Control device for vehicle

Abstract

To provide a control device for a vehicle, capable of improving a response feeling upon up-range operation.SOLUTION: When switching of a shift position to a high side is selected by manual operation, on the basis of a difference in required drive torque in drive torque characteristics between before and after the switching, undershoot control is performed such that, immediately after the switching of the shift position, the required drive torque is temporarily reduced to a value less than a value of the required drive torque in the drive torque characteristics after the switching. As a result, the required drive torque immediately after the switching of the shift position can be temporarily dropped relative to the required drive torque after the switching, so that an actual drive torque step due to up-range operation is appropriately obtained. Thus, a response feeling upon the up-range operation can be improved.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a control device for a vehicle equipped with an electric motor. [Background technology]

[0002] There is a well-known control device for a vehicle that includes an electric motor, a power transmission device that transmits the power of the electric motor to drive wheels, and a shift switching device that is manually operated to selectively switch between a plurality of shift positions (also synonymous with shift ranges) of a drive device that includes the electric motor and the power transmission device. For example, there is a motor torque control device described in Patent Document 1. Patent Document 1 discloses that a characteristic (map) for determining a target value (also synonymous with a required value) of drive torque based on a vehicle speed and an accelerator operation amount is set in advance for each shift range, and that the map for the low range is set so that the target value of the drive torque is larger than that of the map for the drive range (high range) when the vehicle speed and the accelerator operation amount are the same. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-77585 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when the shift range is changed by a shift switching device, that is, by manual operation, depending on the driving torque step, which is the difference in driving torque that accompanies map switching, there is a risk that even when an up-range operation is performed to switch the shift range to the high side, for example, there is a feeling that there is no reaction (or little reaction) in the driving torque (which is also synonymous with change or response).

[0005] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a vehicle control device that can improve the response feeling during up-range operation. [Means for solving the problem]

[0006] The gist of a first invention is a control device for a vehicle including: (a) an electric motor; a power transmission device that transmits power of the electric motor to drive wheels; and a shift switching device that is manually operated to selectively switch between a plurality of shift positions of a drive device including the electric motor and the power transmission device; (b) storing drive torque characteristics in which a required drive torque is calculated based on a vehicle speed and an accelerator operation amount that are predetermined for each of the shift positions, and in which the required drive torque is increased on the low side of the shift position compared to the high side when the vehicle speed and the accelerator operation amount are the same; (c) switching the drive torque characteristics in accordance with the shift position selected by the shift switching device; and (d) when switching of the shift position to the high side is selected by manual operation, performing undershoot control to temporarily reduce the required drive torque to a value lower than the required drive torque in the drive torque characteristic after the switching, based on a difference in the required drive torque in the drive torque characteristic before and after the switching, from immediately after the shift position is switched. Effect of the Invention

[0007] According to the first aspect of the present invention, when the shift position is manually switched to the high side, undershoot control is performed to temporarily reduce the required drive torque immediately after the shift position is switched to a value lower than the required drive torque in the drive torque characteristic after the shift position is switched, based on the difference in the required drive torque in the drive torque characteristic before and after the shift position is switched. This makes it possible to temporarily reduce the required drive torque immediately after the shift position is switched to the required drive torque after the shift position is switched, and an actual drive torque step accompanying an up-range operation can be appropriately obtained. This improves the sense of response during up-range operation. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and a control system for various controls in the vehicle. [Diagram 2] FIG. 2 is a diagram illustrating an example of a shift switching device. [Diagram 3] FIG. 4 is a diagram illustrating an example of a required drive torque map. [Figure 4] FIG. 11 is a diagram illustrating an example of setting an embodiment of undershoot control. [Diagram 5] 4 is a flowchart illustrating a main portion of the control operation of the electronic control device, and is a flowchart illustrating the control operation for improving the response feeling during an up-range operation. [Figure 6] 6 is a diagram showing an example of a time chart when the control operation shown in the flowchart of FIG. 5 is executed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0010] FIG. 1 is a diagram for explaining a schematic configuration of a vehicle 10 to which the present invention is applied, and is also a diagram for explaining main parts of a control system for various controls in the vehicle 10. In FIG. 1, the vehicle 10 is equipped with a first drive unit 12l, a second drive unit 12r, a first drive wheel 14l, a second drive wheel 14r, and a case 16 attached to the vehicle body. The first drive unit 12l is a drive unit on the left side facing the front of the vehicle 10, that is, on the left side in the vehicle width direction, and the second drive unit 12r is a drive unit on the right side in the vehicle width direction. The first drive wheel 14l is a drive wheel on the left side in the vehicle width direction, and the second drive wheel 14r is a drive wheel on the right side in the vehicle width direction.

[0011] The first drive device 12l includes a first electric motor MG1 and a first power transmission device 18l. The second drive device 12r includes a second electric motor MG2 and a second power transmission device 18r. The first drive device 12l and the second drive device 12r are basically configured symmetrically. When the first drive device 12l and the second drive device 12r are not particularly distinguished from each other, they are referred to as drive devices 12. When the first drive wheel 14l and the second drive wheel 14r are not particularly distinguished from each other, they are referred to as drive wheels 14. When the first electric motor MG1 and the second electric motor MG2 are not particularly distinguished from each other, they are referred to as electric motors MG. When the first power transmission device 18l and the second power transmission device 18r are not particularly distinguished from each other, they are referred to as power transmission devices 18.

[0012] The electric motor MG is a rotating electric machine, and is a so-called motor generator. The electric motor MG is connected to a battery 32 provided in the vehicle 10 via an inverter 30 provided in the vehicle 10. The battery 32 is an electricity storage device that supplies and receives electric power to the electric motor MG. The electric motor MG has an MG torque Tmg, which is the torque of the electric motor MG, controlled by an electronic control device 80 described later controlling the inverter 30. The electric motor MG is provided inside a case 16. The vehicle 10 is an electric vehicle equipped with the electric motor MG that functions as a power source for traveling.

[0013] The power transmission device 18 includes a counter gear 20 (first counter gear 20l, second counter gear 20r) and a hypoid gear 22 (first hypoid gear 22l, second hypoid gear 22r) which are a pair of parallel shaft gears housed within the case 16. The power transmission device 18 also includes a drive shaft 24 (first drive shaft 24l, second drive shaft 24r).

[0014] A rotating shaft of one gear of the counter gear 20 is integrally connected to a rotor shaft of the electric motor MG. A rotating shaft of the other gear of the counter gear 20 is integrally connected to a rotating shaft of one gear of the hypoid gear 22. A rotating shaft of the other gear of the hypoid gear 22 is integrally connected to a drive shaft 24. The power transmission device 18 transmits the power of the electric motor MG to the drive wheels 14 via the counter gear 20, the hypoid gear 22, the drive shaft 24, etc. The counter gear 20 functions as a reduction gear. The hypoid gear 22 transmits the power to the drive wheels 14 while reducing the speed. The drive wheels 14 may be the front wheels or the rear wheels.

[0015] FIG. 2 is a diagram for explaining an example of a shift switching device. As shown in FIG. 2(a), the vehicle 10 is equipped with a shift device 50 having an operating member (not shown) operated by the driver to one of a plurality of operating positions POSop. The shift device 50 is an example of a shift switching device that is manually operated to selectively switch a plurality of shift positions (also equivalently to the shift range Rsh) of the drive device 12. The operating position POSop is a signal that indicates the selection state of the shift range Rsh, and includes, for example, P, R, D, +, - operating positions. The shift range Rsh indicates the power transmission state of the drive device 12, and includes, for example, P, R, D, 3, 2, L ranges. The P (parking) operating position indicates the selection state of the P range of the drive device 12, in which the drive device 12 is in a neutral state and a rotating member that rotates together with the drive wheels 14 is mechanically fixed so as not to rotate. The R (reverse running) operating position indicates the selection state of the R range of the drive device 12, which enables reverse running. The D (forward travel) operating position represents a selected state of the D range of the drive device 12 that enables forward travel. The + operating position represents a selected state of switching the shift range Rsh to the high side (high vehicle speed side), i.e., the high range side, in the D, 3, 2, and L ranges of the drive device 12 that enable forward travel, i.e., the forward travel ranges. Switching to the high range side is, for example, an up-range in which the shift range Rsh is switched from the L range to the 2 range, or from the 2 range to the 3 range. The - operating position represents a selected state of switching the shift range Rsh to the low side (low vehicle speed side), i.e., the low range side, in the forward travel range. Switching to the low range side is, for example, a down-range in which the shift range Rsh is switched from the D range to the 3 range, or from the 3 range to the 2 range. The D range is the shift range Rsh on the highest speed side (highest side) of the forward travel ranges, and the L range is the shift range Rsh on the lowest speed side (lowest side) of the forward travel ranges. The 3, 2, and L ranges are manual ranges that are selected by manually operating to the + and - operating positions.

[0016] As shown in FIG. 2B, the vehicle 10 may be provided with a manual operation device 54 for selecting a manual range on the steering wheel 52. The manual operation device 54 is an example of a shift switching device that is manually operated to selectively switch the shift range Rsh, particularly the manual range. The manual operation device 54 has - switches 56 on the left and right on the front of the steering wheel 52, i.e., on the driver's side. The manual operation device 54 has + switches 58 on the left and right on the back of the steering wheel 52. The - switch 56 has a function equivalent to the - operation position of the shift device 50, and the + switch 58 has a function equivalent to the + operation position of the shift device 50. The operation of the - switch 56 and the + switch 58 is valid, for example, in the D range, and the manual range is switched by the operation.

[0017] 1, the vehicle 10 is equipped with an electronic control device 80 as a controller including a control device of the vehicle 10 related to the control of the electric motor MG, etc. The electronic control device 80 is configured to include a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc. The electronic control device 80 performs various controls of the vehicle 10 by the CPU performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM.

[0018] The electronic control device 80 is supplied with various signals (e.g., -switch (down range) signal Sdr, +switch (up range) signal Sur, vehicle speed V, MG1 rotational speed Nmg1, MG2 rotational speed Nmg2, accelerator opening θacc as the amount of accelerator operation by the driver, brake-on signal Bon, operation position POSop, etc.) based on detection values ​​by various sensors (e.g., -switch 56, +switch 58, vehicle speed sensor 60, MG1 rotational speed sensor 62, MG2 rotational speed sensor 64, accelerator opening sensor 66, brake pedal sensor 68, operation position sensor 70, etc.) provided in the vehicle 10. The electronic control device 80 outputs various command signals (e.g., MG control command signal Smg, etc.) to each device (e.g., inverter 30, etc.) provided in the vehicle 10.

[0019] The electronic control device 80 includes an electric motor control unit 82 to realize various controls in the vehicle 10. The electric motor control unit 82 calculates a drive demand amount for the vehicle 10 from the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a drive demand amount map. The drive demand amount is, for example, a drive torque Tr required for the vehicle 10, that is, a required drive torque Trdem [Nm] at the drive wheels 14. The electric motor control unit 82 outputs an MG control command signal Smg to realize the required drive torque Trdem.

[0020] The driving demand map is a relationship for calculating the driving demand that is experimentally or design-wise obtained and stored in advance, i.e., is predetermined, and is, for example, a required driving torque map MAPtr. The electronic control unit 80 stores the required driving torque map MAPtr. The required driving torque map MAPtr is a driving torque characteristic that determines the required driving torque Trdem based on the vehicle speed V and the accelerator opening θacc, and different driving torque characteristics are set for each shift range Rsh.

[0021] Fig. 3 is a diagram for explaining an example of the required driving torque map MAPtr. Fig. 3(a) shows the required driving torque map MAPtr used, for example, in the D range. In Fig. 3(a), the required driving torque map MAPtr shows a predetermined relationship for determining the required driving torque Trdem that changes with the vehicle speed V and the accelerator opening θacc on a two-dimensional coordinate system with the horizontal axis representing the vehicle speed V and the vertical axis representing the required driving torque Trdem.

[0022] FIG. 3B shows the required drive torque map MAPtr used in the D range and the manual range (3, 2, L range) when the accelerator opening θacc is 50[%]. In FIG. 3B, the required drive torque map MAPtr in the D range shown by the thick line is the reference required drive torque map MAPtr. In the required drive torque map MAPtr in the manual range, the required drive torque Trdem is set to be larger when the vehicle speed V is the same, compared to the required drive torque map MAPtr in the D range. In the required drive torque map MAPtr in the manual range, when the vehicle speed V is the same, the required drive torque Trdem is set to be larger in order on the low range side (L range side). Although not shown, the setting of the required drive torque map MAPtr for each shift range Rsh has a similar tendency when the accelerator opening θacc is other than 50[%]. In this way, in the required drive torque map MAPtr, when the vehicle speed V and the accelerator opening θacc are the same, the required drive torque Trdem is increased on the low range side compared to the high range side.

[0023] The electric motor control unit 82 switches the required drive torque map MAPtr in accordance with the shift range Rsh selected by the shift device 50 or the manual operation device 54. For example, in the D range, if the shift device 50 is manually operated to the - operation position or the - switch 56 of the manual operation device 54 is manually operated once, i.e., a downrange operation is performed once, the required drive torque map MAPtr for the 3 range is used, and if a downrange operation is performed once, the required drive torque map MAPtr for the 2 range is used. Also, in the 2 range, if the shift device 50 is manually operated to the + operation position or the + switch 58 of the manual operation device 54 is manually operated once, i.e., an uprange operation is performed once, the required drive torque map MAPtr for the 3 range is used.

[0024] However, when an up-range operation is performed, depending on the drive torque step ΔTrdem that accompanies the switching of the required drive torque map MAPtr, there is a possibility that the driver may feel that there is no response to the up-range operation. The drive torque step ΔTrdem is the difference between the required drive torque Trdem in the required drive torque map MAPtr in the original shift range Rsh (the shift range Rsh before the switching) and the required drive torque Trdem in the required drive torque map MAPtr in the shift range Rsh after the switching. It is desirable to improve the sense of response when the shift range Rsh is switched.

[0025] Therefore, when the up-range is selected by manual operation, that is, when an up-range operation is performed, the motor control unit 82 performs undershoot control CNus of the driving torque Tr based on the driving torque step ΔTrdem. The undershoot control CNus is a control that temporarily reduces the required driving torque Trdem immediately after the shift range Rsh is switched to a value lower than the required driving torque Trdem in the required driving torque map MAPtr for the shift range Rsh after the switch. By temporarily reducing the driving torque Tr immediately after the shift range Rsh is switched, the response feeling can be improved.

[0026] The motor control unit 82 judges whether or not the undershoot control CNus is necessary. When the drive torque step ΔTrdem is equal to or larger than the drive torque step ΔTrdem that provides a sufficient response feeling when the shift range Rsh is switched, the motor control unit 82 judges that the undershoot control CNus is not necessary. On the other hand, when the drive torque step ΔTrdem is equal to or smaller than the drive torque step ΔTrdem that provides a predetermined driving state in which an up-range feeling is not expected to be felt, the motor control unit 82 judges that the undershoot control CNus is not necessary.

[0027] After the undershoot control CNus ends, the motor control unit 82 returns the required drive torque Trdem to the value of the required drive torque Trdem in the required drive torque map MAPtr in the shift range Rsh after the shift. This makes it easier to obtain the original drive torque Tr after the uprange. Note that the required drive torque Trdem in the required drive torque map MAPtr is determined by the vehicle speed V, etc., as described above.

[0028] FIG. 4 is a diagram for explaining an example of setting an embodiment of the undershoot control CNus. FIG. 4(a) is a predetermined undershoot torque rate map for obtaining the undershoot torque Tus in the undershoot control CNus. The undershoot torque Tus is a maximum value of a torque temporarily reduced from the required driving torque Trdem after the shift range Rsh is switched (see FIG. 6 described later). The undershoot torque rate map is a predetermined relationship for obtaining the undershoot torque rate Rtus changed by the driving torque step ΔTrdem on a two-dimensional coordinate system with the horizontal axis representing the driving torque step ΔTrdem and the vertical axis representing the undershoot torque rate Rtus. The undershoot torque rate Rtus is "undershoot torque Tus / required driving torque Trdem after the shift range Rsh is switched". If the driving torque step ΔTrdem is large, the necessity of the undershoot control CNus is reduced. In the undershoot torque rate map, the larger the driving torque step ΔTrdem is, the smaller the undershoot torque rate Rtus is set to be. The electric motor control unit 82 changes the undershoot torque rate Rtus based on the driving torque step ΔTrdem.

[0029] FIG. 4B shows a predetermined undershoot time map for obtaining the undershoot time TMus in the undershoot control CNus. The undershoot time TMus is the time for performing the undershoot control CNus (see FIG. 6 described later). The undershoot time map is a predetermined relationship for obtaining the undershoot time TMus that is changed by the driving torque step ΔTrdem on a two-dimensional coordinate system with the horizontal axis representing the driving torque step ΔTrdem and the vertical axis representing the undershoot time TMus. If the driving torque step ΔTrdem is large, the necessity for the undershoot control CNus is reduced. In the undershoot time map, the larger the driving torque step ΔTrdem is, the shorter the undershoot time TMus is set to. The motor control unit 82 changes the undershoot time TMus based on the driving torque step ΔTrdem.

[0030] FIG. 5 is a flowchart for explaining the main control operations of the electronic control unit 80, that is, the control operations for improving the response during up-range operation, and is executed, for example, repeatedly.

[0031] In FIG. 5, each step of the flow chart corresponds to a function of the electric motor control unit 82. First, in step (hereinafter, step will be omitted) S10, it is determined whether or not an up-range operation has been performed. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, in S20, the original shift range Rsh (current shift range Rsh), the shift range Rsh after switching, the vehicle speed V, and the accelerator opening θacc are read. Next, in S30, the driving torque step ΔTrdem is calculated, and the undershoot torque rate Rtus and the undershoot time TMus are calculated. Next, in S40, it is determined whether or not the undershoot control CNus is necessary. If the driving torque step ΔTrdem is sufficiently large, the undershoot control CNus is not performed. Also, even if the driving torque step ΔTrdem is small, the undershoot control CNus is not performed. If the determination in S40 is positive, in S50, the undershoot control CNus is performed. If the determination in S40 is negative, the undershoot control CNus is not executed in S60.

[0032] FIG. 6 is a diagram showing an example of a time chart when the control operation shown in the flowchart of FIG. 5 is executed. In FIG. 6, the horizontal axis indicates time, and the vertical axis indicates the change in the transient required driving torque Trdem. FIG. 6 shows an example of a case where the range is switched from the 2nd range to the 3rd range by a manual operation (up-range operation). The required driving torque Trdem is changed by the vehicle speed V and the accelerator opening θacc. When the up-range operation (manual up) is performed in the 2nd range (see time t1), the range is switched to the 3rd range (see time t2). When the range is switched to the 3rd range, that is, when the required driving torque Trdem is switched, the undershoot control CNus is executed at the undershoot torque rate Rtus (i.e., the undershoot torque Tus) and the undershoot time TMus calculated using the driving torque step difference ΔTrdem (see time t2-t3).

[0033] As described above, according to this embodiment, when an up-range operation is performed, an undershoot control CNus of the driving torque Tr is performed based on the driving torque step ΔTrdem. This makes it possible to temporarily reduce the required driving torque Trdem immediately after switching the shift range Rsh relative to the required driving torque Trdem after the switching, and to appropriately obtain the actual driving torque step ΔTrdem accompanying the up-range operation. This makes it possible to improve the sense of response during the up-range operation.

[0034] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0035] For example, in the above-described embodiment, the vehicle 10 is an electric vehicle, but the present invention is not limited to this. For example, the present invention can be applied to a hybrid electric vehicle that has an engine and an electric motor as a power source.

[0036] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0037] 10: vehicle 12: drive unit 14: drive wheel 18: power transmission unit 50: shift unit (shift switching unit) 54: manual operation unit (shift switching unit) 80: electronic control unit (control unit) MG: electric motor

Claims

[Claim 1] A control device for a vehicle including an electric motor, a power transmission device that transmits power of the electric motor to drive wheels, and a shift switching device that is manually operated to selectively switch among a plurality of shift positions of a drive device including the electric motor and the power transmission device, a required drive torque is calculated based on a vehicle speed and an accelerator operation amount that are predetermined for each shift position, and a drive torque characteristic is stored in which the required drive torque is increased on the low side of the shift position compared to the high side when the vehicle speed and the accelerator operation amount are the same; The drive torque characteristic is switched in accordance with the shift position selected by the shift switching device, A vehicle control device characterized in that, when the shift position is manually switched to the high side, undershoot control is implemented to temporarily reduce the required drive torque to a value lower than the required drive torque in the drive torque characteristic after the switching, based on a difference between the required drive torque in the drive torque characteristic before and after the switching, from immediately after the shift position is switched.

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