JPH03213766A - Variable speed control device for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent the racing phenomenon of an engine to be generated easily when the oil temperature is low with simple structure by delaying change timing of the fastening condition of one friction element for variable speed by the predetermined time. CONSTITUTION:A multistage change gear set 10 which consists of planetary gear unit 14 achieves the predetermined variable speed stage by switching the fastening condition of, at least, two friction elements for variable speed among clutches 24, 21, 20, 27 and brakes 25, 23. In this case, the oil temperature in an oil pressure control circuit is detected, and when the oil temperature is low, change timing of the fastening condition of one friction element for variable speed is delayed by the predetermined time. When the oil temperature is low, a change of the rising speed of the oil pressure and the lowering speed thereof do not always coincide with each other to easily generate the racing phenomenon of an engine, but it can be prevented with simple structure.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a hydraulic circuit for an automatic transmission.

(Prior Art) In automatic transmissions, for example, switching of the power transmission path of a planetary gear type multi-stage transmission, that is, shifting is performed by switching the engagement state of shifting friction elements such as clutches and brakes. (Refer to Japanese Unexamined Patent Publication No. 109941/1983).

Each of the gear shifting friction elements is actuated by a hydraulic actuator, and therefore a hydraulic circuit is configured to control the supply and discharge of hydraulic pressure to and from the actuator. This hydraulic circuit includes at least 1-2 shift valves, 2-
A plurality of shift valves such as 3-shift valves are provided, and switching of the shift valves is performed by appropriately applying pilot pressure for switching control to the shift valves. Recently, in order to perform gear shifting by electronic control, the pilot pressure for the shift valve is controlled using a solenoid, and the switching of the shift valve, that is, the switching of the engaged state of the gear shifting friction element, is controlled by using a solenoid. It is designed to be done synchronously.

(Problem to be Solved by the Invention) However, since the switching of the engagement state of the above-mentioned transmission friction element is basically performed by supplying and discharging hydraulic pressure to the actuator, when the oil temperature is low, the above-mentioned switching is not possible. There is a problem in that it is difficult to ensure synchronization.

To explain this problem in detail, in shift control, when oil pressure is supplied to the - actuator and oil pressure is discharged from other actuators, when the oil temperature is low, the rise or fall of the oil pressure is slower than when it is high. easy. Furthermore, the changes in the rising speed of oil pressure and the changes in the falling speed due to changes in oil temperature do not necessarily match.
The change in either one is relatively smaller than the change in the other (
When this occurs, there is a delay in switching the engagement state of one of the friction elements relative to each other, and there is a possibility that a so-called engine racing phenomenon may be induced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an automatic transmission speed change control device that suppresses the occurrence of the engine revving phenomenon when the oil temperature is low.

Means and operation for solving problem C) In order to achieve this technical problem, the present invention includes a hydraulic control circuit, and shifts the gear by switching the engagement state of at least two gear shifting friction elements. Assuming that the speed change control device of an automatic transmission is configured, the oil temperature detecting means detects the oil temperature in the hydraulic control circuit, and the timing for changing the engagement state of one of the speed change friction elements is determined. and timing control means that receives a signal from the oil temperature detection means and delays the timing of changing the engagement state of the one gear shifting friction element by a predetermined period when the oil temperature is low. It has a simple structure.

In other words, when the oil temperature is low, by delaying the timing of changing the engagement state of one of the gear shifting friction elements,
This is to suppress the above-mentioned engine racing phenomenon.

(Example) Examples of the present invention will be described below based on the attached drawings.

FIG. 1 is a schematic diagram showing an automatic transmission incorporating the hydraulic control device of the present invention.

In FIG. 1, reference numeral 1 indicates the input shaft of the engine (
A torque converter 2 and a multi-speed gear system 10 are arranged coaxially with the crankshaft 1 (not shown) in order from the engine side. The torque converter 2 includes a pump 3, a turbine 4, and a stator 5, and the pump 3 is fixed to the crankshaft 1. The stator 5 rotates via a one-way clutch 6 on a fixed shaft 7 that is integrated with the case 1) of the multi-speed gear device 10. The one-way clutch 6 connects the stator 5 to the pump 3.
It allows rotation in the same direction, but does not allow rotation in the opposite direction.

The multi-speed gear device IO has a base end fixed to the crankshaft l, a distal end extending through the center of the multi-speed gear device, and drives an oil pump P disposed on the side wall of the device. It has a solid shaft 12 connected to the pump. On the outside of this solid shaft I2, a hollow shaft is connected at its base end to the turbine 4 of the torque converter 2, whose distal end extends to the side wall of the multi-speed gear unit 10, and rotatably supported by the side wall. A turbine shaft 13 is provided. A Ravigneau-type planetary gear unit 14 is provided on the turbine shaft 13, and this planetary gear unit 14 includes a small-diameter sun gear 15, a large-diameter sun gear 16 disposed on the side of the small-diameter sun gear 15 far from the engine, It consists of a long pinion gear 17, a short pinion gear 18, and a ring gear 19.

A coast and forward clutch 20.2 is located on the side of the planetary gear unit 14 that is far from the engine.
1 are arranged in parallel. The forward clutch 20 is a clutch for forward running, and connects and disconnects power transmission between the small diameter sun gear 15 and the turbine shaft 13 via the first one-way clutch 22.

The coast clutch 21 is connected in parallel with the forward clutch 20 and connects and disconnects power transmission between the small diameter sun gear 15 and the turbine shaft 13. A 2-4 brake 2 is provided radially outward of the coast clutch 21.
3 is placed. The 2-4 brake 23 is a band brake, and has a brake drum 23-1 connected to the large-diameter sun gear 16 and a brake band 23-2 hooked to the brake drum. radially outward of the forward clutch 20, and the 2-4
A reverse clutch 24 is arranged on the side of the brake 23. This reverse clutch 24 is a clutch for traveling backwards, and is used to connect and disconnect power transmission between the large-diameter sun gear 16 and the turbine shaft 13 via the brake drum 23-1 of the 2-4 brake 23. .

Radially outward of the planetary gear unit 14,
A low reverse brake 25 is arranged to engage and disengage the carrier 14a of the planetary gear unit 14 and the case loa of the multi-speed gear device 10. Between the brakes 23 and 25 of 2-4 and low reverse, the carrier 14 is connected in parallel with the low reverse brake 25.
A second one-way clutch 26 is arranged to engage and disengage the case loa and the case loa. A 3-4 clutch 27 is disposed on the side of the planetary gear unit 14 on the engine side to connect and disconnect power transmission between the carrier 14a of the planetary gear unit and the turbine shaft 13. On the side of this 3-4 clutch 27 on the engine side,
An output gear 28 connected to the ring gear 19 is arranged, and this gear 28 is connected to the output shaft 2.
It is attached to 8a. In addition, the reference numeral 29 in the figure indicates a lock-up clutch for directly connecting the turbine shaft 13 and the crankshaft l without going through the torque converter 2.

The multi-speed gear device 10 having the structure described above has four forward speeds and one reverse speed, and each clutch 20
．． 21.24 and 27 and each brake 23 and 25
A desired gear position can be obtained by operating the gearbox appropriately. In the above configuration, the operational relationship between each gear stage, clutch, and brake is shown in Table 1 below. Of each clutch and brake, the 2-4 brake 23 (actuator) has two oil chambers, one on the apply side and the other on the release side, and supplies hydraulic pressure to the apply side and releases hydraulic pressure on the release side. The 2-4 brake 23 is engaged only when this occurs, and the 2-4 brake 23 is released in other hydraulic pressure supply modes. The remaining clutches and brakes (their actuators) each have only one oil chamber, and are engaged when hydraulic pressure is supplied to this oil chamber, and when the hydraulic pressure in this oil chamber is released. will be opened to

(Leaving space below) Table (○) Transmission hydraulic pressure control circuit on the drive side (Summary) The multi-stage gearing device 10 having the structure described above uses hydraulic control valves as a switching valve group consisting of the hydraulic control circuit shown in FIG. has. This control valve includes a plurality of valves shown below, and the operation of these plurality of valves causes the above-mentioned first to fourth clutch devices 20.21.24.27 and first to second brake devices 23.25 to be connected. The hydraulic oil is supplied and discharged, and each clutch and brake device is operated according to each speed stage as shown in Table 1.

The operation of each valve will be explained below. The hydraulic fluid discharged into the pressure line 71 from the pump P driven by the engine is the throttle pressure (ps) from the line 72, the throttle modulator pressure (PSM) from the line 73, and the backup pressure (PB) from the line 74. The pressure is regulated to a predetermined line pressure (PL) by a regulator valve 51 that operates according to
supplied to The manual valve 52 is operated in conjunction with a lever on the driver's seat, and depending on the lever operation, P, RIN,
The hydraulic pressure supplied to the boat 52a is shifted to each of the travel ranges D and 2.1, and the hydraulic pressure supplied to the boat 52a is supplied to the other boats of the manual valve 52 according to each range position.

On the other hand, line pressure (PL) acts on the right end of the 1-2 shift valve 53 through the line 71a, which communicates with the line 7e through the orifice 71b.

This line 71a also communicates with the drain side via the 1-2 solenoid 101, and when this solenoid 101 is ON, the line 71a and the drain side communicate with each other, and when it is OFF, it shuts off both, so that the 1-2 shift valve 53 spool 53
A receives the biasing force of the spring 53b at the left end and the hydraulic pressure of the line 71a, and when the solenoid 101 is turned on, it moves to the right and enters the 2nd speed state, and when it is OFF, it moves to the left and enters the 1st speed state. In the D range, from the boat 52b of the manual valve 52 to the line 7
Since the line pressure (PL) is supplied to the FWD clutch 21 through the line 75a, in the 1st speed state of the D range, this line pressure (PC) is supplied to the FWD clutch 21 via the line 75a, and the N-D
The accumulator 54 is moved to the left to connect the lines 76a and 76b, and line pressure (PL) is also supplied to the coast clutch 20 through the lines 75b, 76a, and 76b. Next, when the 1-2 solenoid 101 is turned ON in the D range and the gear is shifted to 2nd speed, the line 75c branched from the line 75 communicating with the boat 52b of the manual valve 52 and the line 77 are connected, and from this line 77, the 3-4 shift is carried out. Line pressure (PL) is supplied to the engagement side of the 2-4 brake 23 via the valve 55. In addition, at the first speed of the L range, the reduced line pressure (PL') from the line 78a communicating with the boat 52c of the manual valve 52 via the Low reducing valve 56 is supplied to the L&R brake 25 via lines 78b to 78d. At the same time, the signal pressure is supplied to the throttle backup valve 57 via the line 78e. Here, the 2-4 brake actuator 23A has a first-order configuration. That is, the inside of the cylinder 23a is defined by the piston 23b into an apply side oil chamber 23c and a release side oil chamber 23d.
A piston rod 23e connected to a band 23-2 of the brake 23 is integrated. This piston 23b is urged downward in FIG. 2 by a spring 23f. In this actuator 23A, the 2-4 brake 23 is engaged only when the conditions that line pressure is supplied to the apply side oil chamber 23c and the oil pressure of the release side oil chamber 23d are released are satisfied. In other words, even if the line pressure is supplied to the apply side oil chamber 23c, the 2-4 brake 23 is released when the line pressure is supplied to the release side oil chamber 23d.

The line pressure (PL) from the boat 52b of the manual valve 52 is connected to the line 79.2-3 shift valve 58.
The line 79a acts on the right end via the line 79a, and the line 79a is communicated with and cut off from the drain side by turning on and off the 2-3 solenoid 102. Therefore, when the solenoid 102 is ON, the vehicle is in the 2nd speed state, and when it is OFF, the vehicle is in the 3rd speed state. Therefore, when shifting from 2nd to 3rd speed, the manual valve 52
The line pressure (
PL) is finally supplied to the 3-4 clutch 27 through the servo control valve 59, 2-3 timing valve 60 and bypass valve 61 to operate it, and the line pressure (PL) is supplied to the 2-4 brake 27.
The brake is also supplied to the release side (release side oil chamber 23d) of No. 3, and this brake is released.

In the 3-4 shift valve 55 as well, the line pressure (PL) supplied from the boat 52b of the manual valve 52 and acting on the right end of the valve is the O of the 3-4 solenoid 103.
It is controlled by N and OFF, and when the solenoid is ON, it is in the 4th speed state, and when it is OFF, it is in the 3rd speed state. Line 75 in 3rd gear
Line pressure (P
L) is supplied to the engagement side (apply side oil chamber 23c) of the 2-4 brake 23, and at the same time, the line pressure (PL) from the boat 52a of the manual valve 52 that bypasses the 1-2 shift valve 53 is shifted to 3-4. Valve 55 and N
- Coast clutch 20 via D accumulator 54
supply to. Turn on the solenoid 103 for 3-4
When changing from speed to fourth speed, the line pressure (PL) that has passed through the 1-2 shift valve 53 is supplied to the engagement side of the 2-4 brake 23 through a circuit 62 having an orifice and a check valve. At this time, the release side hydraulic pressure of the 2-4 brake 23 is drained via the 3-4 capacity valve 63, and the hydraulic pressure of the coast clutch 20 is also drained.

In this way, when the driving range is determined by the manual valve 52, the 1-2 solenoid 10 is activated within this driving range.
By ON-OFF controlling the 1.2-3 solenoid 102 and the 3-4 solenoid 103, each shift valve can be actuated to change gears. Note that the other valves have the following effects.

That is, the L, O W reducing valve 56 reduces the line pressure (PL), thereby reducing the L-R
The hydraulic pressure of the brake (low reverse brake) 25 is reduced to alleviate the shift shock, and a signal pressure is supplied to the throttle backup valve 57. The throttle backup valve 57 controls the hydraulic pressure supply to the regulator valve 51 depending on the presence/absence of the signal pressure, and controls the line pressure (PL) to ensure capacity during engine braking. The throttle valve 64 and the throttle modulator valve 65 are valves that obtain oil pressure according to the accelerator opening degree, and use this oil pressure to match the line pressure (PL) to the engine torque. The 2-3 timing valve 60 and the servo control valve are used to reduce the response delay when shifting from 2nd to 3rd speed and soften the shift shock.

The 3-4 capacity valve 66 is a valve for softening the shift shock when shifting from 3rd to 4th gear.
The 2-capacity valve 63 and the 3-2 timing valve 67 are valves for softening the shift shock from 3rd speed to 2nd speed depending on the throttle opening degree. Furthermore, N
- The D accumulator 54 performs an accumulator action when shifting from the N range to the D range by operating the manual valve 52, and also uses the movement of the accumulator piston 54a at this time to operate the coast clutch 2.
The timing of supplying hydraulic oil to the FWD clutch 21 is slightly delayed from the timing of supplying hydraulic oil to the FWD clutch 21 to prevent abnormal wear of the coast clutch when shifting from the N range to the D range with the accelerator pressed. Furthermore, the lock-up control valve 68 is activated by turning the lock-up clutch 2 on and off by turning the lock-up solenoid 104 on and off.
9 operation control is performed.

The hydraulic control valve 50 configured as described above is operated by the manual valve 52 and the solenoid valve 1 as described above.
01-104, and this ON-OFF control is performed by a control unit (not shown). That is, as is known, there is an engine load detection sensor that detects intake negative pressure, etc., a rotation speed detection sensor that detects engine output rotation or torque converter output rotation that corresponds to the engine rotation speed, and the position of the shift lever. Each of the solenoids 101 to 10 is activated from the control unit based on a signal from a range detection sensor that detects the travel range.
An activation signal is sent to 4, and each solenoid 101 to 104 is actuated by this activation signal to perform automatic gear shifting according to the driving conditions set for each driving range of the transmission IO.

Among the solenoids 101-104, the lock-up solenoid 104 operates the lock-up clutch 29 of the torque converter 2, so it is set by the ON-OFF combination of the other solenoids 101-103. Table 2 shows an example of the gear position.

Note that in the engine brake column, the O mark indicates a speed gear where the engine brake is effective, and the X mark indicates a gear gear where the engine brake is not effective.

As shown in Table 2, since there are three solenoids, eight combinations are possible, and for the first to third gears, both speed stages where the engine brake is effective and speed stages where the engine brake is not effective are set. Next, Table 3 shows an example of the combination of the solenoid signals shown in Table 2 and the speed stage settings in each travel range.

Table 3 From Tables 2 to 3: As described above, the shift from 2nd speed to 3rd speed is performed by switching 1-2 solenoid 101, 2-3 solenoid 102, 3-4 solenoid 03 from 0N to OFF. The related friction elements are 2-4 brake 23.3-4
Clutch 27 and coast clutch 20.

That is, the pressure in the apply side oil chamber 23c of the 2-4 brake is controlled by the 1-2 solenoid 101, and the 1-2 solenoid
When the solenoid 101 is turned on, the apply side oil chamber 23c
When the hydraulic pressure is turned ON (supplied), the 2-4 brake 23 is engaged (ON). Conversely, 1-2 solenoid 10
1 is turned off, and the oil pressure in the apply side oil chamber 23c is turned off.
When F (released), the 2-4 brake 23 is released (OFF).

Further, the 3-4 clutch 27 is controlled by the 2-3 solenoid 102, and when the 2-3 solenoid 102 is turned on, the 3-4 clutch 27 is released, and conversely, when the 2-3 solenoid 102 is turned off, the 3-4 clutch 27 is -4 clutch 2
7 is concluded.

Further, the oil pressure in the release side oil chamber 23d of the 2-4 brake 23 and the coast clutch 20 are controlled by the 3-4 solenoid 103. That is, 3-4 solenoids 10
3 is turned on, the oil pressure in the release chamber 23d is O.
FF is released, and the coast clutch 20 is released. Here, the 2-4 brake 23 is, as mentioned above,
The 2-4 brake 23 is engaged only when the conditions that line pressure is supplied to the apply side oil chamber 23c and the oil pressure in the release side oil chamber 23d are released are satisfied. Therefore, even if the 3-4 solenoid 103 is turned on, the 2-4 brake 23 will be released when the hydraulic pressure is released to the apply-side oil chamber 23c of the 2-4 brake 23. The 2-4 brake 23 is released by the biasing force of the spring 23f described above. Conversely, when the 3-4 solenoid 103 is turned off, the oil pressure in the release side oil chamber 23d is turned on (supplied), and the 2-4 brake 23 is connected to the supply or release of the oil pressure in the apply side oil chamber 23c. will be canceled. Additionally, the coast clutch 20 is engaged.

Based on the above, to explain the control from 2nd to 3rd speed, the 2nd speed mode is when all 1-2 solenoids 101 etc. are turned ON (No. 7 in Table 2), and vice versa.
When it is F, it is considered to be the 3rd speed mode (No. 1 in Table 2).

FIGS. 3 and 5 show the relationship between the ON/OFF states of each solenoid and the speed change mode. As a result, the second speed is generated by engaging the 2-4 brake 23 and releasing the 3-4 clutch 27 and the coast clutch 20. Conversely, the third speed is generated by releasing the 2-4 brake 23 and engaging the 3-4 clutch 27 and the coast clutch 20 (see FIGS. 4 and 6).

In the process of switching from the second speed mode to the third speed mode, in the embodiment, an intermediate step is inserted to suppress the occurrence of engine racing. Here, FIG. 3 and FIG. 4 correspond to each other, and show the control contents when the oil temperature in the circuit is high. FIG. 5 and FIG. 6 correspond to each other and show the control contents when the oil temperature in the circuit is low.

That is, when the oil temperature is high, the engagement of the 3-4 clutch 27 is started in synchronization with the release of the 2-4 brake 23 (FIG. 8, timing T2). As a result, as shown in FIGS. 7 and 8, a half-clutch state (point P in FIG. 8) of the 2-4 brake 23 and 3-4 clutch 27 is generated before the third speed mode is generated. As a result, engine revving can be suppressed.

On the other hand, when the oil temperature is low, a further preceding first intermediate step is provided as shown in FIGS. 5 and 6.

In the figure, the second intermediate step corresponds to the intermediate step when the oil temperature is high.

1. In the first intermediate step, only the engagement of the 3-4 clutch 27 is started, and therefore the 24 brake 23
The engagement of the 3-4 clutch 27 is started prior to the release of the clutch (second intermediate step). That is, when the oil temperature is low, as shown in FIG. 7, the rise of the oil pressure of the 3-4 clutch 27 is slow.
By prioritizing the engagement of the clutch 27 (timing T in FIG. 8), it is possible to prevent the engine from racing.

In other words, as shown in FIG.
By delaying the release of the brake 23 and the clutch 27 from the start of engagement of the 3-4 clutch 27, the half-clutch state of the brake 23 and the clutch 27 is maintained from point P to point P' for a predetermined period of time (
Δt), and therefore this half-clutch state is generated at a higher oil pressure state, making it possible to reliably prevent the engine from revving. FIG. 9 is a flowchart showing the contents of the above control. In this figure, Sl to S8 indicate step numbers.

Such control is performed, for example, by a control unit composed of a microcomputer, and the oil temperature in the circuit is detected by a sensor (effects of the invention). It is possible to prevent the engine from revving, which tends to occur when the engine speed is low, with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a mechanical diagram showing an example of a gear transmission mechanism. FIG. 2 is a circuit diagram showing an example of a hydraulic circuit to which the present invention is applied, which is used in the transmission mechanism shown in FIG. FIG. 3 and FIG. 4 are diagrams showing control modes when the oil temperature is high. FIGS. 5 and 6 are diagrams showing control modes when the oil temperature is low. FIG. 7 and FIG. 8 are action explanatory diagrams. FIG. 9 is a flowchart showing an example of shift control from 2nd speed to 3rd speed. 20: Coast clutch 23: 2-4 brake 23c: 2-4 brake apply side oil chamber 23d:
2-4 Brake release side oil chamber 27: 3-4 clutch 101: ]-2 solenoid 102: 2 3 solenoid 103: 3 4 solenoid 3 Figure 4 Figure 5 (?Lecture) Figure 6 Figure 7 □;! while

Claims (1)

[Claims] (1) In a shift control device for an automatic transmission that includes a hydraulic control circuit and changes gears by switching the engagement state of at least two shift friction elements, an oil temperature detection means for detecting the oil temperature in the hydraulic control circuit. and a timing adjustment means for adjusting the timing of changing the engagement state of one of the speed change friction elements among the speed change friction elements; and upon receiving a signal from the oil temperature detection means, when the oil temperature is low, the one of the speed change friction elements is adjusted. A shift control device for an automatic transmission, comprising: timing control means for delaying the timing of changing the engagement state of the shift friction element by a predetermined period of time;