Control device

Abstract

To provide a control device which can shorten a time lag at a kickdown requirement.SOLUTION: A control device comprises: kickdown detection means for detecting a kickdown requirement; target value setting means for setting a target total gear change ratio being a target value of a total gear change ratio according to the kickdown requirement; pulley ratio change means for lowering an actual pulley ratio being an actual pulley ratio after the detection of the kickdown requirement so as to make it approximate to a target pulley ratio being a pulley ratio corresponding the target total gear change ratio; pulley ratio prediction means for calculating a prediction pulley ratio being a pulley ratio at which the actual pulley ratio arrives after the lapse of a prediction time on the basis of a prediction time which is shorter than a work time necessary for a switching operation of a first engagement element and a second engagement element at switching to a first mode from a second mode; and switching start control means for starting switching control for switching the first engagement element and the second engagement element so that the second mode is transited to the first mode when the prediction pulley ratio reaches the target pulley ratio or lower.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a control device.

Background Art

[0002] As a transmission mounted on a vehicle such as an automobile, a power-split continuously variable transmission mechanism that continuously varies power and can transmit power by splitting it into two paths between an input shaft and an output shaft has been proposed.

[0003] In an example of the power-split continuously variable transmission, the continuously variable transmission mechanism has the same configuration as a known belt-type continuously variable transmission (CVT), that is, a configuration in which an endless belt is wound around a primary pulley and a secondary pulley. The power of the engine input to the input shaft is transmitted to the primary shaft of the continuously variable transmission mechanism. The secondary shaft of the continuously variable transmission mechanism is connected to the sun gear of the planetary gear mechanism.

[0004] In addition, the power-split continuously variable transmission is provided with a parallel-axis gear mechanism. The parallel-axis gear mechanism includes a split drive gear to which the power of the input shaft is transmitted / interrupted, and a split driven gear that forms a gear train with the split drive gear and rotates integrally with the carrier of the planetary gear mechanism. The output shaft is connected to the ring gear of the planetary gear mechanism. The rotation of the output shaft is transmitted to the differential gear and then to the left and right drive wheels from the differential gear.

[0005] In this power-split continuously variable transmission, a belt mode and a split mode are provided as power transmission modes during forward travel.

[0006] In the belt mode, the first clutch that switches the transmission / cutoff of power between the input shaft and the split drive gear is released, the split drive gear is put into a free rotation state (free), and the carrier of the planetary gear mechanism is put into a free rotation state. Also, the second clutch that couples / separates the sun gear and the ring gear of the planetary gear mechanism is engaged, and the sun gear and the ring gear are coupled. Therefore, due to the power output from the continuously variable transmission mechanism, the sun gear and the ring gear rotate integrally, and the output shaft rotates integrally with the ring gear. Thus, in the belt mode, the larger the pulley ratio, which is the speed ratio of the continuously variable transmission mechanism, the larger the total speed ratio (rotation speed of the input shaft / rotation speed of the output shaft), which is the speed ratio of the entire power split continuously variable transmission, in proportion to that speed ratio.

[0007] In the split mode, the second clutch is released, and the coupling between the sun gear and the ring gear of the planetary gear mechanism is released. Also, the first clutch is engaged, and power is transmitted from the input shaft to the split drive gear. That is, the switching between the belt mode and the split mode is achieved by switching the engagement of the first clutch and the second clutch. The power transmitted from the input shaft to the split drive gear is shifted at a constant speed ratio (split point) through the split driven gear from the split drive gear and input to the carrier of the planetary gear mechanism. The sun gear rotates at a rotation speed corresponding to the pulley ratio. Therefore, in the split mode, the larger the pulley ratio, the smaller the total speed ratio, and a total speed ratio below the split point can be realized.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] When a kick-down request is made during driving in split mode, the target value of the total gear ratio (target total gear ratio) is set high, and clutch switching control (clutch-to-clutch) is executed to disengage the first clutch and engage the second clutch in order to shift to belt mode. At this time, in the prior art, when the pulley ratio at the time of a kick-down request is larger than the target pulley ratio corresponding to the target total gear ratio, the clutch switching control is executed after reducing the pulley ratio until the difference from the target pulley ratio becomes zero or substantially zero. Therefore, when the difference is large, the time lag from when the kick-down request is made until the transition to belt mode is completed and acceleration starts becomes large, and there may be a feeling of jerk for the driver.

[0010] An object of the present invention is to provide a control device capable of shortening the time lag at the time of a kick-down request.

Means for Solving the Problems

[0011] To achieve the above object, a control device according to an embodiment of the present invention includes a first engaging element interposed on a first power transmission path between an input shaft and an output shaft, and a second engaging element interposed on a second power transmission path between the input shaft and the output shaft. The second power transmission path has a belt transmission mechanism. By releasing the first engaging element and engaging the second engaging element, a first mode is formed in which the larger the pulley ratio of the belt transmission mechanism, the larger the total transmission ratio between the input shaft and the output shaft. By engaging the first engaging element and releasing the second engaging element, a second mode is formed in which the larger the pulley ratio, the smaller the total transmission ratio. When the pulley ratio is a constant value, the control device controls a continuously variable transmission configured so that no differential rotation occurs in the first engaging element and the second engaging element. The control device includes a kick-down detection means for detecting a kick-down request, a target value setting means for setting a target total transmission ratio which is a target value of the total transmission ratio in response to the kick-down request, a pulley ratio change means for decreasing the actual pulley ratio, which is the actual pulley ratio after detection of the kick-down request, so as to approach the target pulley ratio which is the pulley ratio corresponding to the target total transmission ratio, a pulley ratio prediction means for calculating a predicted pulley ratio which is the pulley ratio expected to be reached after elapse of a prediction time shorter than an operation time required for a switching operation of the first engaging element and the second engaging element when switching from the second mode to the first mode, and a switching start control means for starting a switching control to switch the first engaging element and the second engaging element so as to transition from the second mode to the first mode when the predicted pulley ratio becomes equal to or less than the target pulley ratio.

[0012] According to the above configuration, after a kick-down request, even before the actual pulley ratio reaches the target pulley ratio, if the predicted pulley ratio has reached the target pulley ratio, the switching control is started. Thereby, it becomes possible to shorten the time lag.

[0013] Further, in the above configuration, the control device, after detecting the kick-down request, calculates a predicted arrival rate, which is the ratio of the predicted pulley ratio to the target pulley ratio at a predetermined time point, and an actual arrival rate, which is the ratio of the actual pulley ratio to the target pulley ratio at the predetermined time point, as arrival rate calculation means, and further includes an abnormality determination means for determining that an abnormality has occurred when the difference between the predicted arrival rate and the actual arrival rate at the same time point is equal to or greater than a threshold value.

[0014] According to the above configuration, it is possible to determine the presence or absence of an abnormality after a kick-down request.

[0015] In the above configuration, when it is determined by the abnormality determination means that an abnormality has occurred, the switching start control means may start the switching control when the actual pulley ratio becomes equal to or less than the target pulley ratio, regardless of whether the predicted pulley ratio becomes equal to or less than the target pulley ratio.

[0016] According to the above configuration, at the time of an abnormality, the start timing of the switching control is determined based on the same method as in the prior art, that is, the difference between the actual pulley ratio and the target pulley ratio. Thereby, the robustness of the downshift operation at the time of a kick-down request can be improved.

Effects of the Invention

[0017] According to the present invention, it is possible to provide a control device capable of shortening the time lag at the time of a kick-down request.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

BEST MODE FOR CARRYING OUT THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0020] <Drive system of the vehicle> FIG. 1 is a skeleton diagram showing the configuration of the drive system of the vehicle 1.

[0021] The vehicle 1 is an automobile having the engine 2 as a drive source.

[0022] The engine 2 is provided with an electronic throttle valve for adjusting the intake air amount to the combustion chamber of the engine 2, an injector (fuel injection device) for injecting fuel into the intake air, an ignition plug for generating an electric discharge in the combustion chamber, and the like. Further, the engine 2 is provided with a starter for starting it. The power of the engine 2 is transmitted to the differential gear 5 via the torque converter 3 and the transmission 4, and is transmitted from the differential gear 5 to the left and right drive wheels 7L and 7R via the left and right drive shafts 6L and 6R, respectively.

[0023] The engine 2 is provided with an E / G output shaft 11. The E / G output shaft 11 is rotated by the power generated by the engine 2.

[0024] The torque converter 3 includes a front cover 21, a pump impeller 22, a turbine runner 23, and a lock-up mechanism 24. The E / G output shaft 11 is connected to the front cover 21, and the front cover 21 rotates integrally with the E / G output shaft 11. The pump impeller 22 is disposed on the side opposite to the engine 2 side with respect to the front cover 21. 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 is provided so as to be rotatable about a common rotation axis with the front cover 21.

[0025] The lock-up mechanism 24 includes a lock-up piston 25. The lock-up piston 25 is provided between the front cover 21 and the turbine runner 23. The lock-up mechanism 24 is locked up (engaged) / released based on the differential pressure between the hydraulic pressure in the release oil chamber 26 between the lock-up piston 25 and the front cover 21 and the hydraulic pressure in the engagement oil chamber 27 between the lock-up piston 25 and the pump impeller 22. That is, when the hydraulic pressure in the release oil chamber 26 is higher than the hydraulic pressure in the engagement oil chamber 27, the lock-up piston 25 is separated from the front cover 21 due to the differential pressure, and the lock-up is released. When the hydraulic pressure in the engagement oil chamber 27 is higher than the hydraulic pressure in the release oil chamber 26, the lock-up piston 25 is pressed against the front cover 21 due to the differential pressure, and the lock-up is engaged.

[0026] In the lock-up released state, when the E / G output shaft 11 is rotated, the pump impeller 22 rotates. When the pump impeller 22 rotates, an oil flow from the pump impeller 22 toward the turbine runner 23 is generated. This oil flow is received by the turbine runner 23, and the turbine runner 23 rotates. At this time, the amplification action of the torque converter 3 occurs, and a torque larger than the torque of the E / G output shaft 11 is generated in the turbine runner 23.

[0027] In the locked-up state, when the E / G output shaft 11 rotates, the E / G output shaft 11, the pump impeller 22, and the turbine runner 23 rotate integrally.

[0028] The transmission 4 includes an input shaft 31 and an output shaft 32, and is configured to branch the power input to the input shaft 31 into two paths and transmit it to the output shaft 32, which is a so-called power split type (torque split type) transmission. To form 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.

[0029] The input shaft 31 is connected to the turbine runner 23 of the torque converter 3 and is provided so as to be integrally rotatable about the same rotation axis as the turbine runner 23.

[0030] The output shaft 32 is provided parallel to the input shaft 31. An output gear 37 is supported on the output shaft 32 so as not to rotate relative to the output shaft 32. The output gear 37 meshes with the differential gear 5 (ring gear of the differential gear 5).

[0031] The belt transmission mechanism 33 has the same configuration as a known belt-type continuously variable transmission (CVT). Specifically, the belt transmission mechanism 33 includes a primary shaft 41, a secondary shaft 42 provided parallel to the primary shaft 41, a primary pulley 43 supported on the primary shaft 41 so as not to rotate relative to the primary shaft 41, a secondary pulley 44 supported on the secondary shaft 42 so as not to rotate relative to the secondary shaft 42, and a belt 45 wound around the primary pulley 43 and the secondary pulley 44.

[0032] The primary pulley 43 includes a fixed sheave 51 fixed to the primary shaft 41, and a movable sheave 52 disposed opposite to the fixed sheave 51 with the belt 45 interposed therebetween, and is supported on the primary shaft 41 so as to be movable in its axial direction and non-rotatable relative thereto. On the side opposite to the fixed sheave 51 with respect to the movable sheave 52, a cylinder 53 fixed to the primary shaft 41 is provided, and a hydraulic chamber 54 is formed between the movable sheave 52 and the cylinder 53.

[0033] The secondary pulley 44 includes a fixed sheave 55 fixed to the secondary shaft 42, and a movable sheave 56 disposed opposite to the fixed sheave 55 with the belt 45 interposed therebetween, and is supported on the secondary shaft 42 so as to be movable in its axial direction and non-rotatable relative thereto. On the side opposite to the fixed sheave 55 with respect to the movable sheave 56, a cylinder 57 fixed to the secondary shaft 42 is provided, and a hydraulic chamber 58 is formed between the movable sheave 56 and the cylinder 57. In the rotational axis direction, the positional relationship between the fixed sheave 55 and the movable sheave 56 is reversed from the positional relationship between the fixed sheave 51 and the movable sheave 52 of the primary pulley 43.

[0034] In the belt transmission mechanism 33, the hydraulic pressures supplied to the hydraulic chamber 54 of the primary pulley 43 and the hydraulic chamber 58 of the secondary pulley 44 are respectively controlled, and the groove widths of the primary pulley 43 and the secondary pulley 44 are changed, whereby the pulley ratio is continuously and steplessly changed.

[0035] Specifically, when the pulley ratio is decreased, the hydraulic pressure supplied to the hydraulic chamber 54 of the primary pulley 43 is increased. Thereby, the movable sheave 52 of the primary pulley 43 moves toward the fixed sheave 51 side, and the interval (groove width) between the fixed sheave 51 and the movable sheave 52 becomes smaller. Along with this, the winding diameter of the belt 45 around the primary pulley 43 becomes larger, and the interval (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.

[0036] When the pulley ratio is increased, the hydraulic pressure supplied to the hydraulic chamber 54 of the primary pulley 43 is decreased. As a result, 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), becomes smaller, the distance between the fixed sheave 55 and the movable sheave 56 of the secondary pulley 44 becomes smaller, and the distance between the fixed sheave 51 and the movable sheave 52 becomes larger. Consequently, the pulley ratio between the primary pulley 43 and the secondary pulley 44 becomes larger.

[0037] On the other hand, the thrusts of the primary pulley 43 and the secondary pulley 44 need to be of a magnitude that does not cause slippage (belt slippage) between the primary pulley 43 and the secondary pulley 44 and the belt 45. Therefore, the hydraulic pressures supplied to the hydraulic chamber 54 of the primary pulley 43 and the hydraulic chamber 58 of the secondary pulley 44 are controlled so as to obtain a sufficient clamping pressure that does not cause belt slippage.

[0038] The front reduction gear mechanism 34 is configured to reverse and reduce the power input to the input shaft 31 and transmit it to the primary shaft 41. Specifically, the front reduction gear mechanism 34 includes an input shaft gear 61 that is supported non-rotatably relative to the input shaft 31, and a primary shaft gear 62 that has a larger diameter and more teeth than the input shaft gear 61 and is supported non-rotatably relative to the primary shaft 41 by spline fitting and meshes with the input shaft gear 61.

[0039] 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 in a non-rotatable relative manner by spline fitting. The carrier 72 is externally fitted to the output shaft 32 in a rotatable relative manner. The carrier 72 rotatably supports a plurality of pinion gears 74. The plurality of pinion gears 74 are arranged on the circumference and mesh 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 pinion gear 74 from the outside in the radial direction of rotation of the secondary shaft 42. Further, the output shaft 32 is connected to the ring gear 73, and the ring gear 73 is provided so as to be integrally rotatable about the same axis of rotation as the output shaft 32.

[0040] The split transmission mechanism 36 is a parallel-axis gear mechanism including a split drive gear 81 and a split driven gear 82 that meshes with the split drive gear 81.

[0041] The split drive gear 81 is externally fitted to the input shaft 31 in a rotatable relative manner.

[0042] The split driven gear 82 is provided so as to be integrally rotatable about the same axis of rotation as the carrier 72 of the planetary gear mechanism 35. The split driven gear 82 is formed to have a smaller diameter than the split drive gear 81 and has fewer teeth than the split drive gear 81.

[0043] Further, the transmission 4 includes clutches C1, C2 and a brake B1.

[0044] The clutch C1 (an example of a first engagement element) can be switched by hydraulic pressure between an engaged state in which the input shaft 31 and the split drive gear 81 are directly connected (connected so as to be integrally rotatable) and a released state in which the direct connection is released.

[0045] The clutch C2 (an example of the second engaging element) can be switched by hydraulic pressure between an engaged state in which the sun gear 71 and the ring gear 73 of the planetary gear mechanism 35 are directly connected (connected so as to be rotatable integrally) and a released state in which the direct connection is released.

[0046] The brake B1 can be switched by hydraulic pressure between an engaged state in which the carrier 72 of the planetary gear mechanism 35 is braked and a released state in which the rotation of the carrier 72 is permitted.

[0047] <Power transmission mode> FIG. 2 is a diagram showing the states of the clutches C1, C2 and the brake B1 when the vehicle 1 is moving 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 pulley ratio of the belt transmission mechanism 33 and the total transmission ratio of the entire transmission 4.

[0048] In FIG. 2, "○" indicates that the clutches C1, C2 and the brake B1 are in the engaged state. "×" indicates that the clutches C1, C2 and the brake B1 are in the released state.

[0049] In the passenger compartment of the vehicle 1, a shift lever (select lever) is disposed at a position operable by the driver. In the movable range of the shift lever, for example, a P (parking) position, an R (reverse) position, an N (neutral) position and a D (drive) position are arranged in this order in a row.

[0050] When the shift lever is in the P position, all of the clutches C1, C2 and the brake B1 are released, and a parking lock gear (not shown) is fixed, thereby constituting the P range, which is one of the shift ranges of the transmission 4. Also, when the shift lever is in the N position, all of the clutches C1, C2 and the brake B1 are released and the parking lock gear is not fixed, thereby constituting the 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 idly and the power of the engine 2 is not transmitted to the drive wheels 7L, 7R.

[0051] When the shift lever is in the D position, a forward range, which is one of the shift ranges of the transmission 4, is constituted. The power transmission modes in this forward range include a belt mode (an example of the first mode) and a split mode (an example of the second mode). The belt mode and the split mode are switched by switching (changing over of the clutches C1, C2) between the state in which the clutch C1 is engaged and the state in which the clutch C2 is engaged.

[0052] In the belt mode, as shown in FIG. 2, the clutch C1 and the brake B1 are released and the clutch C2 is engaged. Thereby, the split drive gear 81 is disconnected from the input shaft 31, the carrier 72 of the planetary gear mechanism 35 becomes free (free rotation state), and the sun gear 71 and the ring gear 73 of the planetary gear mechanism 35 are directly connected.

[0053] The power input to the input shaft 31 is reversed and decelerated by the front reduction gear mechanism 34 and transmitted to the primary shaft 41 of the belt transmission mechanism 33, rotating the primary shaft 41 and the primary pulley 43. The rotation of the primary pulley 43 is transmitted via the belt 45 to the secondary pulley 44, rotating the secondary pulley 44 and the secondary shaft 42. 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 gear ratio of the entire transmission 4 coincides with the value obtained by multiplying the pulley ratio of the belt transmission mechanism 33 by the front reduction ratio (rotation speed of the input shaft 31 / rotation speed of the primary shaft 41).

[0054] In the split mode, as shown in FIG. 2, the clutch C1 is engaged and the clutches C2 and the brake B1 are released. Thereby, the input shaft 31 and the split drive gear 81 are coupled, 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 disengaged.

[0055] The power input to the input shaft 31 is transmitted after being speeded up from the split drive gear 81 via the split driven gear 82 to the carrier 72 of the planetary gear mechanism 35. The power transmitted to the carrier 72 is split 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 via the secondary shaft 42, the secondary pulley 44, the belt 45, the primary pulley 43, and the primary shaft 41, and then 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.

[0056] Since the gear ratio between the split drive gear 81 and the split driven gear 82 is constant and invariable (fixed), in the split mode, if the power input to the input shaft 31 is constant, the rotation of the carrier 72 of the planetary gear mechanism 35 is maintained at a constant speed. Therefore, when the pulley ratio is increased, the rotational speed of the sun gear 71 of the planetary gear mechanism 35 decreases, so as shown by the dashed line in Fig. 3, the rotational speed of the ring gear 73 (output shaft 32) of the planetary gear mechanism 35 increases. As a result, in the split mode, as shown in Fig. 4, the larger the pulley ratio of the belt transmission mechanism 33, the smaller the total transmission ratio of the transmission 4, and the sensitivity of the total transmission ratio to the pulley ratio (the ratio of the change amount of the total transmission ratio to the change amount of the pulley ratio) is lower than that in the belt mode.

[0057] The rotation of the output shaft 32 in the belt mode and the split mode is transmitted to the differential gear 5 via the output gear 37. Thereby, the drive shafts 6L, 6R and the drive wheels 7L, 7R of the vehicle 1 rotate in the forward direction.

[0058] When the shift lever is in the R position, a reverse range, which is one of the shift ranges of the transmission 4, is formed. 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 disengaged from the input shaft 31, the sun gear 71 and the ring gear 73 of the planetary gear mechanism 35 are disengaged, and the carrier 72 of the planetary gear mechanism 35 is braked.

[0059] The power input to the input shaft 31 is reversed and decelerated by the front reduction gear mechanism 34 and transmitted to the primary shaft 41 of the belt transmission mechanism 33. From the primary shaft 41, it is transmitted to the secondary shaft 42 via the primary pulley 43, the belt 45, and the secondary pulley 44. Integrally with the secondary shaft 42, the sun gear 71 of the planetary gear mechanism 35 is rotated. 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 movement (belt mode and split mode). Then, integrally with the ring gear 73, the output shaft 32 rotates. The rotation of the output shaft 32 is transmitted to the differential gear 5 via the output gear 37. Thereby, the drive shafts 6L, 6R of the vehicle 1 and the drive wheels 7L, 7R rotate in the reverse direction.

[0060] <Vehicle control system> FIG. 5 is a block diagram showing the configuration of the control system of the vehicle 1.

[0061] The vehicle 1 is equipped with an ECU (Electronic Control Unit) having a configuration including a microcomputer (microcontroller unit). The microcomputer incorporates, 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 a plurality of ECUs having the same configuration as the ECU 91 to control each part. The plurality of ECUs including the ECU 91 are connected so as to enable two-way communication according to the CAN (Controller Area Network) communication protocol.

[0062] The unit including the torque converter 3 and the transmission 4 is equipped with a hydraulic circuit 92 for supplying hydraulic pressure to each part. The ECU 91 controls various valves and the like included in the hydraulic circuit 92 for the shift control of the transmission 4 and the like.

[0063] Various sensors necessary for its 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 operation amount of an accelerator pedal (not shown) operated by the driver.

[0064] In the ECU 91, from the detection signals of the turbine rotation sensor 93, the primary rotation sensor 94, the secondary rotation sensor 95, and the output rotation sensor 96, 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, are obtained. Also, in the ECU 91, from the detection signal of the accelerator sensor 97, the ratio of the operation amount to the maximum operation amount of the accelerator pedal, that is, the accelerator opening, which is a percentage with 0% when the accelerator pedal is not depressed and 100% when the accelerator pedal is fully depressed, is obtained.

[0065] Note that some of the turbine rotation sensor 93, the primary rotation sensor 94, the secondary rotation sensor 95, the output rotation sensor 96, and the accelerator sensor 97 may be connected to other ECUs, and information obtained from some of these sensors may be received from other ECUs.

[0066] <Transmission control> The total gear ratio of the transmission 4 is controlled by changing the pulley ratio by the ECU 91 and engaging / releasing the clutches C1, C2 and the brake B1. In this shift control, first, based on the shift diagram, a target rotational speed corresponding to the accelerator opening and the vehicle speed is set. The shift diagram is a map defining the relationship between the accelerator opening, the vehicle speed, and the target rotational speed, and is stored in the ROM of the ECU 91. Information on the vehicle speed is transmitted from, for example, the engine ECU that controls the engine 2 to the ECU 91. When the target rotational speed is set, a target total gear ratio, which is the target value of the total gear ratio for matching the rotational speed input to the input shaft 31, that is, the turbine rotational speed, to the target rotational speed, is obtained, and a target pulley ratio, which is the target value of the pulley ratio corresponding to the target total gear ratio, is set.

[0067] Thereafter, based on the target of the pulley ratio, command values of 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, and based on each command value, the primary pressure and the secondary pressure are controlled so that the difference between the target pulley ratio and the actual pulley ratio (actual pulley ratio) approaches zero. The actual pulley ratio is obtained by dividing the primary rotational speed by the secondary rotational speed.

[0068] When the total gear ratio is changed across the split point (see Fig. 4) where the total gear ratio is 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 a switch between the belt mode and the split mode (hereinafter simply referred to as "mode switch"). The mode switch is achieved by clutch switching control (an example of switching control) that switches the engagement of the clutches C1, C2. That is, by controlling the hydraulic pressure supplied to the clutches C1, C2, the clutch C1 in the released state (engagement side) is engaged, and the clutch C2 in the engaged state (release side) is released, thereby switching from the belt mode to the split mode. Conversely, by releasing the clutch C1 in the engaged state (release side) and engaging the clutch C2 in the released state (engagement side), the split mode can be switched to the belt mode.

[0069] When a kick-down request is made during driving in split mode, the ECU 91 of this embodiment performs processing to optimize the timing for executing clutch switching control to switch from split mode to belt mode. Detection of the kick-down request may be executed by appropriately using known techniques. For example, when the accelerator pedal is depressed by a predetermined amount or more within a predetermined time, it can be determined that a kick-down request has been made.

[0070] FIG. 6 is a diagram showing a method for determining the timing of clutch switching control at the time of a kick-down request.

[0071] In FIG. 6, point A indicates the split point. Point B is a point indicating the target total gear ratio Rtt set in response to the kick-down request and the target pulley ratio Rbt which is the target pulley ratio corresponding to the target total gear ratio Rtt. Point C is a point indicating the pulley ratio Rb1 at the time of the kick-down request, which is the requested pulley ratio. Point D is a point indicating the actual pulley ratio Rbr which is the actual pulley ratio after the kick-down request. In this example, a situation where the actual pulley ratio Rbr decreases with the passage of time is shown.

[0072] As shown in FIG. 6, in this embodiment, it is assumed that the requested pulley ratio Rb1 is larger than the target pulley ratio Rbt. In such a case, in the prior art, in order to reduce shift shock, after the kick-down request, the actual pulley ratio Rbr after the kick-down request is made to coincide with or substantially coincide with the target pulley ratio Rbt, and then the clutch switching control is started. Therefore, when the difference between the requested pulley ratio Rb1 and the target pulley ratio Rbt is large, the time lag from when the kick-down request is made until the transition to the belt mode is completed and acceleration starts becomes large, and there may be a sense of jerk given to the driver.

[0073] In order to avoid the above problems, the ECU 91 of the present embodiment executes a process of determining the timing to start clutch switching control in consideration of the clutch operation time (an example of the operation time), which is the time required for the switching operation of the clutches C1 and C2 when switching from the split mode to the belt mode.

[0074] When the ECU 91 detects a kick-down request, it calculates a predicted pulley ratio Rbp, which is the pulley ratio predicted to be reached by the actual pulley ratio Rbr after the elapse of the predicted time, based on a predetermined predicted time shorter than the clutch operation time required for the switching operation of the clutches C1 and C2 when switching from the split mode to the belt mode. Then, when the predicted pulley ratio Rbp becomes equal to or less than the target pulley ratio Rbt, the ECU 91 starts clutch switching control to switch from the split mode to the belt mode.

[0075] The clutch operation time can be set by an appropriate method using known techniques. For example, it can be set based on the results of experiments, simulations, etc. performed in advance. The clutch operation time may be a constant value or a value that changes according to predetermined conditions. The clutch operation time is stored, for example, in a memory provided in the ECU 91 and read from the memory and used when a kick-down request is made.

[0076] The predicted time can be set, for example, as a constant value shorter than the clutch operation time. By setting the predicted time shorter than the clutch operation time, control can be performed in the conventional order where the engagement change of the clutches C1 and C2 is completed after the adjustment of the pulley ratio is completed, so there is no concern about the deterioration of the shift shock. The predicted time is stored, like the clutch operation time, in a memory provided in the ECU 91, for example, and read from the memory and used when a kick-down request is made.

[0077] In FIG. 6, point E indicates the predicted pulley ratio Rbp, which is the pulley ratio that the actual pulley ratio Rbr reaches after the prediction time has elapsed. In this example, a situation is shown where the predicted pulley ratio Rbp decreases as the actual pulley ratio Rbr decreases. The predicted pulley ratio Rbp can be calculated by appropriately using known techniques. For example, it can be calculated by multiplying the change rate of the pulley ratio preset for the prediction time.

[0078] In FIG. 6, point F indicates the switching pulley ratio Rb2, which is the pulley ratio at the start of execution of the clutch switching control of the present embodiment. The switching pulley ratio Rb2 illustrated here is the actual pulley ratio Rbr when the predicted pulley ratio Rbp reaches the target pulley ratio Rbt.

[0079] FIG. 7 is a diagram showing the start timing of the clutch switching control at the time of a kick-down request.

[0080] In FIG. 7, time t0 indicates the time when the accelerator opening starts to increase, that is, the time when the driver starts to depress the accelerator pedal. Time t1 indicates the time when the accelerator opening reaches a predetermined value and a kick-down request is detected.

[0081] The target total gear ratio Rtt increases in response to an increase in the accelerator opening and is determined at time t1. The actual pulley ratio Rbr and the predicted pulley ratio Rbp decrease in response to an increase in the target total gear ratio Rtt. The predicted pulley ratio Rbp reaches the target pulley ratio Rbt (see FIG. 6) corresponding to the target total gear ratio Rtt at time t2, and the actual pulley ratio Rbr has reached the target pulley ratio Rbt corresponding to the target total gear ratio Rtt at time t3. In the present embodiment, the clutch switching control for switching from the split mode to the belt mode is started at time t2, and the turbine speed reaches the target value in the belt mode at time t4. On the other hand, in the prior art, the clutch switching control is started at time t3 when a time Δt has elapsed from time t2, and the turbine speed reaches the target value in the belt mode at time t5 when a time Δt has elapsed from time t4. Thus, according to the present embodiment, the time lag that occurs after a kick-down request can be reduced by the time Δt compared to the prior art.

[0082] FIG. 8 is a flowchart showing the processing from a kick-down request to the start of clutch switching control.

[0083] The ECU 91 determines whether or not a kick-down request has been detected (S101). If a kick-down request has not been detected (S101: No), this routine ends. If a kick-down request has been detected (S101: Yes), the target total gear ratio Rtt is set based on the operation at the time of the kick-down request (for example, the accelerator opening, etc.) (S102). Thereafter, the actual pulley ratio Rbr is changed (decreased) so as to approach the target pulley ratio Rbt corresponding to the target total gear ratio Rtt (S103). Also, based on a preset prediction time, a predicted pulley ratio Rbp that the actual pulley ratio Rbr will reach after the prediction time has elapsed is calculated (S104).

[0084] Thereafter, it is determined whether the calculated predicted pulley ratio Rbp is less than or equal to the target pulley ratio Rbt (S105). If the predicted pulley ratio Rbp is not less than or equal to the target pulley ratio Rbt (S105: No), the processes after step S102 are executed again. If the predicted pulley ratio Rbp is less than or equal to the target pulley ratio Rbt (S105: Yes), the ECU 91 starts clutch switching control to switch from the split mode to the belt mode (S106).

[0085] By the above-described processing, when the predicted pulley ratio Rbp reaches the target pulley ratio Rbt even before the actual pulley ratio Rbr reaches the target pulley ratio Rbt after a kick-down request, the clutch switching control is started. Thereby, it is possible to shorten the time lag compared to the case where the clutch switching control is not started until the actual pulley ratio Rbr reaches the target pulley ratio Rbt as in the prior art.

[0086] <Abnormality determination control> The ECU 91 of the present embodiment further determines an abnormality in the processing at the time of a kick-down request and performs processing for coping with the occurrence of an abnormality.

[0087] FIG. 9 is a flowchart showing the abnormality determination process at the time of a kick-down request and the coping process at the time of the occurrence of an abnormality.

[0088] After detecting a kick-down request, the ECU 91 calculates a predicted arrival rate based on the predicted pulley ratio Rbp (S201), and calculates an actual predicted arrival rate based on the actual pulley ratio Rbr (S202). The predicted arrival rate is the ratio of the predicted pulley ratio Rbp to the target pulley ratio Rbt at a predetermined time point (for example, when a certain time has elapsed after detecting a kick-down request) (for example, Rbp / Rbt). The actual arrival rate is the ratio of the actual pulley ratio Rbr to the target pulley ratio Rbt at the same predetermined time point as above (for example, Rbr / Rbt).

[0089] Thereafter, it is determined whether or not the difference between the ideal attainment rate and the actual attainment rate at the same point in time is equal to or greater than the threshold value (S203). If the difference is less than the threshold value (S203: No), it is determined that no abnormality has occurred, and this routine ends. On the other hand, if the difference is equal to or greater than the threshold value (S203: Yes), it is determined that an abnormality has occurred (S204). Regardless of whether the predicted pulley ratio Rbp is less than or equal to the target pulley ratio Rbt, the ECU 91 determines the start timing of clutch switching control to switch from the split mode to the belt mode based on whether the actual pulley ratio Rbr is less than or equal to the target pulley ratio Rbt (S205).

[0090] According to the above processing, the presence or absence of an abnormality is determined based on the difference between the predicted attainment rate and the actual attainment rate. When an abnormality occurs, the start timing of clutch switching control is determined based on the difference between the actual pulley ratio Rbr and the target pulley ratio Rbt in the same manner as in the prior art. Thereby, the robustness of the downshift operation at the time of kickdown demand can be improved.

[0091] A program for causing a computer (for example, the ECU 91 or the like) to execute the processing for realizing various functions in the control device of the above embodiment is a file in an installable format or an executable format, and is recorded on a computer-readable recording medium such as a CD (Compact Disc)-ROM, a flexible disk (FD), a CD-R (Recordable), or a DVD (Digital Versatile Disk) and provided. Further, the program may be provided or distributed via a network such as the Internet.

[0092] As described above, the embodiments of the present invention have been described. However, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. This novel embodiment can be implemented in various other forms. Also, various omissions, replacements, and changes can be made without departing from the gist of the invention. Further, this embodiment is included in the scope and gist of the invention, and is included in the invention described in the claims and the equivalent scope thereof.

Description of Symbols

[0093] 4... Transmission, 31... Input shaft, 32... Output shaft, 33... Belt transmission mechanism, 91... ECU (control device), C1... Clutch (first engagement element), C2... Clutch (second engagement element)

Claims

1. A first engaging element interposed on a first power transmission path between an input shaft and an output shaft, and a second engaging element interposed on a second power transmission path between the input shaft and the output shaft, having a belt transmission mechanism on the second power transmission path, and by releasing the first engaging element and engaging the second engaging element, a first mode in which the total transmission ratio between the input shaft and the output shaft increases as the pulley ratio by the belt transmission mechanism increases, and by engaging the first engaging element and releasing the second engaging element, a second mode in which the total transmission ratio decreases as the pulley ratio increases, and a continuously variable transmission configured such that when the pulley ratio is a constant value, no differential rotation occurs in the first engaging element and the second engaging element, a control device for controlling the continuously variable transmission, kick-down detection means for detecting a kick-down request, target value setting means for setting a target total transmission ratio which is a target value of the total transmission ratio in response to the kick-down request, pulley ratio changing means for decreasing the actual pulley ratio, which is the actual pulley ratio after detection of the kick-down request, so as to approach the target pulley ratio which is the pulley ratio corresponding to the target total transmission ratio, pulley ratio prediction means for calculating a predicted pulley ratio which is the pulley ratio expected to be reached after elapse of the prediction time based on a prediction time shorter than an operation time required for a switching operation of the first engaging element and the second engaging element when switching from the second mode to the first mode, switching start control means for starting switching control to switch the first engaging element and the second engaging element so as to transition from the second mode to the first mode when the predicted pulley ratio becomes less than or equal to the target pulley ratio, A control device comprising.

2. reach rate calculation means for calculating a predicted reach rate which is a ratio of the predicted pulley ratio to the target pulley ratio at a predetermined time point after detection of the kick-down request, and an actual reach rate which is a ratio of the actual pulley ratio to the target pulley ratio at the predetermined time point, abnormality determination means for determining that an abnormality has occurred when a difference between the predicted reach rate and the actual reach rate at the same time point is equal to or greater than a threshold value, The control device according to claim 1, further comprising.

3. When it is determined by the abnormality determination means that an abnormality has occurred, the switching start control means starts the switching control when the actual pulley ratio becomes less than or equal to the target pulley ratio regardless of whether the predicted pulley ratio is less than or equal to the target pulley ratio. The control device according to claim 2.

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