Shift control device for automatic transmission

Abstract

To provide a shift control device for an automatic transmission capable of suppressing uncomfortable feeling due to stopping of engine speed at a high level while suppressing deterioration of acceleration performance during re-acceleration.SOLUTION: A shift control device for an automatic transmission includes a transmission mechanism for setting a shift stage between an engine and a driving wheel, is configured to perform upshift from a first shift stage to a second shift stage when accelerator operation amount drops beyond first predetermined operation amount, and has a controller for setting a transmission ratio of the transmission mechanism. The controller is configured to set a delay time from a time when the accelerator operation amount drops beyond the first predetermined operation amount until the upshift is started on the basis of engine speed (Step S3 and Step S4), when change speed of the accelerator operation amount is faster than predetermined speed (affirmative determination in Step S1).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a shift control device for an automatic transmission configured to be able to set a plurality of gear positions, and more particularly to a shift control device for an automatic transmission configured to change the gear position in response to an accelerator operation amount. [Background technology]

[0002] Patent Document 1 describes a control device for an automatic transmission that can set a gear stage from the first forward gear stage to the sixth forward gear stage. The control device described in Patent Document 1 is configured to set a gear stage according to the throttle opening and the vehicle speed, and is configured to upshift to a gear stage with a one-step smaller gear ratio when the throttle opening falls below a predetermined opening. In addition, when the gear ratio is reduced by upshifting as described above, the engine braking force is reduced, and the driver may feel that the engine braking force is insufficient. Therefore, the control device described in Patent Document 1 is configured to determine a vehicle speed range in which the brakes are frequently operated after the accelerator release operation based on the driving history, and to prohibit upshifting, i.e., to maintain the gear stage set at the time of the accelerator release operation, when the accelerator release speed is faster than the predetermined speed and the vehicle speed at that time is in the vehicle speed range determined as described above. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-257038 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the control device described in Patent Document 1, when the accelerator return speed is faster than a predetermined speed and the vehicle speed is in a predetermined vehicle speed range, upshifting is prohibited. Therefore, by maintaining a gear with a large gear ratio, it is possible to improve acceleration, for example, during re-acceleration. In contrast, by prohibiting upshifting, the engine speed is maintained at a relatively high speed. The accelerator return operation by the driver is performed not only when the engine brake force is applied to the driving wheels as described in Patent Document 1, but also when the driving force is reduced. In addition, the vehicle behavior that the driver feels as a change in driving force includes a change in engine speed. Therefore, if upshifting is prohibited when the driver performs an accelerator return operation with the intention of reducing the driving force, the change in engine speed intended by the driver and the actual change in engine speed will diverge. In other words, the driver may feel uncomfortable with the engine speed remaining high.

[0005] This invention has been made with attention to the above-mentioned technical problems, and aims to provide a shift control device for an automatic transmission that can suppress a decrease in acceleration performance during re-acceleration while suppressing the discomfort caused by the engine speed remaining high. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a gear shift control device for an automatic transmission, the gear shift control device including an input shaft connected to an engine, an output shaft connected to drive wheels, and a gear change mechanism capable of setting a gear ratio between the input shaft and the output shaft to a predetermined gear ratio selected from a plurality of predetermined gear ratios, the gear shift control device being configured to upshift from a first gear ratio of the plurality of gear ratios to a second gear ratio smaller than the first gear ratio when an accelerator operation amount decreases beyond a first predetermined operation amount. It is a placea controller that sets a gear ratio of the transmission mechanism, the controller being configured with a detection unit that detects a rate of change in the accelerator operation amount, and an upshift delay unit that sets a delay time from a point in time when the accelerator operation amount exceeds the first predetermined operation amount to a start of the upshift based on the engine speed when the rate of change in the accelerator operation amount detected by the detection unit is faster than a predetermined speed. The upshift delay unit sets the delay time to be shorter as the engine speed is higher. It is characterized by the above.

[0008] In the present invention, the upshift delay section may set the delay time when the engine speed is equal to or lower than a predetermined rotation speed.

[0009] In the present invention, the upshift delay section may set the delay time based on a vehicle speed.

[0010] In this invention, the automatic transmission mechanism is configured to upshift to a third gear ratio which is even smaller than the second gear ratio when the accelerator operation amount falls below a second predetermined operation amount which is even smaller than the first predetermined operation amount, and the upshift delay unit is configured to set a delay time from the point at which the accelerator operation amount exceeds the second predetermined operation amount to the start of the upshift from the second gear ratio to the third gear ratio, based on the engine speed, when the rate of change of the accelerator operation amount during the upshift from the first gear ratio to the second gear ratio is faster than the predetermined rate. Effect of the Invention

[0011] According to this invention, when the rate of change of the accelerator operation is faster than a predetermined rate, the upshift is started with a delay from the time when the accelerator operation amount exceeds a first predetermined operation amount. That is, time is secured to determine whether or not to re-accelerate. Therefore, when the accelerator operation amount is increased to re-accelerate, it is possible to suppress the upshift being executed at the time when the accelerator operation amount starts to be increased, and further, the upshift is not executed due to the increase in the accelerator operation amount during the delay time. That is, it is possible to maintain the gear ratio at the time when the accelerator operation amount starts to be increased in a large state, and it is possible to suppress the deterioration of the acceleration performance during re-acceleration. Furthermore, when the upshift is delayed in this way, the delay time is set based on the engine speed. Therefore, even if the timing of starting the upshift is delayed as described above, it is possible to suppress the driver from feeling uncomfortable if the engine speed remains high. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram for explaining an example of the configuration of a vehicle equipped with an automatic transmission and a controller that controls an engine and the automatic transmission in an embodiment of the present invention. [Diagram 2] FIG. 13 is a diagram showing a part of a shift map for determining an upshift. [Diagram 3] 3 is a flowchart illustrating an example of control executed by a gear shift control device according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing an example of a map for setting a delay time based on an engine speed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An example of a vehicle equipped with an automatic transmission according to an embodiment of the present invention is shown in Fig. 1. The vehicle Ve shown in Fig. 1 uses an engine (ENG) 1 as a driving force source, and an input shaft of an automatic transmission (T / M) 3, which corresponds to the "transmission mechanism" in the embodiment of the present invention, is connected to an output shaft 2 of the engine 1, and a pair of rear wheels (hereinafter referred to as drive wheels) 8 are connected to an output shaft 4 of the automatic transmission 3 via a propeller shaft 5, a differential gear unit 6, and a drive shaft 7.

[0014] The engine 1 is a conventionally known gasoline engine, diesel engine, or the like, and is configured to output driving torque by burning a mixture of supplied fuel and air, and to output a braking torque (engine brake) corresponding to friction torque, pumping loss, etc., by stopping the combustion of the mixture, i.e., by stopping the supply of fuel.

[0015] The automatic transmission 3 can be configured in the same manner as a conventionally known stepped automatic transmission, and is provided with a plurality of engagement mechanisms such as clutch mechanisms and brake mechanisms, and is configured to set a predetermined gear stage (gear ratio) by engaging a predetermined engagement mechanism or two or more engagement mechanisms. That is, the automatic transmission 3 is configured to be able to switch gear stages by releasing a predetermined engagement mechanism and engaging another engagement mechanism, or by releasing at least one of the engagement mechanisms and engaging at least one of the released engagement mechanisms. The engagement mechanism that performs the engagement and release operations to set the gear stage may be a friction type engagement mechanism or a mesh type engagement mechanism. Furthermore, the engagement mechanism may be a hydraulic engagement mechanism that performs the engagement and release operations by hydraulic pressure, or may be an electromagnetic engagement mechanism that performs the engagement and release operations by electromagnetic force.

[0016] 1 includes an electronic control unit (hereinafter, referred to as ECU) 9 for controlling an engine 1 and an automatic transmission 3. This ECU 9 corresponds to a "controller" in the embodiment of the present invention, and like a conventional ECU, is mainly composed of a microcomputer, and is configured to determine the torque output from the engine 1 and the gears to be set in the automatic transmission 3 based on input signals, pre-stored maps and arithmetic expressions, etc.

[0017] 1 includes an engine control unit 10 for controlling the engine 1, and a gear shift control unit 11 for controlling the automatic transmission 3. The ECU 9 is also connected to an accelerator opening sensor 12 for detecting the amount of operation of an accelerator pedal (accelerator operation amount) not shown, an engine speed sensor 13 for detecting the engine speed, an output shaft speed sensor 14 for detecting the speed of a rotating member on the output side of the automatic transmission 3, such as the propeller shaft 5, and other sensors, and is configured to input the detection values ​​of these sensors 12, 13, and 14.

[0018] The engine control unit 10 calculates the driving force required for the vehicle Ve based on, for example, the accelerator opening input from the accelerator opening sensor 12, the rotation speed corresponding to the vehicle speed input from the output shaft rotation speed sensor 14, and a pre-stored map, and determines the output torque of the engine 1 based on the calculated required driving force and a gear ratio corresponding to the gear set in the automatic transmission 3. Then, a signal (torque output command) for outputting the determined output torque of the engine 1 is output to the engine 1.

[0019] The shift control unit 11 is configured to set the gear ratio based on a shift map that defines the gear ratios set with the accelerator opening and the vehicle speed as parameters, similar to conventional automatic transmission control devices. Fig. 2 shows a part of the shift map. Note that the horizontal axis in Fig. 2 represents the vehicle speed, and the vertical axis represents the accelerator opening, and the shift control unit 11 is configured to upshift to a gear ratio with a smaller gear ratio by changing the vehicle speed or the accelerator opening across the upshift line shown by a solid line.

[0020] Specifically, when the driving state determined by the accelerator opening and vehicle speed is at point A in Fig. 2 and thus the fourth forward gear is set, if the accelerator operation amount is reduced to point B in Fig. 2, an upshift occurs to the fifth forward gear, and if the accelerator operation amount is reduced to point C in Fig. 2, i.e., when the accelerator is released, an upshift occurs to the sixth forward gear. When upshifting beyond one or more gears, such as upshifting from the fourth forward gear to the sixth forward gear, an intermediate gear may be temporarily set before upshifting to the target gear, or a so-called jump shift may be performed in which upshifting to the target gear without setting an intermediate gear. The gear ratio of the fourth forward gear corresponds to the "first gear ratio" in this embodiment of the present invention, the gear ratio of the fifth forward gear corresponds to the "second gear ratio" in this embodiment of the present invention, the gear ratio of the fifth forward gear corresponds to the "third gear ratio" in this embodiment of the present invention, the accelerator opening on the upshift line "4 ⇒ 5" in FIG. 2 corresponds to the "first specified amount of operation" in this embodiment of the present invention, and the accelerator opening on the upshift line "5 ⇒ 6" in FIG. 2 corresponds to the "second specified amount of operation" in this embodiment of the present invention.

[0021] When an upshift is performed as described above, the gear ratio becomes smaller, and the engine speed decreases accordingly. On the other hand, for example, when the accelerator opening is temporarily reduced immediately before going around a corner and the vehicle accelerates again at the exit of the corner, the accelerator opening is suddenly reduced and then increased. When an upshift is performed by temporarily reducing the accelerator opening in this way, the acceleration performance during re-acceleration is reduced compared to when no upshift is performed due to the small gear ratio. Therefore, when the accelerator opening is suddenly reduced, it is preferable not to perform an upshift since there is a possibility of re-acceleration.

[0022] Conversely, if an upshift is not performed when the accelerator opening is suddenly reduced, the gear ratio will remain high and engine 1 will continue to rotate at a high speed, which may cause the driver to feel uncomfortable if the engine speed remains high.

[0023] Therefore, the gear change control device in the embodiment of the present invention is configured to execute an upshift with a delay from the point when the accelerator opening degree crosses the upshift line when the accelerator opening degree is suddenly decreased, and further configured to determine the delay time according to the engine speed. An example of such control is shown in Figure 3. Note that the control example shown in Figure 3 is executed when it is determined that the driver is intentionally decreasing the accelerator opening degree, i.e., when the amount of decrease in the accelerator opening degree becomes equal to or exceeds a predetermined amount.

[0024] In the control example shown in Fig. 3, first, it is determined whether the rate of decrease (rate of change) of the accelerator opening is equal to or greater than a predetermined rate (step S1). The rate of decrease in this step S1 can be found based on a signal detected by the accelerator opening sensor 12. Specifically, the detection value of the accelerator opening sensor 12 is detected at predetermined time intervals, and the rate of decrease in the accelerator opening can be found by dividing the difference from the previously detected detection value by the predetermined time. This step S1 corresponds to the "detection unit" in the embodiment of the present invention.

[0025] In addition, in consideration of the variation in the rate at which the accelerator opening degree decreases, the rate at which the accelerator opening degree decreases may be calculated multiple times and the average value may be used in step S1. Also, this step S1 is a step for determining whether the manner in which the accelerator is currently operated is similar to the manner in which the accelerator is frequently operated immediately before re-accelerating. Therefore, the predetermined speed may be a speed determined in advance by an experiment or simulation, or may be a speed determined based on the driving history, etc.

[0026] If the accelerator opening is gradually decreased or not decreased at all, and the rate at which the accelerator opening is decreased is less than the predetermined rate, the routine ends. In other words, if the accelerator opening is gradually decreased and the upshift line is crossed, an upshift is initiated at the point at which the upshift line is crossed.

[0027] On the other hand, for example, if an upshift is initiated by gradually decreasing the accelerator opening from point A to point B in Figure 2, and during the transitional period in which the upshift is being performed, the accelerator opening is further changed from point B to point C at a predetermined speed or higher, if the upshift that is already being performed is interrupted or returned to the original gear in order to delay the upshift, control may become complicated, or the engine speed that has already begun to decrease may increase, causing the driver to feel uncomfortable. Therefore, if the rate at which the accelerator opening is decreasing is greater than or equal to the predetermined speed and the result is a positive determination in step S1, Isn't it? It is determined whether or not the shift output command is output from the ECU 9 (step S2). This step S2 can be determined based on the output signal of the gear shift control unit 11, etc. In other words, the determination is made based on whether or not a change in behavior, such as the engine speed starting to decrease, is occurring, and is not limited to whether or not the engine speed is starting to decrease.

[0028] If the answer to step S2 is affirmative because an upshift is not in progress, the delay time from when the accelerator opening crosses the upshift line until the upshift begins is set based on the engine speed (step S3), and this routine is then temporarily terminated.

[0029] Normally, when upshifting, an engagement mechanism for setting the gear before the upshift (hereinafter referred to as the release clutch) is released, and then an engagement mechanism for setting the gear after the upshift (hereinafter referred to as the engagement clutch) is engaged. Therefore, the engine speed is maintained until the release clutch is released or until the torque acting on the release clutch decreases to a predetermined torque, and then the engine speed starts to decrease as the engagement clutch begins to engage. In other words, there is an unavoidable delay from the point when the accelerator opening decreases beyond the upshift line until the engine speed starts to decrease.

[0030] Taking such unavoidable delay into consideration, the time that the driver can tolerate from the point when the accelerator opening degree is reduced after crossing the upshift line until the engine speed starts to decrease is obtained in advance through experiments and simulations. Usually, the higher the engine speed, the more uncomfortable the driver feels when an upshift is not performed, i.e., the engine speed does not decrease, and the shorter the time it takes for the driver to feel uncomfortable. Therefore, the above-mentioned permissible time is obtained for each engine speed, and the delay time is determined by subtracting the time required for the upshift from the obtained permissible time.

[0031] The relationship between the engine speed and the delay time is mapped in this way, and in step S3, the delay time is set based on the engine speed at the time this routine is executed and the map. An example of the map constructed as described above is shown in Fig. 4, and it is configured so that the delay time becomes shorter as the engine speed increases, and no delay time is set when the engine speed is equal to or higher than a predetermined speed. This is because the driver feels uncomfortable if the engine speed does not decrease quickly when it is equal to or higher than the predetermined speed.

[0032] On the other hand, if the answer of step S2 is negative because an upshift is in progress, a delay time for the next upshift is set based on the engine speed (step S4), and this routine ends for the time being. This step S4 is a step for determining the time to delay the upshift to be executed after the ongoing upshift is completed when it is determined that the accelerator opening is further decreased during the upshift and an upshift will be performed. Therefore, in step S4, the delay time can be set based on the engine speed and the map shown in FIG. 4, similar to step S3. Note that the above steps S3 and S4 correspond to the "upshift delay unit" in this embodiment of the invention.

[0033] The delay time in steps S3 and S4 described above is set sequentially regardless of whether the accelerator opening changes beyond the upshift line. Therefore, when the accelerator opening decreases beyond the upshift line, the delay time is updated sequentially based on the engine speed, which changes from moment to moment, and the time from the time the upshift line is exceeded is counted. The updated delay time is then compared with the time from the time the upshift line is exceeded, and an upshift is started when it is determined that the time from the time the upshift line is exceeded. Note that if the accelerator opening does not exceed the upshift line, or if the accelerator opening at the time the delay time has elapsed has increased beyond the upshift line, i.e., if an accelerator operation is performed to accelerate again, the gear is maintained without any particular upshift.

[0034] As described above, when the accelerator opening is suddenly decreased, the upshift starts with a delay from the point when the accelerator opening crosses the upshift line. That is, it is possible to secure time to determine whether or not to re-accelerate. Therefore, when the accelerator opening increases to re-accelerate, it is possible to suppress the execution of the upshift at the time when the accelerator opening starts to increase, and further, the upshift is not executed due to the increase in the accelerator opening during the delay time. That is, it is possible to maintain the gear ratio at the time when the accelerator opening starts to increase in a large state, and it is possible to suppress the deterioration of the acceleration performance during re-acceleration. In addition, when the upshift is delayed in this way, the delay time is set based on the engine speed. Specifically, the higher the engine speed, the shorter the delay time is set. Therefore, even if the timing to start the upshift is delayed as described above, it is possible to suppress the driver from feeling uncomfortable if the engine speed remains high.

[0035] As described above, the gear change control device in the embodiment of the present invention may set the delay time before starting an upshift based only on the engine speed, or may set the delay time based on other conditions such as vehicle speed in addition to the engine speed. A table for setting the delay time based on the engine speed and vehicle speed is shown below. [Table 1]

[0036] In the example shown in Table 1, the engine speed for setting the delay time is divided into three, and the higher the engine speed, the shorter the delay time is set. In addition, a delay time according to the vehicle speed is set for each engine speed. Specifically, when the engine speed is high (large), the delay time is longer in the order of high vehicle speed (large), medium vehicle speed (medium), and low vehicle speed (small), and when the engine speed is low (small) or intermediate (medium), the delay time is longer in the order of high vehicle speed (large), low vehicle speed (small), and medium vehicle speed (medium). The delay time according to the vehicle speed can be determined based on a sensory test or the like so that the driver does not feel uncomfortable due to the engine 1 remaining at a high speed.

[0037] It should be noted that the automatic transmission shift control device in the embodiment of the present invention can also perform jump shifts that exceed one gear, such as shifting from forward fourth gear to forward sixth gear, as described above, and even in such a case, the delay time for starting the upshift can be set based on the engine speed, as described above. [Explanation of symbols]

[0038] 1 Engine 3. Automatic transmission 8 Drive wheels 9 Electronic Control Unit (ECU) 10 Engine control unit 11 Gear shift control unit 12 Accelerator opening sensor 13 Engine speed sensor 14 Output shaft speed sensor Vehicle

Claims

1. 1. A shift control device for an automatic transmission, comprising: an input shaft connected to an engine; an output shaft connected to drive wheels; and a shift mechanism capable of setting a gear ratio between the input shaft and the output shaft to a predetermined gear ratio selected from a plurality of predetermined gear ratios, the shift control device being configured to upshift from a first gear ratio of the plurality of gear ratios to a second gear ratio smaller than the first gear ratio when an accelerator operation amount decreases beyond a first predetermined operation amount, a controller for setting a gear ratio of the transmission mechanism; The controller: A detection unit that detects a rate of change in the accelerator operation amount; an upshift delay unit that sets a delay time from when the accelerator operation amount detected by the detection unit exceeds the first predetermined operation amount to when the upshift is started, based on the engine speed; and It is composed of The upshift delay unit sets the delay time to be shorter as the engine speed is higher. A shift control device for an automatic transmission comprising:

2. 2. The shift control device for an automatic transmission according to claim 1, The upshift delay unit sets the delay time when the engine speed is equal to or lower than a predetermined speed. A shift control device for an automatic transmission comprising:

3. 3. The shift control device for an automatic transmission according to claim 1, The upshift delay unit sets the delay time based on a vehicle speed. A shift control device for an automatic transmission comprising:

4. 4. The shift control device for an automatic transmission according to claim 1, the transmission mechanism is configured to upshift to a third gear ratio that is smaller than the second gear ratio when the accelerator operation amount decreases beyond a second predetermined operation amount that is smaller than the first predetermined operation amount, The upshift delay unit is configured to set a delay time from a point in time when the accelerator operation amount exceeds the second predetermined operation amount until the upshift from the second gear ratio to the third gear ratio is started, based on a rotation speed of the engine, when a rate of change in the accelerator operation amount during the upshift from the first gear ratio to the second gear ratio is faster than the predetermined rate. A shift control device for an automatic transmission comprising:

Images