JP4445543B2 - Automatic transmission and method for setting precharge time of automatic transmission - Google Patents

Description

  The present invention relates to an automatic transmission and a method for setting a precharge time for an automatic transmission.

  In the hydraulic control of an automatic transmission, the hydraulic pressure from a hydraulic pressure source is directly controlled by a solenoid valve to control the hydraulic pressure supplied to the friction engagement elements (friction clutch, friction brake). A method of performing non-engagement is known.

  From the request to achieve both shortening of the speed change operation and prevention of the speed change shock, the play area until the clutch starts to be engaged is suddenly contacted, and when the clutch starts to be connected, the connection speed is switched to connect slowly. In general, as shown in FIG. 11, in a play area in the first half of a piston stroke of a clutch piston (hereinafter simply referred to as a piston), a so-called precharge is performed to rapidly fill fluid into the friction engagement element to perform piston operation. Speeding up has been done. After a predetermined precharge time has elapsed, the piston speed is reduced to near zero immediately before the engagement of the frictional engagement element, and at a low oil pressure (standby oil pressure), the piston is made to wait, and the response , Improve followability.

  If the precharge pressure or time is excessive, a so-called shift shock will occur. On the other hand, if the precharge pressure or time is insufficient, the responsiveness and tracking will be impaired. It is necessary to set the pressure and the precharge time. In particular, if an appropriate piston acceleration time can be set by setting an optimal precharge time according to a predetermined precharge pressure at the initial shipment of the vehicle, the environment, automatic transmission, engine, solenoid valve, etc. It is considered that individual differences of vehicles due to variations can be absorbed and stable quality can be provided.

  In order to realize the ideal control, it is desired to propose a method for accurately detecting the contact time of the piston by precharging. As shown in FIG. 11, in the normal shift excluding the garage shift (N → D, N → R), the input shaft rotation does not change until the inertia phase in which the rotation change in the automatic transmission occurs. Can be detected by a torque sensor. However, from the viewpoint of the accuracy of the torque sensor and the fluctuation of the output shaft torque, the actual situation is that the torque sensor has not been actually used.

  By the way, Japanese Patent Application Laid-Open No. 6-11026, Japanese Patent Application Laid-Open No. 11-351365, and Japanese Patent Application Laid-Open No. 9-287657 introduce a method of detecting an inflection point of input shaft rotation. Japanese Patent Laid-Open No. 6-11026 discloses a method for determining the starting point of engagement of the friction element at the time of start using the deceleration amount of the turbine rotational speed. Japanese Patent Laid-Open No. 11-351365 discloses a detection value smaller than the maximum rotational speed. Japanese Patent Application Laid-Open No. 9-287657 discloses a technique for determining a shift start point by detecting twice continuously when combining them and decelerating a predetermined amount at a predetermined time (same number of times), that is, A technique for determining the starting point of the inertia phase based on the rate of change in the rotational speed is introduced.

  However, when the above-described conventional method is used as a general method for determining the contact point of the piston, it is necessary to set a threshold value for each friction engagement element and for each temperature. There is a problem that it is difficult to absorb. For example, at the time of product shipment setting, an appropriate precharge time according to each friction engagement element, temperature, and precharge pressure is unknown, and the piston contacts at an unthinkable speed during a normal shift. In this case, the change of the input shaft rotation is abrupt, and the change is different for each speed change element. Therefore, there is an inconvenience that the threshold value must be set for each.

  FIG. 12 is a waveform when the piston is operated with a predetermined precharge pressure and the friction engagement element is suddenly engaged. As is apparent from the operation principle, the piston is pushed and moved by the hydraulic pressure, and the friction engagement element is engaged, whereby the piston stroke is stopped, the hydraulic pressure is rapidly increased, and torque is transmitted. Although it is clear from the waveform of FIG. 12, for example, the decreasing gradient of the turbine rotational speed is determined by the factor derived from the structure of the friction engagement element. In the conventional method described above, the transmission start point of the output torque is not necessarily set. It is not uniquely required. Thus, even if the conventional method is suitable for detecting the inflection point of the individual input shaft, it can be said that there is a practical limit as a general method for determining the contact point of the piston.

  12 may be used as a piston contact point, that is, a torque generation point. However, when conditions such as temperature or friction engagement elements are different, the hydraulic pressure change point may be used. The actual situation is that the pole points and the torque generation points do not necessarily match.

JP-A-6-11026 JP 11-351365 A

JP-A-9-287657

  The present invention has been made in view of the above circumstances, and the object thereof is applicable regardless of changes in the characteristics of the frictional engagement elements, individual differences of the vehicle, various conditions such as temperature, It is an object of the present invention to provide a highly accurate and robust precharge time setting method and an automatic transmission having such a precharge time setting function.

According to a first aspect of the present invention that provides means for solving the above-described problems, a plurality of friction engagement elements constituting a plurality of shift stages by a combination of engagement and disengagement, and the hydraulic pressure to be supplied a control unit for controlling the engagement and disengagement of the frictional engagement elements by controlling, an automatic transmission having a, the learning mode to learn the pre-charge time according to a predetermined precharged pressure Switching means and precharge time determining means for determining a precharge time based on an input value consisting of at least the turbine speed, which is activated by switching to the learning mode, and the learning is performed in a vehicle stop state. When the mode is switched, the precharge time determining means maintains the input shaft rotation speed of the automatic transmission and causes the control unit to set the precharge time. The hydraulic pressure according to the element, while maintaining a predetermined precharge pressure is transitive the frictional engagement element on the engagement side, in course of by hovering the frictional engagement element on the engagement side, predetermined In the determination cycle, the input value is measured and the process of storing and holding for a predetermined n cycles is repeated , and the input value continuously decreases more than 3 times and less than n times, and the input value Learning and setting as a precharge time the time when the decrease width of the first threshold value exceeds the same threshold value set for learning the precharge time of at least two or more friction engagement elements continuously , An automatic transmission characterized by the above is provided.

Further, according to the second aspect of the present invention, a plurality of friction engagement elements constituting a plurality of shift stages by a combination of engagement and disengagement, and engagement of the friction engagement elements by controlling the hydraulic pressure to be supplied. In a precharge time setting method for an automatic transmission, comprising: a control unit that controls engagement / disengagement; and a precharge time determination unit that determines a precharge time based on at least an input value including a turbine rotational speed. state in the stopped state, while maintaining the input shaft speed of the automatic transmission, wherein the control unit, the hydraulic pressure of the frictional engagement element to configure the precharge time was kept precharged pressure predetermined in, then it changes the frictional engagement element on the engagement side, in course of is shifted to the engagement side the frictional engagement element, wherein the pre-charge time determining means, a predetermined determination cycle, measures the input value Rutotomoni repeats the processing for holding a predetermined n cycles stored, the input value, 3 has decreased continuously over more than n less m times, and decrease the width of the input value is two or more times in succession A precharge time setting method characterized in that at a time when the same threshold value set for learning the precharge time of at least two friction engagement elements is exceeded , the precharge time is learned and set. Is provided.

  When the automatic transmission is provided with an engine speed input means, it is preferable that the precharge time determining means uses a difference value between the turbine speed and the engine speed as an input value.

  According to the present invention, it is possible to absorb individual differences between vehicles and set a preferable precharge time according to a predetermined precharge pressure. The present invention also has the advantage that it is less susceptible to changes in conditions such as the vehicle, automatic transmission, and temperature.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an overall configuration of an automatic transmission according to an embodiment of the present invention. Referring to FIG. 1, the automatic transmission 1 includes a transmission main body 2, a hydraulic control unit 3, and an electronic control unit 4.

  The transmission main body 2 includes an input shaft 11 connected to the turbine 10a of the torque converter 10, an output shaft 12 connected to the wheel side, a double pinion planetary gear G1 and a single pinion planetary gear G2 connected to the input shaft 11. , G3, friction clutches C1, C2, and C3 disposed between the input shaft 11, the double pinion planetary gear G1, and the single pinion planetary gears G2 and G3, and friction brakes B1 and B2. With the above configuration, the engagement / disengagement pair of the friction clutches C1, C2, C3 and the friction brakes B1, B2, which are friction engagement elements, is selected by the hydraulic control unit 3 and the electronic control unit 4, and FIG. Any of the shift speeds illustrated in FIG.

  FIG. 3 is a schematic diagram of a wet multi-plate clutch exemplified as the friction engagement element. Referring to FIG. 3, the piston 31, the return spring 32 serving as a reaction force element of the piston 31, a driven plate 331 fitted to the clutch drum 33 side, and a drive plate 341 fitted to the clutch hub 34 side It is equipped with. When the piston 31 is pressed against the plate portions by hydraulic pressure by the hydraulic control unit 3, friction is generated between the driven plate 331 and the drive plate 341, and the state is shifted to the engaged state, and the turbine rotational speed Nt decreases. On the other hand, when the hydraulic pressure is reduced by the hydraulic pressure control unit 3, the return spring 32 pushes back the piston 31 and shifts to the disengaged state.

  Based on an instruction from the electronic control unit 4, the hydraulic control unit 3 switches an internal hydraulic circuit, selects a friction engagement element, controls the hydraulic pressure to be supplied, and engages / engages the friction engagement element. Control disengagement.

  The electronic control unit 4 includes various sensors including a turbine rotation sensor 13 that detects Nt as the turbine rotation speed of the input shaft 11 (turbine 10a), and a position sensor 14 that detects the position of the selector lever by the driver's operation. Is a computer that drives and controls the hydraulic control unit 3 based on the input value. In addition, the electronic control unit 4 includes a learning mode switching unit 41 configured to be transferred to an operation mode for learning a precharge time, and a precharge time determining unit 42 configured to perform a precharge time setting process. And. When a predetermined operation that can be detected by the computer constituting the electronic control unit 4 is performed, the learning mode switching unit 41 starts a precharge time setting process described later.

  As a specific example, the setting of the precharge time for the friction clutch C3 will be described. When the engine is started, the vehicle is stopped (the output shaft 12 is fixed), and the program for setting is started, for example, the select lever moves from the N range (the friction brake B2 is engaged) to the R range (friction). When the clutch C3 and the friction brake B2 are engaged), the electronic control unit 4 first engages the friction brake B2 via the hydraulic control unit 3. As described above, in the N range, the electronic control unit 4 maintains this state because it is neutral with the friction brake B2 engaged.

  Subsequently, the electronic control unit 4 outputs a drive signal via the hydraulic pressure control unit 3 so that the hydraulic pressure of the friction clutch C3 becomes a predetermined precharge pressure.

  FIG. 4 is a diagram showing a waveform of the engagement hydraulic pressure formed by the above control and a change in the turbine rotational speed Nt. As shown in FIG. 4, the electronic control unit 4 performs the drive control described above, and monitors the turbine speed Nt at a predetermined and sufficiently short determination cycle, for example, at an interval of 5 msec. It is detected whether contact is made (determination in FIG. 4), and the time is set as a precharge time for the friction clutch C3.

Next, details of the determination process will be described with reference to FIG. First, after performing a predetermined initialization process (step S1), the electronic control unit 4 starts control by a predetermined precharge pressure (step S2), and uses the input value Nt received from the turbine rotation sensor 13 as a predetermined value. In order to store and hold n cycles, the contents of Nt, Nt ₁ ,... Nt _n−1 of the previous cycle are set to Nt ₁ , Nt ₂ ... Nt _n and the input value Nt of the current cycle is stored and held. (Step S3). Subsequently, the electronic control unit 4 sets the difference value ΔNt calculated in the previous cycle to ΔNt ₁ and calculates the difference between the input value Nt of the current cycle and the input value Nt ₁ of the previous cycle, The difference value ΔNt is stored and held (step S4). Then, as a result of the above, it is determined whether or not the piston contact is established depending on whether or not the following conditions (1) to (3) are all established (step S5).
(1) ΔNt <threshold value Nt_th (for example, −5 rpm)
(2) ΔNt ₁ <Threshold Nt_th (for example, −5 rpm)
(3) Nt continuously decreases over a predetermined m times (for example, m = 5).
(Nt <Nt ₁ <Nt ₂ ... <Nt _m )
The above condition (3) is for preventing erroneous determination due to noise or the like. When the above conditions (1) to (3) indicating that the piston is in contact are satisfied, the time from the start of the precharge control to the time is learned and set as the maximum value of the precharge time (step S6).

  On the other hand, when the conditions (1) to (3) are not satisfied, the processes of steps S3 to S5 are repeated.

FIG. 6 is a diagram for explaining the determination condition by showing a change in the decrease in the turbine rotational speed Nt in the vicinity of the determination point. As shown in FIG. 6, solid lines (Nt, Nt ₁ , Nt ₂ ,... Nt _n ) connecting black circles are determination limit points, and it is possible to detect a sudden drop in the turbine speed indicating piston contact. Yes. That is, if Nt is continuously lowered in the shaded area, it is determined that the piston is in contact. In the example of FIG. 6, if a change (fall) less than Nt_th (rpm) / determination cycle t (sec) occurs at the current point, it is determined that the piston has contacted.

  7 to 10 show the case where the piston is actually suddenly engaged with the determination cycle of the electronic control unit 4 set to 5 msec, the threshold value is set to -5 rpm, and the number of continuous downs of Nt in (3) is 5 times. The turbine rotational speed Nt and the servo pressure (hydraulic pressure) are plotted. FIG. 7 shows the result of determining the piston contact point of the friction brake B1 at an oil temperature of 80 ° C. and an input rotation speed of 800 rpm. The determination points according to the above conditions shown in FIG. Similarly, FIG. 8 shows the result of determination at different precharge pressures for the same friction brake B1. FIG. 9 shows the results for the friction clutch C1, and FIG. 10 shows the results for the friction engagement element C3. Thus, the robustness that can be determined with the same threshold value and determination cycle even when the friction engagement element and the precharge pressure are different is shown. Further, all the contact determination points of the piston according to the present invention are closer to the actual torque generation point.

  In the present embodiment, only the turbine rotational speed Nt is used as the input value. However, when the precharge pressure is low and the input shaft rotational speed changes slowly, or the vehicle has a large engine rotational fluctuation. It is also preferable to provide a sensor for detecting the engine speed Ne and adopt | Nt−Ne | as an input value to take into account fluctuations in the engine speed. In this case, the inequalities in the conditional expressions (1) to (3) are reversed, and the threshold value is a positive number.

  In FIG. 7 to FIG. 10 showing one experimental result of the present embodiment, the determination cycle of the computer is 5 msec and the threshold is −5 rpm, but the above example is preferable in the prepared automatic transmission. Of course, it shows one experimental result and is not particularly limited.

1 is a diagram illustrating an overall configuration of an automatic transmission according to an embodiment of the present invention. It is a figure which shows the relationship between engagement / disengagement of a friction engagement element, and a gear stage. It is a cross-sectional schematic diagram of the wet multi-plate clutch illustrated as a friction engagement element. It is a figure showing the change of the oil pressure waveform used by the present invention, and turbine revolving speed Nt. It is a flowchart showing the flow of the setting process of the precharge time of one embodiment of this invention. It is a figure for showing change of an input value in the neighborhood of a judgment point, and explaining judgment conditions. It is the figure which showed the experimental result of one embodiment of this invention. It is the figure which showed the experimental result of one embodiment of this invention. It is the figure which showed the experimental result of one embodiment of this invention. It is the figure which showed the experimental result of one embodiment of this invention. It is a figure showing the waveform at the time of the upshift speed change of an automatic transmission. It is the figure which showed the waveform at the time of making a friction engagement element suddenly engage with predetermined | prescribed precharge pressure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic transmission 2 Transmission main body 3 Hydraulic control part 4 Electronic control part 10 Torque converter 10a Turbine 11 Input shaft 12 Output shaft 13 Turbine rotation sensor 14 Position sensor 31 Piston 32 Return spring 33 Clutch drum 34 Clutch hub 41 Learning mode switching means 42 Precharge time determining means 331 Driven plate 341 Drive plate B1, B2 Friction brake C1, C2, C3 Friction clutch G1 Double pinion planetary gear G2, G3 Single pinion planetary gear

Claims (4)

A plurality of friction engagement elements that constitute a plurality of shift speeds by a combination of engagement and disengagement, and a control unit that controls engagement / disengagement of the friction engagement elements by controlling the hydraulic pressure to be supplied. An automatic transmission having
And switching means for learning mode to learn the pre-charge time according to a predetermined precharged pressure,
Precharge time determining means for determining a precharge time based on an input value consisting of at least the turbine speed, which is activated by switching to the learning mode,
When the vehicle is stopped and the learning mode is switched, the precharge time determining means is
While maintaining the input shaft rotational speed of the automatic transmission, the control unit performs the hydraulic pressure related to the friction engagement element for setting the precharge time while maintaining the precharge pressure at a predetermined precharge pressure. Move the friction engagement element to the engagement side,
In the process of shifting the friction engagement element to the engagement side, the process of measuring the input value in a predetermined determination cycle and storing and holding for a predetermined n cycles is repeated.
The input value is continuously decreased m times or more from 3 to less than n , and
Continuously decreasing width of the input value is more than 2 times the learning, the point when exceeding the same threshold value set for the precharge time of at least 2 or more friction engagement elements learning, as a precharge time Setting,
Automatic transmission characterized by. The automatic transmission according to claim 1, wherein
Having an engine speed input means,
The precharge time determining means uses a difference value between the turbine speed and the engine speed as an input value,
Automatic transmission characterized by. A plurality of friction engagement elements that constitute a plurality of shift speeds by a combination of engagement and disengagement, a control unit that controls engagement / disengagement of the friction engagement elements by controlling the hydraulic pressure to be supplied, and at least In a precharge time setting method for an automatic transmission, comprising: precharge time determination means for determining a precharge time based on an input value comprising a turbine rotational speed;
In a state where the input shaft speed of the automatic transmission is maintained in a vehicle stop state,
Wherein the control unit, the hydraulic pressure of the frictional engagement element to configure the pre-charge time, while maintaining the precharged pressure predetermined to transition the frictional engagement element on the engagement side,
In the process of shifting the friction engagement element to the engagement side,
The precharge time determining means is
In a predetermined determination cycle, while repeating the process of measuring the input value and storing and holding for a predetermined n cycles ,
The input value is continuously decreased m times or more from 3 to less than n, and
Reduction width of the input value, two or more times in succession, the point when exceeding the same threshold value set for the precharge time of at least 2 or more friction engagement elements learning, as a precharge time Learning settings,
A precharge time setting method. In the precharge time setting method according to claim 3,
The precharge time determining means uses a difference value between the turbine speed and the engine speed as an input value,
A precharge time setting method.

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