as GSP). Thus, the marked gradient GSP is given by the equation GSP = d(POS) / dt. The comparison of the marked gradient GSP and the magnitude of this marked gradient with the high threshold and the low threshold SGH and SGB of the adjustable parameters can determine the logical state to be assigned to the connection authorization AC.

[0035] In Figure 2 's flowchart, blocks S1 and S2 are state blocks, and blocks CD1 to CD3 are conditional blocks, and these conditional blocks represent the conditions required for the transition from the state of block S1 to the state of block S2 (or vice versa).

[0036] Block S1 represents the authorization state EA that authorizes the closing of the connection member OC. When in this state, the connection authorization AC is activated, AC = "1". The software module COC thus provides the connection command CC = DC to the connection member OC, and if the connection request DC is activated, DC = "1", this connection command causes the connection member to close.

[0037] Block S2 represents the inhibition state EI that inhibits the closing of the coupling member OC. When in this state, the coupling authorization AC is deactivated, AC = "0". The software module COC thus provides the coupling command CC = "0" to the coupling member OC, and this coupling command keeps the coupling member open regardless of the state of the coupling request DC.

[0038] In the conditional blocks CD1 to CD3, the marking of the gradient GSP enables the distinction between a press on the accelerator pedal PA and the relaxation of this accelerator pedal.

[0039] The conditional block CD1 manages the transition from the authorization state EA of block S1 towards the inhibition state EI of block S2.

[0040] In the conditional block CD1, when the marking of the gradient GSP verifies the case of a press on the accelerator pedal PA, the amplitude of the gradient GSP is compared with the high threshold SGH.

[0041] In the case where the amplitude of the gradient GSP is greater than the high threshold SGH (IGSPI > SGH), it is determined that this press on the accelerator pedal PA may cause at least one gear ratio change after the closing of the coupling member OC. The conditional block CD1 thus activates the output Y, Y = "1", and this output verifies the transition towards block S2 and thus the inhibition state EI. The coupling authorization AC is thus deactivated, AC = "0", and the closing of the coupling member OC is inhibited.

[0042] In the case where the amplitude of the gradient GSP is not greater than the high threshold SGH, it is determined that this press on the accelerator pedal PA cannot cause a gear ratio change after the closing of the coupling member OC. The conditional block CD1 thus activates the output N, N = "1", and this output verifies the loopback to block S1 and thus the authorization state EA. The coupling authorization AC thus remains activated, AC = "1", and the closing of the coupling member OC is authorized.

[0043] The conditional blocks CD2 and CD3 manage the transition from the inhibition state EI of block S2 towards the authorization state EA of block S1.

[0044] In the conditional block CD2, when the sign of the gradient GSP verifies the case of a press on the accelerator pedal PA, the amplitude of the gradient GSP is compared with the low threshold SGB.

[0045] When the magnitude of the gradient GSP is less than the low threshold SGB (IGSBI < SGB), a weak evolution of the accelerator pedal PA is detected, and it is impossible to cause a change in the transmission ratio after the closing of the coupling member OC. The condition block CD2 thus activates the output Y, Y = "1", and this output triggers the counting of the confirmation duration DT in the condition block CD3. The confirmation duration DT of the condition block CD3 is a parameter that can be set and can confirm the sufficient persistence of the detection of IGSBI < SGB by the block CD2.

[0046] In the condition block CD3, if the block CD2 detects that IGSBI < SGB persists during a time t greater than the confirmation duration DT (t > DT), the condition block CD2 thus activates the output Y, Y = "1", and this output verifies the transition towards the block S1 and thus the return towards the authorized state EA. The coupling authorization AC is thus activated, AC = "1", and the authorized coupling member OC is closed. In the opposite case, that is, if it is detected that IGSBI < SGB is interrupted before the end of the confirmation duration DT (t > DT), the condition block CD2 thus activates the output N, N = "1", and this output verifies the loopback towards the block S2 and thus the prohibited state EI. The coupling authorization AC thus remains inactive, AC = "0", and the prohibited coupling member OC is closed.

[0047] In the condition block CD2, if the magnitude of the gradient GSP does not drop below the low threshold SGB, a significant evolution of the accelerator pedal PA is detected, that is, an evolution that remains likely to cause a change in the transmission ratio after the closing of the coupling member OC. The condition block CD2 thus activates the output N, N = "1", and this output verifies the loopback towards the block S2 and thus the prohibited state EI. The coupling authorization AC thus remains inactive, AC = "0", and the prohibited coupling member OC is closed.

[0048] As an example, considering that the position POS of the said accelerator pedal is measured as a percentage of the total travel of the pedal between the fully relaxed state of the pedal (which corresponds to POS = 0%) and the fully depressed state of the pedal (which corresponds to POS = 100%), the following values can be assigned to the high threshold SGH, the low threshold SGB, and the confirmation duration DT:

[0049] SGH = 200% / s (parameterizable in the range from 0 to 10000% / s);

[0050] SGB = 50% / s (parameterizable in the range from 0 to 10000% / s); and

[0051] DT = 100 ms (parameterizable in the range from 0 to 1000 ms).

[0052] It is noted that the measuring unit of the position POS can be millimeters (mm), degrees (°), or radians.

[0053] In the present invention, the comparison result of the marked gradient of the position of the accelerator pedal with a high threshold and a low threshold is used as a decision criterion, and the decision criterion determines the connection of the wheel axle in the powertrain to the automatic transmission when the driver gradually presses the accelerator pedal. The present invention provides a "dynamic correction" applied to the connection request of the wheel axle, which is activated when the driver gradually presses the accelerator pedal. Due to the present invention, the connection request of the wheel axle is verified only after the transmission ratio to be engaged in the transmission is stable. The connection of the wheel axle can directly intervene in the transmission ratio and is thus faster. Thereby, the acceleration phenomenon at multiple times mentioned above is avoided and the driving pleasure during the acceleration process is improved.

[0054] The present invention is not limited to the specific embodiments described herein as examples. Those skilled in the art can provide different modifications and variations within the protection scope of the present invention according to the application of the present invention.

Claims

1. A control method for controlling the connection of a wheel axle in a traction chain of a vehicle to a drive machine (MM), the traction chain including an automatic transmission (BV) and a connection member (OC) for connecting to the drive machine (MM), the control method including providing a connection command (CC) for the connection member (OC) by a computer (CTRL) of the vehicle based on actuation of an accelerator pedal (PA) of the vehicle, characterized in that, The control method includes: detecting (CD1, SGH) an actuation of a predetermined type of the accelerator pedal (PA), the actuation of the predetermined type being capable of causing a change in at least one transmission ratio in the automatic transmission (BV); and, when the actuation of the predetermined type is detected, blocking (S2, EI, AC) the coupling command (CC) so as to prohibit torque transmission through the coupling member (OC), wherein the detection includes: calculating a marked gradient (GSP) of the position (POS) of the accelerator pedal (PA); and, comparing the magnitude (IGSPI) of the marked gradient (GSP) with a high threshold and a low threshold (SGH, SGB), and detecting the actuation of the predetermined type when the magnitude (IGSPI) exceeds the high threshold (SGH), the detection further including a confirmation duration (CD3, DT), the confirmation duration being the time required to cancel (S1, EA) the blocking (S2, EI) of the coupling command (CC), and the cancellation (S1, EA) occurring when the magnitude (IGSPI) of the marked gradient (GSP) does not exceed (CD2) the low threshold (SGB) for the confirmation duration (CD3, DT).

2. The control method according to claim 1, wherein The actuation of the predetermined type is a gradual press on the accelerator pedal (PA).

3. The control method according to claim 1 or 2, characterized in that The high threshold and the low threshold (SGH, SGB) have values of adjustable parameters.

4. The control method according to claim 1 or 2, characterized in that, The confirmation duration (DT) has a value of an adjustable parameter.

5. A computer (CTRL), the computer including a memory (MEM) storing program instructions for implementing the control method according to any one of claims 1 to 4.

6. A vehicle equipped with an automatic transmission (BV), characterized in that, The vehicle includes the computer (CTRL) according to claim 5.

7. The vehicle according to claim 6, characterized in that, The vehicle is of a hybrid power type.

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