JP4743432B2 - Control device for automatic transmission - Google Patents

Description

  The present invention relates to a control device for an automatic transmission that controls a hydraulic pressure applied to a piston of a friction engagement element to switch a gear position of a transmission mechanism.

  An automatic transmission for an automobile transmits the driving force of an engine to an input shaft of a transmission gear mechanism through a torque converter, shifts the transmission gear mechanism to transmit it to an output shaft, and rotationally drives the drive wheels. ing. Generally, a transmission gear mechanism has a plurality of gears arranged between an input shaft and an output shaft, and a plurality of power transmission paths having different speed ratios are formed between the input shaft and the output shaft. Friction engagement elements such as clutches and brakes are provided inside, and the hydraulic pressure applied to the pistons of each friction engagement element is individually controlled in response to a shift speed change request. The gear ratio is switched by selectively switching the release and switching the power transmission path between the input and output shafts.

  In conventional hydraulic control of a general automatic transmission, when a hydraulic pressure is supplied to a friction engagement element in response to a gear change request and the friction engagement element is engaged, it is time to perform a shift. Since control for supplying hydraulic pressure to the frictional engagement element is started, the response of the frictional engagement element may vary depending on the hydraulic pressure supply history to the frictional engagement element.

  For example, when hydraulic pressure is supplied in a state where hydraulic oil is not filled in the piston chamber of the friction engagement element (a state where air exists), such as when the friction engagement element is engaged for the first time after the engine is started, When the frictional engagement element is reengaged in the middle of releasing the frictional engagement element by lowering the supply hydraulic pressure of the frictional engagement element that is once filled and engaged with the hydraulic oil in accordance with the speed change. As shown in the above, when the hydraulic pressure is supplied when the hydraulic oil is already filled in the piston chamber of the friction engagement element, the amount of hydraulic oil flowing into the piston chamber is different. Even if the same timing is set, the time (responsiveness) required until the friction engagement element actually operates to transmit torque will vary. As described above, when the responsiveness when engaging the friction engagement element during the shift is varied, a large shift shock may occur.

As a countermeasure against this, as described in Patent Document 1 (Japanese Patent Laid-Open No. 5-296327), the rotational speed of the piston chamber (the rotational speed of the clutch drum) of the frictional engagement element that is released after the end of the shift is determined. When the pressure exceeds a predetermined value, a low hydraulic pressure is supplied to the piston chamber of the friction engagement element so that the piston does not stroke for a predetermined time to fill the hydraulic oil. There is one that maintains a state in which hydraulic oil is filled in the piston chamber by a centrifugal force due to rotation to prevent variation in responsiveness when the friction engagement element is engaged at the next shift.
Japanese Patent Laid-Open No. 5-296327 (page 4, etc.)

  By the way, some recent automatic transmissions have a model equipped with a manual mode (a mode in which the gear stage is switched manually). Even when the rotational speed of the piston chamber of the friction engagement element is low, the gear stage switching request is issued. May occur.

  However, the technique of the above-mentioned patent document 1 supplies the hydraulic pressure to the piston chamber of the friction engagement element when the rotational speed of the piston chamber of the friction engagement element becomes equal to or higher than a predetermined value. When the rotation speed of the piston chamber of the friction engagement element is low and lower than the predetermined value, the centrifugal force decreases and the piston chamber is filled with hydraulic oil. It cannot be maintained. For this reason, when shifting at a low speed when the rotational speed of the piston chamber of the friction engagement element is lower than a predetermined value, the responsiveness when engaging the friction engagement element varies, and a large shift shock occurs. May occur.

  Further, the technique of Patent Document 1 supplies a low hydraulic pressure that does not cause the piston to stroke when the rotational speed of the piston chamber of the friction engagement element becomes equal to or higher than a predetermined value. In the unlikely event that the piston strokes due to variations in hydraulic pressure and the frictional engagement element is dragged (a phenomenon in which the frictional engagement element is in a semi-engaged state), the rotational speed of the piston chamber is high at a predetermined value or higher. Therefore, there is a possibility that the frictional heat due to the drag becomes excessive and the frictional engagement element burns out.

  The present invention has been made in consideration of these circumstances. Therefore, the object of the present invention is to ensure that a large shift shock is generated due to a variation in response when the friction engagement element is engaged during a shift. Another object of the present invention is to provide a control device for an automatic transmission that can prevent the frictional engagement element from burning out.

In order to achieve the above object, the invention according to claim 1 selectively controls engagement and release of each friction engagement element by individually controlling the hydraulic pressure applied to the pistons of the plurality of friction engagement elements. In a control device for an automatic transmission that switches the gear stage of the transmission mechanism by switching, the rotational speed of the piston chamber of the friction engagement element is detected directly or indirectly by the rotational speed detection means. When the rotational speed of the piston chamber of the frictional engagement element to be released at a certain speed is less than a predetermined value, the piston chamber of the frictional engagement element has a low holding hydraulic pressure so that the piston of the frictional engagement element does not stroke. The pressurization control previously applied to the engine is executed by the non-shift hydraulic control means.

  In this configuration, in the friction engagement element to be released when the speed change mechanism is not shifted, when the rotational speed of the piston chamber is equal to or lower than a predetermined value, a pressurizing pressure that preliminarily applies a holding hydraulic pressure that does not cause the piston to stroke is applied to the piston chamber. By executing the control, it is possible to maintain a state in which the hydraulic fluid is filled in the piston chamber. On the other hand, when the rotational speed of the piston chamber is higher than a predetermined value, the pressurization control is not executed, but the state in which the hydraulic fluid is filled in the piston chamber by the centrifugal force due to the rotation can be maintained.

  Thus, when the speed change mechanism is not shifted, the piston chamber can be maintained in a state where the piston chamber is filled with all the rotational speed regions of the piston chamber of the friction engagement element to be released. It is possible to prevent the occurrence of a large shift shock by preventing variation in responsiveness when engaging the engaging elements.

  Moreover, since the pressurization control is executed when the rotational speed of the piston chamber of the friction engagement element is equal to or less than a predetermined value, even if the piston strokes due to hydraulic pressure variations and the friction engagement element is dragged, Since the rotation speed of the piston chamber is at a low speed of a predetermined value or less, the frictional heat due to drag does not become excessive, and the friction engagement element can be prevented from being burned out.

  In this case, the holding hydraulic pressure may be changed according to the rotation speed of the piston chamber during the pressurization control. In this way, the holding hydraulic pressure is changed in response to the change in the centrifugal force acting on the hydraulic oil in the piston chamber according to the rotational speed of the piston chamber and the change in the upper limit hydraulic pressure at which the piston does not stroke. The holding hydraulic pressure can be set to an appropriate value, and a hunting phenomenon in which the hydraulic pressure is switched on / off when the rotational speed of the piston chamber is close to a predetermined value can be prevented.

  According to a third aspect of the present invention, as substitute information for the rotational speed of the piston chamber, at least one of the output shaft rotational speed, the input shaft rotational speed, and the rotational speed of the internal combustion engine of the speed change mechanism, the gear stage of the speed change mechanism, May be used. Since the rotational speed of the piston chamber changes according to the combination of the rotational speed of the output shaft and input shaft of the transmission mechanism, the rotational speed of the internal combustion engine, and the speed change stage of the transmission mechanism, the output shaft rotational speed of the transmission mechanism and the input shaft By using at least one of the rotational speed and the rotational speed of the internal combustion engine and the shift speed of the speed change mechanism, information that accurately reflects the rotational speed of the piston chamber can be obtained.

  Further, as in the fourth aspect, when the pressurization control is started, the quick filling control for temporarily increasing the hydraulic pressure command value higher than the holding hydraulic pressure may be executed. In this way, the hydraulic oil can be quickly applied by quickly filling the piston chamber of the friction engagement element with the hydraulic oil during the pressurization control.

  Several embodiments embodying the best mode for carrying out the present invention will be described below.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the automatic transmission 11 will be described with reference to FIGS. 1 and 2. As shown in FIG. 2, an input shaft 13 of a torque converter 12 is connected to an output shaft of an engine (not shown), and a hydraulically driven transmission gear mechanism 15 (speed change) is connected to the output shaft 14 of the torque converter 12. Mechanism). Inside the torque converter 12, a pump impeller 31 and a turbine runner 32 constituting a fluid coupling are provided to face each other, and a stator 33 for rectifying the flow of oil is provided between the pump impeller 31 and the turbine runner 32. It has been. The pump impeller 31 is connected to the input shaft 13 of the torque converter 12, and the turbine runner 32 is connected to the output shaft 14 of the torque converter 12.

  The torque converter 12 is provided with a lock-up clutch 16 for engaging or disengaging between the input shaft 13 side and the output shaft 14 side. The output torque of the engine is transmitted to the transmission gear mechanism 15 via the torque converter 12, is shifted by a plurality of gears (such as planetary gears) of the transmission gear mechanism 15, and is transmitted to the drive wheels (front wheels or rear wheels) of the vehicle. Is done.

  The transmission gear mechanism 15 is provided with a plurality of clutches C0, C1, C2 and brakes B0, B1, which are friction engagement elements for switching a plurality of shift stages. As shown in FIG. The gear ratio is switched by switching engagement / release of C1 and C2 and the brakes B0 and B1 with hydraulic pressure and switching a combination of gears for transmitting power.

  FIG. 3 shows a combination of engagement of the clutches C0, C1, C2 and the brakes B0, B1 of the four-speed automatic transmission. The circles are held in the engaged state (torque transmission state) at that gear stage. The clutch and brake are shown, and the unmarked state shows the released state. For example, in the throttle depression state of the D range, as the vehicle speed increases, it is upshifted to first speed, second speed, third speed, and fourth speed. In the shift from the first speed to the second speed, B0 is released from the engagement of C0 and B0, and B1 is newly engaged. In the shift from the second speed to the third speed, B1 is released from the engagement of C0 and B1, and C2 is newly engaged. In the shift from the third speed to the fourth speed, C0 is released from the engagement of C0 and C2, and B1 is newly engaged.

  As shown in FIG. 1, the transmission gear mechanism 15 is provided with a hydraulic pump 18 driven by engine power, and a hydraulic control circuit 17 is provided in an oil pan (not shown) for storing hydraulic oil (oil). Is provided. The hydraulic control circuit 17 includes a line pressure control circuit 19, an automatic transmission control circuit 20, a lock-up control circuit 21, a manual switching valve 26, and the like. The hydraulic oil pumped up from the oil pan by the hydraulic pump 18 is line pressure controlled. This is supplied to the automatic transmission control circuit 20 and the lockup control circuit 21 via the circuit 19. The line pressure control circuit 19 is provided with a hydraulic pressure control valve (not shown) for controlling the hydraulic pressure from the hydraulic pump 18 to a predetermined line pressure. The automatic transmission control circuit 20 has a transmission gear mechanism. A plurality of shift hydraulic control valves (not shown) for controlling the hydraulic pressure supplied to the 15 clutches C0, C1, C2 and the brakes B0, B1 are provided. The lockup control circuit 21 is provided with a lockup control hydraulic control valve (not shown) for controlling the hydraulic pressure supplied to the lockup clutch 16.

  A manual switching valve 26 that is switched in conjunction with the operation of the shift lever 25 is provided between the line pressure control circuit 19 and the automatic transmission control circuit 20. When the shift lever 25 is operated to the neutral range (N range) or the parking range (P range), even if the energization to the hydraulic control valve of the automatic transmission control circuit 20 is stopped (OFF), The hydraulic pressure supplied to the transmission gear mechanism 15 by the manual switching valve 26 is switched so that the transmission gear mechanism 15 is in a neutral state.

  On the other hand, the engine is provided with an engine rotation speed sensor 27 for detecting the engine rotation speed Ne, and the transmission gear mechanism 15 is supplied with the input shaft rotation speed Nt of the transmission gear mechanism 15 (the output shaft rotation speed of the torque converter 12). An input shaft rotational speed sensor 28 for detecting and an output shaft rotational speed sensor 29 for detecting the output shaft rotational speed No of the transmission gear mechanism 15 are provided.

  Output signals of these various sensors are input to an automatic transmission electronic control circuit (hereinafter referred to as “AT-ECU”) 30. The AT-ECU 30 is mainly composed of a microcomputer, and executes each program stored in a built-in ROM (storage medium) so that the speed change of the speed change gear mechanism 15 is performed according to a preset speed change pattern. In addition, to each hydraulic control valve of the automatic transmission control circuit 20 in response to a shift speed change request (target shift speed change request) generated according to the operating position of the shift lever 25 and the operating conditions (throttle opening, vehicle speed, etc.). As shown in FIG. 3, the clutches C0, C1, C2 and the brakes B0, B1 are controlled by controlling the energization of the clutches C0, C1, C2 and the brakes B0, B1, respectively. The gear ratio of the transmission gear mechanism 15 is switched by switching the engagement / release of the brakes B0 and B1 and switching the combination of gears that transmit power. It switched.

  In the following description, the clutches C0, C1, C2 and the brakes B0, B1 are collectively referred to simply as “clutch”. A clutch that switches from the released state to the engaged state when the transmission gear mechanism 15 is shifted and a clutch that is kept engaged when the transmission gear mechanism 15 is not engaged are referred to as an “engagement side clutch”. The clutch that switches from the disengaged state to the disengaged state and the clutch that is maintained in the disengaged state at the time of non-shifting are referred to as “disengagement side clutch”.

  As shown in FIG. 4, each clutch has a piston 36 movably provided in a piston chamber 35 formed in the clutch drum 34, and the hydraulic pressure of the hydraulic oil filled in the piston chamber 35 rises to increase the piston. When the hydraulic pressure in the piston chamber 35 is lowered and the piston 36 moves in the release direction by the urging force of the return spring 37, the release state is achieved.

  When the transmission gear mechanism 15 is not shifted, the disengagement-side clutch is maintained in a state in which the piston chamber 35 is filled with hydraulic oil by centrifugal force when the rotational speed of the piston chamber 35 is high to some extent. When the speed is low, the centrifugal force becomes small, so that the hydraulic oil easily leaks from the seal 39 provided in the oil passage 38.

  Therefore, the AT-ECU 30 executes a non-shift hydraulic control program shown in FIG. 6 to be described later, thereby releasing at the gear stage at that time when the shift gear mechanism 15 is not shifted as shown in the time chart of FIG. When the rotational speed of the piston chamber 35 is detected and the rotational speed of the piston chamber 35 is equal to or lower than a predetermined determination value in the disengagement side clutch that maintains the state, the piston chamber 35 has a predetermined holding oil pressure (the piston 36 is engaged in the engagement direction). By executing the pressurization control that preliminarily applies a hydraulic pressure that does not cause a stroke), the piston chamber 35 is maintained in a state where the hydraulic oil is filled. On the other hand, when the rotational speed of the piston chamber 35 is higher than the determination value, the pressurization control is not executed, and the state in which the working oil is filled in the piston chamber 35 by the centrifugal force due to the rotation is maintained.

  Hereinafter, the processing content of the non-shift hydraulic control program of FIG. 6 executed by the AT-ECU 30 will be described.

[Non-shifting hydraulic control program]
The non-shifting hydraulic control program shown in FIG. 6 is executed at a predetermined cycle while the AT-ECU 30 is powered on, and serves as non-shifting hydraulic control means in the claims. When this program is started, first, at step 101, it is determined whether or not the transmission gear mechanism 15 is not shifting, and if it is determined that it is not shifting, the process proceeds to step 102, and this time It is determined whether or not the clutch to be controlled is a disengagement side clutch to be disengaged at the current gear position.

  If it is determined in step 102 that the clutch is the disengagement side clutch, the process proceeds to step 103 where the engine rotational speed Ne detected by the engine rotational speed sensor 27 and the input shaft rotational speed Nt detected by the input shaft rotational speed sensor 28 are processed. And the rotational speed of the piston chamber 35 of the release side clutch based on at least one of the output shaft rotational speeds No detected by the output shaft rotational speed sensor 29 and the current gear position.

  Since the rotational speed of the piston chamber 35 of the disengagement side clutch changes according to the combination of the engine rotational speed Ne, the input shaft rotational speed Nt, the output shaft rotational speed No, and the gear position, the engine rotational speed Ne and the input shaft rotational speed. If at least one of Nt and the output shaft rotational speed No and the current shift speed are used, the rotational speed of the piston chamber 35 of the disengagement side clutch can be accurately calculated. The processing in step 103 serves as a rotational speed detecting means in the claims.

  In the case where the rotational speed of the piston chamber 35 of the disengagement side clutch is at one of the engine speed Ne, the input shaft rotational speed Nt, and the output shaft rotational speed No, the engine rotational speed sensor. The rotational speed of the piston chamber 35 of the release side clutch may be detected from the output of any one of 27, the input shaft rotational speed sensor 28, and the output shaft rotational speed sensor 29.

  Thereafter, the routine proceeds to step 104, where it is determined whether or not the rotational speed of the piston chamber 35 of the release side clutch is equal to or lower than a predetermined determination value. Here, for example, the determination value is set to a lower limit value of the rotational speed of the piston chamber 35 that can maintain the state in which the hydraulic fluid is filled in the piston chamber 35 by centrifugal force due to rotation or a value slightly higher than that. ing.

  If it is determined in step 104 that the rotational speed of the piston chamber 35 of the disengagement side clutch is equal to or lower than the determination value, the centrifugal force becomes small and the piston chamber 35 cannot be maintained filled with hydraulic oil. When it is determined that there is a possibility, the process proceeds to step 105, and the pressurization control for preliminarily applying the holding hydraulic pressure to the piston chamber 35 of the releasing clutch is executed by setting the hydraulic pressure command value of the releasing clutch to the holding hydraulic pressure. . Thereby, the state where the hydraulic oil is filled in the piston chamber 35 is maintained. Here, the holding hydraulic pressure is set to, for example, an upper limit value of the hydraulic pressure at which the piston 36 does not stroke in the engagement direction or a value slightly lower than that in the region where the rotational speed of the piston chamber 35 is equal to or less than the determination value.

  On the other hand, when it is determined in step 104 that the rotational speed of the piston chamber 35 of the release side clutch is higher than the determination value, it is determined that the state in which the hydraulic oil is filled in the piston chamber 35 by centrifugal force can be maintained. Then, the process proceeds to step 106 and the pressurization control is prohibited.

  In the first embodiment described above, in the disengagement-side clutch that is maintained in the disengaged state at the gear position at the time when the transmission gear mechanism 15 is not shifted, when the rotational speed of the piston chamber 35 is equal to or less than the determination value, the piston chamber 35 Since the pressurization control for preliminarily applying the holding hydraulic pressure is executed, the state where the piston chamber 35 is filled with the hydraulic oil can be maintained by the pressurization control. On the other hand, when the rotation speed of the piston chamber 35 is higher than the determination value, the pressurization control is not executed, but the state in which the working oil is filled in the piston chamber 35 by the centrifugal force due to the rotation can be maintained.

  As a result, when the speed change gear mechanism 15 is not shifted, the piston chamber 35 can be maintained in a state where the piston chamber 35 is filled in all the rotational speed regions of the piston chamber 35 of the release side clutch. It is possible to prevent occurrence of a large shift shock by preventing variation in response when engaging the gears.

  Moreover, since the pressurization control is executed when the rotational speed of the piston chamber 35 of the disengagement side clutch is equal to or lower than the determination value, the piston 36 should be stroked in the engagement direction due to the hydraulic pressure variation, and the clutch may be dragged. However, since the rotation speed of the piston chamber 35 is at a low rotation speed equal to or less than the determination value, it is possible to prevent the clutch from being burned out.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In the first embodiment, the holding hydraulic pressure at the time of pressurization control is a fixed value, but in the second embodiment, by executing a non-shifting hydraulic control program in FIG. As shown, the holding hydraulic pressure is changed according to the rotational speed of the piston chamber 35 of the release side clutch when the pressurization control is started.

  In the non-shift hydraulic control program shown in FIG. 8, after detecting the rotational speed of the piston chamber 35 of the disengagement clutch when the transmission gear mechanism 15 is not shifted (steps 101 to 103), the process proceeds to step 103a and shown in FIG. With reference to the holding hydraulic pressure map, the holding hydraulic pressure corresponding to the rotation speed of the piston chamber 35 of the disengagement side clutch is calculated.

  The holding hydraulic pressure map shown in FIG. 9 indicates that the holding hydraulic pressure is held at the first predetermined value (for example, 50 kPa) in the region where the rotation speed of the piston chamber 35 is lower than the first predetermined value (for example, 1000 rpm). In a region where the rotational speed of 35 is higher than a second predetermined value (for example, 1500 rpm), the holding hydraulic pressure is set to be maintained at a second predetermined value (for example, 0 kPa = atmospheric pressure).

  Further, in the region where the rotation speed of the piston chamber 35 is not less than the first predetermined value and not more than the second predetermined value (for example, 1000 to 1500 rpm), the holding hydraulic pressure is increased to the first predetermined value as the rotation speed of the piston chamber 35 increases. It is set to decrease from (for example, 50 kPa) toward a second predetermined value (for example, 0 kPa). Alternatively, by calculating the holding oil pressure by interpolation, the holding oil pressure decreases from a first predetermined value (for example, 50 kPa) toward a second predetermined value (for example, 0 kPa) as the rotational speed of the piston chamber 35 increases. You may set as follows. As a result, when the pressurization control is started, the holding hydraulic pressure is increased as the rotational speed of the piston chamber 35 is decreased (see FIG. 7).

  Thereafter, the routine proceeds to step 104, where it is determined whether or not the rotational speed of the piston chamber 35 of the release side clutch is equal to or lower than the determination value, and it is determined that the rotation speed of the piston chamber 35 of the release side clutch is equal to or lower than the determination value. In this case, the pressure control for preliminarily applying the holding hydraulic pressure to the piston chamber 35 of the release side clutch is executed, thereby maintaining the state in which the hydraulic oil is filled in the piston chamber 35 (step 105).

  On the other hand, when it is determined that the rotational speed of the piston chamber 35 of the disengagement side clutch is higher than the determination value, it is determined that the state in which the piston chamber 35 is filled with hydraulic oil can be maintained by centrifugal force. Then, the pressurization control is prohibited (step 106).

  In the second embodiment described above, since the holding hydraulic pressure is increased as the rotation speed of the piston chamber 35 is decreased when the pressurization control is started, the piston chamber 35 is decreased as the rotation speed of the piston chamber 35 is decreased. The holding hydraulic pressure can be increased and the holding hydraulic pressure can be set to an appropriate value in response to the fact that the centrifugal force acting on the hydraulic oil in the inside decreases and the upper limit hydraulic pressure at which the piston 36 does not stroke is high. Further, it is possible to prevent a hunting phenomenon in which the hydraulic pressure is switched on / off when the rotation speed of the piston chamber 35 is close to the determination value.

  In the second embodiment, the holding hydraulic pressure is calculated according to the rotational speed of the piston chamber 35 of the release side clutch with reference to the holding hydraulic pressure map shown in FIG. The holding oil pressure may be calculated according to the input shaft rotation speed Nt and the gear position with reference to the holding oil pressure map shown in FIG. The holding hydraulic pressure map shown in FIG. 10 is created using the characteristic that the rotational speed of the piston chamber 35 changes according to the input shaft rotational speed Nt and the gear position. The relationship is set so as to be substantially the same as the map of FIG.

  Further, using the output shaft rotation speed No, the engine rotation speed Ne, and the vehicle speed instead of the input shaft rotation speed Nt, the holding hydraulic pressure is calculated according to the output shaft rotation speed No and the gear position, or the engine rotation speed Ne The holding hydraulic pressure may be calculated according to the shift speed, or the holding hydraulic pressure may be calculated according to the vehicle speed and the shift speed.

Next, Embodiment 3 of the present invention will be described with reference to FIGS.
In the third embodiment, by executing a non-shift hydraulic control program shown in FIG. 12 to be described later, as shown in the time chart of FIG. 11, the hydraulic pressure command value is temporarily held when the pressurization control is started. The quick filling control is performed so as to be higher than that.

  In the non-shift hydraulic control program shown in FIG. 12, after detecting the rotational speed of the piston chamber 35 of the release clutch when the transmission gear mechanism 15 is not shifted (steps 101 to 103), the process proceeds to step 104 to It is determined whether or not the rotational speed of the piston chamber 35 is equal to or less than a determination value.

  If it is determined in step 104 that the rotation speed of the piston chamber 35 of the release side clutch is equal to or lower than the determination value, the process proceeds to step 104a, where the release side clutch hydraulic pressure command value is temporarily higher than the holding hydraulic pressure. By executing the quick filling control set to the filling hydraulic pressure, the clutch control valve of the release side clutch is quickly moved to the pressure adjusting position, so that the piston chamber 35 is quickly filled with the hydraulic oil.

  Thereafter, the process proceeds to step 105, where a pressure control for preliminarily applying the holding oil pressure to the piston chamber 35 of the release side clutch is executed by setting the oil pressure command value of the release side clutch to the holding oil pressure. Maintain a state of full hydraulic fluid.

  In the third embodiment described above, since the quick filling control for temporarily setting the hydraulic pressure command value to the filling hydraulic pressure higher than the holding hydraulic pressure is executed when the pressurization control is started, In addition, the hydraulic oil can be quickly filled in the piston chamber 35 of the release side clutch, and the holding hydraulic pressure can be quickly applied.

  In the first to third embodiments, the present invention is applied to a 4-speed automatic transmission. However, the present invention may be applied to an automatic transmission of 3rd speed or less or 5th speed or more.

It is a schematic block diagram of the whole automatic transmission in Example 1 of this invention. It is a figure which shows typically the mechanical structure of an automatic transmission. It is a figure which shows the combination of engagement / release of clutch C0-C2 and brake B0, B1 for every gear stage. It is a longitudinal cross-sectional view of a clutch. 3 is a time chart illustrating pressurization control according to the first embodiment. 6 is a flowchart illustrating a flow of processing of a non-shift hydraulic control program according to the first embodiment. 6 is a time chart illustrating pressurization control according to the second embodiment. It is a flowchart which shows the flow of a process of the hydraulic control program at the time of non-shifting of Example 2. It is a figure which shows notionally an example of the map of the holding | maintenance hydraulic pressure of Example 2. FIG. FIG. 10 is a diagram conceptually illustrating an example of a holding oil pressure map in a modified example of the second embodiment. 6 is a time chart illustrating pressurization control according to a third embodiment. 12 is a flowchart illustrating a flow of processing of a non-shift hydraulic control program according to a third embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Automatic transmission, 12 ... Torque converter, 15 ... Transmission gear mechanism (transmission mechanism), 17 ... Hydraulic control circuit, 18 ... Hydraulic pump, 20 ... Automatic transmission control circuit, 27 ... Engine rotational speed sensor, 28 ... Input shaft Rotational speed sensor, 29 ... Output shaft rotational speed sensor, 30 ... AT-ECU (hydraulic pressure control means during non-shifting, rotational speed detection means), 34 ... clutch drum, 35 ... piston chamber, 36 ... piston, C0 to C2 ... clutch (Friction engagement element), B0, B1... Brake (friction engagement element)

Claims (4)

A control device for an automatic transmission that selectively switches the engagement and release of each friction engagement element and switches the gear stage of the transmission mechanism by individually controlling the hydraulic pressure applied to the pistons of the plurality of friction engagement elements In
Rotational speed detecting means for directly or indirectly detecting the rotational speed of the piston chamber of the friction engagement element;
When the speed change mechanism is not shifting, the holding hydraulic pressure is low enough that the piston of the friction engagement element does not make a stroke when the rotational speed of the piston chamber of the friction engagement element to be released at the current speed is less than or equal to a predetermined value. A control device for an automatic transmission, comprising: a non-shifting hydraulic pressure control means for executing a pressurization control for preliminarily applying the pressure to the piston chamber of the friction engagement element.   2. The automatic transmission control device according to claim 1, wherein the non-shift hydraulic control means changes the holding hydraulic pressure in accordance with a rotation speed of the piston chamber during the pressurization control.   At least one of the output shaft rotation speed, the input shaft rotation speed, and the rotation speed of the internal combustion engine of the transmission mechanism and the shift stage of the transmission mechanism are used as substitute information for the rotation speed of the piston chamber. The control device for an automatic transmission according to claim 1 or 2.   4. The non-shifting hydraulic pressure control means executes a quick filling control that temporarily makes a hydraulic pressure command value higher than the holding hydraulic pressure when starting the pressurizing control. A control device for an automatic transmission according to claim 1.

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