JP2019168006A - Vehicle control device - Google Patents

Abstract

To be able to improving the fuel consumption while restricting the steep changes in vehicle acceleration.SOLUTION: A vehicle control device comprises: a driving source; a non-stage transmission having an input side element into which the power output from the driving source is inputted, an output side element from which the power is outputted on the drive wheel side, and a power transmission member for transmitting power between the input side element and the output side element; and a clutch for connecting/disconnecting the power transmission between the driving source and the input side element. A control part is provided capable of coasting control in which by releasing the clutch to coast the vehicle; and when estimating that the acceleration change amount exceeds the threshold value in a change in acceleration that can occur in the vehicle due to the start of the coasting control, the control part, when starting the coasting control, the change gear ratio of the non-stage transmission is shifted from the target gear ratio to the low speed side.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a vehicle control device.

  In recent years, for the purpose of improving the fuel consumption of a vehicle, a control is used in which the vehicle is coasted under a predetermined condition while no power is transmitted from the drive source to the drive wheels. For example, as such control, there is coasting control in which the vehicle is coasted by releasing a clutch provided in a power transmission system including a transmission, as disclosed in Patent Document 1.

JP 2012-219904 A

  By the way, in the conventional technology related to coasting control in which the clutch provided in the power transmission system is released to coast the vehicle, the acceleration of the vehicle may change sharply due to the start of coasting control.

  Specifically, in the coasting control, the transmission of power between the drive source side (upstream side) part and the drive wheel side (downstream side) part of the clutch is interrupted by releasing the clutch. The Thereby, the portion closer to the drive source than the clutch is not rotated along with the rotation of the drive wheel. As a result, the kinetic energy of the drive wheels is not spent on the drive source side of the clutch, so that fuel efficiency can be improved. Here, when the coasting control is started after the clutch is released, the equivalent moment of inertia around the axle in the power transmission system decreases sharply. As a result, the acceleration of the vehicle increases sharply. Such a steep change in the acceleration of the vehicle becomes a factor that makes the driver feel uncomfortable or a factor that makes the behavior of the vehicle unstable.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a novel device capable of improving fuel efficiency while suppressing a sudden change in vehicle acceleration. Another object of the present invention is to provide an improved vehicle control apparatus.

  In order to solve the above problems, according to an aspect of the present invention, a drive source, an input-side element to which power output from the drive source is input, an output-side element that outputs power to the drive wheel side, and the A continuously variable transmission having a power transmission member for transmitting power between the input side element and the output side element; and a clutch for connecting and disconnecting power transmission between the drive source and the input side element. A control device for a vehicle, comprising: a control unit capable of executing coasting control for releasing the clutch and coasting the vehicle, wherein the control unit is caused by the coasting control being started. When the acceleration change amount in the change in acceleration that can occur in the vehicle is predicted to exceed a threshold value, the vehicle control is performed to shift the speed ratio of the continuously variable transmission from the target speed ratio to the low speed side when starting the coasting control. An apparatus is provided.

  The control unit may predict the acceleration change amount based on a parameter related to a running resistance of the vehicle.

  The control unit may predict a larger value as the acceleration change amount as the running resistance of the vehicle is larger based on the parameter.

  When the acceleration change amount is predicted to exceed the threshold, the control unit reduces the speed ratio of the continuously variable transmission from the target speed ratio based on the acceleration change amount when starting the coasting control. You may shift to the side.

  The control unit shifts the gear ratio of the continuously variable transmission from the target gear ratio to a low speed side when starting the coasting control, and then gradually changes the gear ratio of the continuously variable transmission to the target gear ratio. You may return to.

  As described above, according to the present invention, it is possible to improve fuel efficiency while suppressing abrupt change in vehicle acceleration.

It is a mimetic diagram showing a schematic structure of a power transmission system concerning an embodiment of the present invention. It is a block diagram which shows an example of a function structure of the control apparatus which concerns on the same embodiment. It is a flowchart which shows an example of the flow of the process which the control apparatus which concerns on the same embodiment performs. It is a figure for demonstrating the connection / disconnection state of the power transmission in a power transmission system in case the forward / reverse switching mechanism is open | released. It is a figure which shows an example of transition of each state quantity of a vehicle about the case where control by the control apparatus which concerns on a reference example is performed. It is explanatory drawing which shows an example of transition of each state quantity of a vehicle about the case where control by the control apparatus which concerns on the embodiment is performed.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. Configuration of power transmission system>
First, with reference to FIG.1 and FIG.2, the structure of the power transmission system 1 which concerns on embodiment of this invention is demonstrated.

  FIG. 1 is a schematic diagram showing a schematic configuration of a power transmission system 1 according to the present embodiment. FIG. 2 is a block diagram illustrating an example of a functional configuration of the control device 100 according to the present embodiment.

  The power transmission system 1 is mounted on a vehicle. For example, as shown in FIG. 1, the engine 10, the torque converter 20, the forward / reverse switching mechanism 30, the CVT 40, the transfer clutch 50, the oil pump 60, A valve unit 70 and a control device 100 are provided. The engine 10 corresponds to an example of a drive source according to the present invention. The CVT 40 corresponds to an example of a continuously variable transmission according to the present invention. The forward / reverse switching mechanism 30 corresponds to an example of a clutch according to the present invention that connects and disconnects transmission of power between the drive source and the input side element in the continuously variable transmission.

  In the power transmission system 1, for example, the torque converter 20, the forward / reverse switching mechanism 30, and the CVT 40 are connected to the output side of the engine 10 in this order. The power output from the engine 10 is transmitted to the forward / reverse switching mechanism 30 via the torque converter 20. The power transmitted to the forward / reverse switching mechanism 30 is transmitted to the CVT 40 by switching the rotation direction to the forward direction or the backward direction. The power transmitted to the CVT 40 is shifted by the CVT 40 and output to the drive wheel side. The power output from the CVT 40 is transmitted to the front wheels 17f as drive wheels via the front wheel side drive shaft 14f, the front differential gear 15f, and the front wheel side axle 16f. Further, when the transfer clutch 50 is engaged, the power output from the CVT 40 is rear wheels as drive wheels via the transfer clutch 50, the rear wheel side drive shaft 14r, the rear differential gear 15r, and the rear wheel side axle 16r. 17r.

  The engine 10 is an internal combustion engine that generates power using gasoline or the like as fuel. As described above, the engine 10 corresponds to an example of a drive source according to the present invention. The engine 10 has a crankshaft 11 as an output shaft. A mechanical oil pump 60 is connected to the crankshaft 11 via a gear train 12. The crankshaft 11 is connected to the torque converter 20.

  The oil pump 60 is driven by the rotation of the crankshaft 11 of the engine 10 to generate hydraulic pressure supplied to the valve unit 70. The valve unit 70 is connected to each of the torque converter 20, the forward / reverse switching mechanism 30, the CVT 40, and the transfer clutch 50 through an oil path, and can adjust the hydraulic pressure supplied to these devices. The valve unit 70 is provided with a control valve (for example, a proportional electromagnetic control valve) for controlling the hydraulic pressure supplied to each device.

  The torque converter 20 includes a pump impeller 22 connected to the crankshaft 11 of the engine 10 via a front cover 23, and a turbine liner 21 facing the pump impeller 22 and connected to the turbine shaft 25. Hydraulic oil is supplied into the torque converter 20, and power output from the engine 10 is transmitted from the pump impeller 22 to the turbine liner 21 via the hydraulic oil. In the torque converter 20, a lockup clutch 24 that directly connects the crankshaft 11 of the engine 10 and the turbine shaft 25 is provided. The turbine shaft 25 is connected to the forward / reverse switching mechanism 30.

  When the lockup clutch 24 is released (in other words, when the lockup state of the torque converter 20 is released), the power output from the engine 10 is transferred to the forward / reverse switching mechanism 30 via the hydraulic oil. Communicated. On the other hand, when the lockup clutch 24 is engaged (in other words, when the torque converter 20 is in the lockup state), the power output from the engine 10 is directly transmitted to the forward / reverse switching mechanism 30. .

  The forward / reverse switching mechanism 30 includes a planetary gear 31, a forward clutch 32, and a reverse brake 33. The forward / reverse switching mechanism 30 is connected to the primary shaft 44 of the CVT 40. In the forward / reverse switching mechanism 30, the rotation direction of the primary shaft 44 of the CVT 40 can be switched according to the engaged state of the forward clutch 32 and the reverse brake 33. When the forward clutch 32 is engaged and the reverse brake 33 is released, the input shaft 34 connected to the turbine shaft 25 is directly connected to the primary shaft 44, so the primary shaft 44 rotates in the forward rotation direction, and the vehicle It is possible to move forward. Further, since the forward clutch 32 is released and the reverse brake 33 is engaged, the input shaft 34 is connected to the primary shaft 44 via the planetary gear 31, so that the primary shaft 44 rotates in the reverse direction and the vehicle travels backward. Is possible.

  Further, when the forward clutch 32 and the reverse brake 33 are both released, the power from the engine 10 is not transmitted to the primary shaft 44. On the other hand, as described above, when either the forward clutch 32 or the reverse brake 33 is engaged, the power from the engine 10 is transmitted to the primary shaft 44. The power transmitted to the primary shaft 44 is transmitted to the primary pulley 41 which is an input side element of the CVT 40. Therefore, transmission of power between the engine 10 and the primary pulley 41 is connected / disconnected by the forward / reverse switching mechanism 30. Thus, the forward / reverse switching mechanism 30 corresponds to an example of a clutch according to the present invention that connects and disconnects transmission of power between the drive source and the input side element in the continuously variable transmission. The state where both the forward clutch 32 and the reverse brake 33 are released corresponds to the state where the forward / reverse switching mechanism 30 is released, and the state where either the forward clutch 32 or the reverse brake 33 is engaged is a forward / reverse switching mechanism 30. Corresponds to a state in which is fastened.

  The CVT 40 includes a primary pulley 41, a secondary pulley 42, a chain 43, a primary shaft 44, and a secondary shaft 45. The primary pulley 41 corresponds to an example of an input side element to which power output from a drive source is input. The secondary pulley 42 corresponds to an example of an output side element that outputs power to the drive wheel side. The chain 43 corresponds to an example of a power transmission member that transmits power between the input side element and the output side element. Thus, the CVT 40 corresponds to an example of a continuously variable transmission according to the present invention having an input side element, an output side element, and a power transmission member.

  The primary shaft 44 and the secondary shaft 45 are arranged in parallel to each other, the primary pulley 41 is fixed to the primary shaft 44, and the secondary pulley 42 is fixed to the secondary shaft 45. A chain 43 that transmits power between the primary pulley 41 and the secondary pulley 42 is wound around the primary pulley 41 and the secondary pulley 42. Each pulley is provided with a fixed sheave and a movable sheave, and a chain 43 is sandwiched between the fixed sheave and the movable sheave. Specifically, the chain 43 is clamped when the movable sheave is pressed toward the fixed sheave by the hydraulic pressure supplied to each pulley. By adjusting the hydraulic pressure supplied to each pulley, the clamping pressure of the chain 43 in each pulley is adjusted, and the winding radius of the chain 43 on each pulley is adjusted. Thereby, the transmission ratio of CVT 40 is adjusted. The CVT 40 shifts the power input to the primary shaft 44 at a gear ratio adjusted in this way and outputs it to the secondary shaft 45. The secondary shaft 45 is connected to the front wheel side drive shaft 14 f via the gear train 13.

  The front wheel side drive shaft 14f is connected to a front wheel 17f as a drive wheel via a front differential gear 15f and a front wheel side axle 16f. The power transmitted from the secondary shaft 45 to the front wheel side drive shaft 14f via the gear train 13 is distributed and transmitted to the left and right front wheels 17f via the front wheel side axle 16f by the front differential gear 15f.

  Further, a rear wheel side drive shaft 14r is connected to the front wheel side drive shaft 14f via a transfer clutch 50. The rear wheel side drive shaft 14r is connected to a rear wheel 17r as a drive wheel via a rear differential gear 15r and a rear wheel side axle 16r. The transfer clutch 50 connects and disconnects power transmission between the front wheel side drive shaft 14f and the rear wheel side drive shaft 14r. When the transfer clutch 50 is engaged, the power transmitted from the secondary shaft 45 to the front wheel side drive shaft 14f via the gear train 13 is transmitted to the rear wheel side drive shaft 14r. As a result, the power transmitted to the rear wheel side drive shaft 14r is distributed and transmitted to the left and right rear wheels 17r via the rear wheel side axle 16r by the rear differential gear 15r. In this case, the vehicle is in a four-wheel drive mode. On the other hand, when the transfer clutch 50 is released, the power transmitted from the secondary shaft 45 to the front wheel side drive shaft 14f via the gear train 13 is not transmitted to the rear wheel side drive shaft 14r. In this case, the vehicle is in the front wheel drive mode.

  The power transmission system 1 can be provided with various sensors. For example, the power transmission system 1 includes an acceleration sensor 201, a vehicle speed sensor 202, an accelerator opening sensor 203, a primary rotation sensor 204, and a secondary rotation sensor 205.

  The acceleration sensor 201 detects the acceleration of the vehicle and outputs a detection result.

  The vehicle speed sensor 202 detects the vehicle speed, which is the speed of the vehicle, and outputs a detection result.

  The accelerator opening sensor 203 detects the accelerator opening corresponding to the amount of operation of the accelerator pedal by the driver, and outputs the detection result.

  The primary rotation sensor 204 detects the rotation speed of the primary shaft 44 and outputs a detection result.

  The secondary rotation sensor 205 detects the rotational speed of the secondary shaft 45 and outputs a detection result.

  The control device 100 includes a CPU (Central Processing Unit) that is an arithmetic processing unit, a ROM (Read Only Memory) that is a storage element that stores programs used by the CPU, operational parameters, and the like, and parameters that change as appropriate during execution of the CPU. It is composed of a RAM (Random Access Memory) or the like that is a storage element for temporary storage.

  The control device 100 communicates with each device in the power transmission system 1. Communication between the control device 100 and each device is realized by using, for example, CAN (Controller Area Network) communication. For example, the control device 100 communicates with the engine 10, the valve unit 70, and each sensor.

  For example, as illustrated in FIG. 2, the control device 100 includes an acquisition unit 110 and a control unit 130.

  The acquisition unit 110 acquires various types of information used in processing performed by the control device 100. In addition, the acquisition unit 110 outputs the acquired information to the control unit 130.

  For example, the acquisition unit 110 acquires a detection result output from each sensor by communicating with each sensor in the power transmission system 1.

  The control unit 130 executes each process using the information acquired by the acquisition unit 110. Specifically, control unit 130 controls the operations of engine 10, forward / reverse switching mechanism 30, and CVT 40 according to the traveling state of the vehicle. In the present embodiment, the control unit 130 can execute coasting control that opens the forward / reverse switching mechanism 30 and causes the vehicle to coast. Thereby, fuel consumption can be improved.

  The control unit 130 includes, for example, a prediction unit 131, an engine control unit 132, a forward / reverse switching mechanism control unit 133, and a CVT control unit 134.

  The prediction unit 131 predicts whether or not the acceleration change amount ΔA in the change in acceleration that can occur in the vehicle due to the start of coasting control exceeds a threshold value. The acceleration change amount ΔA corresponds to the change amount of the acceleration of the vehicle in such a change in acceleration. The prediction result by the prediction unit 131 is used for control by the CVT control unit 134 at the start of coasting control.

  The engine control unit 132 controls the operation of the engine 10. Specifically, the engine control unit 132 controls the throttle opening, ignition timing, fuel injection amount, and the like by controlling the operation of each device in the engine 10. Thereby, the engine control unit 132 can control the output of the engine 10. Specifically, the engine control unit 132 controls the output of the engine 10 according to an acceleration request calculated based on the detection result of the accelerator opening.

  The forward / reverse switching mechanism control unit 133 controls the operation of the forward / reverse switching mechanism 30. Specifically, the forward / reverse switching mechanism control unit 133 controls the hydraulic pressure supplied to the forward clutch 32 and the reverse brake 33 by controlling the operation of the valve unit 70. Thereby, the forward / reverse switching mechanism control unit 133 can control the fastening state of the forward / reverse switching mechanism 30.

  The forward / reverse switching mechanism control unit 133 basically controls the fastening state of the forward / reverse switching mechanism 30 according to the shift position. For example, the forward / reverse switching mechanism control unit 133 opens the forward / reverse switching mechanism 30 when the shift position is the P range (parking range) or the N range (neutral range). Further, for example, the forward / reverse switching mechanism control unit 133 causes the forward / reverse switching mechanism 30 to be fastened when the shift position is the D range (drive range) or the R range (reverse range). The forward / reverse switching mechanism 30 is fastened so that the primary shaft 44 rotates in the forward rotation direction when the shift position is in the D range and the primary shaft 44 rotates in the reverse rotation direction when the shift position is in the R range. Is done.

  Here, in the present embodiment, the forward / reverse switching mechanism control unit 133 opens the forward / reverse switching mechanism 30 when the coasting control start condition is satisfied, for example, while the shift position is in the D range. To start coasting control for allowing the vehicle to coast. As a result, the kinetic energy of the drive wheels is not spent on rotating the portion closer to the engine 10 than the forward / reverse switching mechanism 30, and fuel efficiency can be improved.

  When executing coasting control, the engine control unit 132 may set the engine 10 in a fuel cut state in which fuel injection is not performed, or may maintain an operating state in which fuel injection is performed. When the coasting control is executed, the fuel consumption can be further improved by setting the engine 10 to the fuel cut state. On the other hand, by maintaining the engine 10 in the operating state when the coasting control is executed, the acceleration response of the vehicle after the coasting control is finished can be improved.

  The CVT control unit 134 controls the operation of the CVT 40. Specifically, the CVT control unit 134 controls the hydraulic pressure supplied to the primary pulley 41 and the secondary pulley 42 by controlling the operation of the valve unit 70. Thereby, CVT control part 134 can control the gear ratio of CVT40.

  The CVT control unit 134 basically determines a target gear ratio based on the vehicle speed and the accelerator opening, and controls the CVT 40 so that the gear ratio approaches the target gear ratio. For example, the CVT control unit 134 controls the gear ratio of the CVT 40 based on the detection results of the rotation speed of the primary shaft 44 and the rotation speed of the secondary shaft 45.

  Here, in the present embodiment, the CVT control unit 134 performs the coasting control when it is predicted that the acceleration change amount ΔA in the change in acceleration that can occur in the vehicle due to the start of the coasting control exceeds the threshold value. At the start, the gear ratio of the CVT 40 is shifted from the target gear ratio to the low speed side (in other words, the gear ratio is increased from the target gear ratio). Note that the target gear ratio is a target value of the gear ratio determined based on the traveling state of the vehicle (specifically, the vehicle speed and the accelerator opening degree) as described above in the normal time when coasting control is not performed. .

  Note that the functions of the control device 100 may be divided by a plurality of control devices. In that case, the plurality of control devices may be connected to each other via a communication bus such as CAN. Moreover, the control apparatus 100 may have functions other than said function. For example, the control device 100 may control the operations of the torque converter 20 and the transfer clutch 50. Some functions may be omitted from the functions of the control device 100. For example, the function of controlling the operation of the engine 10 may be omitted from the function of the control device 100.

<2. Operation of control device>
Then, with reference to FIGS. 3-6, operation | movement of the control apparatus 100 which concerns on embodiment of this invention is demonstrated.

  FIG. 3 is a flowchart illustrating an example of a flow of processing performed by the control device 100 according to the present embodiment. The control flow shown in FIG. 3 is repeated, for example, every preset time. Note that the control flow shown in FIG. 3 is started in a state where coasting control is not executed.

  When the control flow shown in FIG. 3 is started, first, in step S501, the control unit 130 determines whether or not a coasting control start condition is satisfied. When it is determined that the coasting control start condition is satisfied (step S501 / YES), the process proceeds to step S503. On the other hand, if it is not determined that the coasting control start condition is satisfied (step S501 / NO), the determination process of step S501 is repeated.

  Various conditions can be applied as starting conditions for coasting control.

  For example, the control unit 130 confirms that the vehicle speed exceeds the first vehicle speed reference value, the gradient of the travel path is less than the gradient reference value, and the accelerator opening is less than the opening degree reference value. Apply as a starting condition. Note that the gradient of the travel path takes a positive value when the travel path is an uphill, and takes a negative value when the travel path is a downhill. For example, the control unit 130 can calculate a pitch angle, which is an inclination angle with respect to the pitch direction of the vehicle, as the gradient of the traveling road based on the acceleration of the vehicle.

  The lower the vehicle speed, the smaller the kinetic energy of the drive wheels, so the degree of improvement in fuel efficiency by executing coasting control is reduced. Therefore, specifically, the first vehicle speed reference value is set to a value that can appropriately determine whether or not the vehicle speed is high enough that the degree of improvement in fuel efficiency by executing coasting control is equal to or higher than a desired level. Set as appropriate.

  In addition, the greater the gradient of the travel path, the more easily the vehicle decelerates due to its own weight. Therefore, the degree of improvement in fuel efficiency by executing coasting control decreases. Therefore, specifically, the gradient reference value is a value that can appropriately determine whether or not the traveling road gradient is small enough that the degree of improvement in fuel efficiency by executing coasting control is greater than or equal to a desired level. Set as appropriate. For example, the gradient reference value may be appropriately set to a value that can appropriately determine whether or not the traveling road is an uphill.

  Further, the opening reference value is specifically a value that can appropriately determine whether or not the accelerator pedal is not depressed by the driver (that is, the accelerator operation is not performed). Set as appropriate.

  In step S503, the prediction unit 131 predicts whether or not the acceleration change amount ΔA in the change in acceleration that can occur in the vehicle due to the start of coasting control exceeds a threshold value. When it is predicted that the acceleration change amount ΔA exceeds the threshold (step S503 / YES), the process proceeds to step S505. On the other hand, when it is not determined that the acceleration change amount ΔA exceeds the threshold value (step S503 / NO), the process proceeds to step S513.

  When coasting control is started, the acceleration of the vehicle can increase with a decrease in the equivalent moment of inertia around the axle in the power transmission system 1 due to the opening / closing of the forward / reverse switching mechanism 30. Specifically, the threshold value is appropriately set to a value that can appropriately determine whether or not the acceleration change amount ΔA is large enough to cause the driver to feel uncomfortable or cause the vehicle behavior to become unstable.

  The acceleration change amount ΔA in the change in acceleration that can occur as described above due to the start of coasting control depends on the running resistance of the vehicle, and specifically increases as the running resistance increases. Therefore, it is preferable that the prediction unit 131 predicts the acceleration change amount ΔA based on a parameter related to the running resistance of the vehicle. Specifically, it is preferable that the predicting unit 131 predicts a larger value as the acceleration change amount ΔA as the running resistance increases, based on the parameters.

  Various values can be applied as parameters related to the running resistance of the vehicle. For example, the prediction unit 131 predicts the acceleration change amount ΔA based on the vehicle speed as the parameter. Specifically, since the traveling resistance increases as the vehicle speed increases, the prediction unit 131 predicts a large value as the acceleration change amount ΔA. For example, the prediction unit 131 predicts the acceleration change amount ΔA based on the gradient of the traveling road as the parameter. Specifically, the prediction unit 131 predicts a large value as the acceleration change amount ΔA because the traveling resistance increases as the gradient of the traveling path increases.

  In step S505, the control unit 130 opens the forward / reverse switching mechanism 30 to start coasting control, and shifts the gear ratio of the CVT 40 from the target gear ratio to the low speed side.

  Thus, in the present embodiment, the control unit 130 performs coasting control when it is predicted that the acceleration change amount ΔA in the change in acceleration that can occur in the vehicle due to the start of coasting control exceeds the threshold value. When starting, the gear ratio of the CVT 40 is shifted from the target gear ratio to the low speed side. Specifically, opening / closing of the forward / reverse switching mechanism 30 is performed by the forward / reverse switching mechanism control unit 133, and shifting of the CVT 40 is performed by the CVT control unit 134.

  FIG. 4 is a diagram for explaining a connection / disconnection state of power transmission in the power transmission system 1 when the forward / reverse switching mechanism 30 is opened.

  As shown in FIG. 4, when the forward / reverse switching mechanism 30 is opened by coasting control, the portion R1 on the engine 10 side (upstream side) of the forward / reverse switching mechanism 30 and the driving wheel side ( Transmission of power to and from the downstream portion R2 is interrupted. As a result, the power transmission system 1 is in a state in which the portion R1 on the engine 10 side from the forward / reverse switching mechanism 30 is not rotated along with the rotation of the drive wheels. Therefore, the equivalent inertia moment around the axle in the power transmission system 1 becomes the equivalent inertia moment around the axle of the drive wheel side portion R2 from the forward / reverse switching mechanism 30.

Here, the equivalent inertia moment I ₀ around the axle of the portion R2 on the drive wheel side from the forward / reverse switching mechanism 30 is, for example, when the transfer clutch 50 is engaged and the vehicle is in the four-wheel drive mode: 1).

In Expression (1), I ₄₄ represents the moment of inertia of the primary shaft 44, I ₄₅ represents the moment of inertia of the secondary shaft 45, I _14f represents the moment of inertia of the front wheel side drive shaft 14f, and I _14r represents the rear Represents the moment of inertia of the wheel-side drive shaft 14r, I _16f represents the total value of the moment of inertia of the pair of left and right front wheel side axles 16f, I _16r represents the sum of the moment of inertia of the pair of left and right rear wheel side axles 16r, I _17f represents the total value of the moment of inertia of the pair of left and right front wheels 17f, I _17r represents the total value of the moment of inertia of the pair of left and right rear wheels 17r, r ₄₀ represents the gear ratio of the CVT ₄₀ , and r ₁₃ represents the gear train. represents a gear ratio of _{13, r 16} represents each of the gear ratio of the front differential gear 15f and the rear differential gear 15r.

Therefore, the equivalent inertia moment I ₀ around the axle of the portion R2 on the drive wheel side of the forward / reverse switching mechanism 30 increases as the speed ratio r40 of the CVT ₄₀ increases. Therefore, when the coasting control is started, the equivalent inertia moment I ₀ can be increased by increasing the speed ratio r ₄₀ by shifting the speed ratio r _{40 of the} CVT ₄₀ from the target speed ratio to the low speed side. Thereby, since the sudden change of the equivalent inertia moment around the axle in the power transmission system 1 can be suppressed before and after the start of the coasting control, it is possible to suppress the vehicle acceleration from rapidly increasing. .

  Here, the greater the acceleration change amount ΔA, the greater the risk of giving the driver a sense of incongruity or destabilizing the behavior of the vehicle. Therefore, a sharp change in vehicle acceleration before and after the start of coasting control is effective. There is a greater need for suppression. Therefore, the CVT control unit 134 preferably shifts the speed ratio of the CVT 40 from the target speed ratio to the low speed side based on the acceleration change amount ΔA. Specifically, the CVT control unit 134 changes the gear ratio of the CVT 40 so that the change in the equivalent moment of inertia around the axle in the power transmission system 1 decreases before and after the start of coasting control as the acceleration change amount ΔA increases. It is preferable to shift the speed.

  Next, in step S507, the CVT control unit 134 gradually returns the gear ratio of the CVT 40 to the target gear ratio.

  Specifically, the CVT control unit 134 shifts the gear ratio of the CVT 40 from the target gear ratio to the low speed side, and then sets the gear ratio of the CVT 40 as quickly as possible while suppressing discomfort to the driver. It is preferable to return to the ratio.

  Next, in step S509, the control unit 130 determines whether or not the coasting control end condition is satisfied. When it is determined that the coasting control end condition is satisfied (step S509 / YES), the process proceeds to step S511. On the other hand, when it is not determined that the coasting control end condition is satisfied (step S509 / NO), the determination process of step S509 is repeated.

  Various conditions can be applied as the coasting control end condition.

  For example, the control unit 130 applies that the accelerator operation or the brake operation is performed as the end condition. Specifically, the control unit 130 can determine that the accelerator operation or the brake operation has been performed based on the accelerator opening and the brake operation amount.

  For example, the control unit 130 applies that the acceleration of the vehicle exceeds the acceleration reference value as an end condition. Specifically, the acceleration reference value is appropriately set to a value that can appropriately determine whether the acceleration is large enough to make the behavior of the vehicle unstable.

  In addition, for example, the control unit 130 applies that the vehicle degree is below the second vehicle speed reference value as an end condition. Specifically, the second vehicle speed reference value is appropriately set to a value that can appropriately determine whether the vehicle speed is low enough that the degree of improvement in fuel efficiency is excessively reduced by continuing coasting control. .

  In step S511, the forward / reverse switching mechanism control unit 133 fastens the forward / reverse switching mechanism 30 and ends the coasting control. Then, the control flow shown in FIG. 3 ends.

  As described above, if NO is determined in the determination process in step S503, the process proceeds to step S513. In step S513, the forward / reverse switching mechanism control unit 133 opens the forward / reverse switching mechanism 30 and starts coasting control. Here, in step S513, control for shifting the gear ratio of the CVT 40 from the target gear ratio to the low speed side is not executed. Following step S513, the determination process of step S509 is performed.

  Thus, when it is predicted that the acceleration change amount ΔA in the change in acceleration that can occur in the vehicle due to the start of coasting control is predicted to be equal to or less than the threshold value, control unit 130 determines the gear ratio of CVT 40 as the target speed change. The coasting control is started without executing the control for shifting from the ratio to the low speed side. When the acceleration change amount ΔA is less than or equal to the threshold value, the influence that makes the driver feel uncomfortable due to the change in acceleration that can occur in the vehicle due to the start of coasting control or the influence that makes the behavior of the vehicle unstable Too small. Therefore, in such a case, fuel efficiency can be effectively improved by starting coasting control without executing control for shifting the speed ratio of the CVT 40 from the target speed ratio to the low speed side.

  Here, with reference to FIG. 5 and FIG. 6, the transition of each state quantity of the vehicle when the control device according to the reference example and the control devices of the control device 100 according to the present embodiment are controlled will be described. To do.

  FIG. 5 is a diagram illustrating an example of transition of each state quantity of the vehicle when control by the control device according to the reference example is performed. FIG. 5 shows the transition of each state quantity of the vehicle when the vehicle is traveling in a state where the accelerator operation is not performed and the coasting control start condition is satisfied at time T1.

  Similar to the control device 100 according to the present embodiment, the control device according to the reference example starts coasting control that opens the forward / reverse switching mechanism 30 and coasts the vehicle when coasting control start conditions are satisfied. . On the other hand, unlike the control device 100 according to the present embodiment, the control device according to the reference example does not execute control for shifting the gear ratio of the CVT 40 from the target gear ratio at the start of coasting control. Specifically, FIG. 5 shows an example of transition of each state quantity of the vehicle when the control device according to the reference example is applied to the above-described power transmission system 1 of the vehicle.

  As shown in FIG. 5, before time T1, the vehicle is traveling in a state where the shift position is in the D range and the forward / reverse switching mechanism 30 is fastened. Here, at time T1, as the start condition for coasting control is satisfied, the forward / reverse switching mechanism 30 is opened and coasting control is started. Thereby, at time T1, the equivalent moment of inertia around the axle in the power transmission system decreases sharply, so that the acceleration of the vehicle increases sharply as shown in FIG.

  FIG. 5 shows a state in which the decrease speed of the vehicle speed changes steeply at time T1 with such a steep increase in acceleration. Here, in the reference example, when the coasting control is started, the control for changing the speed ratio of the CVT 40 from the target speed ratio is not executed, so that the speed ratio of the CVT 40 is changed before and after the time T1, as shown in FIG. The target speed ratio is controlled over the entire range.

  As described above, in the reference example, at time T1, the forward / reverse switching mechanism 30 is opened and coasting control is started, so that the acceleration of the vehicle increases sharply. Thereby, while improving the fuel consumption, there is a risk that the driver may feel uncomfortable or the behavior of the vehicle may become unstable.

  FIG. 6 is a diagram illustrating an example of transition of each state quantity of the vehicle when the control by the control device 100 according to the present embodiment is performed. In the example shown in FIG. 6, the transition of the vehicle speed, the vehicle acceleration, and the transmission ratio of CVT 40 up to time T1 is the same as the example shown in FIG. Further, in FIG. 6, the transition of each state quantity in the example shown in FIG. 5 is partially shown by a two-dot chain line.

  As described above, in the present embodiment, the control unit 130 performs the coasting control when it is predicted that the acceleration change amount ΔA in the change in acceleration that can occur in the vehicle due to the start of the coasting control exceeds the threshold value. Is started, the gear ratio of the CVT 40 is shifted from the target gear ratio to the low speed side. Here, the example shown in FIG. 6 corresponds to an example in which the acceleration change amount ΔA is predicted to exceed the threshold at time T1. Therefore, at time T1 when the coasting control start condition is satisfied, the forward / reverse switching mechanism 30 is opened and coasting control is started, and the gear ratio of the CVT 40 is shifted from the target gear ratio to the low speed side. Thereby, before and after the time T1 when the coasting control is started, the steep change of the equivalent inertia moment around the axle in the power transmission system 1 is suppressed, and as shown in FIG. Is suppressed from rising sharply.

  FIG. 6 shows a state in which the steep change in the decrease speed of the vehicle speed is suppressed at the time T1 as the steep change in acceleration is suppressed in this way. Further, FIG. 6 shows a state in which the gear ratio of CVT 40 is shifted from the target gear ratio to the low speed side and increased at time T1. Thereafter, as shown in FIG. 6, after the time T1, the speed ratio of the CVT 40 is gradually returned to the target speed ratio, and the acceleration of the vehicle gradually increases accordingly.

  As described above, in the present embodiment, at time T1, when the coasting control is started, the gear ratio of the CVT 40 is shifted from the target gear ratio to the low speed side, thereby suppressing the vehicle acceleration from rapidly increasing. Thereby, it is possible to improve fuel efficiency while suppressing a sudden change in the acceleration of the vehicle.

<3. Effect of control device>
Then, the effect of the control apparatus 100 which concerns on embodiment of this invention is demonstrated.

  In the control device 100 according to the present embodiment, the control unit 130 performs the coasting control when it is predicted that the acceleration change amount ΔA in the change in acceleration that may occur in the vehicle due to the start of the coasting control exceeds the threshold value. Is started, the gear ratio of the CVT 40 is shifted from the target gear ratio to the low speed side. Thereby, it is possible to suppress a steep change in the equivalent moment of inertia around the axle in the power transmission system 1 before and after the start of coasting control. Therefore, it is possible to suppress a sudden increase in the acceleration of the vehicle. Therefore, fuel consumption can be improved while suppressing a sudden change in vehicle acceleration.

  In the control device 100 according to the present embodiment, the control unit 130 preferably predicts the acceleration change amount ΔA based on a parameter related to the running resistance of the vehicle. Thereby, the acceleration change amount ΔA depending on the running resistance of the vehicle can be predicted more appropriately. Therefore, it is possible to more appropriately determine whether or not the acceleration change amount ΔA is large enough to cause the driver to feel uncomfortable or cause the vehicle behavior to become unstable.

  In the control device 100 according to the present embodiment, the control unit 130 preferably predicts a larger value as the acceleration change amount ΔA as the vehicle running resistance increases, based on a parameter related to the vehicle running resistance. Thereby, the acceleration change amount ΔA depending on the running resistance of the vehicle can be predicted more appropriately. Therefore, it is possible to more appropriately determine whether or not the acceleration change amount ΔA is large enough to cause the driver to feel uncomfortable or cause the vehicle behavior to become unstable.

  Further, in the control device 100 according to the present embodiment, the control unit 130 determines the gear ratio of the CVT 40 based on the acceleration change amount ΔA when starting the coasting control when the acceleration change amount ΔA is predicted to exceed the threshold value. It is preferable to shift from the target gear ratio to the low speed side. As a result, a sudden change in the equivalent inertia moment around the axle in the power transmission system 1 before and after the start of coasting control can be appropriately suppressed based on the acceleration change amount ΔA. A steep change in vehicle acceleration can be appropriately suppressed based on the acceleration change amount ΔA.

  In the control device 100 according to the present embodiment, the control unit 130 shifts the gear ratio of the CVT 40 from the target gear ratio to the low speed side when starting coasting control, and then sets the gear ratio of the CVT 40 to the target gear ratio. It is preferable to gradually return. Thus, after starting coasting control, it is possible to improve fuel efficiency by reducing the equivalent moment of inertia around the axle in the power transmission system 1 while suppressing the driver from feeling uncomfortable.

<4. Conclusion>
As described above, in the control device 100 according to the present embodiment, when the acceleration change amount ΔA in the change in acceleration that can occur in the vehicle due to the start of the coasting control is predicted to exceed the threshold value, the coasting is performed. When the control is started, the gear ratio of the CVT 40 is shifted from the target gear ratio to the low speed side. As a result, it is possible to suppress a steep change in the equivalent moment of inertia around the axle in the power transmission system 1 before and after the start of coasting control, thereby suppressing fuel consumption while suppressing a sudden change in vehicle acceleration. Can be improved.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can make various modifications or application examples within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, the processes described using the flowcharts in this specification may not necessarily be executed in the order shown in the flowcharts. Some processing steps may be performed in parallel. Further, additional processing steps may be employed, and some processing steps may be omitted.

  Further, for example, the configuration of the power transmission system of the vehicle to which the control device 100 is applied is not limited to the power transmission system 1 described with reference to FIG. The power transmission system of the vehicle to which the control device 100 is applied includes a drive source, a continuously variable transmission in which power output from the drive source is input to the input side element, and the drive source and the input side element. For example, the presence or absence and arrangement of components other than these components in the power transmission system may be variously changed.

  For example, in the above description, an example in which the engine 10 is provided as a drive source in a vehicle to which the control device 100 is applied has been described, but another drive source may be provided as a drive source. For example, the drive source provided in the vehicle to which the control device 100 is applied may be a motor.

  Further, for example, in the above description, an example in which a CVT 40 of a chain type CVT having a chain wound between pulleys is provided as a continuously variable transmission in a vehicle to which the control device 100 is applied. Another continuously variable transmission may be provided as a machine. For example, a continuously variable transmission provided in a vehicle to which the control device 100 is applied may be a belt-type CVT having a belt as a power transmission member or a toroidal CVT.

DESCRIPTION OF SYMBOLS 1 Power transmission system 10 Engine 13 Gear train 14f Front wheel side drive shaft 14r Rear wheel side drive shaft 15f Front differential gear 15r Rear differential gear 16f Front wheel side axle 16r Rear wheel side axle 17f Front wheel 17r Rear wheel 20 Torque converter 30 Forward / reverse switching mechanism 31 planetary gear 32 forward clutch 33 reverse brake 34 input shaft 40 CVT
41 Primary pulley 42 Secondary pulley 43 Chain 44 Primary shaft 45 Secondary shaft 50 Transfer clutch 60 Oil pump 70 Valve unit 100 Control device 110 Acquisition unit 130 Control unit 131 Prediction unit 132 Engine control unit 133 Forward / reverse switching mechanism control unit 134 CVT control unit 201 acceleration sensor 202 vehicle speed sensor 203 accelerator opening sensor 204 primary rotation sensor 205 secondary rotation sensor

Claims (5)

A driving source;
An input side element to which power output from the driving source is input; an output side element for outputting power to the drive wheel; and a power transmission member for transmitting power between the input side element and the output side element. Continuously variable transmission,
A clutch for connecting and disconnecting transmission of power between the drive source and the input side element;
A vehicle control device comprising:
A controller capable of executing coasting control for releasing the clutch and coasting the vehicle;
When it is predicted that an acceleration change amount in a change in acceleration that may occur in the vehicle due to the start of the coasting control exceeds a threshold value, the control unit performs the stepless control when starting the coasting control. Shifting the gear ratio of the transmission from the target gear ratio to the low speed side,
Vehicle control device. The control unit predicts the acceleration change amount based on a parameter related to a running resistance of the vehicle.
The vehicle control device according to claim 1. The control unit predicts a larger value as the acceleration change amount as the running resistance of the vehicle is larger based on the parameter.
The vehicle control device according to claim 2. When the acceleration change amount is predicted to exceed the threshold, the control unit reduces the speed ratio of the continuously variable transmission from the target speed ratio based on the acceleration change amount when starting the coasting control. Shift to the side,
The control apparatus of the vehicle as described in any one of Claims 1-3. The control unit shifts the gear ratio of the continuously variable transmission from the target gear ratio to a low speed side when starting the coasting control, and then gradually changes the gear ratio of the continuously variable transmission to the target gear ratio. Back to
The vehicle control device according to any one of claims 1 to 4.

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