Shift control method for vehicle

Abstract

The present invention comprises, when shifting is initiated, a step in which a controller sets a predetermined first target rotational speed for controlling the EOP; a step in which the controller determines a target current according to the first target rotational speed; a step in which the controller maintains the target rotational speed until the EOP driving current reaches the target current; a step in which, when the EOP driving current exceeds the first target rotational speed, the controller linearly reduces the rotational speed of the EOP from a predetermined second target rotational speed to a third target rotational speed; and a step in which the EOP driving power is increased so that the frictional force of the friction clutch is increased so that the slip of the friction clutch is less than a predetermined reference slip.

Description

Technology Field

[0001] The present invention relates to a method for controlling the transmission of a vehicle. Background Technology

[0003] FIG. 1 is a configuration of an electric vehicle transmission to which the present invention can be applied.

[0004] The input shaft (IN), which is rotated by the power of the motor generator (MG), can drive the first drive gear (D1) through the one-way clutch (OWC), and the second drive gear (D2) can be switched to be connected to the input shaft (IN) through the friction clutch (FC). The output shaft (OUT) is equipped with a first driven gear (P1) that meshes with the first drive gear (D1) and a second driven gear (P2) that meshes with the second drive gear (D2), so that the power transmitted through the first driven gear (P1) or the second driven gear (P2) can be transmitted to the differential (DF) through the output gear (OG).

[0005] The input shaft (IN) is equipped with a dog clutch (or synchronous device; DC) that can implement reverse gearing by fixing the first drive gear (D1) to the input shaft (IN) and reversing gearing by the reverse rotation of the motor generator (MG).

[0006] In a transmission configured as described above, when shifting from 1st gear to 2nd gear, the shift to 2nd gear is completed simply by engaging the friction clutch (FC) while in the 1st gear driving state.

[0007] In other words, the gear shift from 1st to 2nd is achieved by engaging a single friction clutch (FC).

[0009] The matters described as the background technology of the above invention are intended only to enhance understanding of the background of the invention and should not be construed as an acknowledgment that they constitute prior art already known to those skilled in the art. Prior art literature

[0010] KR 1020160005210 A The problem to be solved

[0011] The present invention aims to provide a transmission control method for a vehicle equipped with a transmission that performs transmission by engaging a friction clutch, wherein the friction clutch can be controlled with a simpler configuration, thereby reducing the number of parts required for the transmission while ensuring appropriate transmission performance, ultimately thereby further improving the marketability of the vehicle. means of solving the problem

[0013] The transmission control method of the vehicle according to the present invention for achieving the above-mentioned purpose is,

[0014] A transmission shift control method for a transmission equipped with an EOP directly connected to a friction clutch,

[0015] When shifting is initiated by engaging the friction clutch, the controller sets a predetermined first target rotational speed to control the EOP;

[0016] The step of the controller determining a target current according to the first target rotational speed;

[0017] A step of maintaining the target rotational speed until the EOP driving current, which is the current driving the EOP by the controller, reaches the target current;

[0018] When the EOP driving current exceeds the target current, the controller linearly reduces the rotational speed of the EOP from a predetermined second target rotational speed to a third target rotational speed;

[0019] A step of increasing the EOP driving power, which is the power driving the EOP, so that the frictional force of the friction clutch is increased and the slip of the friction clutch is less than a predetermined reference slip;

[0020] It is characterized by being composed including

[0022] The above first target rotational speed is set according to the ATF oil temperature and the APS signal;

[0023] The higher the above ATF oil temperature, and the greater the amount of accelerator pedal operation indicated by the APS signal, the higher the above first target rotational speed can be set.

[0025] The target current according to the above first target rotational speed is

[0026] In a situation where the above EOP is rotated at the above first target rotational speed, the EOP driving current can be set to the time when the filling of ATF in the path from the EOP to the friction clutch is completed and the piston starts to move.

[0028] The above controller

[0029] Set the third target rotation speed according to the temperature of the ATF;

[0030] By setting the piston stroke time of the friction clutch according to the signal of the APS;

[0031] The second target rotation speed can be set using the third target rotation speed and the stroking time.

[0033] The above third target rotational speed is set higher as the temperature of the ATF increases;

[0034] The stroke time of the above piston can be set shorter as the APS signal indicates a larger amount of accelerator pedal operation.

[0036] The controller can set the second target rotational speed so as to secure an ATF flow rate that fills the space created by the stroke of the piston by linearly changing the rotational speed of the EOP from the second target rotational speed to the third target rotational speed during the stroke time.

[0038] In the step of increasing the above EOP driving power,

[0039] The above controller can increase the driving power of the EOP according to a predetermined pressure profile selected based on the APS signal.

[0041] The above pressure profile may be selected to consist of a higher level of pressure as the APS signal indicates a larger amount of accelerator pedal operation.

[0043] After performing the step of increasing the above EOP driving power,

[0044] If the slip of the friction clutch is greater than or equal to a predetermined reference slip, a step of further increasing the EOP driving power until the slip of the friction clutch becomes less than the reference slip;

[0045] Can perform more.

[0047] If the step of further increasing the above EOP driving power is performed,

[0048] The above controller can learn the additionally increased EOP driving power until the slip of the friction clutch becomes less than the reference slip, and in subsequent shift control, the additionally increased EOP driving power is reflected in the EOP driving power according to the pressure profile. Effects of the invention

[0050] The present invention enables the control of the friction clutch with a simpler configuration in a vehicle equipped with a transmission that performs shifting by engaging a friction clutch, thereby reducing the number of parts required for the transmission while ensuring appropriate shifting performance, ultimately thereby further improving the marketability of the vehicle. Brief explanation of the drawing

[0052] FIG. 1 is a drawing illustrating the structure of an electric vehicle transmission to which the present invention can be applied. FIG. 2 is a diagram illustrating the configuration of a hydraulic control device for controlling the transmission of FIG. 1 to which the present invention can be applied. FIG. 3 is a flowchart illustrating an embodiment of a vehicle transmission control method according to the present invention. Figure 4 is a graph illustrating a vehicle transmission control method according to the present invention. Specific details for implementing the invention

[0053] Referring to FIGS. 1 and FIGS. 2, the friction clutch (FC) of FIG. 1 is controlled by directly receiving hydraulic pressure discharged from an electric oil pump (EOP), and the motor (M) of the EOP is controlled by a controller (CLR).

[0054] A portion of the ATF (Auto Transmission Fluid), which is the oil discharged from the above EOP, is used through the orifice (OF) for lubricating and cooling the friction clutch (FC) as well as other gears.

[0056] Referring to FIG. 3, an embodiment of the transmission control method of a vehicle according to the present invention is a transmission control method for a transmission having an EOP directly connected to a friction clutch (FC), wherein when a transmission is initiated by engaging the friction clutch (FC), a controller (CLR) sets a predetermined first target rotational speed (V1) for controlling the EOP (S10); the controller (CLR) determines a target current according to the first target rotational speed (V1) (S20); the controller (CLR) maintains the target rotational speed until the EOP driving current, which is the current driving the EOP, reaches the target current (S30); and when the EOP driving current exceeds the target current, the controller (CLR) linearly reduces the rotational speed of the EOP from a predetermined second target rotational speed (V2) to a third target rotational speed (V3) (S40). The method is configured to include a step (S50) of increasing the EOP driving power, which is the power driving the EOP, so that the frictional force of the friction clutch (FC) is increased so that the slip of the friction clutch (FC) becomes less than a predetermined reference slip.

[0057] In other words, the present invention allows the hydraulic pressure acting on the friction clutch (FC) to be directly controlled by controlling the EOP without hydraulic control by a separate solenoid valve, etc., thereby enabling smooth shifting operation while reducing the number of parts.

[0058] Here, the term 'EOP directly connected to the friction clutch' means that, as shown in FIG. 2, no separate solenoid valve or the like is provided between the EOP and the friction clutch (FC), so that the hydraulic pressure of the ATF discharged from the EOP acts directly on the friction clutch (FC).

[0059] In addition, the term 'shifting achieved by engaging a friction clutch' means that shifting is achieved by engaging only one friction clutch, such as shifting from 1st gear to 2nd gear by engaging a friction clutch (FC) in a transmission like Fig. 1.

[0060] That is, in the case of conventional transmissions that perform shifting using hydraulics, a so-called CLUTCH-TO-CLUTCH shifting is generally performed in which one clutch is released while another clutch is engaged, but the shifting situation to which the present invention is applied is such that shifting is achieved by engaging only one friction clutch without any clutch being separately released.

[0062] The first target rotational speed (V1) is set according to the ATF oil temperature and the APS signal; the higher the ATF oil temperature and the greater the amount of accelerator pedal operation indicated by the APS signal, the higher the first target rotational speed (V1) is set.

[0063] This is because as the oil temperature of the ATF increases, the viscosity of the ATF decreases, thereby increasing the leakage amount, and if the APS signal indicates a larger amount of accelerator pedal operation, it indicates that the driver intends to accelerate the vehicle more quickly; therefore, the first target rotational speed (V1) is set relatively higher to enable faster gear shifting.

[0064] The target current according to the first target rotational speed (V1) is set as the EOP driving current when the piston starts to move after the filling of ATF in the path from the EOP to the friction clutch (FC) is completed, in a situation where the EOP is rotated at the first target rotational speed (V1).

[0065] When shifting begins, the controller (CLR) controls the EOP to the first target speed (V1) and monitors the EOP driving current until it reaches the target current. The fact that the EOP driving current has reached the target current indicates that the ATF is fully filled in the path from the EOP to the friction clutch (FC) and that the piston of the friction clutch (FC) has now started to move.

[0066] That is, this process corresponds to section A of FIG. 4, and is a process in which all ATF is filled from the EOP to the pressure chamber where the piston of the friction clutch (FC) is located in order to engage the friction clutch (FC) when shifting is initiated. As described above, if the controller (CLR) continues to drive while maintaining the rotational speed of the EOP at the first target rotational speed (V1), the ATF discharged from the EOP is completely filled up to the pressure chamber. Subsequently, the pressure in the passage increases until the piston overcomes the elastic force of the return spring and begins to move, and accordingly, the EOP driving current increases. By utilizing this principle, it is determined that the filling of ATF in the passage from the EOP to the pressure chamber of the friction clutch (FC) is completed.

[0067] For reference, in the present invention, the friction clutch (FC) may be configured such that a plurality of clutch discs and clutch plates are arranged between two rotating bodies subject to power interruption, and when the clutch discs and clutch plates are pressed against each other, a frictional force is generated between the two rotating bodies. The clutch discs and clutch plates are pressed by a piston that slides linearly by hydraulic pressure within a pressure chamber, and when hydraulic pressure is not supplied to the pressure chamber, the piston does not press the clutch discs and clutch plates by means of a return spring, thereby interrupting the power between the two rotating bodies.

[0068] As described above, when the ATF filling is completed in the path from the EOP to the friction clutch (FC) and the piston begins to move, and the EOP driving current exceeds the first target rotational speed (V1), the controller (CLR) performs a step (S40) of linearly reducing the rotational speed of the EOP from the second target rotational speed (V2) to the third target rotational speed (V3).

[0069] This process corresponds to section B of Fig. 4, and is a process in which the piston of the friction clutch (FC) overcomes the elastic force of the return spring and begins to move, moving to a position where it begins to press the clutch disc and the clutch plate.

[0070] The movement of the piston as described above is called piston stroking, and after completing the piston stroking, the EOP rotational speed at which the clutch disc and clutch plate are pressed to generate frictional force in the friction clutch (FC) begins to be applied in earnest corresponds to the third target rotational speed (V3).

[0071] The controller (CLR) sets the third target rotational speed (V3) according to the temperature of the ATF; sets the piston stroke time of the friction clutch (FC) according to the signal of the APS; and sets the second target rotational speed (V2) using the third target rotational speed (V3) and the stroke time.

[0072] The above third target rotational speed (V3) is set higher as the temperature of the ATF increases; and the stroke time of the piston is set shorter as the APS signal indicates a larger amount of accelerator pedal operation.

[0073] That is, the third target rotational speed (V3) is set higher as the ATF temperature increases, taking into account that leakage in the hydraulic circuit increases as the ATF temperature increases, and the stroking time is set shorter as the APS signal indicates a larger amount of accelerator pedal operation, thereby promoting faster gear shifting.

[0074] The controller (CLR) sets the second target rotational speed (V2) so that the rotational speed of the EOP can be linearly changed from the second target rotational speed (V2) to the third target rotational speed (V3) during the stroking time, thereby securing the ATF flow rate that fills the space created by the stroke of the piston.

[0075] That is, the controller (CLR) has the volume of the space generated by the stroke of the piston, that is, the space to be filled with ATF according to the piston's stroke, pre-designed through multiple experiments and analyses, so that when the third target rotational speed (V3) and the piston stroke time are determined, the second target rotational speed (V2) is set so that the flow rate to fill the volume during the piston stroke time can be secured.

[0076] When the second target rotational speed (V2) is set as described above, the controller (CLR) rapidly adjusts the EOP from the first target rotational speed (V1) to the second target rotational speed (V2), and then gradually adjusts it to the third target rotational speed (V3), thereby completing the stroke of the piston.

[0078] Subsequently, in the step (S50) of increasing the EOP driving power, the controller (CLR) increases the driving power of the EOP according to a predetermined pressure profile selected according to the APS signal.

[0079] The above pressure profile is a profile that increases the frictional force of the friction clutch (FC) over time. In order to suppress the occurrence of shifting shock as much as possible and to facilitate rapid shifting, multiple profiles are pre-entered into a storage device, etc., based on the APS signal through multiple experiments and analyses, so that the controller (CLR) can refer to them. As the APS signal indicates a larger amount of accelerator pedal operation, a profile consisting of a higher level of pressure is selected, thereby facilitating faster engagement of the friction clutch (FC) and thus enabling faster shifting.

[0080] Here, adjusting the driving power of the EOP according to the pressure profile is because the pressure applied by the piston to the clutch disc and clutch plate is determined according to the driving power of the EOP.

[0081] For reference, this process corresponds to section C of Fig. 4. Fig. 4 indicates that the rotational speed of the EOP is controlled in this section as well, taking into account continuity with other sections. This rotational speed of the EOP refers to a rotational speed that causes the EOP driving power to follow the pressure profile.

[0082] As described above, when the driving power of the EOP is gradually increased according to the selected pressure profile, the friction clutch (FC) engages, and the slip of the friction clutch (FC) must be less than the reference slip. When the slip of the friction clutch (FC) is less than the reference slip in this manner, the gear shift is substantially completed.

[0083] Therefore, the above reference slip can be determined design-wise through multiple experiments and analyses as a value at a level where shifting can be judged as completed, as described above.

[0084] However, even after performing the step of increasing the EOP driving power, if the slip of the friction clutch (FC) is greater than or equal to the reference slip, the step (S60) of further increasing the EOP driving power is performed until the slip of the friction clutch (FC) becomes less than the reference slip, thereby reducing the slip of the friction clutch (FC) to less than the reference slip and allowing the gear shift to be terminated.

[0085] When the step of further increasing the EOP driving power as described above is performed, the controller (CLR) learns the additionally increased EOP driving power until the slip of the friction clutch (FC) becomes less than the reference slip, and in subsequent shift control, the additionally increased EOP driving power is reflected in the EOP driving power according to the pressure profile, thereby enabling faster shifting during the next shift under the same conditions.

[0086] As described above, the present invention can form the hydraulic pressure required for engaging the friction clutch (FC) that performs shifting by directly controlling the EOP without separately providing a solenoid valve or the like for controlling hydraulic pressure, thereby improving assembly and reducing costs by reducing the number of required parts, while also enabling smooth and stable shifting operation, which can greatly contribute to improving the marketability of the vehicle.

[0088] Although the present invention has been illustrated and described in relation to specific embodiments, it will be obvious to those skilled in the art that the present invention can be modified and changed in various ways without departing from the technical spirit of the invention as provided by the following claims. Explanation of the symbols

[0089] M; Motor CLR; controller OF; orifice FC; Friction clutch V1; 1st target rotation speed V2; 2nd target rotation speed V3; 3rd target rotation speed

Claims

Claim 1 A method for controlling a transmission of a vehicle equipped with an EOP directly connected to a friction clutch, wherein when a transmission is initiated by engaging the friction clutch, the controller sets a predetermined first target rotational speed for controlling the EOP; the controller determines a target current according to the first target rotational speed; the controller maintains the target rotational speed until the EOP driving current, which is the current driving the EOP, reaches the target current; when the EOP driving current exceeds the target current, the controller linearly reduces the rotational speed of the EOP from a predetermined second target rotational speed to a third target rotational speed; and the controller increases the EOP driving power, which is the power driving the EOP, so that the frictional force of the friction clutch increases so that the slip of the friction clutch becomes less than a predetermined reference slip. Claim 2 A method for controlling the transmission of a vehicle according to claim 1, wherein the first target rotational speed is set according to the ATF oil temperature and the APS signal; and wherein the first target rotational speed is set higher as the ATF oil temperature is higher and as the APS signal indicates a larger amount of accelerator pedal operation. Claim 3 A method for controlling a transmission of a vehicle according to claim 1, wherein the target current according to the first target rotational speed is set as the EOP driving current when the piston starts to move after the filling of ATF in the passage from the EOP to the friction clutch is completed in a situation where the EOP is rotated at the first target rotational speed. Claim 4 A method for controlling a vehicle's transmission according to claim 1, wherein the controller sets the third target rotational speed according to the temperature of the ATF; sets the piston stroke time of the friction clutch according to the signal of the APS; and sets the second target rotational speed using the third target rotational speed and the stroke time. Claim 5 A vehicle transmission control method according to claim 4, wherein the third target rotational speed is set higher as the temperature of the ATF increases; and the stroking time of the piston is set shorter as the APS signal indicates a larger amount of accelerator pedal operation. Claim 6 A method for controlling a vehicle's transmission, wherein, in claim 4, the controller sets the second target rotational speed so as to secure an ATF flow rate that fills the space created by the stroke of the piston by linearly changing the rotational speed of the EOP from the second target rotational speed to the third target rotational speed during the stroking time. Claim 7 A method for controlling a vehicle's transmission, wherein, in the step of increasing the EOP driving power according to claim 1, the controller increases the driving power of the EOP according to a predetermined pressure profile selected according to an APS signal. Claim 8 A method for controlling the transmission of a vehicle according to claim 7, wherein the pressure profile is selected to consist of a higher level of pressure as the APS signal indicates a larger amount of accelerator pedal operation. Claim 9 A method for controlling the transmission of a vehicle according to claim 7, characterized in that, after performing the step of increasing the EOP driving power, if the slip of the friction clutch is greater than or equal to a predetermined reference slip, the method further performs the step of further increasing the EOP driving power until the slip of the friction clutch becomes less than the reference slip. Claim 10 A method for controlling a vehicle's transmission, characterized in that, in the case of performing the step of further increasing the EOP driving power according to claim 9, the controller learns the additionally increased EOP driving power until the slip of the friction clutch becomes less than the reference slip, and in subsequent transmission control, the additionally increased EOP driving power is reflected in the EOP driving power according to the pressure profile.

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