JP4817256B2 - Control device for automatic transmission - Google Patents

Description

  The present invention relates to a control device for an automatic transmission, and more particularly to a control device applied to an automatic transmission that includes a torque converter with a lock-up device.

  In general, an internal combustion engine (hereinafter referred to as an engine), which is a power source of a vehicle such as an automobile, has a specified maximum number of revolutions. Use at an overspeed exceeding the allowable maximum speed (so-called overrev or red zone) is to be avoided as a source of various troubles.

  On the other hand, the automatic transmission reduces the driver's operational burden by automatically selecting the optimal gear ratio according to the degree of depression of the accelerator pedal of the driver and the vehicle speed. Of course, the above limitation (overspeed) is also applied to the machine.

  In other words, an automatic transmission generally includes a torque converter and a transmission gear device, and transmits engine torque output from the engine to the transmission gear device via the torque converter. It is a mechanism for shifting to a gear ratio and transmitting it to a wheel (for example, see Patent Document 1).

  Shift control in the automatic transmission is performed based on a so-called shift diagram in which engine load (that is, throttle opening) and vehicle speed are input parameters. This shift diagram can be written, for example, in the form of a two-dimensional graph with the vertical axis representing the throttle opening and the horizontal axis representing the vehicle speed.

  FIG. 4 is a diagram showing a conventional shift diagram, in which two characteristic lines are a downshift line 1 and an upshift line 2, respectively. When the combination of the throttle opening and the vehicle speed exceeds these shift lines, a downshift (shift to the low speed side shift stage) or an upshift (shift to the high speed side shift stage) is performed. For the sake of simplicity, this diagram shows a shift diagram of two shift speeds. For convenience of explanation, the low-speed shift speed of the two shift speeds is set to the first speed, and the high-speed shift speed is set to the first speed. It will be described as the second speed.

  In this figure, when the vehicle is stopped, the vehicle speed and the throttle opening are almost zero. The combination of the throttle opening and the vehicle speed at this time is located substantially at the origin of the shift diagram. This position is defined as a point P1. When the accelerator pedal is depressed by the driver in this state, the throttle opening increases and at the same time the vehicle speed increases. Eventually, the point P1 moves in the direction of increasing the composite of these two parameters (throttle opening and vehicle speed). Will do. Here, assuming that the position of the point P1 after the movement is a point P2, the upshift line 2 is traversed from the left to the right, so that an upshift (shift from the first speed to the second speed) is performed. The downshift is the opposite. That is, when the depression amount of the accelerator pedal decreases or the vehicle speed drops on an uphill road or the like and the combination of the throttle opening and the vehicle speed crosses the downshift line 1 from right to left, for example, the point P2 Is moved to the point P3, a downshift (shift from the second speed to the first speed) is performed.

  That is, in the process in which the combination of the throttle opening and the vehicle speed is moving from the point P1 to the point P2, the left side region is the low speed side speed range region (here, the first speed) with the upshift line 2 as the boundary, In the process where the right side region is the high speed side gear region (here, the second speed) and the combination of the throttle opening and the vehicle speed is moving from the point P2 to the point P3, the downshift line 1 is the boundary. The left region is a low speed side gear region (first speed here), and the right region is a high speed side gear region (second speed here). As described above, the region between the downshift line 1 and the upshift line 2 is set to a low speed side speed range region (here, the first speed) or a high speed side speed range depending on the moving direction of the combination of the throttle opening and the vehicle speed. It is a conventional measure to prevent so-called shift busy that occurs in the vicinity of the shift line, so that hysteresis is provided to be used as one of the (second speed here).

  In the illustrated shift diagram, in the so-called kick-down region where the engine load is a predetermined value or more, so that it is easy to downshift during acceleration in a high load region where the engine load is a predetermined value or more, An upshift line and a downshift line are set to protrude to the high vehicle speed side. To explain this, it is assumed that the combination of the throttle opening and the vehicle speed is at the point P2, and at this time, the accelerator pedal is greatly depressed by the driver, the throttle opening increases rapidly, and the throttle opening and the vehicle speed change. Assume that the combination has moved from point P2 to point P4. Since this point P4 is located beyond the downshift line 1 in the kickdown region, in this case, a forced downshift from the high speed side gear stage to the low speed side gear stage, that is, kickdown occurs regardless of the vehicle speed. Then, rapid acceleration is performed according to the driver's intention.

  Therefore, in this kickdown, as long as the driver continues to depress the accelerator pedal, the vehicle speed continues to increase, and the point P4 moves rightward to a position beyond the upshift line 2 (point P5). At that point, the kickdown is finished and an upshift is performed.

  As described above, according to the shift control using the shift diagram of FIG. 4, so-called kick-down control is executed in which the shift speed is downshifted by at least one stage by abruptly depressing the accelerator pedal during cruising. Therefore, for example, overtaking can be performed smoothly.

JP-A-2-176263

  However, in the above-described conventional technology, the engine speed is kept low until the maximum speed of the engine is maintained while the engine is prevented from overspeeding, and the engine potential is further extracted to further improve the power performance. However, there are still problems to be solved.

  This will be described in detail. As shown in FIG. 4, the shift diagram is for determining a desired shift speed using the throttle opening and the vehicle speed as input parameters. The “vehicle speed” of this input parameter is generally determined by the automatic transmission. If the slip of the torque converter is ignored because the output shaft speed is used, the output shaft speed of the automatic transmission ÷ gear ratio (the gear ratio of the automatic transmission selected at that time) = engine speed Number ". In this way, when the slip of the torque converter is ignored, a certain relationship corresponding to the selected gear ratio is established between the vehicle speed and the engine speed, so that the upshift of the kick down region in the shift diagram of FIG. By setting the upper limit vehicle speed a of the line 2 to a vehicle speed corresponding to the allowable maximum engine speed, the engine can be prevented from over-rotating.

  However, many torque converters incorporate a lock-up device, and the state of the lock-up device in the kick-down region is a lock-up state in which there is no slip according to the state of the lock-up device immediately before entering the kick-down region. Since not only the (directly connected state) but also a non-lock-up state with a certain amount of slip can be taken, especially in the non-lock-up state, the engine speed exceeds the amount of the slip. As a result, as described above In addition, if the "upper limit vehicle speed a of the upshift line 2 in the kickdown region in the shift diagram of FIG. 4 is set to a vehicle speed corresponding to the maximum allowable engine speed", the engine will There is an inconvenience that overspeeding may occur.

  In order to avoid this inconvenience, for example, the upper limit vehicle speed a of the upshift line 2 in the kick-down area in the shift diagram of FIG. 4 may be lowered by a required margin. Since the engine cannot be turned to the maximum number of revolutions, the engine potential cannot be maximized. This new inconvenience causes a problem that the acceleration performance is deteriorated particularly in an engine (such as a diesel engine) having a low allowable maximum rotational speed.

  Therefore, an object of the present invention is to detect the lock-up state and the non-lock-up state of the torque converter, and draw out the engine potential by selecting and using an appropriate shift diagram according to the detection result. Thus, an object of the present invention is to provide a control device for an automatic transmission that can further improve power performance.

According to a first aspect of the present invention, in a control device for an automatic transmission having a torque converter with a lockup device, a load detection means for detecting an engine load, a vehicle speed detection means for detecting a vehicle speed, and a lockup of the torque converter. The automatic shift with reference to a shift diagram having a lockup detection means for detecting a state and a non-lockup state, and an upshift line and a downshift line based on detection results of the load detection means and the vehicle speed detection means Gear ratio control means for selecting the optimum gear position of the machine and controlling the gear ratio of the automatic transmission, wherein the gear ratio control means detects the lock-up state of the torque converter by the lock-up detection means. In the case of the lockup, the lockup shift diagram is referred to. Is detected, at least the upshift line in the high load region where the engine load is equal to or greater than a predetermined value is set to a lower speed side than the upshift line of the lockup shift diagram. The vehicle speed detected by the vehicle speed detecting means with reference to a diagram, wherein the upper limit vehicle speed of the upshift line in the high load region of the lockup shift diagram is equivalent to the vehicle speed corresponding to the maximum allowable engine speed. The reference for the lockup shift diagram is allowed when the upper limit vehicle speed of the downshift line in the high load region of the lockup shift diagram is exceeded. Device.
According to a second aspect of the present invention, there is provided a control device for an automatic transmission having a torque converter with a lockup device, a load detection means for detecting an engine load, a vehicle speed detection means for detecting a vehicle speed, and a lockup of the torque converter. The automatic shift with reference to a shift diagram having a lockup detection means for detecting a state and a non-lockup state, and an upshift line and a downshift line based on detection results of the load detection means and the vehicle speed detection means Gear ratio control means for selecting the optimum gear position of the machine and controlling the gear ratio of the automatic transmission, wherein the gear ratio control means detects the lock-up state of the torque converter by the lock-up detection means. In the case of the lockup, the lockup shift diagram is referred to. Is detected, at least the upshift line in the high load region where the engine load is equal to or greater than a predetermined value is set to a lower speed side than the upshift line of the lockup shift diagram. The upper limit vehicle speed of the upshift line in the high load region of the lockup shift diagram is equivalent to the vehicle speed corresponding to the maximum allowable engine speed, and the lockup shift diagram is referred to. And the downshift line of the non-lock-up shift diagram are linear in response to an increase in the vehicle speed and the engine load between the region where the engine load is less than the predetermined value and the high load region. And the up-shift lines of both the lock-up shift diagram and the non-lock-up shift diagram are Than square downshift line in accordance with the increase of the vehicle speed and the engine load at a high vehicle speed side and low load side is set as a linearly increasing characteristic, further downshifting of said lock-up shift line map The upper limit vehicle speed of the line is set higher than the upper limit vehicle speed of the downshift line of the non-lockup shift diagram, and the upper limit vehicle speed of the upshift line of the lockup shift diagram is set to the non-lockup shift diagram. The control device for an automatic transmission is characterized in that the vehicle speed is higher than the upper limit vehicle speed of the upshift line.

  According to the present invention, the lock-up state and the non-lock-up state of the torque converter are detected, and an appropriate shift diagram according to the detection result is selected and used. It is possible to provide a control device for an automatic transmission that can further improve performance.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an overall configuration diagram of an embodiment. Specifically, a power train configuration of a vehicle including an automatic transmission having a torque converter with a lock-up device is shown together with a control system thereof. The engine 10, the automatic transmission 11, and the torque converter 12 that drives and connects between them.

  The engine 10 includes a throttle valve 14 whose opening degree is controlled according to the depression amount of the accelerator pedal 13, and an air amount corresponding to the opening degree of the throttle valve 14 (hereinafter referred to as a throttle opening degree) and the engine rotational speed. It inhales through the air cleaner 15. The engine 10 includes a group of injectors (hereinafter referred to as an injector group 16) provided for each cylinder and an ignition device (not shown), and these are controlled by an engine controller 18. The engine controller 18 includes a signal Q from the intake air amount sensor 19 that detects the engine intake air amount Q, a signal I from the idle switch 20 that is turned on when the accelerator pedal 13 is released, and an engine rotation sensor 17 that detects the engine speed. The signal Ne from is input.

  Based on these input information, the engine controller 18 injects a predetermined amount of fuel from the injector group 16 into a predetermined cylinder according to the operating state of the engine 10. Further, when the accelerator pedal is released when the driver removes his / her foot from the accelerator pedal 13, fuel cut is performed to stop the fuel supply in order to prevent waste of fuel consumption during coasting. Further, during the fuel cut, the wheel-side rotating element rotated by the wheel that rotates during coasting and the engine-side rotating element are mechanically connected by a lockup device (lockup clutch 12c described later). Then, control for preventing engine stall, specifically, lock-up by slip fastening (also referred to as slip lock-up) is performed, and control for preventing engine rotation from becoming zero is executed. Alternatively, fuel cut recovery is performed to restart fuel supply to prevent engine stall. By providing such a fuel cut function, it is possible to improve the fuel consumption rate by stopping the fuel supply to the combustion chamber of the engine 10 during coasting (inertia traveling in an engine non-driving state). Fuel cut start (also referred to as fuel cut-in) is performed after a predetermined cut-in delay time has elapsed after the throttle valve 14 is fully closed during travel. The cut-in delay time is generally a time required for all the air in the pipe between the fully closed throttle valve 14 and the combustion chamber of the engine 10 to be taken into the combustion chamber of the engine 10.

  The engine controller 18 ignites spark plugs of a predetermined cylinder at a predetermined timing via an ignition device (not shown) according to the operating state of the engine based on the input information. As a result, the engine 10 is operated as specified, and the fuel is cut as specified during coasting. Further, the engine controller 18 prevents engine stall by performing fuel cut recovery for re-injecting a predetermined amount of fuel from the injector group 16 to a predetermined cylinder when the engine rotation falls below a predetermined value.

  Rotational torque (also referred to as engine torque) generated in the engine 10 is transmitted to the automatic transmission 11 via the torque converter 12. The automatic transmission 11 determines a selected gear position by a combination of ON / OFF of the shift solenoids 22 and 23 in the control valve 21, and automatically shifts through the torque converter 12 with a gear ratio corresponding to the selected gear position. The rotational torque from the engine 10 transmitted to the machine 11 is shifted, and this shift power is output from the output shaft 25 to the drive wheel 26.

  The torque converter 12 includes an engine-side input element (pump impeller 12a) driven by the rotational torque of the engine 10, a transmission-side output element (turbine runner 12b) facing the pump impeller 12a via a working fluid, And a lock-up device (lock-up clutch 12c) that can mechanically directly connect the input / output elements (pump impeller 12a and turbine runner 12b) without any working fluid.

  The lock-up clutch 12c has a fastening pressure (also referred to as a lock-up pressure) determined by a drive duty command of the lock-up solenoid 24 in the control valve 21, and the torque converter input / output elements (pump impeller 12a and turbine runner 12b) are mechanically connected. Thus, the slip rotation of the torque converter 12 is limited.

  The lockup pressure determines the lockup capacity of the lockup clutch 12c. When the lockup capacity is determined to be 0, an input / output element is not coupled at all and is in a non-engaged state (non-lockup state). In this non-lock-up state, the input / output elements (pump impeller 12a and turbine runner 12b) of the torque converter 12 are coupled via a working fluid, and a torque increasing function and a torque fluctuation absorbing function are exhibited. Further, when a lockup capacity smaller than the engine torque is given, power is transmitted between the input / output elements (pump impeller 12a and turbine runner 12b) of the torque converter 12 through the working fluid and also through the lockup clutch 12c. In a so-called slip lock-up state (non-lock-up state). On the other hand, when a lockup capacity larger than the engine torque is applied, the input / output elements (pump impeller 12a and turbine runner 12b) of the torque converter 12 are mechanically coupled and connected without any working fluid ( In this lock-up state, the torque increasing function and the torque fluctuation absorbing function cannot be obtained, but the rotational torque of the engine 10 can be transmitted to the automatic transmission 11 without wasting it. Can be improved.

  The transmission controller 27 controls ON / OFF of the shift solenoids 22 and 23 and the drive duty command of the lockup solenoid 24. The transmission controller 27 includes a signal I from the idle switch 20, a signal from the throttle opening sensor 28 that detects the opening of the throttle valve 14 (throttle opening TVO), and the output rotational speed Nt of the torque converter 12. And a signal from the transmission output rotation sensor 31 for detecting the rotation speed No (corresponding to the vehicle speed) of the transmission output shaft 25 are input.

  The transmission controller 27 performs shift control of the automatic transmission 11 as follows based on these input information by a known calculation. First, based on the planned shift diagram based on the vehicle speed VSP obtained from the transmission output rotational speed No and the throttle opening TVO, the optimum shift stage for the current vehicle operating state is selected, and the optimum shift stage is set. The ON / OFF of the shift solenoids 22 and 23 is controlled so that the shift is performed.

  The transmission controller 27 further checks whether or not the torque increase function and the torque fluctuation absorption function of the torque converter 12 are unnecessary from the above input information, and performs duty control of the lockup solenoid 24 based on the determination result. When the lock-up region is executed, the torque converter 12 is brought into a lock-up state in which the input / output elements are directly connected by engaging the lock-up clutch 12c (increasing the lock-up capacity). By releasing 12c (decreasing the lock-up capacity), the non-lock-up state (non-fastened state) in which the direct connection between the input and output elements is released is set.

  Incidentally, the lock-up state is executed under constant speed drive traveling at a high vehicle speed that does not require a torque increasing action and a torque fluctuation absorbing action. This state is generally called overdrive (OD).

  The engine controller 18 and the transmission controller 27 are capable of bidirectional communication, and perform coordinated control for executing fuel cut or fuel cut recovery for the engine 10 in accordance with the engagement and release of the lockup clutch 12c. And

Next, the shift control in this embodiment will be described.
FIG. 2 is a diagram showing a schematic flow of a shift control program executed by the transmission controller 27. In this figure, this shift control program that is periodically executed every predetermined short time is obtained from the signal TVO from the throttle opening sensor 28, the signal No from the transmission output rotation sensor 31, and the turbine rotation sensor 30. The signal Nt and the signal Ne from the engine rotation sensor 17 are read (step S1). Here, the signal No corresponds to “vehicle speed”.

  Next, it is determined whether or not “not changing gear” (step S2). “Not in shifting” means a state in which the ON / OFF of the shift solenoids 22 and 23 is not controlled by the transmission controller 27 so that the shifting to the optimum shift stage is performed. It means not. If the decision result in the step S2 is YES, that is, if it is not “shifting”, it is next decided whether or not it is “locking up” (step S3). “During lock-up” means a state in which the lock-up clutch 12c of the torque converter 12 is engaged and controlled by the transmission controller 27. In short, the lock-up clutch 12c of the torque converter 12 is in the lock-up state. It means a certain time. Specifically, if the difference between the engine rotational speed Ne and the turbine rotational speed Nt is within a predetermined rotational speed that is substantially close to zero, it is determined that the lockup is being performed.

  When the determination result in step S3 is No, that is, when “not in gear change” and not in “lock up”, a “non-lock-up shift diagram” to be described later is selected (step S4). . Then, based on the selected shift diagram, the optimum shift stage corresponding to the throttle opening TVO and the vehicle speed (No) read in advance is selected, and the required shift control (upshift or downshift or current shift) is selected. Step maintenance) is executed (step S5), and the current shift control program is terminated.

On the other hand, when the determination result in step S3 is YES, that is, in the case of “not in gear change” and in the case of “locking up” (the difference between the engine speed Ne and the turbine speed Nt is a predetermined value close to substantially zero. If it is less than the number of revolutions, it is next determined whether “vehicle speed> predetermined value” (step S6). Here, "predetermined value" is the throttle opening degree when switching the shift line despite constant is a value downshift corresponds to inadvertently does not occur the vehicle speed, the lock-up during a downshift, which will be described later The upper limit vehicle speed A is set. If “vehicle speed> predetermined value” is not satisfied, a “non-lock-up shift diagram” to be described later is selected (step S4). If “vehicle speed> predetermined value” is satisfied, “lock-up shift diagram” to be described later is selected. "Shift diagram" is selected (step S7). Then, similarly to the above, based on the selected shift map, the optimum shift stage corresponding to the throttle opening TVO and the vehicle speed (No) read in advance is selected, and the required shift control (upshift or After executing downshift or maintaining the current gear position (step S5), the current shift control program is terminated.

  FIG. 3 is a diagram showing two shift diagrams in the present embodiment. In this specification, it is referred to as a “shift diagram”, but there is no particular meaning to this calling method. It may be a shift map, a shift table, or other names. In short, it is sufficient if it outputs an optimum shift speed corresponding to the throttle opening and the vehicle speed, and the name and structure thereof are not limited.

  (A) is a non-lock-up shift diagram 32, and (b) is a lock-up shift diagram 33. FIG. Each of these shift diagrams is expressed in a two-dimensional graph in which the vertical axis represents the throttle opening and the horizontal axis represents the vehicle speed. This is a schematic representation of what is used to switch between the two gear stages. In the following description, the low speed side gear stage is set to the first speed, and the high speed side gear stage is set to the second speed, but this is for convenience of explanation.

  Both the non-lockup shift diagram 32 and the lockup shift diagram 33 are set with two shift lines. The left shift line of the non-lock-up shift diagram 32 is a downshift line 34, the right shift line is an upshift line 35, and similarly, the left shift line of the lockup shift diagram 33 is a downshift line. 36, the shift line on the right is the upshift line 37.

  The downshift lines 34 and 36 and the upshift lines 35 and 37 are substantially similar except for the kickdown area shown in each figure, which is an area of a predetermined throttle opening or more (for example, 7/8 opening or more). Yes. In other words, the downshift lines 34 and 36 maintain a constant value until the throttle opening reaches a certain opening from 0 at a predetermined low vehicle speed a, and thereafter, the vehicle speed increases until the kickdown region is reached. In the same manner, the upshift lines 35 and 37 have a throttle opening of 0 at a vehicle speed B slightly higher than the low vehicle speed A. A constant value is maintained until a certain degree of opening is reached, and thereafter, the characteristic gradually increases linearly as the vehicle speed and the throttle opening increase until reaching the kick-down region.

The difference between the non-lock-up shift diagram 32 and the lock-up shift diagram 33 is the shape of the kick-down area (particularly the upper limit vehicle speed). That is, the upper limit vehicle speed of the downshift line 36 in the lockup shift diagram 33 (hereinafter referred to as the lockup downshift upper limit vehicle speed A) is the upper limit vehicle speed of the downshift line 34 in the non-lockup shift diagram 32 (not shown). The point on the higher vehicle speed side than the downshift upper limit vehicle speed B at the time of lockup) and the upper limit vehicle speed of the upshift line 37 in the lockup shift line diagram 33 (referred to as the upshift upper limit vehicle speed C at the time of lockup). Non-lock-up shift line This is different in that it is on the higher vehicle speed side than the upper limit vehicle speed of the up-shift line 35 in FIG.

Here, the definition of each upper limit vehicle speed is as follows.
(1) Downshift upper limit vehicle speed A at lock-up:
The lock-up downshift upper limit vehicle speed A is a vehicle speed with hysteresis provided to the upper limit vehicle speed C in order to prevent shift busy.
(2) Downshift upper limit vehicle speed B when not locked up:
The non-lock-up downshift upper limit vehicle speed B is a vehicle speed with hysteresis provided to the upper limit vehicle speed C in order to prevent shift busy.
(3) Upshift upper limit vehicle speed C at lock-up:
The upshift upper limit vehicle speed C at the time of lockup is a vehicle speed corresponding to the allowable maximum rotation speed of the engine 10 (maximum engine rotation speed when the engine 10 does not fall into an overspeed state).
(4) Upshift upper limit vehicle speed D when not locked up:
The non-lock-up upshift upper limit vehicle speed D is a vehicle speed slightly lower than the vehicle speed corresponding to the allowable maximum number of revolutions of the engine 10, and is, for example, about 5 to 10 km / h higher than the above-described lockup upshift upper limit vehicle speed C. The vehicle speed is low. This vehicle speed difference (about 5 to 10 km / h) is also determined in consideration of slipping of the torque converter 12.

  These four upper limit vehicle speeds A to D have a relationship of “B <A <D <C”.

  As described above, in the present embodiment, the lock-up state and the non-lock-up state of the torque converter 12 are detected, and two shift diagrams (non-lock-up shift diagram 32, lock-up state) are detected according to these states. Since any one of the shift map 33) is selected and the selected shift map is used to select the optimum gear position suitable for the throttle opening TVO and the vehicle speed (No) at that time, When the torque converter 12 is stepped up to the kick-down range when the torque converter 12 is in the lock-up state, the engine speed remains the same until the maximum speed (allowable maximum speed) that does not enter the over-speed range is reached. Acceleration can be continued using this gear position, so that the potential of the engine 10 can be maximized to further improve the power performance. Specific effect that it is Rukoto is obtained.

  In other words, it is assumed that the combination of the current throttle opening and the vehicle speed is, for example, at the point P2 in the lock-up state. At this time, the accelerator pedal is greatly depressed by the driver, the throttle opening increases rapidly, and the throttle opening And the vehicle speed combination moves from point P2 to point P4. Since this point P4 is located beyond the downshift line 36 in the kickdown region, in this case, a forced downshift from the high speed side gear stage to the low speed side gear stage, that is, a kickdown occurs regardless of the vehicle speed. Then, rapid acceleration is performed according to the driver's intention. In this kickdown region, since the lockup is in progress, as long as the lockup shift diagram 33 is selected and the driver continues to depress the accelerator pedal, the vehicle speed continues to increase and the point P4 moves to the right. When the position reaches the position (point P5 ′) beyond the upshift line 37, the kickdown is finished and the upshift is performed.

  Further, it is assumed that the combination of the current throttle opening and the vehicle speed is, for example, at the point P6 in the lock-up state. At this time, the accelerator pedal is greatly depressed by the driver, the throttle opening increases rapidly, and the throttle opening And the vehicle speed combination is moved from point P6 to point P7. In this kick-down region, since the vehicle is locked up, the vehicle speed continues to increase as long as the lock-up shift diagram 33 is selected and the driver continues to depress the accelerator pedal.

  A point P5 shown between the points P4 and P5 ′ is a non-lockup shift diagram 32 or a kickdown end point (from the low speed side gear stage to the high speed side speed change) of the prior art (FIG. 4) for comparison. Upshift to stage). The kickdown end point P5 is located at a position exceeding the upper limit vehicle speed D (upshift upper limit vehicle speed D at non-lockup) in the non-lockup shift diagram 32, but the kickdown end in the lockup shift diagram 33 is shown. The point P5 ′ is at a higher vehicle speed side than that, that is, “the maximum rotation at which the engine speed determined from the vehicle speed (No) and the gear ratio of the automatic transmission at that time does not enter the overspeed region. The number exceeds the maximum number (allowable maximum speed). On the other hand, the kick-down end point P5 of the non-lock-up shift diagram 32 or the prior art (FIG. 4) is at least on the low vehicle speed side by the slip amount of the torque converter 12 from the above-described maximum allowable rotational speed. Therefore, the kick-down end point P5 ′ of the lockup shift diagram 33 in the present embodiment is at a position where the rotational speed of the engine 10 exceeds the maximum rotational speed (allowable maximum rotational speed) that does not enter the overspeed range. Therefore, the potential of the engine 10 can be extracted at least by the point P5 to the upper limit vehicle speed C, and the power performance can be further improved.

In this embodiment, as determined in step S6, the combination of the throttle opening and the vehicle speed is determined by the upper limit vehicle speed B in the kick-down region on the downshift line 34 in the non-lockup shift diagram 32 and the lock. When the shift shift line 36 in the upshift map 33 is in the area h (see the hatched portion in FIG. 3B) between the kickdown area and the upper limit vehicle speed A in the downshift line 36, the shift map is switched (unlocked). It is desirable not to perform switching from the upshift diagram 32 to the lockup diagram 33. If the combination of the throttle opening and the vehicle speed is within the above range C, switching the shift diagram, for example, after the accelerator pedal is depressed, the accelerator pedal is in a constant state during acceleration, This is because the shift diagram is switched by switching the state of the lockup clutch, and as a result, an inadvertent downshift unintended by the driver may occur.

  Further, in the present embodiment, when the combination of the throttle opening and the vehicle speed is in an area D (see FIG. 3B) between the upper limit vehicle speed D and the upper limit vehicle speed C in the kick-down area, When switching the shift diagram (switching from the lock-up shift diagram 33 to the non-lock-up shift diagram 32) based on the determination of the lock-up state, the torque converter 12 continues until the start of the upshift inertia phase. It is desirable to delay the release of the lockup clutch 12c. In this way, it is possible to reliably prevent overrev until the start of the upshift inertia phase.

1 is an overall configuration diagram of an embodiment. FIG. 4 is a diagram showing a schematic flow of a shift control program executed by a transmission controller 27. It is a figure which shows the two shift diagrams in this embodiment. It is a figure which shows the conventional shift diagram.

Explanation of symbols

S3 step (lock-up detection means)
S5 step (gear ratio control means)
10 Engine 11 Automatic transmission 12 Torque converter 12c Lock-up clutch (lock-up device)
27 Transmission controller (automatic transmission control device)
28 Throttle opening sensor (load detection means)
31 Transmission output rotation sensor (vehicle speed detection means)
32 Non-lock-up shift diagram 33 Lock-up shift diagram

Claims (2)

In a control device for an automatic transmission having a torque converter with a lock-up device,
Load detection means for detecting engine load;
Vehicle speed detection means for detecting the vehicle speed;
Lockup detection means for detecting a lockup state and a non-lockup state of the torque converter;
Based on the detection results of the load detection means and the vehicle speed detection means, an optimum shift stage of the automatic transmission is selected with reference to a shift diagram having an upshift line and a downshift line, and the gear ratio of the automatic transmission is determined. Gear ratio control means for controlling,
The gear ratio control means refers to the lockup shift diagram when the lockup state of the torque converter is detected by the lockup detection means, while the lockup detection means unlocks the torque converter. When an up state is detected, at least the upshift line in the high load region where the engine load is equal to or greater than a predetermined value is set to a lower speed side than the upshift line of the lockup shift diagram. While referring to the shift diagram for
The upper limit vehicle speed of the upshift line in the high load region of the lockup shift map is equivalent to the vehicle speed corresponding to the maximum allowable engine speed,
When the vehicle speed detected by the vehicle speed detecting means exceeds the upper limit vehicle speed of the downshift line in the high load region of the lockup shift diagram, the lockup shift diagram is allowed to be referred to. A control device for an automatic transmission. In a control device for an automatic transmission having a torque converter with a lock-up device,
Load detection means for detecting engine load;
Vehicle speed detection means for detecting the vehicle speed;
Lockup detection means for detecting a lockup state and a non-lockup state of the torque converter;
Based on the detection results of the load detection means and the vehicle speed detection means, an optimum shift stage of the automatic transmission is selected with reference to a shift diagram having an upshift line and a downshift line, and the gear ratio of the automatic transmission is determined. Gear ratio control means for controlling,
The gear ratio control means refers to the lockup shift diagram when the lockup state of the torque converter is detected by the lockup detection means, while the lockup detection means unlocks the torque converter. When an up state is detected, at least the upshift line in the high load region where the engine load is equal to or greater than a predetermined value is set to a lower speed side than the upshift line of the lockup shift diagram. While referring to the shift diagram for
The upper limit vehicle speed of the upshift line in the high load region of the lockup shift map is equivalent to the vehicle speed corresponding to the maximum allowable engine speed,
In addition, the downshift lines of both the lock-up shift diagram and the non-lock-up shift diagram are used to calculate the vehicle speed and the engine between the region where the engine load is less than the predetermined value and the high load region. It is set as a characteristic that gradually increases linearly with an increase in load, and both the upshift lines of the lock-up shift diagram and the non-lock-up shift diagram are more than the downshift lines of both. Set as a characteristic that gradually increases linearly as the vehicle speed and the engine load increase on the high vehicle speed side and the low load side ,
Furthermore, the upper limit vehicle speed of the downshift line of the lockup shift diagram is set higher than the upper limit vehicle speed of the downshift line of the non-lockup shift diagram,
An automatic transmission control device, wherein an upper limit vehicle speed of an upshift line in the lockup shift diagram is set higher than an upper limit vehicle speed of an upshift line in the non-lockup shift diagram.

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