JP2014228034A - Shift control device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shift control device for an automatic transmission, for determining the necessity for a down-shift properly thereby to improve the fuel consumption while avoiding the delay of an acceleration.SOLUTION: A shift control device comprises: gear change stage determining means 11 for deciding a gear stage of an automatic transmission 3 on the basis of an acceleration opening and a vehicle speed; first calculation means 15 for calculating a first physical quantity, on which there is reflected the running state of a vehicle 1 measured or deduced in the case where the present gear stage at the instant when the gear stage decided at the gear change stage determination means 11 is lower than the present shift stage; second calculation means 16 for calculating a second physical quantity, on which there is reflected the running state of the vehicle 1 deduced in the case where a downshift is made to the gear stage determined at the time point by the gear stage deciding means; and downshift restricting means 17 for restricting the downshift of the automatic transmission 3 on the basis of a first physical quantity calculated by the first calculation means 15 and a second physical quantity calculated by the second calculation means 16.

Description

  The present invention relates to a shift control device that controls a downshift operation of an automatic transmission mounted on a vehicle.

  2. Description of the Related Art Conventionally, there is known a technique for improving traveling performance by temporarily limiting a speed change operation in a speed change control device that controls an automatic transmission of a vehicle. For example, in a vehicle in which the shift stage (gear stage) of the automatic transmission is set according to the accelerator opening, if the accelerator pedal is operated intermittently during travel on a congested road, the speed changes as the accelerator opening increases or decreases. The steps are frequently changed, and the vehicle may not run smoothly. Therefore, there is a technique for preventing excessive switching of the shift speeds by limiting the downshift immediately after the upshift and the upshift immediately after the downshift.

  There is also known a technique for determining whether or not a shift operation is necessary in accordance with a driver's intention to accelerate in a shift control device that sets a shift stage of an automatic transmission according to a vehicle speed and an accelerator opening. That is, even in the case of the accelerator opening degree to be downshifted in normal shift control, if the accelerator opening change amount is large to some extent, it is judged that the driver intends to accelerate and the downshift is prohibited. Yes (see, for example, Patent Document 1). By such control, it is possible to avoid the acceleration delay associated with the shift-down operation and improve the driving operability.

JP 2002-227995 JP

  However, in the conventional shift control device, it may not be possible to appropriately determine whether or not the shift down should be limited. For example, when a vehicle passes through an ETC gate installed at an entrance toll gate of a highway, it is accelerated again after decelerating to a speed of 20 [km / h] or less in the vicinity of the ETC roadside device. At this time, even if the accelerator opening is substantially constant, a downshift may occur due to a decrease in the vehicle speed. Such a shift speed switching operation hinders rapid acceleration immediately after passing through the ETC gate, and makes the driver feel uncomfortable. In addition, since there is a rampway connected to the main road of the expressway at the end of the ETC gate, there is often no need to suddenly accelerate until downshifting, and fuel consumption deteriorates due to extra downshifting. In these situations, it can be said that it is preferable to increase restrictions on the downshift of the automatic transmission.

  On the other hand, it is not always necessary to limit downshifting when passing through the ETC gate. Depending on the relationship between the motion state of the host vehicle and the motion state of other surrounding vehicles, In some cases, the vehicle can run more smoothly if the vehicle is suddenly accelerated after shifting. In other words, there are situations where it is preferable to weaken the restrictions on downshifting.

  One of the purposes of this case was devised in view of the above-mentioned problems. It is an automatic decision-making tool that can determine the necessity of downshifting appropriately and improve fuel efficiency while avoiding acceleration delays. It is providing the transmission control apparatus of a transmission. The present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiments for carrying out the invention described later, and other effects of the present invention are to obtain a function and effect that cannot be obtained by conventional techniques. Can be positioned.

  (1) A shift control device for an automatic transmission disclosed herein is a shift control device that controls a downshift operation of an automatic transmission mounted on a vehicle, and is based on the driver's accelerator operation or the speed of the vehicle. Shift stage determination means for determining the shift stage of the automatic transmission is provided. The vehicle running state that is actually measured or estimated when the current gear position at the time when the gear position determined by the gear position determining means is lower than the current gear position of the automatic transmission is maintained. First calculation means for calculating the reflected first physical quantity is provided.

  Further, it is assumed that the shift stage determined by the shift stage determination means is downshifted to the shift stage determined by the shift stage determination means when the shift stage is lower than the current shift stage of the automatic transmission. And a second calculating means for calculating a second physical quantity that reflects the traveling state of the vehicle estimated in the case. Furthermore, a downshift limiting means for limiting a downshift of the automatic transmission based on the first physical quantity calculated by the first calculation means and the second physical quantity calculated by the second calculation means is provided. .

Here, “the time point when the shift speed determined by the shift speed determination means becomes lower than the current shift speed of the automatic transmission” is defined as “reference time”.
The first calculation means calculates a first physical quantity that reflects the traveling state of the vehicle that is actually measured or estimated when the current gear position at the reference time is maintained. On the other hand, the second calculation means reflects the vehicle running state estimated when it is assumed that the downshift to the shift speed determined by the shift speed determination means is performed at the reference time. Is calculated.

  The downshift limiting means determines whether or not the automatic transmission needs to be downshifted based on the first physical quantity and the second physical quantity, and depends on the judgment result of the condition judging means. And controlling means for implementing or limiting (prohibiting) the downshift.

  (2) Further, the position of the vehicle at the time when the first gear is determined as the first physical quantity by the first gear is lower than the current gear of the automatic transmission. It is preferable to calculate a physical quantity that correlates with the actual relative displacement with reference to. In this case, the second calculation means determines the shift speed determination means when the shift speed determined by the shift speed determination means becomes lower than the current shift speed of the automatic transmission as the second physical quantity. It is preferable to calculate a physical quantity correlated with a virtual relative displacement estimated based on the position, which is estimated when it is assumed that a downshift is made to the determined gear position.

  That is, it is preferable that the first calculation unit calculates a physical quantity correlated with an actual relative displacement with respect to the position of the vehicle at a reference time as the first physical quantity. Similarly, it is preferable that the second calculation means calculates, as the second physical quantity, a physical quantity correlated with a virtual relative displacement based on the position, which is estimated when it is assumed that a downshift is performed at a reference time. .

  The physical quantity correlated with the actual relative displacement is based not only on the actual relative displacement but also on the actual speed obtained by time differentiation of the actual relative displacement, the actual translational acceleration obtained by time differentiation, jerk, and the momentum of the vehicle at the reference time. The actual relative momentum, the actual relative mechanical energy based on the mechanical energy of the vehicle at the reference time, etc. are included. Similarly, the physical quantity correlated with the virtual relative displacement includes not only the virtual relative displacement but also a virtual velocity obtained by time differentiation of the physical relative displacement, a virtual translational acceleration obtained by time differentiation of the virtual displacement, a virtual jerk, a virtual relative momentum, and a virtual mechanics. Energy is included.

  Specific examples of physical quantities that do not correlate with relative displacement (the actual relative displacement, the virtual relative displacement) include lateral acceleration (that is, actual lateral acceleration, virtual lateral acceleration), yaw rate (actual yaw rate, virtual yaw rate), roll rate. (The same applies hereinafter), yaw angle, roll angle, and the like.

(3) Moreover, it is preferable that the downshift limiting means determines that a displacement difference obtained by subtracting the virtual relative displacement from the actual relative displacement is positive as a necessary condition for limiting the downshift.
That is, it is preferable to determine that the actual relative displacement is larger than the virtual relative displacement as a necessary condition for limiting the downshift. In other words, when the actual relative displacement is equal to or less than the virtual relative displacement, it is preferable to release the restriction on the downshift.

(4) Further, the downshift limiting means determines that a change gradient of a displacement difference obtained by subtracting the virtual relative displacement from the actual relative displacement is positive as a sufficient condition for limiting the downshift. Is preferred.
That is, it is preferable to limit the downshift if at least the displacement difference is increasing.

  (5) In addition, the first calculation means and the second calculation means are engine rotation speed, engine output, total reduction ratio, travel resistance, equivalent inertia moment value of the vehicle, time required for the downshift, and the speed change. The actual relative displacement and the virtual relative displacement are calculated based on the elapsed time from the time point when the shift speed determined by the speed determination means becomes lower than the current shift speed of the automatic transmission (that is, the reference time). It is preferable.

(6) In addition, the downshift restriction unit cancels the downshift restriction based on the difference between the first physical quantity and the second physical quantity when the accelerator opening degree or the accelerator opening change rate exceeds a predetermined value. It is preferable to do.
(7) In addition, the downshift limiting unit is configured to reduce the downshift based on a difference between the first physical quantity and the second physical quantity when an in-vehicle ETC device that performs automatic toll collection with a roadside device through wireless communication is operated. It is preferable to start limiting.

  According to the shift control device of the disclosed automatic transmission, it is possible to appropriately determine whether or not to limit the downshift by limiting the downshift based on the first physical quantity and the second physical quantity. That is, it is possible to select a gear stage that provides a more advantageous running state by comparing the running state when the downshift is not performed and when the downshift is performed. Therefore, it is possible to improve fuel efficiency by avoiding unnecessary downshifts while improving the acceleration and traveling performance of the vehicle.

1 is a diagram illustrating a block configuration of a shift control device for an automatic transmission according to an embodiment and a configuration of a vehicle to which the shift control device is applied. FIG. 3 is a shift map related to determination of a temporary downshift request in the present speed change control device. It is a figure for demonstrating the calculation content in this transmission control apparatus, (a) shows the driving | running | working state of the vehicle which did not downshift after generation | occurrence | production of a temporary downshift request | requirement, (b) is a temporary downshift request | requirement. The traveling state of the vehicle when downshifting at the time of occurrence is shown. It is an example of the flowchart which concerns on the downshift restriction | limiting implemented with this transmission control apparatus. It is a time chart for demonstrating the control effect | action of this transmission control apparatus, Comprising: The driving | running | working state in case a downshift becomes advantageous, (a) is an accelerator opening, (b) is a vehicle speed, (c) is relative Displacement, (d) is the displacement difference. It is a time chart for demonstrating the control effect | action of this transmission control apparatus, Comprising: The driving | running | working state in case a downshift is not advantageous is shown, (a) is an accelerator opening, (b) is a vehicle speed, (c) is relative Displacement, (d) is the displacement difference.

  A shift control apparatus for an automatic transmission applied to a vehicle will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit of the present embodiment, and can be selected or combined as necessary.

[1. vehicle]
The shift control apparatus for an automatic transmission according to this embodiment is applied to the vehicle 1 shown in FIG. The power train of the vehicle 1 is provided with an engine 2 and an automatic transmission 3. The engine 2 is an internal combustion engine (for example, a gasoline engine or a diesel engine) that burns gasoline or light oil. The driving force generated by the engine 2 is shifted and decelerated by the automatic transmission 3 and then transmitted to driving wheels via various power transmission mechanisms (not shown). The automatic transmission 3 is a transmission that decelerates the output rotational speed of the engine 2 and transmits it to the drive wheel side. For example, the automatic transmission 3 is an AT (torque converter AT), a DCT, a CVT having a reduction ratio set in multiple stages is there. The shift stage (gear stage) of the automatic transmission 3 is automatically controlled by the shift control device 10 according to the driving operation of the driver, without being operated by the clutch.

The vehicle 1 includes an accelerator opening sensor 4 that detects the accelerator opening A 4, a vehicle speed sensor 5 that detects the vehicle speed V (actual vehicle speed) 5, an engine rotation speed sensor 6 that detects the engine rotation speed Ne, and the vehicle 1. An acceleration sensor 7 is provided for detecting a longitudinal acceleration G (longitudinal acceleration). The measurement values from these sensors 4 to 7 are transmitted to the shift control device 10.
The shift control device 10 is configured as, for example, an LSI device or an embedded electronic device in which a microprocessor, ROM, RAM, and the like are integrated, and is connected to a communication line of an in-vehicle network provided in the vehicle 1. The shift control device 10 controls the upshift operation and the downshift operation of the automatic transmission 3, but in this embodiment, the control during downshift will be described in detail.

[2. Shift control device]
The shift control device 10 has a function of determining whether a downshift is requested by the driver. This downshift request by the driver is referred to as a “temporary downshift request”. Further, when a temporary downshift request is generated, the transmission control device 10 obtains both a physical quantity corresponding to the actual running state and a physical quantity corresponding to the virtual running state, and downshifts based on these physical quantities. Has a function of determining whether to limit or downshift.

  As elements for realizing the above functions, the shift control device 10 is provided with a temporary determination unit 11 (speed stage determination means), a first calculation unit 15, a second calculation unit 16, and a downshift restriction unit 17. These elements may be realized by an electronic circuit (hardware), may be programmed as software, or some of these functions are provided as hardware, and the other part is software. It may be a thing.

[2-1. Provisional judgment unit]
The temporary determination unit 11 determines whether or not there is a temporary downshift request, and acquires information on the time at which the temporary downshift request occurs. Here, when both the first temporary downshift condition and the second temporary downshift condition are satisfied, it is determined that the temporary downshift request is satisfied (generated). Also, the time when the temporary downshift request is changed from the unsatisfied state to the established state (the time when the temporary downshift request is generated) is acquired. The provisional determination unit 11 includes an accelerator determination unit 12, a shift map determination unit 13, and an acquisition unit 14 (acquisition means).

The accelerator determination unit 12 determines a first temporary downshift condition. Here, as an index for determining the strength of the downshift request by the driver, the accelerator opening and the magnitude of the accelerator opening change rate are determined. The first temporary downshift condition is exemplified below.
= First temporary downshift condition =
Condition A: The accelerator opening A is equal to or less than a predetermined opening A ₁ (A ≦ A ₁ ).
Condition B: The accelerator opening change rate dA / dt is equal to or less than a predetermined value A ₂ (dA / dt ≦ A ₂ ).
Here, when the conditions A and B are both satisfied, it is determined that the downshift request by the driver is not so strong (not urgent), and it is determined that the first temporary downshift condition is satisfied. . The determination result here is transmitted to the acquisition unit 14.

The shift map determination unit 13 determines a second temporary downshift condition. Here, the shift stage of the automatic transmission 3 is provisionally determined based on the shift map in which the shift stages corresponding to the engine speed Ne and the accelerator opening A are determined, and the success or failure of the second temporary downshift condition is met. Is judged. Specifically, for example, it is determined whether or not the following condition C is satisfied.
= Second temporary downshift condition =
Condition C: The operating point has entered a region at a lower speed than the actual gear

  The shift map is a multi-dimensional map that associates the driving state of the vehicle 1 with the gear position of the automatic transmission 3. The shift map illustrated in FIG. 2 is a two-dimensional map in which regions of the respective speed stages are set in a coordinate plane with the vertical axis and the horizontal axis being the accelerator opening A and the vehicle speed V. On this map, the driving state of the vehicle 1 at a certain time is expressed as a point on the coordinate plane corresponding to the accelerator opening A and the vehicle speed V at that time. If this point is called an operating point, it is determined that “the second temporary downshift condition is satisfied” when the operating point crosses the boundary line of each gear and enters the region on the low speed side. The second temporary downshift condition continues to hold until the operating point enters the region corresponding to the original shift speed again. The determination result here is transmitted to the acquisition unit 14.

When the first and second temporary downshift conditions are both established, the acquisition unit 14 determines that “the provisional downshift request has been established” and acquires the time at which the provisional downshift request has started to be established. It is. This time information is transmitted to the first calculation unit 15 and the second calculation unit 16, and is used as a reference time when calculating the first physical quantity and the second physical quantity.
In addition, when at least one of the first and second provisional downshift conditions is not established, the acquisition unit 14 determines that “the provisional downshift request has disappeared (the provisional downshift request has disappeared)”, and Information to that effect is transmitted to the first calculation unit 15 and the second calculation unit 16. In this case, the first calculation unit 15 and the second calculation unit 16 stop calculating the first physical quantity and the second physical quantity.

[2-2. First calculation unit]
As shown in FIG. 3A, the first calculation unit 15 (first calculation means) is configured to measure or estimate the vehicle 1 that is actually measured or estimated when the vehicle 1 maintains the gear position without downshifting after the reference time. The first physical quantity reflecting the traveling state is calculated. The value of the first physical quantity is calculated during a period in which downshifting is restricted (that is, a period in which a temporary downshift request is generated and no actual downshifting is performed). Therefore, the actual running state of the vehicle 1 that continues to run without downshifting is reflected in the first physical quantity here. The information on the first physical quantity calculated here is transmitted to the downshift restriction unit 17.

  As a specific example of the first physical quantity, a physical quantity corresponding to the motion state of the vehicle 1 can be considered. For example, the actual relative displacement X1 with the position of the vehicle 1 at the reference time as the reference position, or a physical quantity correlated with the actual relative displacement X1 (for example, the actual vehicle speed V corresponding to the time derivative of the actual relative displacement X1, or more The actual translational acceleration a1 obtained by time-differentiating and the jerk that is the time-differentiated value]. As other physical quantities, it is possible to use actual relative momentum based on the momentum of the vehicle 1 at the reference time, actual relative mechanical energy based on the mechanical energy of the vehicle 1 at the reference time, and the like.

  Here, a method for calculating the actual relative displacement X1 will be exemplified. The actual relative displacement X1 can be obtained by integrating the actual translational acceleration a1 twice. The actual translational acceleration a1 is calculated based on the engine rotational speed Ne, the engine output, the running resistance, the equivalent moment of inertia value of the vehicle 1, and the elapsed time from the reference time. The engine output is a value corresponding to the product of the engine torque calculated based on the engine speed Ne and the accelerator opening A and the engine speed Ne. Further, the travel resistance is calculated based on the vehicle speed V and the road surface inclination angle θ on which the vehicle 1 travels. The road surface inclination angle θ can be calculated based on the longitudinal acceleration G of the vehicle 1. The equivalent moment of inertia value of the vehicle 1 is given in advance as a predetermined value unique to the vehicle 1.

  The driving force of the vehicle 1 is calculated from the engine output and the driving wheel rotation speed. Further, the value obtained by subtracting the running resistance from the driving force of the vehicle 1 and dividing it by the equivalent moment of inertia value is a value corresponding to the actual translational acceleration a1 of the vehicle 1. Therefore, the actual translational acceleration a1 of the vehicle 1 can be described as a function for each parameter of the engine rotational speed Ne, the engine output, the running resistance, the equivalent moment of inertia value, and the elapsed time from the reference time.

[2-3. Second calculation unit]
As shown in FIG. 3B, the second calculation unit 16 (second calculation means) reflects the traveling state of the vehicle 1 estimated when the vehicle 1 is assumed to be downshifted to the reference time. Two physical quantities are calculated. The second physical quantity is a virtual physical quantity that reflects the traveling state of the vehicle 1 when it is assumed that a downshift has been performed. The information on the second physical quantity calculated here is transmitted to the downshift restriction unit 17.

  As a specific example of the second physical quantity, similarly to the first physical quantity, a physical quantity corresponding to the motion state of the vehicle 1 can be considered. For example, a virtual relative displacement X2 with the position of the vehicle 1 at the reference time as a reference position, or a physical quantity correlated with the virtual relative displacement X2 (for example, a virtual vehicle speed corresponding to a time derivative of the virtual relative displacement X2, Virtual translational acceleration a2 obtained by time differentiation, virtual jerk] and the like. Alternatively, it is possible to use virtual relative momentum based on the momentum of the vehicle 1 at the reference time, or virtual relative mechanical energy based on the mechanical energy of the vehicle 1 at the reference time. However, the second physical quantity calculated by the second calculation unit 16 is a physical quantity having the same dimension as the first physical quantity calculated by the first calculation unit 15.

  Here, a method for calculating the virtual relative displacement X2 is exemplified. The virtual relative displacement X2 can be obtained by integrating the virtual translational acceleration a2 twice. Further, the virtual translational acceleration a2 includes the total speed reduction ratio when the vehicle 1 is downshifted, the engine speed Ne, the engine output, the running resistance, the equivalent moment of inertia value, and the elapsed time from the reference time. It is calculated based on the time required for the shift. The total reduction ratio when the vehicle 1 is downshifted is given as a preset value for each gear stage of the automatic transmission 3, and is obtained based on the gear stage of the automatic transmission 3 at the reference time. The time required for downshifting is also given as a value set in advance for each gear stage of the automatic transmission 3, and is obtained based on the gear stage at the reference time.

  The virtual engine rotational speed Ne2 related to the calculation of the virtual translational acceleration a2 is calculated as a value obtained by multiplying the driving wheel rotational speed corresponding to the vehicle speed V detected by the vehicle speed sensor 5 and the total reduction ratio when downshifting. . However, since the clutch and the like of the automatic transmission 3 can be disengaged from the reference time until the time required for downshifting, the virtual engine speed Ne2 is the same as the actual engine speed Ne. It shall be. As a result, the virtual engine torque can be calculated based on the virtual engine rotational speed Ne2 and the accelerator opening A, and the value obtained by multiplying the virtual engine torque and the virtual engine rotational speed Ne2 corresponds to the virtual engine output. Value.

  The virtual driving force of the vehicle 1 is calculated from the virtual engine output and the driving wheel rotation speed. Further, the value obtained by subtracting the running resistance from the virtual driving force of the vehicle 1 and dividing it by the equivalent moment of inertia value is a value corresponding to the virtual translational acceleration a2 of the vehicle 1. Therefore, the virtual translational acceleration a2 of the vehicle 1 is the virtual engine speed Ne2, engine output, running resistance, equivalent moment of inertia value, elapsed time from the reference time, total reduction ratio when downshifted, and time required for downshifting. It is described as a function for each parameter.

[2-4. Downshift limiter]
The downshift restriction unit 17 controls the state of the shift stage based on the first physical quantity and the second physical quantity. The downshift restriction unit 17 includes a condition determination unit 18 and a control unit 19.

The condition determination unit 18 determines whether to limit the downshift of the automatic transmission 3 or to perform the downshift. Here, based on the magnitude relationship between the first physical quantity and the second physical quantity, the value of the difference between them, the value of the ratio, or the like, it is determined whether to limit the downshift or to implement the downshift. A condition related to this determination is called a downshift restriction condition. The downshift restriction conditions in this embodiment are as follows. The determination result here is transmitted to the control unit 19.
= Downshift restriction condition =
Condition D: The displacement difference obtained by subtracting the virtual relative displacement X2 from the actual relative displacement X1 is positive (X1-X2> 0).
Condition E: change gradient of displacement difference (X1-X2) is positive [d (X1-X2) / dt> 0]

  The condition determination unit 18 determines that the downshift is limited when both the conditions D and E are satisfied. On the other hand, when at least one of the conditions is not satisfied, it is determined that the downshift is performed. Condition D is to determine that the actual relative displacement X1 is larger than the virtual relative displacement X2. On the other hand, the condition E is to determine that the displacement difference between the actual relative displacement X1 and the virtual relative displacement X2 is increasing. In the present embodiment, the condition D is a necessary condition for limiting the downshift, and the condition E is a sufficient condition for limiting the downshift.

  The control unit 19 controls the gear position of the automatic transmission 3 based on the determination result in the condition determination unit 18. When it is determined that the downshift is limited, a control signal is output to the automatic transmission 3 so as to maintain the shift stage of the automatic transmission 3 before the provisional downshift request is generated. On the other hand, when it is determined that the downshift is to be performed, a control signal for downshifting the automatic transmission 3 is output. Thereby, for example, the friction engagement element of the clutch device built in the automatic transmission 3 is disconnected, and the friction engagement element is connected after the shift stage is switched to the low speed stage side.

  Note that the control unit 19 of the present embodiment starts the downshift restriction when both the first and second temporary downshift conditions are satisfied, and the shift stage of the automatic transmission 3 until the restriction is released. Function to maintain. Therefore, it can be said that the control unit 19 releases the downshift restriction of the automatic transmission 3 based on the determination result in the condition determination unit 18.

[3. flowchart]
FIG. 4 illustrates a flowchart relating to downshift control of the automatic transmission 3. This flowchart is repeatedly performed at a predetermined cycle set in advance. Here, the description of the upshift control of the automatic transmission 3 is omitted.

  In step A10, information on the accelerator opening A and the engine rotational speed Ne is read into the speed change control device 10, the accelerator opening change rate dA / dt is calculated, and the operation on the shift map as shown in FIG. 2 is performed. A point is grasped. The value of the accelerator opening change rate dA / dt is approximated to the value obtained by subtracting the previous value of the accelerator opening A from the current value of the accelerator opening A and dividing it by the calculation period Δt, for example, if the calculation cycle of this flow is set to Δt .

  In step A20, the shift map determination unit 13 determines whether or not the above condition C, that is, the operating point on the shift map has entered the low speed stage region. Here, if the operating point does not enter the low speed side region, it is determined that the downshift is unnecessary, and the control of this flowchart is finished as it is. On the other hand, if the operating point has entered the low speed stage region, it is determined that the second temporary downshift condition is satisfied, and the process proceeds to step A30.

In step A30, the above conditions A and B are determined. That is, it is determined whether the accelerator opening A is equal to or less than the predetermined opening A ₁ and the accelerator opening change rate dA / dt is equal to or less than the predetermined value A ₂ . When neither of these conditions is satisfied, it is interpreted that the driver intends sharp acceleration, the process proceeds to Step A80, and the control unit 19 performs a downshift. On the other hand, when both of these conditions are satisfied, the process proceeds to step A40 in order to more accurately determine whether or not the downshift should be limited. At this time, the acquisition unit 14 acquires reference time information.

  In Step A40, the first calculation unit 15 calculates the actual relative displacement X1 with reference to the position of the vehicle 1 at the reference time. Further, the second calculation unit 16 calculates a virtual relative displacement X2 that is a displacement when it is assumed that the vehicle 1 is downshifted at the reference time and that is based on the position of the vehicle 1 at the reference time.

  In step A50, the condition determining unit 18 determines whether or not the condition D, that is, the displacement difference obtained by subtracting the virtual relative displacement X2 from the actual relative displacement X1 is positive (X1-X2> 0). . While this condition D is satisfied, it is advantageous to limit the downshift (that is, to maintain the gear position and not change to the low speed side) to earn a traveling distance with the same engine output. If it is determined that there is, the process proceeds to step A60. On the other hand, if the condition D is not satisfied, it is determined that the travel distance will not be increased compared to the case where the downshift is not limited even if the downshift is further limited, and the process proceeds to step A80 and the downshift is performed. Note that if the downshift is restricted until step A80 is executed, the restriction is lifted.

  In step A60, the condition determination unit 18 determines whether the condition E, that is, whether or not the change gradient of the displacement difference (X1-X2) is positive [d (X1-X2) / dt> 0]. . While this condition E is satisfied, it is determined that limiting the downshift is advantageous for increasing the speed of the vehicle 1 with the same engine output, and the process proceeds to step A70. On the other hand, when the condition E is not satisfied, it is determined that the speed does not increase compared to the case where the downshift is not performed even when the downshift is further limited, and the process proceeds to step A80 and the downshift is performed.

  In step A70, the control unit 19 limits the downshift. In other words, the downshift is not performed even though the operating point has entered a region of a lower speed than the actual gear, and the gear before the provisional downshift condition is satisfied is maintained.

[4. Action]
[4-1. When downshifting is advantageous]
FIGS. 5A to 5D are time charts for explaining the motion state when the vehicle 1 passes through the ETC gate on the highway. Between the times t _{0 to} t ₁ shown in FIG. 5B, this corresponds to the state in which the vehicle 1 passes through the ETC gate. The vehicle speed V during this period is, for example, around 15 [km / h]. When the vehicle 1 is an accelerator pedal at the time t ₁ that has passed through the ETC gate is depressed, as shown in FIG. 5 (a), the accelerator opening degree A increases gradually. Here, the accelerator opening degree A is a predetermined angle A ₁ or less, and the accelerator opening change rate dA / dt is equal to or less than the predetermined value A _2, it is assumed that the condition A, condition B are both satisfied.

The shift map determination unit 13 grasps the operating point on the shift map based on the engine speed Ne and the accelerator opening A. When entering the area of the low speed stage than the actual gear position is the operating point in time t _2, the provisional downshift request is generated. On the other hand, the shift stage of the automatic transmission 3 is not immediately switched to the low speed stage when the temporary downshift condition is satisfied, but the travel state when the downshift is not performed and the travel state when the downshift is performed After being compared, the one that is advantageous in traveling is selected.

For example, with reference to the position of the vehicle 1 at time t ₂ when the temporary downshift request is generated, the actual relative displacement X1 of the vehicle 1 when no down shift, as shown by a solid line in FIG. 5 (c), the It rises according to the total reduction ratio of the vehicle 1 at that time. On the other hand, the virtual relative displacement X2 in the case of downshift time t _2, as shown by the broken line in FIG. 5 (c), the while accompanied by time of the time lag according to the downshift, than if no downshift Ascend quickly.

Thus, the value of the displacement difference obtained by subtracting the virtual relative displacement X2 from the actual relative displacement X1 (X1-X2), as shown in FIG. 5 (d), after the temporary increase from time t _2, the maximum time t ₃ Takes a value. Also, becomes zero at time t _4, then becomes a negative value. Time t _3, as shown in FIG. 5 (b), corresponds to the time at which the vehicle speed and (dashed line) is the same in the case of down-shift vehicle speed (solid line) when no down-shift. The time t _4, as shown in FIG. 5 (c), corresponding to the actual relative displacement X1 (solid line) and the virtual relative displacement X2 (broken line) and is the same time.

In the present embodiment, as the downshift restriction condition, it is determined that the displacement difference (X1-X2) value is positive and the displacement difference change gradient (d (X1-X2) / dt) is positive. because, the automatic transmission 3 becomes a time t ₃ is to down-shift.

[4-2. When downshift is not advantageous]
FIGS. 6A to 6D are time charts for explaining an exercise state when the depression of the accelerator pedal after passing through the ETC gate is lighter than in the above case. 6 corresponds to a state in which the vehicle 1 passes through the ETC gate between times t _{5 and} t ₆ shown in FIG. When the vehicle 1 is an accelerator pedal at the time t ₆ which has passed through the ETC gate is depressed, as shown in FIG. 6 (a), the accelerator opening degree A increases gradually gentle gradient. It is assumed that the increasing gradient of the accelerator opening A is smaller than that shown in FIG.

When the operating point at the time t ₇ is than the actual gear position enters the area of the low speed stage, the temporary downshift request is generated. Here, the actual relative displacement X1 of the vehicle 1 when not downshifting rises gradually as compared with the above case, as shown by a solid line in FIG. 6C. On the other hand, the virtual relative displacement X2 in the case of downshift time t _7, but gradually increases as compared with the above case, there are cases where increase in virtual relative displacement X2 can not keep up with the rise of the actual relative displacement X1.

  This is because the required load factor for the same accelerator opening A decreases as the engine speed Ne increases. As the accelerator opening A is smaller, the virtual engine output calculated by the second calculation unit 16 is smaller than the actual engine output calculated by the first calculation unit 15. This makes it difficult for the change gradient (virtual vehicle speed) of the virtual relative displacement X2 to exceed the change gradient (vehicle speed V) of the actual relative displacement X1, and the displacement difference (X1-X2) is monotonous as shown in FIG. 6 (d). To increase. That is, in this case, it is more advantageous in traveling to continue limiting the downshift than to perform the downshift.

  In contrast, in the present embodiment, as long as the displacement difference (X1-X2) and its change gradient (d (X1-X2) / dt) are positive, the downshift restriction is continued. Therefore, the gear position at the time when the temporary downshift request is generated is maintained as it is, and this state is maintained until the temporary downshift request disappears.

[5. effect]
(1) In the shift control device 10 described above, as the first physical quantity, for example, the actual relative displacement X1 with the position of the vehicle 1 at the reference time as the reference position, or the physical quantity correlated with the actual relative displacement X1 [the actual relative displacement X1 The actual vehicle speed V corresponding to the time derivative, the actual translation acceleration a1] obtained by further differentiating the actual vehicle speed V, and the like are calculated. Further, as the second physical quantity, for example, a virtual relative displacement X2 with the position of the vehicle 1 at the reference time as a reference position, or a physical quantity correlated with the virtual relative displacement X2 [virtual equivalent to the virtual differential displacement X2 obtained by time differentiation. The vehicle speed, virtual translational acceleration a2] obtained by further differentiating the vehicle speed, and the like are calculated. Based on the first physical quantity and the second physical quantity, for example, the downshift of the automatic transmission 3 is limited based on the difference or ratio thereof.

  With such a control configuration, it is possible to appropriately determine whether or not the downshift should be limited. That is, it is possible to select a more advantageous traveling state by comparing the traveling state between the case where the downshift is not performed and the case where the downshift is performed. Therefore, it is possible to improve fuel efficiency by avoiding unnecessary downshifts while improving acceleration and running performance after a downshift request is generated.

  For example, as shown in FIGS. 5A to 5D, when downshifting becomes advantageous after limiting downshifting when a temporary downshift request is generated, the limitation is released at that point. It is possible to extend the travel distance immediately after passing through the ETC gate. This also leads to the merit that the selection range of actions that can be taken by the vehicle 1 can be expanded when the order of entering the rampway is determined in accordance with the behavior of other vehicles traveling in adjacent lanes. That is, it is easy to make the other vehicle precede and smoothly follow the vehicle thereafter, or it is easy to lead the vehicle 1 ahead of the other vehicle without difficulty.

  Further, as shown in FIGS. 6A to 6D, when the downshift is not advantageous, the downshift restriction can be continued and the fuel consumption of the vehicle 1 can be improved. This also leads to the advantage that unnecessary gear changes can be reduced and sudden changes in shift shock, vehicle speed V, and longitudinal acceleration G can be suppressed.

  (2) In particular, in the transmission control device 10 described above, the physical quantity correlated with the actual relative displacement X1 is used as the first physical quantity, and the physical quantity correlated with the virtual relative displacement X2 is used as the second physical quantity. With such a control configuration, the motion state of the vehicle 1 can be quantitatively and appropriately evaluated. Therefore, it is possible to improve fuel efficiency while improving the acceleration and running performance of the vehicle 1 more appropriately as compared with the case where a physical quantity that is not correlated with the actual relative displacement X1 and the virtual relative displacement X2 is used.

  Specific examples of physical quantities that correlate with relative displacement include vehicle speed, translational acceleration, jerk (time differential value of acceleration), momentum, and mechanical energy. On the other hand, as a specific example of the physical quantity not correlated with the relative displacement, a lateral acceleration, a yaw rate, a roll rate, a yaw angle, a roll angle, and the like can be considered.

  (3) Further, in the above-described shift control device 10, as a necessary condition for limiting the downshift, a displacement difference obtained by subtracting the virtual relative displacement X2 from the actual relative displacement X1 is positive (X1-X2> 0). ) As a result, it is possible to appropriately select a control that can earn more travel distance after the provisional downshift request is generated. For example, when it is desired to further increase the travel distance within a predetermined time immediately after passing the ETC lane on a highway, is it better to immediately downshift or maintain the gear stage without downshifting? It is possible to appropriately judge whether it is good. Thereby, it is possible to enter the main line, the rampway, etc. ahead of other vehicles traveling in the adjacent lane. In addition, the frequency of downshifts when entering the main line, rampway, etc. from the toll gate can be reduced.

  (4) In the shift control apparatus 10 described above, as a sufficient condition for limiting the downshift, the change gradient [d (X1-X2) / dt of the displacement difference obtained by subtracting the virtual relative displacement X2 from the actual relative displacement X1. ] Is positive. Thus, the advantageous running state can be maintained while the preceding distance that the vehicle 1 can earn when not downshifting compared to when downshifting is increased. On the other hand, by releasing the downshift restriction when the preceding distance starts to decrease, it becomes easy to maintain an advantageous traveling state even after the downshift, and the decrease in the preceding distance can be suppressed.

  (5) Further, in the first calculation unit 15 of the transmission control device 10 described above, the actual translational acceleration is based on the engine rotational speed Ne, the engine output, the running resistance, the equivalent moment of inertia value of the vehicle 1, and the elapsed time from the reference time. a1 is calculated, and the actual relative displacement X1 is calculated by integrating this twice. Similarly, the second calculation unit 16 calculates the virtual translational acceleration a2 based on the engine rotational speed Ne, the engine output, the running resistance, the equivalent moment of inertia value, the elapsed time from the reference time, the total reduction ratio, and the time required for the downshift. The virtual relative displacement X2 is calculated by integrating this twice. Thereby, the actual relative displacement X1 and the virtual relative displacement X2 can be calculated with high accuracy.

[6. Modified example]
Various modifications of the control performed by the shift control device 10 are conceivable. For example, the first temporary downshift condition, the second temporary downshift condition, the downshift restriction condition, and the like described in the above embodiment may be changed as appropriate according to the embodiment.
In addition, since the condition D of the above-described embodiment is a necessary condition for limiting the downshift, it is preferable to cancel the downshift limitation when the condition D is not satisfied. On the other hand, since the condition E is a sufficient condition for limiting the downshift, it is preferable to continue limiting the downshift as long as the condition E is satisfied. Thus, the timing restriction downshift in the graph shown in FIG. 5 (d) is released, so that the time t ₃ after and time t ₄ before, it is preferable to set the downshift limit condition.

  Further, in the above-described embodiment, the control that always determines whether or not to limit the downshift of the automatic transmission 3 is exemplified, but the control configuration that performs such determination only under a specific situation. It is good. For example, when the vehicle 1 passes through the ETC gate, it may be determined whether to limit the downshift. In this case, the downshift restriction condition may be that the in-vehicle ETC device that performs automatic toll collection with the roadside device by wireless communication is activated. By such control, it is possible to effectively limit the downshift when the vehicle 1 gradually accelerates from the state where the vehicle 1 is slowed down, to prevent acceleration delay of the vehicle 1 and to improve fuel efficiency. it can.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Engine 3 Automatic transmission 4 Accelerator opening degree sensor 5 Vehicle speed sensor 6 Engine rotational speed sensor 7 Acceleration sensor 10 Shift control apparatus 11 Temporary determination part (speed stage determination means)
12 Accelerator determination unit 13 Shift map determination unit 14 Acquisition unit 15 First calculation unit (first calculation means)
16 2nd calculation part (2nd calculation means)
17 Downshift limiter (Downshift limiter)
18 Condition determining unit (condition determining means)
19 Control unit (control means)

Claims (7)

In a shift control device for controlling a downshift operation of an automatic transmission mounted on a vehicle,
A shift speed determining means for determining a shift speed of the automatic transmission based on a driver's accelerator operation or the speed of the vehicle;
The vehicle running state that is actually measured or estimated when the current gear position at the time when the gear position determined by the gear position determining means becomes lower than the current gear position of the automatic transmission is reflected. First calculating means for calculating the first physical quantity;
When it is assumed that the shift stage determined by the shift stage determination unit is downshifted to the shift stage determined by the shift stage determination unit when the shift stage is lower than the current shift stage of the automatic transmission. Second calculating means for calculating a second physical quantity reflecting the estimated traveling state of the vehicle;
Downshift limiting means for limiting the downshift of the automatic transmission based on the first physical quantity calculated by the first calculating means and the second physical quantity calculated by the second calculating means;
A shift control device for an automatic transmission, comprising: The first calculating means uses the vehicle position as a reference when the gear position determined by the gear position determining means is lower than the current gear position of the automatic transmission as the first physical quantity. Calculate the physical quantity that correlates with the relative displacement,
The second calculation means determines the determination by the shift speed determination means when the shift speed determined by the shift speed determination means becomes lower than the current shift speed of the automatic transmission as the second physical quantity. 2. The shift control of an automatic transmission according to claim 1, wherein a physical quantity correlated with a virtual relative displacement based on the position, which is estimated when it is assumed that the shift is shifted to a predetermined gear position, is calculated. apparatus. The downshift limiting means determines, as a necessary condition for limiting the downshift, that a displacement difference obtained by subtracting the virtual relative displacement from the actual relative displacement is positive. A shift control device for an automatic transmission as described. The downshift limiting means determines, as a sufficient condition for limiting the downshift, that a change gradient of a displacement difference obtained by subtracting the virtual relative displacement from the actual relative displacement is positive. The shift control device for an automatic transmission according to claim 2 or 3. The first calculating means and the second calculating means are determined by the engine speed, engine output, total reduction ratio, travel resistance, equivalent moment of inertia value of the vehicle, time required for the downshift, and the shift speed determining means. 5. The actual relative displacement and the virtual relative displacement are calculated based on an elapsed time from a time point when the shifted gear position becomes lower than a current gear position of the automatic transmission. The shift control device for an automatic transmission according to any one of the above. The downshift limiting means cancels the downshift limitation based on a difference between the first physical quantity and the second physical quantity when an accelerator opening degree or an accelerator opening change rate exceeds a predetermined value. The shift control device for an automatic transmission according to any one of claims 1 to 5. The downshift limiting means starts limiting the downshift based on a difference between the first physical quantity and the second physical quantity when an in-vehicle ETC device that performs automatic toll collection with a roadside device by wireless communication is activated. The shift control apparatus for an automatic transmission according to any one of claims 1 to 6, wherein

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