vehicle

Abstract

To provide a vehicle capable of achieving a driving feeling desired by a user even when a traveling mode is switched in a stage of gradually increasing the engine speed in transient shift control.SOLUTION: A vehicle 1 includes: a mode setting unit 98 for selecting a traveling mode from a normal mode and a power mode; and an ECU 91. The ECU 91 executes a transient shift control in which the input rotational speed is increased through a first shift stage for increasing the input rotational speed for a predetermined period and a second shift stage for increasing the input rotational speed more gradually than in the first shift stage, provided that the accelerator opening degree increases at a variation rate exceeding a predetermined value, and when the traveling mode is switched to the power mode in the middle of the second shift stage during execution of the transient shift control in the normal mode, the target rotation speed is changed to a value corresponding to the power mode, and the transient shift control is restarted.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a vehicle. [Background technology]

[0002] Conventionally, as disclosed in the following Patent Document 1, a vehicle equipped with a continuously variable transmission has been provided in which the user can select a driving mode from a plurality of modes such as a normal mode and a power mode by operating a selector switch or the like that can be operated at will. The power mode is a driving mode that has higher acceleration than the normal mode and is set for the purpose of realizing a sporty driving feeling, etc. Therefore, when the power mode is turned on, control is executed to set the target rotation speed higher than that in the normal mode in order to make the most of the output characteristics of the engine in the high rotation speed range. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-44723 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the inventors have investigated the behavior of a vehicle in which a driving mode such as a power mode can be selected as in the above-mentioned conventional technology when the accelerator opening is suddenly increased by kickdown or the like.

[0005] When the accelerator opening is suddenly increased by kickdown or the like, it is preferable to perform control to increase the engine speed in stages in order to avoid excessive load acting on the engine and transmission due to a sudden increase in engine speed. Specifically, when kickdown is performed in a vehicle equipped with a continuously variable transmission, first, in an initial stage (first shift stage), control is performed to increase the engine speed toward the target speed in a short period of time, thereby performing control to perform significant acceleration according to the user's request. Then, in the next stage (second shift stage), control is performed (transient shift control) to gradually increase the engine speed toward the target speed. By performing control through such stages, it is possible to perform smooth acceleration while suppressing a sudden large load acting on the engine and transmission.

[0006] On the other hand, when the accelerator opening degree is suddenly increased, and control is performed through a plurality of stages including the first and second shift stages described above, it is assumed that an operation to select a driving mode in which the target rotation speed is set high, such as the power mode described above, is performed during the second shift stage. If such a driving mode switching is performed during the second shift stage, the target rotation speed is set high, but there is no significant change in the speed of increase in the rotation speed or acceleration, which may cause a problem that it is difficult to achieve the driving feeling desired by the user.

[0007] Therefore, the present invention aims to provide a vehicle that allows the user to arbitrarily select one driving mode from a plurality of driving modes including a first mode and a second mode in which the target rotation speed is set higher than that in the first mode, and that can achieve the driving feeling desired by the user even if the driving mode is switched to the second mode at the stage where the engine rotation speed is gradually increased in transient shift control that is performed when the accelerator opening increases at a fluctuation rate exceeding a predetermined threshold value. [Means for solving the problem]

[0008] (1) A vehicle of the present invention includes a transmission, a power source that outputs power to the transmission, a mode setting unit that accepts a drive mode that can be arbitrarily selected from a plurality of drive modes including a predetermined first mode and a second mode in which a target rotation speed is set higher than that of the first mode, and a control device, and the control device includes a first shift stage in which an input rotation speed from the power source to the transmission is increased for a predetermined period of time toward a target rotation speed on condition that an accelerator opening degree increases at a rate of change exceeding a predetermined threshold value, and a second shift stage in which the first shift stage is increased. step and then a second shift stage in which the input rotation speed from the power source is increased toward the target rotation speed more gradually than in the first shift stage, thereby executing a transient shift control to increase the input rotation speed. During the process of executing the transient shift control with the first mode selected, the target rotation speed is changed to a value corresponding to the second mode and the transient shift control is restarted, on the condition that the driving mode is switched from the first mode to the second mode during the second shift stage.

[0009] As described above in (1), the vehicle of the present invention restarts the transitional shift control on the condition that the driving mode is switched from the first mode to the second mode during the second shift stage while the transitional shift control is being performed in the state where the first mode is selected. As a result, in the vehicle of the present invention, when the driving mode is switched from the first mode to the second mode while the engine speed is gradually increasing in the second shift stage after the first shift stage is completed, the target speed is changed to a value corresponding to the second mode and the transitional shift control is restarted, thereby performing the first shift stage in which the input speed is increased more steeply than in the second shift stage. Therefore, the vehicle of the present invention can realize the driving feeling desired by the user even if the driving mode is switched from the first mode to the second mode during the second shift stage while the transitional shift control is being performed in the state where the first mode is selected.

[0010] (2) In the vehicle of the present invention, the transmission may have a belt transmission mechanism between an input shaft to which power is input and an output shaft that outputs the power.

[0011] In the vehicle of the present invention, the transmission is provided with a belt transmission mechanism as described above in (2), which enables infinitely variable speed changes, and therefore transient shift control can be performed smoothly and quickly compared to when a general transmission such as an automatic transmission is used. Therefore, by configuring the vehicle of the present invention as described above in (2), the driving feeling during the execution of transient shift control can be further improved.

[0012] (3) The vehicle of the present invention may be configured such that the transmission includes a first engagement element interposed on a first power transmission path between an input shaft to which power is input and an output shaft to which power is output, and a second engagement element interposed on a second power transmission path between the input shaft and the output shaft, and has a belt transmission mechanism on the second power transmission path, and by releasing the first engagement element and engaging the second engagement element, a first mode is entered in which the total transmission ratio between the input shaft and the output shaft becomes larger as the belt transmission ratio by the belt transmission mechanism becomes larger, and by engaging the first engagement element and releasing the second engagement element, a second mode is entered in which the total transmission ratio becomes smaller as the belt transmission ratio becomes larger.

[0013] By configuring the transmission as described above in (3), the vehicle of the present invention can achieve the driving feeling desired by the user while improving power transmission efficiency and improving fuel efficiency by expanding the gear ratio range. Effect of the Invention

[0014] According to the present invention, the above-mentioned problems of the present invention can be solved. [Brief description of the drawings]

[0015] [Figure 1]1 is a skeleton diagram showing the configuration of a drive system of a vehicle that employs a transmission system according to an embodiment of the present invention. [Diagram 2] 2 is a diagram showing the states of each engagement element included in a transmission constituting the gear shift system of FIG. 1. [Diagram 3] 2 is a collinear diagram showing the relationship between the rotational speeds (rotational speeds) of a sun gear, a carrier, and a ring gear of a planetary gear mechanism provided in a transmission that constitutes the transmission system of FIG. 1. [Figure 4] 2 is a diagram showing the relationship between the pulley ratio of a belt transmission mechanism included in a transmission constituting the transmission system of FIG. 1 and the reduction ratio (unit speed ratio) of the entire power split type continuously variable transmission. [Diagram 5] 2 is a diagram showing the configuration of a control system provided in the gear shift system of FIG. 1. [Figure 6] 4 is a timing chart for explaining the behavior of acceleration, target rotation speed, engine rotation speed, and accelerator opening degree when there is no change in the driving mode before and after the start of transient shift control performed in the shift system of FIG. 1. [Figure 7] 4 is a timing chart for explaining the behavior of acceleration, target rotation speed, engine rotation speed, and accelerator opening degree when the driving mode is changed after the start of transient shift control performed in the shift system of FIG. 1. [Figure 8] 4 is a flowchart showing a flow of control performed when a transient shift control is executed in relation to a driving mode in the shift system of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A transmission system S according to an embodiment of the present invention will be described in detail below with reference to the drawings, taking as an example a vehicle 1 equipped with the transmission system.

[0017] <Vehicle drive system> 1 is a skeleton diagram showing the configuration of a drive system of a vehicle 1. The vehicle 1 is an automobile that uses an engine 2 as a drive source.

[0018] The engine 2 is provided with an electronic throttle valve for adjusting the amount of intake air into the combustion chamber of the engine 2, an injector (fuel injection device) for injecting fuel into the intake air, and a spark plug for generating an electric discharge in the combustion chamber. The engine 2 is also provided with a starter for starting the engine 2. The power of the engine 2 is transmitted to a differential gear 5 via a torque converter 3 and a transmission 4, and is transmitted from the differential gear 5 to left and right drive wheels 7L, 7R via left and right drive shafts 6L, 6R, respectively.

[0019] The torque converter 3 includes a front cover 21, a pump impeller 22, a turbine runner 23, and a lock-up mechanism 24. The drive source output shaft 11 is connected to the front cover 21, and the front cover 21 rotates integrally with the drive source output shaft 11. The pump impeller 22 is disposed on the opposite side of the front cover 21 to the engine 2 side. The pump impeller 22 is provided so as to be rotatable integrally with the front cover 21. The turbine runner 23 is disposed between the front cover 21 and the pump impeller 22, and provided so as to be rotatable about a common rotation axis with the front cover 21.

[0020] The lockup mechanism 24 includes a lockup piston 25. The lockup piston 25 is provided between the front cover 21 and the turbine runner 23. The lockup mechanism 24 is locked up (engaged) / unlocked (released) by a pressure difference between the hydraulic pressure of a release oil chamber 26 between the lockup piston 25 and the front cover 21 and the hydraulic pressure of an engagement oil chamber 27 between the lockup piston 25 and the pump impeller 22. That is, when the hydraulic pressure of the release oil chamber 26 is higher than the hydraulic pressure of the engagement oil chamber 27, the pressure difference causes the lockup piston 25 to move away from the front cover 21, resulting in lockup OFF. When the hydraulic pressure of the engagement oil chamber 27 is higher than the hydraulic pressure of the release oil chamber 26, the pressure difference causes the lockup piston 25 to be pressed against the front cover 21, resulting in lockup ON.

[0021] In the lock-up off state, when the drive source output shaft 11 rotates, the pump impeller 22 rotates. When the pump impeller 22 rotates, a flow of oil is generated from the pump impeller 22 toward the turbine runner 23. This oil flow is received by the turbine runner 23, causing the turbine runner 23 to rotate. At this time, the amplifying effect of the torque converter 3 occurs, and a torque larger than the torque of the drive source output shaft 11 is generated in the turbine runner 23.

[0022] In the lock-up on state, when the drive source output shaft 11 rotates, the drive source output shaft 11, the pump impeller 22, and the turbine runner 23 rotate together.

[0023] An oil pump 9 is provided between the torque converter 3 and the transmission 4. The oil pump 9 is a mechanical oil pump. A pump shaft of the oil pump 9 is provided to rotate integrally with a pump impeller 22 of the torque converter 3. As a result, when the pump impeller 22 rotates due to the power output from the engine 2, the pump shaft of the oil pump 9 rotates, and oil pressure is generated from the oil pump 9.

[0024] The transmission 4 is a so-called power split type (torque split type) transmission that includes an input shaft 31 and an output shaft 32 and is configured so that the power input to the input shaft 31 can be branched into two paths and transmitted to the output shaft 32. In order to configure the two power transmission paths, the transmission 4 includes a belt transmission mechanism 33, a front reduction gear mechanism 34, a planetary gear mechanism 35, and a split transmission mechanism 36.

[0025] The input shaft 31 is connected to the turbine runner 23 of the torque converter 3 and is provided so as to be rotatable integrally with the turbine runner 23 about the same rotation axis.

[0026] The output shaft 32 is provided in parallel to the input shaft 31. An output gear 37 is supported on the output shaft 32 so as to be non-rotatable relative to the input shaft 31. The output gear 37 meshes with the differential gear 5 (a ring gear of the differential gear 5).

[0027] The belt transmission mechanism 33 is configured by a belt-type continuously variable transmission (CVT). Specifically, the belt transmission mechanism 33 includes a primary shaft 41, a secondary shaft 42, a primary pulley 43, a secondary pulley 44, and a belt 45. The primary shaft 41 and the secondary shaft 42 are provided in parallel to each other. The primary pulley 43 is a pulley supported by the primary shaft 41 so as not to rotate relative thereto. The secondary pulley 44 is a pulley supported by the secondary shaft 42 so as not to rotate relative thereto. The belt 45 is wound around the primary pulley 43 and the secondary pulley 44.

[0028] The primary pulley 43 includes a fixed sheave 51 and a movable sheave 52. The fixed sheave 51 is a sheave fixed to the primary shaft 41. The movable sheave 52 is disposed opposite to the fixed sheave 51 with the belt 45 interposed therebetween, and is a sheave supported by the primary shaft 41 so as to be movable in the axial direction of the primary shaft 41 but not rotatable relative thereto. A cylinder 53 is provided on the opposite side of the fixed sheave 51 with respect to the movable sheave 52. The cylinder 53 is fixed to the primary shaft 41. A hydraulic chamber 54 is formed between the movable sheave 52 and the cylinder 53.

[0029] The secondary pulley 44 includes a fixed sheave 55 and a movable sheave 56. The fixed sheave 55 is a sheave fixed to the secondary shaft 42. The movable sheave 56 is disposed opposite the fixed sheave 55 with the belt 45 interposed therebetween, and is supported on the secondary shaft 42 so as to be movable in the axial direction and non-rotatable relative thereto. A cylinder 57 is provided on the opposite side of the movable sheave 56 to the fixed sheave 55. The cylinder 57 is fixed to the secondary shaft 42. A hydraulic chamber 58 is formed between the movable sheave 56 and the cylinder 57. In the rotation axis direction, the positional relationship between the fixed sheave 55 and the movable sheave 56 is reversed to the positional relationship between the fixed sheave 51 and the movable sheave 52 of the primary pulley 43.

[0030] In the belt transmission mechanism 33, the oil pressure supplied to the hydraulic chamber 54 of the primary pulley 43 and the hydraulic chamber 58 of the secondary pulley 44 are controlled to change the groove widths of the primary pulley 43 and the secondary pulley 44. This allows the belt transmission mechanism 33 to continuously and steplessly change the belt transmission ratio (pulley ratio between the primary pulley 43 and the secondary pulley 44).

[0031] Specifically, when the belt speed change ratio is reduced, the hydraulic pressure supplied to the hydraulic chamber 54 of the primary pulley 43 is increased. As a result, the movable sheave 52 of the primary pulley 43 moves toward the fixed sheave 51, and the gap (groove width) between the fixed sheave 51 and the movable sheave 52 becomes smaller. Accordingly, the winding diameter of the belt 45 around the primary pulley 43 becomes larger, and the gap (groove width) between the fixed sheave 55 and the movable sheave 56 of the secondary pulley 44 becomes larger. As a result, the pulley ratio between the primary pulley 43 and the secondary pulley 44 becomes smaller.

[0032] When the belt transmission ratio is increased, the hydraulic pressure supplied to the hydraulic chamber 54 of the primary pulley 43 is reduced. This reduces the thrust ratio, which is the ratio of the thrust of the primary pulley 43 (primary thrust) to the thrust of the secondary pulley 44 (secondary thrust), and reduces the gap between the fixed sheave 55 and the movable sheave 56 of the secondary pulley 44, while increasing the gap between the fixed sheave 51 and the movable sheave 52. As a result, the pulley ratio between the primary pulley 43 and the secondary pulley 44 increases.

[0033] On the other hand, the thrust of the primary pulley 43 and the secondary pulley 44 must be large enough to prevent slippage (belt slippage) between the primary pulley 43 and the belt 45 and between the secondary pulley 44 and the belt 45. Therefore, the hydraulic pressure supplied to the hydraulic chamber 54 of the primary pulley 43 and the hydraulic chamber 58 of the secondary pulley 44 is controlled so as to obtain a clamping pressure sufficient to prevent belt slippage.

[0034] The front reduction mechanism 34 is configured to reverse and reduce the speed of the power input to the input shaft 31 and transmit it to the primary shaft 41. Specifically, the front reduction mechanism 34 includes an input shaft gear 61 and a primary shaft gear 62. The input shaft gear 61 is a gear supported on the input shaft 31 so as not to rotate relative to it. The primary shaft gear 62 is a gear that has a larger diameter and a larger number of teeth than the input shaft gear 61 and meshes with the input shaft gear 61. The primary shaft gear 62 is supported on the primary shaft 41 by spline fitting so as not to rotate relative to it.

[0035] The planetary gear mechanism 35 includes a sun gear 71, a carrier 72, and a ring gear 73. The sun gear 71 is supported on the secondary shaft 42 by spline fitting so as not to rotate relative to the secondary shaft 42. The carrier 72 is fitted onto the output shaft 32 so as to rotate relative to the output shaft 32. The carrier 72 rotatably supports a plurality of pinion gears 74. A plurality of pinion gears 74 are arranged on a circumference, and each of the pinion gears 74 meshes with the sun gear 71. The ring gear 73 has an annular shape that collectively surrounds the plurality of pinion gears 74, and meshes with each of the pinion gears 74 from the outside in the rotational radial direction of the secondary shaft 42. The output shaft 32 is connected to the ring gear 73, and the ring gear 73 is provided so as to be rotatable integrally with the output shaft 32 about the same rotation axis.

[0036] The split transmission mechanism 36 is a parallel shaft gear mechanism including a split drive gear 81 and a split driven gear 82 that meshes with the split drive gear 81.

[0037] The split drive gear 81 is fitted onto the input shaft 31 so as to be capable of relative rotation.

[0038] The split driven gear 82 is provided so as to be rotatable integrally with the carrier 72 of the planetary gear mechanism 35 about the same rotation axis as the carrier 72. The split driven gear 82 is formed to have a smaller diameter than the split drive gear 81, and has a smaller number of teeth than the split drive gear 81.

[0039] The transmission 4 also includes clutches C1, C2 and a brake B1.

[0040] The clutch C1 (first engagement element) is hydraulically switched between an engaged state in which the input shaft 31 and the split drive gear 81 are directly connected (coupled so as to be rotatable together) and a released state in which the direct connection is released.

[0041] The clutch C2 (second engagement element) is hydraulically switched between an engaged state in which the sun gear 71 and the ring gear 73 of the planetary gear mechanism 35 are directly connected (coupled so as to be rotatable together) and a released state in which the direct connection is released.

[0042] The brake B1 is hydraulically switched between an engaged state in which the carrier 72 of the planetary gear mechanism 35 is braked, and a released state in which the carrier 72 is permitted to rotate.

[0043] <Power transmission mode> Fig. 2 is a diagram showing the states of the clutches C1, C2 and the brake B1 when the vehicle 1 moves forward and backward. Fig. 3 is a collinear diagram showing the relationship between the rotational speeds (rotational speeds) of the sun gear 71, the carrier 72 and the ring gear 73 of the planetary gear mechanism 35. Fig. 4 is a diagram showing the relationship between the belt speed ratio (pulley ratio) of the belt speed change mechanism 33 and the total speed ratio (unit speed ratio) of the entire transmission 4.

[0044] 2, "◯" indicates that the clutches C1, C2 and the brake B1 are in an engaged state, and "×" indicates that the clutches C1, C2 and the brake B1 are in a released state.

[0045] A displacement member that can be displaced between a plurality of positions is provided in a position operable by the driver in the cabin of the vehicle 1. In this embodiment, a shift lever (select lever) is provided as the displacement member. Within the movable range of the shift lever, for example, a P (parking) position, an R (reverse) position, an N (neutral) position, a D (drive) position, an S (sports) position, and a B (brake) position are provided in a line in this order.

[0046] When the shift lever is in the P position, the clutches C1, C2 and the brake B1 are all released and a parking lock gear (not shown) is locked, thereby forming a P range, which is one of the shift ranges of the transmission 4. When the shift lever is in the N position, the clutches C1, C2 and the brake B1 are all released and the parking lock gear is not locked, thereby forming an N range, which is one of the shift ranges of the transmission 4. When both the clutch C1 and the brake B1 are released, the power of the engine 2 is transmitted to the secondary shaft 42 and the secondary shaft 42 rotates, but the sun gear 71 and the pinion gear 74 of the planetary gear mechanism 35 rotate freely, and the power of the engine 2 is not transmitted to the drive wheels 7L, 7R.

[0047] When the shift lever is in the D, S, or B position, a forward range is established, which is one of the shift ranges of the transmission 4. The power transmission modes in this forward range include a belt mode and a split mode. The belt mode and the split mode are switched between an engaged state of the clutch C1 and an engaged state of the clutch C2 (switching between the clutches C1 and C2).

[0048] In the belt mode, as shown in Fig. 2, the clutch C1 and the brake B1 are released, and the clutch C2 is engaged. As a result, the split drive gear 81 is disconnected from the input shaft 31, the carrier 72 of the planetary gear mechanism 35 becomes free (in a freely rotating state), and the sun gear 71 and the ring gear 73 of the planetary gear mechanism 35 are directly connected.

[0049] The power input to the input shaft 31 is reversed and reduced in speed by the front reduction gear mechanism 34 and transmitted to the primary shaft 41 of the belt transmission mechanism 33, causing the primary shaft 41 and the primary pulley 43 to rotate. The rotation of the primary pulley 43 is transmitted to the secondary pulley 44 via the belt 45, causing the secondary pulley 44 and the secondary shaft 42 to rotate. Since the sun gear 71 and the ring gear 73 of the planetary gear mechanism 35 are directly connected, the sun gear 71, the ring gear 73, and the output shaft 32 rotate integrally with the secondary shaft 42. Therefore, in the belt mode, as shown in Figs. 3 and 4, the total speed ratio (unit speed ratio) of the transmission 4 coincides with a value obtained by multiplying the belt speed ratio (pulley ratio between the primary pulley 43 and the secondary pulley 44) of the belt transmission mechanism 33 by the front reduction gear ratio α (rotation speed of the input shaft 31 / rotation speed of the primary shaft 41).

[0050] 2, in the split mode, the clutch C1 is engaged, and the clutch C2 and the brake B1 are released. As a result, the input shaft 31 and the split drive gear 81 are connected, and the rotation of the input shaft 31 can be transmitted to the carrier 72 of the planetary gear mechanism 35 via the split drive gear 81 and the split driven gear 82, and the sun gear 71 and the ring gear 73 of the planetary gear mechanism 35 are disconnected.

[0051] The power input to the input shaft 31 is accelerated and transmitted to the carrier 72 of the planetary gear mechanism 35 from the split drive gear 81 through the split driven gear 82. The power transmitted to the carrier 72 is divided and transmitted from the carrier 72 to the sun gear 71 and the ring gear 73. The power of the sun gear 71 is transmitted to the primary shaft gear 62 through the secondary shaft 42, the secondary pulley 44, the belt 45, the primary pulley 43, and the primary shaft 41, and is transmitted from the primary shaft gear 62 to the input shaft gear 61. Therefore, in the belt mode, the input shaft gear 61 serves as the driving gear and the primary shaft gear 62 serves as the driven gear, whereas in the split mode, the primary shaft gear 62 serves as the driving gear and the input shaft gear 61 serves as the driven gear.

[0052] Since the gear ratio between the split drive gear 81 and the split driven gear 82 is constant and unchanging (fixed), in the split mode, if the power input to the input shaft 31 is constant, the rotation speed of the carrier 72 of the planetary gear mechanism 35 is maintained at a constant speed. Therefore, when the belt transmission ratio is increased, the rotation speed of the sun gear 71 of the planetary gear mechanism 35 decreases, and the rotation speed of the ring gear 73 (output shaft 32) of the planetary gear mechanism 35 increases, as shown by the dashed line in Fig. 3. As a result, in the split mode, as shown in Fig. 4, the greater the belt transmission ratio of the belt transmission mechanism 33, the smaller the reduction gear ratio of the transmission 4 becomes, and the sensitivity of the reduction gear ratio to the belt transmission ratio (the ratio of the change in the reduction gear ratio to the change in the belt transmission ratio) is lower than in the belt mode.

[0053] In the belt mode and the split mode, the rotation of the output shaft 32 is transmitted to the differential gear 5 via the output gear 37. As a result, the drive shafts 6L, 6R and the drive wheels 7L, 7R of the vehicle 1 rotate in the forward direction.

[0054] Regardless of whether the shift lever is in the D, S, or B position, in the forward ranges, gear shift control is performed to automatically and continuously change the gear ratio steplessly. However, when the shift lever is in the S position (S range), the gear ratio is changed so that the engine speed is maintained higher than when the shift lever is in the D position (D range). This allows the driver to enjoy sportier driving in the S range compared to the D range, and also provides stronger engine braking during deceleration. When the shift lever is in the B position (B range), the gear ratio is changed so that the engine speed is maintained even higher than in the S range, and provides stronger engine braking than in the S range during deceleration.

[0055] When the shift lever is in the R position, a reverse range, which is one of the shift ranges of the transmission 4, is established. In the reverse range, as shown in Fig. 2, the clutches C1 and C2 are released and the brake B1 is engaged. As a result, the split drive gear 81 is disconnected from the input shaft 31, the sun gear 71 and the ring gear 73 of the planetary gear mechanism 35 are disconnected, and the carrier 72 of the planetary gear mechanism 35 is braked.

[0056] The power input to the input shaft 31 is reversed and reduced in speed by the front reduction gear mechanism 34, and is transmitted to the primary shaft 41 of the belt transmission mechanism 33, and is transmitted from the primary shaft 41 to the secondary shaft 42 via the primary pulley 43, the belt 45, and the secondary pulley 44, and rotates the sun gear 71 of the planetary gear mechanism 35 together with the secondary shaft 42. Since the carrier 72 of the planetary gear mechanism 35 is braked, when the sun gear 71 rotates, the ring gear 73 of the planetary gear mechanism 35 rotates in the opposite direction to the sun gear 71. The rotation direction of this ring gear 73 is opposite to the rotation direction of the ring gear 73 during forward travel (belt mode and split mode). The output shaft 32 rotates together with the ring gear 73. The rotation of the output shaft 32 is transmitted to the differential gear 5 via the output gear 37. As a result, the drive shafts 6L, 6R and the drive wheels 7L, 7R of the vehicle 1 rotate in the reverse direction.

[0057] <Vehicle control system> FIG. 5 is a block diagram showing the configuration of a control system of the vehicle 1.

[0058] The vehicle 1 is provided with an ECU 91 (Electronic Control Unit) configured to include a microcontroller (microcontroller unit) as a control device. The microcontroller includes, for example, a CPU, a non-volatile memory such as a flash memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory). Although only one ECU 91 is shown in FIG. 5, the vehicle 1 is equipped with multiple ECUs having the same configuration as the ECU 91 to control each part. The multiple ECUs including the ECU 91 are connected to enable two-way communication using a CAN (Controller Area Network) communication protocol.

[0059] The ECU 91 controls an electronic throttle valve, an injector, a spark plug, and the like provided in the engine 2 to start, stop, and adjust the output of the engine 2. It also controls various valves included in a hydraulic circuit 92 that supplies hydraulic pressure to each part of the unit including the torque converter 3 and the transmission 4 to control lockup of the torque converter 3 and shifting of the transmission 4.

[0060] Various sensors required for the control are connected to the ECU 91. As an example, the ECU 91 is connected to a turbine rotation sensor 93 that outputs a pulse signal synchronized with the rotation of the turbine runner 23 of the torque converter 3 as a detection signal, a primary rotation sensor 94 that outputs a pulse signal synchronized with the rotation of the primary shaft 41 as a detection signal, a secondary rotation sensor 95 that outputs a pulse signal synchronized with the rotation of the secondary shaft 42 as a detection signal, an output rotation sensor 96 that outputs a pulse signal synchronized with the rotation of the output shaft 32 as a detection signal, and an accelerator sensor 97 that outputs a detection signal corresponding to the amount of operation of an accelerator pedal (not shown) operated by the driver.

[0061] A mode setting unit 98 is also connected to the ECU 91. The mode setting unit 98 is configured with switches, dials, and the like that can be operated by the user. The mode setting unit 98 is for accepting and setting an operation for the user to arbitrarily select a driving mode of the vehicle 1. By operating the mode setting unit 98, it is possible to select and set any one of a plurality of driving modes including a normal mode (first mode) which is a normal driving mode, and a power mode (second mode) which has higher acceleration than the normal mode and is for realizing a sporty driving feeling.

[0062] The ECU 91 obtains the turbine rotation speed, which is the rotation speed of the turbine runner 23, the primary rotation speed, which is the rotation speed of the primary shaft 41 (primary pulley 43), the secondary rotation speed, which is the rotation speed of the secondary shaft 42 (secondary pulley 44), and the output rotation speed, which is the rotation speed of the output shaft 32, from the detection signals of the turbine rotation sensor 93, the primary rotation sensor 94, the secondary rotation speed, which is the rotation speed of the secondary shaft 42 (secondary pulley 44), and the output rotation speed, which is the rotation speed of the output shaft 32. The ECU 91 also obtains the accelerator opening, which is the ratio of the operation amount to the maximum operation amount of the accelerator pedal, from the detection signal of the accelerator sensor 97, in other words, the accelerator opening, which is a percentage where 0% is when the accelerator pedal is not depressed and 100% is when the accelerator pedal is fully depressed.

[0063] In addition, some of the turbine rotation sensor 93, primary rotation sensor 94, secondary rotation sensor 95, output rotation sensor 96 and accelerator sensor 97 may be connected to another ECU, and information obtained from some of these sensors may be received from the other ECU.

[0064] <Gear shift control> The total gear ratio of the transmission 4 is controlled by the ECU 91 by changing the belt gear ratio and engaging / disengaging the clutches C1, C2 and the brake B1. In this gear shift control, a target rotation speed is set according to the accelerator opening and the vehicle speed based on a gear shift diagram. The gear shift diagram is a map that defines the relationship between the accelerator opening and the vehicle speed and the target rotation speed, and is stored in the ROM of the ECU 91. Information on the vehicle speed is transmitted to the ECU 91, for example, from the engine ECU that controls the engine 2. Once the target rotation speed is set, a target for the total gear ratio that makes the rotation speed input to the input shaft 31, i.e., the turbine rotation speed, coincide with the target rotation speed is obtained, and a target for the belt gear ratio according to the target is set.

[0065] Thereafter, command values ​​for the primary pressure, which is the hydraulic pressure supplied to the movable sheave 52 of the primary pulley 43, and the secondary pressure, which is the hydraulic pressure supplied to the movable sheave 56 of the secondary pulley 44, are set based on the target belt speed ratio, and the primary pressure and secondary pressure are controlled based on each command value so that the deviation between the target belt speed ratio and the actual belt speed ratio approaches zero. The actual belt speed ratio is calculated by dividing the primary rotation speed by the secondary rotation speed.

[0066] When the total gear ratio is changed across a split point (split gear ratio) equal to the gear ratio between the split drive gear 81 and the split driven gear 82, the change in the total gear ratio is accompanied by switching between the belt mode and the split mode (hereinafter simply referred to as "mode switching"). The mode switching is achieved by control for switching the engagement of the clutches C1 and C2 (clutch-to-clutch control). That is, by controlling the hydraulic pressure supplied to the clutches C1 and C2, the clutch C1 (engagement side) in the released state is engaged and the clutch C2 (release side) in the engaged state is released, thereby switching from the belt mode to the split mode. Conversely, the clutch C1 (release side) in the engaged state is released and the clutch C2 (engagement side) in the released state is engaged, thereby switching from the split mode to the belt mode.

[0067] Here, in the vehicle 1 according to this embodiment, transient shift control is executed on the condition that the accelerator opening suddenly increases at a rate of change exceeding a predetermined threshold, such as when so-called kickdown is performed. The transient shift control is a control for increasing the input rotation speed to the transmission 4 through a plurality of stages including a first shift stage and a second shift stage. In the vehicle 1 according to this embodiment, the control is executed for increasing the input rotation speed through two stages consisting of the first shift stage and the second shift stage.

[0068] As shown in FIG. 6, the first shift stage is a stage in which the input rotation speed from the engine 2, which is the power source, to the transmission 4 is increased for a predetermined period of time toward the target rotation speed. In this stage, the acceleration also increases significantly in conjunction with the engine rotation speed increasing toward the target rotation speed. In addition, the second shift stage is a stage in which the input rotation speed from the engine 2, which is the power source, to the transmission 4 is increased for a predetermined period of time toward the target rotation speed. step This is a stage performed after the first shift stage, in which the input rotation speed from the engine 2, which is the power source, to the transmission 4 is increased toward the target rotation speed more slowly than in the first shift stage. In this stage, the acceleration also increases slowly as the engine rotation speed increases slowly.

[0069] Here, in the vehicle 1, when the driving mode set in the mode setting unit 98 is not changed before and after the start of the transient shift control, as shown in FIG. 6, the input rotation speed is increased through two stages consisting of a first shift stage and a second shift stage. On the other hand, when the driving mode is switched from the normal mode to the power mode while the input rotation speed is increased more slowly toward the target rotation speed in the second shift stage than in the first shift stage after the start of the transient shift control, the target rotation speed is changed to a value corresponding to the second mode and the transient shift control is restarted as shown in FIG. 7. Therefore, in the transient shift when the driving mode is the normal mode, the engine rotation speed, which was increasing slowly in the second shift stage, starts to increase significantly again toward the target rotation speed after the setting change when the transient shift control is restarted and the first shift stage is started. The acceleration also decreases slightly with the restart of the transient shift control, and then increases significantly. When a predetermined period has elapsed after the restart of the transient shift control, the transition to the second shift stage occurs again. In the second shift stage, the input rotation speed increases more slowly toward the target rotation speed after the setting change than in the first shift stage. As a result, the acceleration also increases more slowly than in the first shift stage. In this way, in the vehicle 1, when an operation to switch the driving mode from the normal mode to the power mode is performed in the second shift stage, the transient shift control is restarted, thereby realizing a driving feeling desired by the user. Hereinafter, the control performed when the transient shift control is executed in relation to the above-mentioned driving modes will be described in detail with reference to the flowchart shown in FIG. 8.

[0070] (Step 1) In step 1, the ECU 91 checks whether the rate of change in the accelerator opening is equal to or greater than a predetermined threshold. This checks whether the accelerator opening has suddenly increased, for example, when kicking down is performed. If it is checked that the rate of change in the accelerator opening is equal to or greater than the predetermined threshold, the control flow proceeds to step 2.

[0071] (Step 2) In step 2, the ECU 91 sets a target rotation speed. After the target rotation speed is set, the control flow proceeds to step 3.

[0072] (Step 3) In step 3, the ECU 91 executes a first shift stage of the transient shift control. That is, the ECU 91 starts a control for increasing the input rotation speed to the transmission 4 at a predetermined increasing gradient for a predetermined time toward the target rotation speed set in step 2. Thereafter, the control flow proceeds to step 4.

[0073] (Step 4) In step 4, the ECU 91 checks whether the timing for ending the first shift stage of the transitional shift control has arrived. If the timing for ending the first shift stage has not arrived, the first shift stage is continued. On the other hand, if it is confirmed that the timing for ending the first shift stage has arrived, the first shift stage is ended and the control flow proceeds to step 5.

[0074] (Step 5) In step 5, the ECU 91 starts a second shift stage of the transient shift control. That is, the ECU 91 performs control to increase the input rotation speed to the transmission 4 toward the target rotation speed set in step 2. In the second shift stage in step 4, the increase gradient of the input rotation speed to the transmission 4 is set lower than that in the first shift stage in step 3. When the second shift stage of the transient shift control is started in step 4, the control flow proceeds to step 6.

[0075] (Step 6) In step 6, the ECU 91 checks whether or not an operation to switch the driving mode from the normal mode to the power mode has been performed by operating the mode setting unit 98. If the switching of the driving mode to the power mode has been confirmed, the control flow proceeds to step 7, and if the switching to the driving mode has not been confirmed, the control flow proceeds to step 8.

[0076] (Step 7) When the control flow proceeds from step 6 to step 7, the ECU 91 performs a process of changing the target rotation speed to a value corresponding to the driving mode in preparation for restarting the transitional shift control. Thereafter, the control flow returns to step 3 to restart the transitional shift control.

[0077] (Step 8) When the control flow proceeds from step 6 to step 8 described above, it is confirmed whether or not the input rotation speed has reached the target rotation speed. If the input rotation speed has not reached the target rotation speed, the control flow returns to step 6 and the second shift control continues. On the other hand, if it is confirmed that the input rotation speed has reached the target rotation speed, the second shift control ends and a series of control flows is completed.

[0078] <Action and effect> The vehicle 1 of the present embodiment described above has the following characteristic configurations (a) to (c), which enable the vehicle 1 to achieve the unique effects described below.

[0079] (a) The vehicle 1 of this embodiment includes a transmission 4, an engine 2 (power source) that outputs power to the transmission 4, a mode setting unit 98 that accepts a drive mode that can be arbitrarily selected from a plurality of drive modes including a predetermined normal mode (first mode) and a power mode (second mode) in which a target rotation speed is set higher than that in the normal mode, and an ECU 91 (control device), and the ECU 91 controls the vehicle 1 to perform a first shift stage in which the input rotation speed from the engine 2 to the transmission 4 is increased over a predetermined period of time toward the target rotation speed on the condition that the accelerator opening degree increases at a fluctuation rate exceeding a predetermined threshold value, and a second shift stage in which the input rotation speed from the engine 2 to the transmission 4 is increased over a predetermined period of time toward the target rotation speed on the condition that the accelerator opening degree increases at a fluctuation rate exceeding a predetermined threshold value. stepand then a second shift stage in which the input rotation speed from the engine 2 is increased toward the target rotation speed more gradually than in the first shift stage, thereby executing a transient shift control to increase the input rotation speed. During the process of executing the transient shift control with the normal mode selected, the target rotation speed is changed to a value corresponding to the power mode and the transient shift control is restarted on the condition that the driving mode is switched from the normal mode to the power mode during the second shift stage.

[0080] In the vehicle 1 of the present embodiment, as described above in (a), the transitional shift control is restarted on the condition that the driving mode is switched from the normal mode to the power mode in the middle of the second shift stage during the process of executing the transitional shift control in the state in which the normal mode is selected. As a result, in the vehicle 1 of the present embodiment, when the driving mode is switched from the normal mode to the power mode in the state in which the engine speed is gradually increased in the second shift stage after the first shift stage is completed, the target speed is changed to a value corresponding to the power mode and the transitional shift control is restarted, thereby performing the first shift stage in which the input speed is increased more steeply than in the second shift stage. Therefore, in the vehicle 1 of the present embodiment, even if the driving mode is switched from the normal mode to the power mode in the middle of the second shift stage during the process of executing the transitional shift control in the state in which the normal mode is selected, the driving feeling desired by the user can be realized.

[0081] (b) In the vehicle 1 of this embodiment, the transmission 4 preferably has a belt transmission mechanism 33 between the input shaft 31 to which power is input and the output shaft 32 that outputs the power.

[0082] In the vehicle 1 of this embodiment, the transmission 4 is provided with the belt transmission mechanism 33 as described above in (b), which enables infinitely variable speed changes, and therefore the transitional shift control can be performed more smoothly and quickly than when a general transmission such as an automatic transmission is used. Therefore, by being configured as described above in (b), the vehicle 1 of this embodiment can further improve the driving feeling when transitional shift control is being performed.

[0083] (c) In the vehicle 1 of this embodiment, the transmission 4 includes a clutch C1 (first engagement element) interposed on a first power transmission path between the input shaft 31 to which power is input, and the output shaft 32 to which the power is output, and a clutch C2 (second engagement element) interposed on a second power transmission path between the input shaft 31 and the output shaft 32, and has a belt transmission mechanism 33 on the second power transmission path. By releasing the clutch C1 and engaging the clutch C2, a normal mode is entered in which the total transmission ratio between the input shaft 31 and the output shaft 32 becomes larger as the belt transmission ratio of the belt transmission mechanism 33 increases, and by engaging the clutch C1 and disengaging the clutch C2, a power mode is entered in which the total transmission ratio becomes smaller as the belt transmission ratio increases.

[0084] By configuring the transmission 4 as described above in (c), the vehicle 1 of this embodiment can achieve the driving feeling desired by the user while improving power transmission efficiency and improving fuel efficiency by expanding the gear ratio range.

[0085] <<Variations>> The vehicle 1 illustrated in the above embodiment is merely one example of the present invention, and the configurations related to (a) to (c) above may be different from those illustrated in the above embodiment, for example, without departing from the spirit of the present invention. Furthermore, the vehicle 1 may be provided with other configurations in addition to or instead of the configurations included in (a) to (c) above, or may be configured with some of the configurations omitted. Specifically, the following modified examples are possible.

[0086] In this embodiment, an example has been shown in which the engine 2 is used as a driving source and driving force is input to the transmission 4, but the present invention is not limited to this, and the driving source may be something that operates by receiving power from a motor or the like in addition to the engine 2, or instead of the engine 2.

[0087] In this embodiment, an example has been given of ECU91 having all of the functions of the target total gear ratio setting unit, belt gear ratio changing unit, and switching control unit, but the present invention is not limited to this, and at least one of the target total gear ratio setting unit, belt gear ratio changing unit, and switching control unit may be configured by an ECU other than ECU91.

[0088] In the present embodiment, the transitional shift control is performed through two shift stages, the first shift stage and the second shift stage, but the present invention is not limited to this, and other shift stages may be provided. Also, in the present embodiment, the vehicle 1 is shown to have a selectable driving mode from two modes, the normal mode and the power mode, but the present invention is not limited to this, and other driving modes may be selectable.

[0089] In this embodiment, as shown in (b) above, the transmission 4 has a belt transmission mechanism 33 between an input shaft 31 to which power is input and an output shaft 32 that outputs the power, and as shown in (c) above, an example is shown in which the transmission is a so-called power split (torque split) transmission, but the vehicle 1 of the present invention is not limited to this, and it is also possible to have another type of transmission 4.

[0090] The present invention is not limited to the above-mentioned embodiments and modifications, and other embodiments may be possible within the scope of the claims. The components of the above-mentioned embodiments may be arbitrarily selected and combined. Any component of the embodiment may be arbitrarily combined with any component described in the means for solving the problems or any component that embodies any component described in the means for solving the problems. We intend to obtain rights to these as well through amendments to this application or divisional applications, etc. [Industrial Applicability]

[0091] The present invention can be suitably used in all vehicles in which the driving mode can be selected from a plurality of modes with different target rotation speeds, and which executes transient shift control under the condition that the accelerator opening increases at a rate of fluctuation exceeding a predetermined threshold value. [Explanation of symbols]

[0092] 1: Vehicle 2: Engine 4: Transmission 31: Input shaft 32: Output shaft 33: Belt transmission mechanism 91: ECU (control unit) 98: Mode setting section C1: Clutch (first engagement element) C2: Clutch (second engagement element)

Claims

1. The gearbox and A power source that outputs power to the transmission; a mode setting unit that can arbitrarily select and set one of a plurality of driving modes including a predetermined first mode and a second mode in which a target rotation speed is set higher than that of the first mode; A control device; A vehicle equipped with The control device, On the condition that the accelerator opening degree increases at a rate of change exceeding a predetermined threshold value, a first shift stage in which an input rotational speed from the power source to the transmission is increased over a predetermined period of time toward a target rotational speed; a second shift stage in which the input rotation speed from the power source is increased toward the target rotation speed more slowly than in the first shift stage after the first shift stage; A transient shift control is executed to increase the input rotation speed through a plurality of steps including and during a process of executing the transitional shift control with the first mode selected, on condition that the driving mode is switched from the first mode to the second mode during the second shift stage, the target rotation speed is changed to a value corresponding to the second mode, and the transitional shift control is restarted.

2. 2. The vehicle according to claim 1, wherein the transmission has a belt transmission mechanism between an input shaft to which power is input and an output shaft to which the power is output.

3. The transmission, a first engagement element disposed on a first power transmission path between an input shaft to which power is input and an output shaft to which the power is output; a second engagement element interposed in a second power transmission path between the input shaft and the output shaft, a belt transmission mechanism on the second power transmission path; a first mode in which a total speed ratio between the input shaft and the output shaft increases as a belt speed ratio by the belt speed change mechanism increases due to the release of the first engagement element and the engagement of the second engagement element, 2. The vehicle according to claim 1, wherein engagement of the first engagement element and disengagement of the second engagement element result in a second mode in which the total speed ratio becomes smaller as the belt speed ratio increases.

Images