JPH03194256A - Speed change control device for automatic transmission - Google Patents

Abstract

PURPOSE:To contrive improvement of hold characteristic by feedback-controlling engine torque in a condition that a release pressure of a release side friction engaging device is kept at almost a fixed value, in the case of holding a rotational speed of a rotay member to a predetermined value. CONSTITUTION:An AT control computer 8 holds a rotational speed of a rotary member in the vicinity of a synchronous rotational speed after a speed change to engage an engaging side friction engaging device by sliding a release side friction engaging device, in the case of attaining a specific speed change by releasing the one friction engaging device and by engaging the other friction engaging device, of an automatic transmission 2. This hold control is performed by feedback-controlling torque of an engine 1 by adjusting a fuel injection amount and an intake air amount or ignition timing by an E/G control computer 7 in a condition that a release pressure of the release side friction engaging device is generated at almost a fixed value. Thus by making it possible to effectively cancel disturbance in the case of the hold much more improvement in the hold characteristic can be contrived.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a shift control device for an automatic transmission that may achieve a specific shift by simultaneously operating two frictional engagement devices.

[Conventional technology]

When achieving a specific shift in an automatic transmission, it is often necessary to engage or disengage two frictional engagement devices simultaneously (so-called clutch-to-clutch shifting). In this case, unless the engagement or disengagement of each frictional engagement device is properly synchronized, the gear train of the automatic transmission may become rigid (unrotatable) momentarily.
Alternatively, problems such as a sudden drop in output shaft torque may occur due to the neutral state. For this reason, conventionally, when performing such control, a one-way clutch that performs substantially the same function as one of the frictional engagement devices is provided to prevent such problems from occurring. However, this method of synchronizing each friction engagement device by using a one-way clutch not only has problems such as increased weight and occupancy of storage space due to the addition of the one-way clutch. There is also the problem that when the driving direction is reversed (when engine braking should be applied), the one-way clutch slips and engine braking is not effective. In view of these points, in recent years, the following technology has been disclosed as a technology for successfully achieving such "clutch-Raul clutch shifting" without using a one-way clutch (SAEPaper 890529). This technology releases one frictional engagement device and
When a specific gear shift is achieved by engaging the other friction engagement device, the rotation speed of the rotating member in the automatic transmission is brought to around the synchronous rotation speed after the shift by sliding the friction engagement device on the disengaged side. The friction engagement device on the engagement side is engaged during the hold control. With this method, if you can hold the rotation speed accurately,
Under various operating conditions (for example, under conditions where the accelerator depression speed, accelerator opening after depression, etc. change), even if the engagement pressure of the friction engagement device on the engagement side is low and engagement is delayed, Alternatively, even if the engagement pressure is too high and the engagement is accelerated, the gear shift can be achieved without causing the engine to rev up or causing a large shift shock.

[Problem to be solved by the invention]

However, in reality, it is extremely difficult to accurately hold the rotational speed of a predetermined rotating member near the synchronous rotational speed after shifting under various operating conditions. For example, even if you try to perform feedback control of the clutch engagement pressure according to the rotation speed near the synchronous rotation speed, there is always a response delay in the hydraulic system, so it is impossible to set a large gain to avoid instability. , if the gain is small, the followability naturally decreases, so the hold performance decreases accordingly. In addition, since gear shifting is generally performed in conjunction with changes in accelerator opening or vehicle speed, the throttle opening often changes during gear shifting, especially when the accelerator is depressed at low and medium openings. In the case of such a shift, the change in engine torque during the shift is large, and it can be said that it is extremely difficult to maintain the synchronous rotational speed at a constant value against this disturbance. The present invention has been made in view of these problems, and in particular achieves both responsiveness or followability and stability regarding this hold control, and maintains an excellent hold function, thereby achieving a small shift shock. ``It is an object of the present invention to provide a speed change control device for an automatic transmission that can realize clutch-to-clutch change 3!J.

[Means to solve problem B]

In the present invention, when a specific speed change is achieved by disengaging one friction engagement device and engaging the other friction engagement device, the rotating member is moved by sliding the friction engagement device on the releasing side. In a shift control device for an automatic transmission, the speed change control device for an automatic transmission is configured to hold the rotational speed of the rotational speed near the synchronous rotational speed after shifting, and to engage the frictional engagement device on the engagement side during this hold control. The above object is achieved by providing means for achieving hold control by feedback control that increases or decreases engine torque while keeping the release pressure of the friction engagement device on the release side substantially constant.

[Effect]

In the present invention, when performing control to hold the rotational speed of a specific rotating member in an automatic transmission near the synchronous rotational speed after shifting, this hold control is performed by controlling the engagement pressure of the friction engagement device to a constant value. This is achieved through feedback control that increases or decreases the engine torque while maintaining the engine torque. Generally, in order to control the rotational speed of a rotating member during gear shifting, it is necessary to change the engagement pressure of a frictional engagement device. This is because the rotational speed of the rotating member during gear shifting is determined by how much the two friction materials in the friction engagement device are slid, and it is the friction engagement device that determines how much the two friction materials in the friction engagement device are slid. This is because it is nothing but the engagement pressure of the coupling device. However, as mentioned above, even if an attempt is made to feedback the engagement pressure of the friction engagement device so that the rotational speed of the rotating member is constant, instability is avoided because there is always a response delay in the hydraulic system. Therefore, it is not possible to set a very large gain, and on the other hand, if the gain is small, the followability will naturally decrease, and the bold performance will decrease accordingly, so the reality is that good bold control cannot be achieved. . For this reason, the present invention focuses on the fact that the present control does not actively change the rotational speed of the rotating member, but instead holds it at a certain constant value. (Focusing on the idea that if possible, it is enough), we completely changed the perspective of feedback control and offset the disturbance (increase or decrease in load) by increasing or decreasing the engine torque while keeping the engagement pressure of the friction engagement device constant. Thus, good bold characteristics can be obtained. Increases and decreases in engine torque (increases and decreases in load) do not have the property of actively changing the rotational speed of the members, but as long as the engagement pressure of the friction engagement device is maintained at a constant pressure in a sliding state, By increasing or decreasing the engine torque, the rotational speed of the member can be increased or decreased sufficiently to the extent that feedback control can be realized. In the present invention, since the engagement pressure of the friction engagement device is constant, there is basically no element that actively tries to change the rotation speed, and it simply cancels out the incoming disturbance (increase or decrease in load). Since the control is executed from this viewpoint, there is no room for problems such as wasted time or response delay in the hydraulic system, and more stable hold characteristics can be obtained. Note that in the present invention, since feedback control is achieved by increasing or decreasing the engine torque, means for controlling the engine torque independently of the accelerator pedal is essential. Therefore, when increasing or decreasing engine torque during this bold control, we do not just increase or decrease (fine adjustment) to offset the load, but actively reduce the absolute amount of engine torque generated during gear shifting. If the above adjustment is made to increase or decrease (finely adjust) the disturbance, even better results can be obtained since the torque handled by the frictional engagement device is reduced. Furthermore, in the present invention, the method by which the engine torque is increased or decreased is not limited to this, and various well-known methods can be employed. In general, it is preferable to increase or decrease the amount of intake air because it allows a wide range of increase or decrease, and has the advantage that there are no secondary problems or any problems at all. However, this method of increasing/decreasing the amount of intake air does not have very good responsiveness, so if a method of delaying the ignition timing, which has excellent responsiveness, is used in combination, even better engine torque control can be achieved.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is an overall schematic diagram of an integrated automatic transmission and engine control device to which the present invention is adopted. In the engine 1, the fuel injection amount at the injection valve 19 and the ignition timing at the distributor 20 are controlled by the engine control computer 7, so that an engine output corresponding to the accelerator opening degree of the accelerator pedal 22 and the engine rotation speed is obtained. It has become. That is, the accelerator pedal 22 is connected to the intake pipe 24 of the engine 1.
The main throttle valve 26 opens and closes in conjunction with the movement of the main throttle valve 26, and the sub-throttle valve 30 opens and closes in conjunction with the movement of the motor 28, which is driven by commands from the engine control computer 7 regardless of the accelerator pedal 22.
are arranged in series, and this sub-throttle valve 30
By opening and closing the engine torque can be reduced according to the present invention. Further, in the automatic transmission 2, the solenoid valves 81 to S3 of the hydraulic control device 3 are controlled by the automatic transmission control computer 8, and as a result of changing the oil passage in the hydraulic control device 3, the engagement of each friction engagement device is changed. The matching state is selectively changed, and a gear position corresponding to the vehicle speed and accelerator opening degree can be obtained. The engine control computer 7 includes an engine rotation speed detected by an engine rotation sensor 9 and an intake amount sensor 10.
intake air amount according to the intake air temperature, intake air temperature according to the intake air temperature sensor 11, throttle opening of the main throttle valve 26 according to the throttle sensor 12, vehicle speed according to the vehicle speed sensor 13,
Engine water temperature signals from an engine water temperature sensor 14 and brake ON signals from a brake switch 15 are input. The engine control computer 7 determines the fuel injection amount and ignition timing based on these signals. In addition, the engine control rule computer 7 is also input in parallel with each solenoid signal of the solenoid valves 81 to S3, which are ON-OFF controlled by the automatic transmission control computer 8, and an engine torque request signal SGG. The type and timing of the shift of the automatic transmission are determined by the above, and the engine torque control during the shift is executed by opening and closing the sub-throttle valve 30. On the other hand, the automatic transmission control computer 8 receives signals from the throttle sensor 12, vehicle speed sensor 13, engine water temperature sensor 14, brake switch 15, etc., as well as a shift lever signal from a shift position sensor 16.
position, a driving selection pattern such as fuel economy-oriented driving or power performance-oriented driving by the pattern select switch 17, a signal for permission to shift to overdrive by the overdrive switch 18, and the input shaft rotation speed of the automatic transmission. A signal from the turbine rotation speed sensor 21, etc. is input, and the electromagnetic valves 81 to S3 are controlled ON-OFF so that a gear position corresponding to the vehicle speed and the accelerator opening is obtained. FIG. 3 shows the transmission section of the automatic transmission 612. This transmission section includes a torque converter 20, an overdrive mechanism 40, and an underdrive aM60. The torque converter 20 includes a pump 21 and a turbine 2.
2 and a stator 23, and is equipped with a lock-up clutch 24. The overdrive mechanism 40 includes a set of planetary gears including a sun gear 43, a planetary pinion 42 that meshes with the sun gear 43, a carrier 41 that supports the planetary pinion 42, and a ring gear 44 that meshes with the planetary pinion 42. The rotational state of this planetary gear device is controlled by clutch Co and brake B.
o, and one-way clutch FO. The underdrive mechanism 60 includes a common sun gear 61
, a planetary binion 64. which meshes with the sun gear 61.
65, a 2Mi planetary gear device consisting of a carrier 66.67 that supports the planetary pinion 64.65, and a ring gear 62.63 that meshes with the planetary pinion 64.65, and the rotation state of this planetary gear device and the over The connection state with the drive mechanism 40 is determined by clutches c, , c
2. Controlled by brakes B2, B3, and one-way clutch F2. Each gear stage is clutch CO, CI, C2, brake BO,
This is achieved by engaging B2 and B3 as shown in FIG. 4 (indicated by O in FIG. 4). At this time, the one-way clutches FO and F2 are activated (locked) at the positions marked with ◎ in Fig. 4 during driving (when power is being transmitted from the engine to the wheels). Here, the shift between the second gear and the third gear is performed using the brake B.
Therefore, in this gear train, the present invention is applied to the shift between the second gear and the third gear. There is. FIG. 5 shows the control flow. This control flow shows downshift control from the third gear to the second gear. First, in step 302, the value of flag F is checked. This flag F is used to store the current state of the automatic transmission, and is initially set to 0, so the process proceeds to step 304. In step 304, it is checked whether the gear is being shifted from the third gear to the second gear. If the shift is not from the third gear to the second gear, the process proceeds to step 350, where a shift process to that effect is performed. In step 306, first, a command to lower the oil pressure is issued in order to cause the clutch C2, which is the frictional engagement device on the disengagement side, to slip. Further, in step 308, a hydraulic pressure supply command (engagement standby command) for the brake B2, which is the friction engagement device on the engagement side, is issued. In step 310, it is determined whether or not slipping of clutch C2 has occurred. If slipping has not occurred yet, flag F is set to 1 in step 312, and after being reset, the determination in step 310 is made again. repeated. Eventually, in step 310, it is determined that clutch C2 has slipped, but the process proceeds to step 314, where the oil pressure of clutch C2 is held at the oil pressure at which it started slipping. In step 316, it is determined whether or not the input shaft rotational speed (turbine rotational speed) Nt of the automatic transmission has reached approximately the synchronous rotational speed due to slipping of the clutch C2. Note that the synchronous rotational speed is a value obtained by multiplying the vehicle speed No. by the gear ratio ρ after the shift (second gear). If it is determined that the synchronous rotational speed has not been reached, the flag F is set to 2 in step 318, and after being reset, the determination in step 316 is repeated. Eventually, when it is determined that the turbine rotational speed Nt has become approximately the synchronous rotational speed, the process proceeds to step 320 and thereafter, where a command to reduce the engine torque is issued and feedback control based on the increase/decrease in the engine torque is executed. Specifically, in step 320, engine torque Te is significantly reduced to a predetermined value Tea. Along with this,
In step 321, the difference ΔNt i between the turbine rotational speed Nt i and the synchronous rotational speed Nt,i is calculated. Note that the subscript i here indicates the first calculation cycle. In step 322, the difference ΔNt i between the current synchronous rotation speed and the previous synchronous rotation speed ΔNt 1
By calculating the difference between the two and multiplying the difference by a constant Kll, the range of change ΔTe 1 of the engine torque is calculated. In step 323, the previous engine torque Te
The current engine torque Tel is obtained by adding the obtained change width ΔTe 1 to H-1, and this is output. 5 To change the engine torque, a torque down request command (including a torque down timing command) is transmitted from the automatic transmission control computer 8 to the engine control computer 7 via the communication line SG4, and the engine control computer 7 controls the motor 28. This is done by controlling the opening degree of the sub-throttle valve 30 through the throttle valve 30. Note that, for example, the method using ignition retardation does not allow large increases or decreases in engine torque due to its nature, and it cannot be changed for a very long period of time. It is a good method to use the sub-throttle valve control only at the beginning of torque reduction, or to use the ignition retard method only for the increase/decrease in feedback control. In step 324, it is checked again whether the turbine rotational speed Nt is maintained at approximately the synchronous rotational speed by feedback control based on the increase/decrease of the engine torque. If the synchronous rotational speed is less than 6, the flag F is set to 3 in step 326, and the feedback control in steps 321 and subsequent steps and the determination in step 324 are repeated until the synchronous rotational speed becomes almost synchronous. Eventually, if it is determined in step 324 that the rotational speed is approximately synchronous, the process proceeds to step 328, where the value of count N is updated to N+1. In step 330, the value of count N is set to a predetermined value N.
A determination is made as to whether or not the value has reached N', and the flag F is set to 4 in step 332 until N' is reached, and after being reset, the process returns to immediately before step 324. In this way, when it is determined that the predetermined count time N' has elapsed since the rotational speed reached the synchronous rotation speed, the hydraulic pressure of the brake B2 is increased (the brake B2 is engaged).
. In step 336, it is determined whether the rotational speed has reached (completely) the synchronous rotational speed. If the rotational speed has not reached the synchronous rotational speed, the flag F is set to 5 in step 342, and after resetting, the synchronous rotational speed is checked again. It will be done. Eventually, when it is determined that the turbine rotational speed Nt has (completely) reached the synchronous rotational speed, it is determined that the shift has substantially ended, and in step 344, a complete drain command for the clutch C2 is issued, and the clutch C2 is released. Along with step 3
At 40, a return command for engine 1 to lux is issued. Further, in step 342, the flag and count N are each reset. Next, FIG. 1 qualitatively shows the effects of the above embodiment. First, at time a, a shift from the third gear to the second gear is determined, and the hydraulic pressure PC2 of the clutch C2 is drained, and at the same time, a supply command (standby command) of the hydraulic pressure pH 12 of the play "f B 2" is issued.Clutch The oil pressure PC2 of C2 is initially lowered to a predetermined value Pc21, and then gradually lowered further. As a result, slipping of clutch C2 occurs at time C2.
This is detected and PO2 is held at a constant value. When the slippage of the clutch C2 progresses and the turbine rotational speed Nt becomes close to the synchronous rotational speed at time d, the engine torque is reduced and, at the same time, the engine torque is feedback-controlled so that the turbine rotational speed Nt is maintained near the synchronous rotational speed. do. During this time, the oil pressure PC2 is maintained at the constant value. In this embodiment, since the absolute amount of engine torque is reduced during the period of feedback control, the absolute amount of torque (load) handled by the frictional engagement device is reduced, and even higher holdability can be ensured. At time f, it was determined that the hold was established and the system was stable.
A command to increase the hydraulic pressure PI32 of the brake B2 is issued, and when complete synchronization is detected, the hydraulic pressure P of the clutch C2 is increased. Issue the 2nd release command. The release command for the hydraulic pressure PC2 may be issued at time f, if necessary. Engine torque is gradually increased between times gh. Even if the engagement pressure level PB21 of the hydraulic pressure PB2 of the brake B2 is a little too high, the variation formula ΔNt of the turbine rotational speed (input shaft rotational speed of the automatic transmission) Nt is small, and the output shaft torque T09 due to the torsion of the train system. Since there is a delay in the rise of , there is almost no effect on the output shaft torque To of the automatic transmission. Normally, in so-called "clutch-to-clutch shifting," it is extremely difficult to control the timing and level of pressure increase on the engaging side, and various variations can cause brisk torque changes and engine surge as shown by the broken line. However, as described above, according to this embodiment, extremely good downshift characteristics can be obtained. It should be noted that the present invention can also be applied to a "clutch-to-clutch shift" when upshifting from the second gear to the third gear in this gear train, for example. In this case, the friction engagement device on the releasing side becomes the brake B2, and the friction engagement device on the engagement side becomes the clutch C2. In the above embodiment, when performing feedback control, the absolute amount of engine torque was reduced to further improve the holdability, but in the present invention, this reduction in the absolute amount of engine torque is , this is not required. 0

【Effect of the invention】

As explained above, according to the present invention, when holding the rotational speed of the rotating member at a predetermined value, feedback control is adopted in which the engagement pressure is kept constant and the engine torque is increased or decreased. This provides an excellent effect in that the external disturbances can be effectively offset, the hold characteristics are significantly improved, and as a result, "clutch-to-clutch shifting" can be performed extremely well.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the transient characteristics of various parameters during gear shifting that qualitatively shows the effects of the embodiment of the present invention, and FIG. 2 is a diagram of an automatic transmission for a vehicle to which the embodiment of the present invention is applied. and an overall schematic diagram of the engine; FIG. 3 is a Sugerton diagram showing the gear train of the automatic transmission; FIG. 4 is a line diagram showing the engagement state of the frictional engagement device of the automatic transmission; is a flowchart showing a control flow executed by the apparatus of the embodiment. C2... Disengagement side friction engagement device, B2... Engagement side friction engagement device, Nt... Turbine rotation speed (rotation speed to be held at synchronous rotation speed), Te... Engine torque.

Claims (1)

[Claims] (1) When achieving a specific speed change by disengaging one friction engagement device and engaging the other friction engagement device, the rotating member is moved by sliding the friction engagement device on the releasing side. In a shift control device for an automatic transmission configured to hold a rotational speed near a synchronous rotational speed after shifting, and to engage an engagement-side frictional engagement device during this hold control, the rotational speed is held. A shift control device for an automatic transmission, comprising means for achieving the control by feedback control for increasing and decreasing engine torque while keeping the release pressure of the friction engagement device on the release side substantially constant.