Automatic transmission control device

Abstract

To provide an automatic transmission control device which prevents neutral control from being unintentionally released while the same is in execution and prevents a vehicle from being slid down due to unintended commencement of the neutral control.SOLUTION: An automatic transmission control device determines whether a vehicle is in a stopped state on the basis of a first threshold T1 which is shorter than a second threshold T2 when neutral control is in execution. Thus, even in a case where, for example, a small diameter gear 42 is rotated due to fluctuation in a rotation speed of an engine 12, the automatic transmission control device is less likely to determine that the vehicle is not in the stopped state than when the second threshold T2 is used. Also, when the neutral control is not in execution, the automatic transmission control device determines whether the vehicle is in the stopped state on the basis of the second threshold T2 which is longer than the first threshold T1. Thus, the automatic transmission control device is less likely to determine that the vehicle is not in the stopped state than when the first threshold T1 is used.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a control device for an automatic transmission that executes neutral control when predetermined start conditions are met, including the condition that the vehicle is in a stopped state, and to a technology that prevents the neutral control from being unintentionally released when the neutral control is being executed, and also prevents the vehicle from rolling downhill due to the unintentional start of neutral control. [Background technology]

[0002] There is a well-known automatic transmission control device that executes neutral control to release the input clutch when a predetermined start condition including a condition that the vehicle is in a stopped state is satisfied. For example, the automatic transmission control device described in Patent Document 1 is such a device. Patent Document 1 describes that the neutral control is executed when, for example, the following conditions are satisfied: the vehicle is in a stopped state, the operation position is a forward driving position, the accelerator is not being operated, and the brake is being operated. The device uses a sensor that detects the pulse period (edge ​​interval) of a pulse signal generated by the rotation of a rotating member (shaft of a primary pulley), and determines that the vehicle is in a stopped state if the pulse period detected by the sensor is longer than a predetermined threshold value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-183843 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in an automatic transmission control device such as that disclosed in Patent Document 1, the input clutch is maintained in a slip state (half-engaged state) to perform neutral control, so that if the rotating member rotates slightly due to, for example, engine rotation fluctuations, it is determined that the vehicle is not stopped, and the neutral control is released unintentionally. In response to this, it is conceivable to set the threshold value to be relatively short so that the vehicle is determined to be stopped even if the rotating member rotates slightly due to engine rotation fluctuations, etc. However, since the vehicle is determined to be stopped and neutral control is started even when it is not actually stopped, there is a possibility that the vehicle may slide down a slope, for example, due to slippage of the input clutch.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide an automatic transmission control device that prevents unintended release of neutral control when neutral control is being executed, and prevents the vehicle from rolling down due to unintended initiation of neutral control. [Means for solving the problem]

[0006] The gist of the first invention is that (a) a control device for an automatic transmission that executes neutral control to release an input clutch when predetermined start conditions are met, including a condition that the vehicle is in a stopped state, (b) the control device has a sensor that detects a pulse period of a pulse signal generated by rotation of a rotating member on the output side of the input clutch, (c) when the neutral control is being executed, the control device determines that the vehicle is in a stopped state if the pulse period is longer than a predetermined first threshold, (d) when the neutral control is not being executed, the control device determines that the vehicle is in a stopped state if the pulse period is longer than a predetermined second threshold, and (e) the first threshold is shorter than the second threshold.

[0007] A second aspect of the present invention is the first aspect of the present invention, wherein when the pulse period becomes longer than the second threshold value, the neutral control is started.

[0008] A third aspect of the present invention is characterized in that, in the first or second aspect of the present invention, when the pulse period becomes equal to or less than the first threshold value, the neutral control is released.

[0009] A fourth aspect of the present invention is characterized in that in any one of the first to third aspects of the present invention, the neutral control maintains the input clutch in a slip state.

[0010] The gist of the fifth invention is that in any one of the first to fourth inventions, the automatic transmission includes a continuously variable transmission and a gear transmission mechanism having at least one gear ratio, arranged in parallel with the continuously variable transmission. Effect of the Invention

[0011] According to the control device for an automatic transmission of the first invention, (b) a sensor is provided for detecting a pulse period of a pulse signal generated by the rotation of a rotating member on the output side of the input clutch, (c) when the neutral control is being performed, the vehicle is determined to be in a stopped state if the pulse period is longer than a first predetermined threshold value, (d) when the neutral control is not being performed, the vehicle is determined to be in a stopped state if the pulse period is longer than a second predetermined threshold value, and (e) the first threshold value is shorter than the second threshold value. Therefore, when the neutral control is being performed, it is determined whether the vehicle is in a stopped state based on the first threshold value that is shorter than the second threshold value. Therefore, even if the rotating member rotates due to, for example, engine rotation fluctuations, it is more difficult to determine that the vehicle is not in a stopped state than when the second threshold value is used. This makes it possible to suppress the neutral control from being unintentionally released when the neutral control is being performed. In addition, when the neutral control is not being executed, it is determined whether the vehicle is stopped based on the second threshold value, which is longer than the first threshold value, so that it is less likely to be determined that the vehicle is stopped when it is not actually stopped, compared to when the first threshold value is used. Therefore, it is less likely that the neutral control will be unintentionally started when the vehicle is not actually stopped, so that it is possible to suppress the vehicle from rolling downhill.

[0012] According to the automatic transmission control device of the second aspect of the present invention, when the pulse period becomes longer than the second threshold, the neutral control is started. Therefore, since the second threshold is longer than the first threshold, it becomes difficult to preferably start the neutral control when the vehicle is not actually stopped.

[0013] According to the automatic transmission control device of the third aspect of the present invention, when the pulse period becomes equal to or shorter than the first threshold value, the neutral control is released. Therefore, since the first threshold value is shorter than the second threshold value, even if the rotating member rotates due to, for example, engine rotation fluctuations, it is difficult to determine that the vehicle is not in a stopped state.

[0014] According to the automatic transmission control device of the fourth aspect of the present invention, the neutral control is performed by maintaining the input clutch in a slip state, and therefore, compared to a case in which the input clutch is completely released and the neutral control is performed, the neutral control can be quickly released when it is determined that the vehicle is not at a standstill, for example.

[0015] According to the automatic transmission control device of the fifth aspect of the present invention, the automatic transmission includes a continuously variable transmission and a gear transmission mechanism having at least one gear ratio and disposed in parallel with the continuously variable transmission. Therefore, in the automatic transmission including the continuously variable transmission and the gear transmission mechanism, it is possible to prevent the neutral control from being unintentionally released while the neutral control is being executed, and to prevent the vehicle from rolling downhill due to the unintentional start of the neutral control. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic diagram for explaining the general configuration of a vehicle power transmission device equipped with an automatic transmission according to one embodiment of the present invention, in which a plurality of parallel shafts are shown developed so as to be positioned within a single plane. [Diagram 2] 2A and 2B are diagrams showing pulse signals generated by the rotation of a rotating member provided in the automatic transmission of FIG. 1, where FIG. 2A is a diagram showing a pulse signal when the rotational speed of the rotating member is faster than the rotational speed of the rotating member of FIG. 2B, and FIG. 2B is a diagram showing a pulse signal when the rotational speed of the rotating member is slower than the rotational speed of the rotating member of FIG. 2A. [Diagram 3] 2 is a diagram showing the relationship between the rotation speed of a rotating member provided in the automatic transmission of FIG. 1 and the pulse period of a pulse signal. [Figure 4] 1. FIG. 4 is a diagram showing a pulse period threshold value that is a determination value for determining whether or not the vehicle is in a stationary state in a stationary state determination section provided in the electronic control device of FIG. [Diagram 5]2 is a flowchart for explaining a main part of the control operation of the electronic control device of FIG. 1, and is a flowchart for explaining an example of the control operation when starting neutral control and when releasing neutral control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0018] FIG. 1 is a schematic diagram for explaining the schematic configuration of a vehicle power transmission device 10 having an automatic transmission 16 according to an embodiment of the present invention, in which a plurality of parallel shafts are expanded to be positioned on one plane. The vehicle power transmission device 10 is a horizontal type suitable for use in FF (front engine, front drive) vehicles, and power from an engine 12, which is a driving power source for traveling, is transmitted from a torque converter 14, which serves as a fluid transmission device, to a differential gear device 18 via the automatic transmission 16, and distributed to left and right driving wheels 20L, 20R. The torque converter 14 includes a pump impeller 14p connected to the crankshaft of the engine 12 and a turbine impeller 14t connected to an input shaft 22 of the automatic transmission 16, and transmits power via a fluid (hydraulic oil) and is directly connected via a lock-up clutch LU.

[0019] The automatic transmission 16 includes an input shaft 22 provided integrally with a turbine shaft which is an output rotating member of the torque converter 14, a belt-type continuously variable transmission (STV) 24 connected to the input shaft 22, a forward / reverse switching device 26 and a gear transmission mechanism 28 which are also connected to the input shaft 22 and provided in parallel with the belt-type continuously variable transmission 24, an output shaft 30 which is a common output rotating member of the belt-type continuously variable transmission 24 and the gear transmission mechanism 28, and a reduction gear unit 32, and a small-diameter gear 34 of the reduction gear unit 32 is meshed with a ring gear 36 of the differential gear unit 18. In the automatic transmission 16 thus configured, power from the engine 12 is transmitted from the torque converter 14 to the output shaft 30 via the belt-type continuously variable transmission 24, or is transmitted to the output shaft 30 via the forward / reverse switching device 26 and the gear transmission mechanism 28 without passing through the belt-type continuously variable transmission 24. The power is then transmitted from the output shaft 30 through a reduction gear device 32 and a differential gear device 18 to the left and right drive wheels 20L, 20R.

[0020] In this manner, the automatic transmission 16 of the present embodiment is provided with a first power transmission path TP1 that transmits the power from the engine 12 from the input shaft 22 to the output shaft 30 via the forward / reverse switching device 26 and the gear shift mechanism 28, and a second power transmission path TP2 that transmits the power from the engine 12 from the input shaft 22 to the output shaft 30 via the belt-type continuously variable transmission 24, in parallel as power transmission paths that transmit the power from the engine 12 from the input shaft 22 to the output shaft 30, and the first power transmission path TP1 and the second power transmission path TP2 are switched depending on the running state of the vehicle. For this reason, the automatic transmission 16 is provided with a forward clutch (input clutch) C1 that connects and disconnects (connects and disconnects) the power transmission in the first power transmission path TP1, a reverse brake B1, and a belt running clutch C2 that connects and disconnects the power transmission in the second power transmission path TP2. The forward clutch C1 is a clutch that is engaged when the power from the engine 12 is transmitted from the input shaft 22 to the output shaft 30 via the first power transmission path TP1, and the belt running clutch C2 is a clutch that is engaged when the power from the engine 12 is transmitted from the input shaft 22 to the output shaft 30 via the second power transmission path TP2. The first power transmission path TP1 is further provided with a synchromesh clutch S1 in series with the forward / reverse switching device 26 and the gear shift mechanism 28, specifically downstream of them. The forward clutch C1 and the synchromesh clutch S1 provided on the first power transmission path TP1 are engaged to enable forward running. The belt running clutch C2 provided on the second power transmission path TP2 is engaged to enable forward running. The forward clutch C1, the synchromesh clutch S1, and the belt running clutch C2 are all hydraulic clutches.

[0021] The engine 12 is equipped with an engine control device 40 having various devices necessary for output control of the engine 12, such as an electronic throttle device, a fuel injection device, an ignition device, etc. The engine 12 is controlled by an electronic control device (control device) 100 (described later) in response to an accelerator operation amount θacc, which is an operation amount of an accelerator pedal corresponding to a drive amount required by the driver for the vehicle, thereby controlling an engine torque Te, which is an output torque of the engine 12.

[0022] The forward / reverse switching device 26 is mainly constituted by a double-pinion type planetary gear device, in which the carrier 26c is integrally connected to the input shaft 22, and the sun gear 26s is connected to a small diameter gear (rotating member) 42 arranged coaxially and rotatably relative to the input shaft 22, while the ring gear 26r is selectively stopped from rotating via a reverse brake B1, and the carrier 26c and the sun gear 26s are selectively connected via a forward clutch C1. When the forward clutch C1 is engaged and the reverse brake B1 is released, the input shaft 22 is directly connected to the small diameter gear 42 to establish a forward power transmission state, and when the reverse brake B1 is engaged and the forward clutch C1 is released, the small diameter gear 42 is rotated in the opposite direction relative to the input shaft 22 to establish a reverse power transmission state. When both the forward clutch C1 and the reverse brake B1 are released, the vehicle enters a neutral state in which power transmission through the first power transmission path TP1 is interrupted.

[0023] The forward clutch C1 and the reverse brake B1 are both multi-plate hydraulic friction engagement devices in which multiple friction materials are frictionally engaged by hydraulic cylinders, and the C1 engagement oil pressure Pc1 and B1 engagement oil pressure Pb1 supplied to the hydraulic cylinders are respectively regulated and controlled by two linear solenoid valves (not shown) provided in the hydraulic control circuit 38, thereby continuously adjusting their engagement forces, i.e., transmission torque capacities.

[0024] The gear transmission mechanism 28 includes a small diameter gear 42, a large diameter gear 46 that is non-rotatably mounted on the countershaft 44 and meshes with the small diameter gear 42, and a small diameter idler gear 48 that is coaxially mounted on the countershaft 44 and rotatable relative thereto. A synchromesh clutch S1 is provided between the countershaft 44 and the idler gear 48 to connect and disconnect power transmission therebetween. The synchromesh clutch S1 includes a synchromesh mechanism such as a synchronizer ring. When a clutch hub sleeve 50 is moved in a connecting direction, which is the left direction in FIG. 1, by a hydraulic cylinder (not shown), the idler gear 48 is rotated synchronously with the countershaft 44 via the synchronizer ring. When the clutch hub sleeve 50 is further moved, the idler gear 48 is connected to the countershaft 44 via spline teeth provided on the inner peripheral surface of the clutch hub sleeve 50 so as to be non-rotatable relative thereto. The hydraulic cylinder of the synchronous mesh clutch S1 is supplied with an S1 engagement oil pressure Ps1 that is pressure-controlled by a linear solenoid valve (not shown) provided in the hydraulic control circuit 38, and the synchronous mesh clutch S1 is engaged in synchronous mesh based on the S1 engagement oil pressure Ps1.

[0025] The idler gear 48 meshes with a large diameter gear 58 provided on the output shaft 30, and when either the forward clutch C1 or the reverse brake B1 is engaged and the synchromesh clutch S1 is connected, the power from the engine 12 is transmitted from the input shaft 22 to the output shaft 30 via the forward / reverse switching device 26, the gear transmission mechanism 28, the idler gear 48, and the large diameter gear 58 in this order, thereby establishing a first power transmission path TP1. Note that speed change (reduction) also occurs between the small diameter idler gear 48 and the large diameter gear 58, and it can be considered that the gear transmission mechanism 28 is composed of these and other elements.

[0026] The belt-type continuously variable transmission 24 includes a primary pulley 60 with a variable effective diameter provided on the input shaft 22, a secondary pulley 64 with a variable effective diameter provided on a rotating shaft 62 coaxial with the output shaft 30, and a transmission belt 66 wound around the pair of variable pulleys 60, 64, and power is transmitted through friction between the pair of variable pulleys 60, 64 and the transmission belt 66. The pair of variable pulleys 60, 64 include hydraulic cylinders 60c, 64c, respectively, as hydraulic actuators that apply thrust to change the V-groove width, and for example, the primary hydraulic pressure Ppri supplied to the hydraulic cylinder 60c is controlled by a linear solenoid valve (not shown) provided in the hydraulic control circuit 38, thereby changing the V-groove width of both variable pulleys 60, 64, changing the wrapping diameter (effective diameter) of the transmission belt 66, and continuously changing the speed ratio γ2. In addition, the secondary hydraulic pressure Psec supplied to the hydraulic cylinder 64c is regulated and controlled by a linear solenoid valve (not shown) provided in the hydraulic control circuit 38, thereby adjusting the belt clamping pressure so that the transmission belt 66 does not slip.

[0027] The output shaft 30 is arranged coaxially with the rotary shaft 62 so as to be rotatable relative thereto, and a belt-driving clutch C2 provided between the output shaft 30 and the secondary pulley 64 connects and disconnects the power transmission between the output shaft 30 and the secondary pulley 64. When the belt-driving clutch C2 is engaged, the power from the engine 12 is transmitted from the input shaft 22 to the output shaft 30 via the belt-type continuously variable transmission 24, and a second power transmission path TP2 is established. The belt-driving clutch C2 is a multi-plate type friction engagement device in which a plurality of friction materials are frictionally engaged by a hydraulic cylinder, and the C2 engagement hydraulic pressure Pc2 supplied to the hydraulic cylinder is adjusted by a linear solenoid valve (not shown) provided in the hydraulic control circuit 38, thereby continuously adjusting the engagement force, i.e., the transmission torque capacity. The pump impeller 14p is provided with a mechanical oil pump 68, which is driven to rotate by the engine 12 to output hydraulic pressure, and the hydraulic pressure is used as a hydraulic pressure source for the hydraulic control circuit 38.

[0028] In such a vehicle power transmission device 10, the speed ratio γ1 of the first power transmission path TP1, which is determined by the gear ratio of the gear shift mechanism 28, is greater than the maximum value γ2max of the speed ratio γ2 of the second power transmission path TP2. When the vehicle starts or runs under high load, the vehicle runs in a gear driving mode using the first power transmission path TP1, and when the vehicle speed V increases or the required driving force decreases, the vehicle is switched to a belt driving mode using the second power transmission path TP2. Mode switching (upshift) from the gear driving mode to the belt driving mode is performed by a clutch-to-clutch shift (CtoC) in which the forward clutch C1 is released and the belt driving clutch C2 is engaged. Mode switching (downshift) from the belt driving mode to the gear driving mode is performed by a clutch-to-clutch shift in which the belt driving clutch C2 is released and the forward clutch C1 is engaged. The gear ratios γ1 and γ2 are the ratios (Nt / Nout) of the turbine rotation speed Nt to the output rotation speed (rotation speed of the output shaft 30), and the maximum value γ2max of the gear ratios γ1 and γ2 is greater than 1.0, so that the output shaft 30 is rotated at a reduced speed relative to the input shaft 22. The output rotation speed Nout corresponds to the vehicle speed V, and the turbine rotation speed Nt coincides with the rotation speed (input rotation speed) of the input shaft 22. The gear transmission mechanism 28 includes a small diameter gear 42 and a large diameter gear 46, and has one gear ratio.

[0029] Returning to Fig. 1, the vehicle, i.e., the power transmission device 10 for a vehicle, is provided with an electronic control device 100 as a controller including a control device for the automatic transmission 16. The electronic control device 100 is configured to include a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various controls of the vehicle by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 100 executes output control of the engine 12, speed change control and belt clamping pressure control of the belt-type continuously variable transmission 24, and hydraulic control for switching the respective operating states of a plurality of engagement devices, i.e., the reverse brake B1, the forward clutch C1, the belt running clutch C2, and the synchronous mesh clutch S1.

[0030] The electronic control device 100 is supplied with various detection signals (e.g., the operation position POSsh of a shift lever 114, the engine rotation speed sensor 104, the accelerator operation amount sensor 106, the brake switch 108, the vehicle speed sensor 110, the rotation sensor (sensor) 112, etc.) from various sensors provided in the vehicle (e.g., a shift position sensor 102, an engine rotation speed sensor 104, an accelerator operation amount sensor 106, a brake switch 108, a vehicle speed sensor 110, a rotation sensor (sensor) 112, etc.) respectively. The rotation sensor 112 is a sensor that detects the pulse period T [sec] of a pulse signal P (see FIG. 2) generated by the rotation of a rotating member, for example, the small diameter gear 42, which is an output side rotating member of the first power transmission path TP1, on the forward clutch C1 side, i.e., the period [sec] from the rising edge of the pulse signal P to the rising edge of the next pulse signal P. The pulse signal P is a rectangular wave signal obtained by converting an AC voltage output from an electromagnetic pickup sensor, for example, by a periodic change in an air gap caused by the rotation of a gear-shaped rotor (not shown) fixed to the shaft portion 42a of the small diameter gear 42. Fig. 2 shows the pulse signal P generated by the rotation of the small diameter gear 42, with Fig. 2(a) showing the pulse signal P when the rotation speed Ng [rpm] of the small diameter gear 42 is faster than the rotation speed Ng [rpm] of the small diameter gear 42 in Fig. 2(b) to be described later, and Fig. 2(b) showing the pulse signal P when the rotation speed Ng [rpm] of the small diameter gear 42 is slower than the rotation speed Ng [rpm] of the small diameter gear 42 in Fig. 2(a). Fig. 3 shows the relationship between the rotation speed Ng of the small diameter gear 42 and the pulse period T of the pulse signal P. As shown in FIGS. 2 and 3, the higher the rotation speed Ng of the small diameter gear 42, the shorter the pulse period T of the pulse signal P becomes, and the lower the rotation speed Ng of the small diameter gear 42, the longer the pulse period T of the pulse signal P becomes.

[0031] The electronic control device 100 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, a hydraulic control command signal Scvt for controlling the shifting of the belt-type continuously variable transmission 24 and the belt clamping pressure, etc., and a hydraulic control command signal Sbcs for controlling the operating states of each of the multiple engagement devices, i.e., the reverse brake B1, the forward clutch C1, the belt driving clutch C2, and the synchronous mesh clutch S1) to each device (e.g., the engine control device 40, the hydraulic control circuit 38, etc.) provided in the vehicle. In response to these various command signals, the hydraulic control circuit 38 outputs, for example, the B1 engagement oil pressure Pb1 supplied to the hydraulic cylinder of the reverse brake B1, the C1 engagement oil pressure Pc1 supplied to the hydraulic cylinder of the forward clutch C1, the C2 engagement oil pressure Pc2 supplied to the hydraulic cylinder of the belt driving clutch C2, the S1 engagement oil pressure Ps1 supplied to the hydraulic cylinder of the synchronous mesh clutch S1, the primary oil pressure Ppri supplied to the hydraulic cylinder 60c of the primary pulley 60, and the secondary oil pressure Psec supplied to the hydraulic cylinder 64c of the secondary pulley 64.

[0032] As shown in FIG. 1, the electronic control device 100 includes an engine control unit 120 that functions as an engine control means, a gear shift control unit 122 that functions as a gear shift control means, and a neutral control unit 124 that functions as a neutral control means, in order to realize various controls in the vehicle.

[0033] The engine control unit 120 calculates the required driving force Fdem by applying the accelerator operation amount θacc and the vehicle speed V to, for example, a driving force map, which is a relationship that has been experimentally or design-wise determined and stored in advance, i.e., a predetermined relationship. The engine control unit 120 sets a target engine torque Tetgt at which the required driving force Fdem is obtained, and outputs a command to the engine control device 40 to control the engine 12 so as to obtain the target engine torque Tetgt.

[0034] When the operation position POSsh is in the D position (forward driving position), the shift control unit 122 executes switching control for switching between the gear driving mode and the belt driving mode. Specifically, the shift control unit 122 stores a shift map which is a predetermined relationship for switching between the first speed gear stage corresponding to the gear ratio γ1 of the first power transmission path TP1 in the gear driving mode and the second speed gear stage corresponding to the maximum value γ2max of the gear ratio γ2 of the second power transmission path TP2 in the belt driving mode. The shift map is composed of the vehicle speed V and the accelerator operation amount θacc, and an upshift line for determining an upshift to the second speed gear stage, i.e., switching to the belt driving mode, and a downshift line for determining a downshift to the first speed gear stage, i.e., switching to the gear driving mode, are set on the shift map. The gear shift control unit 122 determines whether or not a gear shift is necessary by applying the actual vehicle speed V and accelerator operation amount θacc to the gear shift map, and executes the gear shift (i.e., switching of the driving mode) based on the result of the determination.

[0035] In addition, the shift control unit 122 outputs a command to the hydraulic control circuit 38 to control the gear ratio of the belt-type continuously variable transmission 24 to a target gear ratio γtgt calculated based on the accelerator opening, vehicle speed V, etc., during driving in a belt driving mode via the second power transmission path TP2, for example.

[0036] Furthermore, when the operating position POSsh is switched, for example, from the N position to the D position when the vehicle is stopped or traveling at a low speed, the gear shift control unit 122 outputs a command to the hydraulic control circuit 38 to switch the forward clutch C1 and the synchromesh clutch S1 to an engaged state and to switch the reverse brake B1 and the belt driving clutch C2 to a released state. As a result, when the operating position POSsh is in the D position when the vehicle is stopped or traveling at a low speed, a forward gear driving mode that enables forward driving via the first power transmission path TP1 is selected in the vehicle.

[0037] The neutral control unit 124 executes neutral control when a predetermined start condition CDS is satisfied, including a condition that the vehicle is in a stopped state. The neutral control is a control that reduces the engine load when the vehicle is in a stopped state and improves fuel efficiency when the vehicle is in a stopped state by releasing and maintaining in a slip state the forward clutch C1 that is engaged by the shift control unit 122 as described above when the accelerator is OFF, the vehicle is in a stopped state, the brake is ON, and the operation position POSsh is in the D position. In other words, the neutral control is a control that essentially cuts off the power transmission through the first power transmission path TP1 by maintaining the forward clutch C1 in a slip state.

[0038] As shown in Fig. 1, the neutral control unit 124 includes a start condition satisfaction determination unit 124a functioning as a start condition satisfaction determination means, a release condition satisfaction determination unit 124b functioning as a release condition satisfaction determination means, and a stop state determination unit 124c functioning as a stop state determination means. When the neutral control is not being executed, the start condition satisfaction determination unit 124a determines whether or not a predetermined start condition CDS is satisfied, for example, whether or not a first condition CD1, a second condition CD2, a third condition CD3, and a fourth condition CD4 that are previously determined are satisfied. The first condition CD1 is, for example, a condition that the operation position POSsh is in the D position, and the first condition CD1 is satisfied when the shift position sensor 102 determines that the operation position POSsh is in the D position. The second condition CD2 is, for example, a condition that the accelerator pedal is not operated, and the second condition CD2 is satisfied when the accelerator pedal operation amount sensor 106 determines that the accelerator pedal is not operated (accelerator operation). The third condition CD3 is, for example, a condition that the brake is being operated, and the third condition CD3 is satisfied when it is determined by the brake switch 108 that the brake pedal is being operated (brake operation). The fourth condition CD4 is a condition that the vehicle is in a stopped state, and the fourth condition CD4 is satisfied when it is determined by the stopped state determination unit 124c that the vehicle is in a stopped state.

[0039] The release condition satisfaction determination unit 124b determines whether or not a predetermined release condition CDE is satisfied when the neutral control is being executed. For example, when at least one of the first condition CD1, the second condition CD2, the third condition CD3, and the fourth condition CD4 is not satisfied when the neutral control is being executed, the release condition satisfaction determination unit 124b determines that the predetermined release condition CDE is satisfied.

[0040] The stopped state determination unit 124c determines whether the vehicle is in a stopped state when the neutral control is being executed. For example, as shown in Fig. 4, when the neutral control is being executed, i.e., when the neutral control is operating, if the pulse period T [sec] detected from the rotation sensor 112 is longer than a predetermined first threshold value T1 [sec], the stopped state determination unit 124c determines that the vehicle is in a stopped state (vehicle stopped state). Also, as shown in Fig. 4, when the neutral control is operating, if the pulse period T is equal to or less than the first threshold value T1, the stopped state determination unit 124c determines that the vehicle is in a moving state (vehicle non-stop state).

[0041] The stopped state determination unit 124c also determines whether the vehicle is in a stopped state when the neutral control is not being executed. For example, as shown in Fig. 4, when the neutral control is not being executed, i.e., when the neutral control is not in operation, if the pulse period T [sec] detected from the rotation sensor 112 is longer than a predetermined second threshold value T2 [sec], the stopped state determination unit 124c determines that the vehicle is in a stopped state (vehicle stopped state). Also, as shown in Fig. 4, when the neutral control is not in operation, if the pulse period T is equal to or less than the second threshold value T2, the stopped state determination unit 124c determines that the vehicle is in a moving state (vehicle non-stop state).

[0042] The first threshold T1 is a pulse period T set by experiments or the like so that the stopped state determination unit 124c determines that the vehicle is in a stopped state even when, for example, the small diameter gear 42 rotates slightly due to a rotation fluctuation of the engine 12 or the like and a pulse signal P is generated from the rotation sensor 112 when the neutral control is being executed. The second threshold T2 is a pulse period T set by experiments or the like so that the stopped state determination unit 124c does not determine that the vehicle is in a stopped state even when, for example, the vehicle is not actually stopped on a slope or the like when the neutral control is not being executed. As shown in FIG. 4, the first threshold T1 is set to be shorter than the second threshold T2. FIG. 4 is a diagram showing thresholds T1 and T2 of the pulse period T, which are determination values ​​for determining whether the vehicle is in a stopped state or not in the stopped state determination unit 124c.

[0043] When the start condition satisfaction determination unit 124a determines that the predetermined start condition CDS is satisfied while the neutral control is not being performed, the neutral control unit 124 requests the start of neutral control. When the start of neutral control is requested, the neutral control unit 124 outputs a command to maintain the forward clutch C1 in a slip state to the hydraulic control circuit 38. That is, when the neutral control is not being performed, for example, when the first condition CD1, the second condition CD2, and the third condition CD3 are each satisfied, the pulse period T becomes longer than the second threshold value T2, the fourth condition CD4 is satisfied, and the start condition satisfaction determination unit 124a determines that the predetermined start condition CDS is satisfied, the neutral control unit 124 starts the neutral control.

[0044] Furthermore, when the neutral control is being executed, if the release condition satisfaction determination unit 124b determines that the predetermined release condition CDE is satisfied, the neutral control unit 124 requests the release of the neutral control. In response to the request for release of the neutral control, the neutral control unit 124 outputs a command to put the forward clutch C1 into a fully engaged state to the hydraulic control circuit 38. That is, when the neutral control is being executed, for example, if the pulse period T becomes equal to or less than the first threshold value T1, the fourth condition CD4 is no longer satisfied, and the release condition satisfaction determination unit 124b determines that the predetermined release condition CDE is satisfied, the neutral control unit 124 releases the neutral control.

[0045] Fig. 5 is a flowchart for explaining the main parts of the control operation of the electronic control device 100, and is a flowchart for explaining an example of the control operation when starting the neutral control and when canceling the neutral control. In the flowchart of Fig. 5, the start (START) is defined as the time when the first condition CD1, the second condition CD2, and the third condition CD3 are each satisfied.

[0046] First, in step S10 (hereinafter, step will be omitted) corresponding to the functions of the start condition satisfaction determination unit 124a and the stop state determination unit 124c, it is determined whether or not the predetermined start condition CDS is satisfied, that is, whether or not the vehicle is in a stopped state. If the determination in S10 is negative, that is, if it is determined that the pulse period T is equal to or less than the second threshold value T2 and the vehicle is in a moving state, the predetermined start condition CDS is not satisfied and S10 is executed again. If the determination in S10 is positive, that is, if it is determined that the pulse period T is longer than the second threshold value T2 and the vehicle is in a stopped state, the predetermined start condition CDS is satisfied and S20 corresponding to the function of the neutral control unit 124 is executed. In S20, the start of neutral control is requested. Next, in S30 corresponding to the function of the neutral control unit 124, neutral control for maintaining the forward clutch C1 in a slip state is executed (started).

[0047] Next, in S40 corresponding to the functions of the release condition satisfaction determination unit 124b and the stop state determination unit 124c, it is determined whether or not the predetermined release condition CDE is satisfied, for example, whether or not the vehicle is in a stopped state. If the determination in S40 is positive, that is, if it is determined that the pulse period T is longer than the first threshold value T1 and the vehicle is in a stopped state, the predetermined release condition CDE is not satisfied and S40 is executed again. If the determination in S40 is negative, that is, if it is determined that the pulse period T is equal to or less than the first threshold value T1 and the vehicle is in a moving state, the predetermined release condition CDE is satisfied and S50 corresponding to the function of the neutral control unit 124 is executed. In S50, release of the neutral control is requested, and the forward clutch C1 is brought into a fully engaged state to release the neutral control.

[0048] As described above, the electronic control device 100 of the automatic transmission 16 of this embodiment has a rotation sensor 112 that detects the pulse period T of the pulse signal P generated by the rotation of the small diameter gear 42, which is a rotating member on the output side of the forward clutch C1, and when the neutral control is being performed, it is determined that the vehicle is in a stopped state if the pulse period T is longer than a predetermined first threshold value T1, and when the neutral control is not being performed, it is determined that the vehicle is in a stopped state if the pulse period T is longer than a predetermined second threshold value T2, and the first threshold value T1 is shorter than the second threshold value T2. Therefore, when the neutral control is being performed, it is determined whether the vehicle is in a stopped state based on the first threshold value T1 that is shorter than the second threshold value T2, so that even if the small diameter gear 42 rotates due to, for example, a rotation fluctuation of the engine 12, it is more difficult to determine that the vehicle is not in a stopped state than when the second threshold value T2 is used. This makes it possible to suppress the neutral control from being unintentionally released when the neutral control is being performed. In addition, when the neutral control is not being executed, it is determined whether the vehicle is stopped based on the second threshold T2, which is longer than the first threshold T1, so that it is less likely to be determined that the vehicle is stopped when it is not actually stopped, compared to the case where the first threshold T1 is used. Therefore, it is less likely that the neutral control will be unintentionally started when the vehicle is not actually stopped, so that it is possible to suppress the vehicle from rolling downhill.

[0049] Furthermore, according to the electronic control device 100 of the automatic transmission 16 of this embodiment, when the pulse period T becomes longer than the second threshold value T2, the neutral control is started. Therefore, since the second threshold value T2 is longer than the first threshold value T1, it becomes difficult to preferably start the neutral control when the vehicle is not actually stopped.

[0050] According to the electronic control device 100 of the automatic transmission 16 of this embodiment, when the pulse period T becomes equal to or less than the first threshold value T1, the neutral control is released. Therefore, since the first threshold value T1 is shorter than the second threshold value T2, even if the small diameter gear 42 rotates due to, for example, a rotational fluctuation of the engine 12, it is difficult to appropriately determine that the vehicle is not in a stopped state.

[0051] According to the electronic control device 100 of the automatic transmission 16 of this embodiment, the neutral control is to maintain the forward clutch C1 in a slip state. Therefore, compared to the case where the forward clutch C1 is completely released and the neutral control is executed, the neutral control can be quickly released when it is determined that the vehicle is not in a stopped state, for example.

[0052] Furthermore, according to the electronic control device 100 of the automatic transmission 16 of this embodiment, the automatic transmission 16 includes the belt-type continuously variable transmission 24 and the gear shift mechanism 28 having one gear ratio and provided in parallel with the belt-type continuously variable transmission 24. Therefore, in the automatic transmission 16 including the belt-type continuously variable transmission 24 and the gear shift mechanism 28, it is possible to prevent the neutral control from being unintentionally released while the neutral control is being executed, and it is also possible to prevent the vehicle from rolling downhill due to the unintentional start of the neutral control.

[0053] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0054] For example, in the above-described first embodiment, the automatic transmission 16 includes the belt-type continuously variable transmission 24 and the gear shift mechanism 28 provided in parallel with the belt-type continuously variable transmission 24, but the automatic transmission 16 may include, for example, only the belt-type continuously variable transmission 24, or may be a stepped automatic transmission having a plurality of gear ratios. In other words, the automatic transmission 16 may be any type of automatic transmission as long as it can substantially cut off the power transmission path in the automatic transmission by releasing the input clutch and putting it into a slip state.

[0055] Further, in the above-described first embodiment, the gear transmission mechanism 28 has one gear ratio, but the configuration of the gear transmission mechanism 28 may be changed so that the gear transmission mechanism 28 has two or more gear ratios, for example.

[0056] In addition, in the above-mentioned Example 1, the predetermined start conditions CDS were the first condition CD1, the second condition CD2, the third condition CD3, and the fourth condition CD4, but, for example, the second condition CD2 and the third condition CD3 may be removed from the predetermined start conditions CDS, or a new condition may be added to the predetermined start conditions CDS.

[0057] In the above-described first embodiment, the rotation sensor 112 is a sensor that detects the pulse period T of the pulse signal P generated by the rotation of the small diameter gear 42. However, for example, the rotation sensor 112 may be a sensor that detects the pulse period T of the pulse signal P generated by the rotation of a rotating member other than the small diameter gear 42 and located on the output side of the forward clutch C1.

[0058] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0059] 16: Automatic transmission 24: Belt-type continuously variable transmission (continuously variable transmission) 28: Gear transmission mechanism (gear transmission mechanism) 42: Small diameter gear (rotating part) 100: Electronic control device (control device) 112: Rotation sensor (sensor) 124: Neutral control unit 124a: Start condition establishment determination unit 124b: Release condition fulfillment determination unit 124c: Stop state determination unit C1: Forward clutch (input clutch) CDS: Predetermined start condition CD4: 4th condition (condition) P: Pulse signal T: Pulse period T1: First threshold T2: Second threshold

Claims

1. A control device for an automatic transmission that executes neutral control to release an input clutch when a predetermined start condition is satisfied, the start condition including a condition that a vehicle is in a stopped state, a sensor for detecting a pulse period of a pulse signal generated by the rotation of a rotating member on the output side of the input clutch, When the neutral control is being executed, it is determined that the vehicle is in a stopped state if the pulse period is longer than a predetermined first threshold value, When the neutral control is not being executed, it is determined that the vehicle is in a stopped state if the pulse period is longer than a predetermined second threshold value, The first threshold is shorter than the second threshold.

2. A control device for an automatic transmission comprising:

2. When the pulse period becomes longer than the second threshold value, the neutral control is started.

2. The automatic transmission control device according to claim 1.

3. When the pulse period becomes equal to or less than the first threshold value, the neutral control is released.

3. The control device for an automatic transmission according to claim 1 or 2.

4. The neutral control maintains the input clutch in a slip state.

4. The automatic transmission control device according to claim 1,

5. The automatic transmission includes a continuously variable transmission and a gear transmission mechanism having at least one gear ratio, the gear transmission mechanism being arranged in parallel with the continuously variable transmission.

5. The control device for an automatic transmission according to claim 1.

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