JPH03544B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an automatic transmission. (Prior Art) Automatic transmissions commonly used today are constructed by combining a hydraulic torque converter and a multi-stage gear type transmission mechanism having a gear mechanism such as a planetary gear mechanism. A hydraulic mechanism is normally used for speed change control of such automatic transmissions, and the hydraulic circuit is switched using a mechanical or electromagnetic switching valve. The engine power transmission system is switched by operating elements as appropriate to obtain the desired gear position. When switching the hydraulic circuit using an electromagnetic switching valve, an electronic device detects when the vehicle's running state exceeds a predetermined shift line, and a signal from this device is used to switch the electromagnetic switching valve. It is common practice to selectively operate the hydraulic circuit and thereby change the speed by switching the hydraulic circuit. Automatic transmissions that utilize hydraulic torque converters have extremely excellent characteristics, and various types have been developed and put into practical use for vehicles. However, in such automatic transmissions, under certain conditions, the pressure of the pressurized fluid supplied to the friction elements such as the clutch is insufficient, which causes the friction means to slip, reducing the power transmission efficiency. There was a risk that the engine brake would not work properly. Therefore, for example, in the automatic transmission described in Japanese Patent Application Laid-open No. 56-24255, under such conditions that the pressure of the pressure fluid is insufficient, for example, the range selected with the select lever is the 1st or 2nd range. In such cases, the pressure is increased by the hydraulic pressure regulating valve to prevent the friction means from slipping. Hereinafter, control to increase the pressure of the pressure fluid in this manner will be referred to as backup control. However, in conventional automatic transmissions, including the automatic transmission disclosed in JP-A No. 56-24255, when backup control is performed, that state continues to be maintained, resulting in an increase in pump load and The drawback was that the shot was also larger. The slippage of the friction means is particularly
The reason why this occurs when shifting from the range to the 1st or 2nd range is considered to be due to the following reason. For example, considering front brakes, the fixed element rotates in the opposite direction to the tightening direction of the band during engine braking, so the tightening force becomes weaker during engine braking, causing slippage (the clutch also responds to inertial force). similar results). Furthermore, during engine braking, the low gear range is expanded to the high vehicle speed side, so the engine braking torque increases, and slippage occurs when the line pressure is set when the throttle is fully closed. (Object of the Invention) Therefore, an object of the present invention is to provide an automatic transmission that can achieve both backup control and shift shock reduction. The present invention is such that one range can be selected from a plurality of ranges with different shift zones by a select lever, and
A speed change gear mechanism connected to the output shaft of the engine, a plurality of friction elements that switch the power transmission path of the speed change gear mechanism, and a plurality of shift valves that switch the supply of pressure fluid to a hydraulic actuator that operates these friction elements. In the automatic transmission, the automatic transmission is configured to operate each of the shift valves and create a desired one of a plurality of gears, the fluid pressure supplied to the fluid actuator being increased. Backup means to
A range sensor that detects when the range is set to the engine brake range by the select lever and outputs a detection signal, and when the detection signal from the range sensor is received, it corresponds to completion of engagement of the friction element. By temporarily operating the backup means only for a period of time,
The present invention is characterized by comprising a control means for temporarily increasing the fluid pressure. (Effect of the invention) In the automatic transmission of the present invention having the above configuration, D
When the range is changed to the engine brake range, that is, the 2,1 range, the backup means is temporarily operated only during a period corresponding to the completion of engagement of the friction elements, and the fluid pressure supplied to the hydraulic actuator is temporarily increased. As a result, back-up is performed only when necessary, making it possible to quickly shift gears when switching from D range to 1 or 2 ranges, prevent increase in pump load, and reduce gear changes during gear changes. Prevention of shock can also be achieved at the same time. Embodiments Hereinafter, a control device for an automatic transmission according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a cross section of a mechanical part of an automatic transmission incorporating a control device according to an embodiment of the present invention and a hydraulic control circuit. Structure of Automatic Transmission The automatic transmission includes a torque converter 10, a multi-stage gear transmission mechanism 20, and an overdrive planetary gear transmission mechanism 50 disposed between the torque converter 10 and the multi-stage gear transmission mechanism 20. has been done. The torque converter 10 includes a pump 11 coupled to an engine output shaft 1, a turbine 12 disposed opposite the pump 11, and a stator 13 disposed between the pump 11 and the turbine 12. A converter output shaft 14 is coupled to the converter output shaft 14 . Converter output shaft 14 and pump 1
A lock-up clutch 15 is provided between the lock-up clutch 1 and the lock-up clutch 15. This lockup clutch 15 is
The clutch 1 is constantly pushed in the engagement direction by hydraulic oil pressure circulating within the torque converter 10.
5 is maintained in the released state by release hydraulic pressure supplied from the outside. The multi-stage gear transmission mechanism 20 includes a front planetary gear mechanism 2
1 and a rear planetary gear mechanism 22, and a sun gear 23 of the front planetary gear mechanism 21 and a rear planetary gear mechanism 22.
It is connected to the sun gear 24 by a connecting shaft 25. The input shaft 26 of the multi-stage gear transmission mechanism 20 is connected to the connecting shaft 25 via a front clutch 27 and to the internal gear 29 of the front planetary gear mechanism 21 via a rear clutch 28, respectively. The connecting shaft 25, that is, the sun gear 23,
24 and the transmission case is the front brake 30.
is provided. The planetary carrier 31 of the front planetary gear mechanism 21 and the internal gear 33 of the rear planetary gear mechanism 22 are connected to an output shaft 34, and a rear brake 36 is connected between the planetary carrier 35 of the rear planetary gear mechanism 22 and the transmission case.
A one-way clutch 37 is provided. This one-way clutch 37 is connected to the rear brake 36
The unidirectionality is released by the operation of . The overdrive planetary gear transmission mechanism 50 is
A planetary carrier 52 that rotatably supports a planetary gear 51 is connected to the output shaft 14 of the torque converter 10, and a sun gear 53 is connected to an internal gear 55 via a direct coupling clutch 54. An overdrive brake 56 is provided between the sun gear 53 and the transmission case, and the internal gear 55 is connected to the input shaft 26 of the multi-gear transmission mechanism 20. The multi-gear transmission mechanism 20 is of a conventionally known type and has three forward speeds and one reverse speed.
28 and brakes 30 and 36 as appropriate, a desired gear stage can be obtained. The overdrive planetary gear transmission 50 connects the shafts 14 and 26 in a direct connection state, when the direct coupling clutch 54 is engaged and the brake 56 is released, and when the brake 56 is engaged and the clutch 54 is released. Shafts 14 and 26 are coupled in overdrive. Hydraulic Control Circuit The automatic transmission described above includes a hydraulic control circuit as shown in the drawings. This hydraulic control circuit has an oil pump 100 driven by an engine output shaft 1, and the pressure of the hydraulic oil discharged from this oil pump 100 into a pressure line 101 is adjusted by a pressure regulating valve 102, and the pressure is adjusted by a select valve. 10
Guided by 3. The select valve 103 has 1, 2,
It has shift positions D, N, R, and P, and when the select valve is in the 1, 2, and D positions, the pressure line 101 communicates with port a of the valve 103. Port a is the actuator 1 for actuating the rear clutch 28.
04 and the rear clutch 28 is held engaged when the valve 103 is in the position described above. Port a is also connected near the left end of the 1-2 shift valve 110, pushing its spool to the right in the figure. Port a is further connected to the right end of the 1-2 shift valve 110 via the first line L1, to the right end of the 2-3 shift valve 120 via the second line L2, and to the right end of the 2-3 shift valve 120 via the third line L3. 3-
4 are connected to the upper ends of the shift valves 130, respectively. The first, second and third lines L1, L
First, second and third drain lines D1, D2 and D3 are branched from 2 and L3, respectively, and these drain lines D1, D2, D3
There are first, second and third solenoid valves SL1, SL1, which open and close the drain lines D1, D2, D3.
SL2 and SL3 are connected. The above-mentioned solenoid valves SL1, SL2, SL3 are normally closed valves, and when the line 101 and port a are in communication and are in a non-energized state, each drain line D1, D2, D3
, thereby increasing the pressure in the first, second, and third lines. Port a is further connected to the front brake 3 via the 1-2 shift valve 110, i.e. via the line 143 when the spool of said valve 110 moves to the left.
In this way, when the port a is communicated with the engagement side pressure chamber of the actuator 108, hydraulic pressure is introduced into the engagement side pressure chamber. The front brake 30 is held in the operating direction. On the other hand, a line 142 is connected to the withdrawal side pressure chamber of the actuator 108, and this line 142 is connected to the 1-2 shift valve 110 and the 2-2 shift valve 110.
When the spools of the three-shift valve 120 both move to the left in the figure, they are communicated with port a via line 143. When the line 142 is connected to the port a in this way, the same hydraulic pressure is introduced from the port a into both the engagement side pressure chamber and the disengagement side pressure chamber of the actuator 108.
Due to the difference in pressure receiving area, the front brake 30 is now operated in the releasing direction. Also,
Pressure in line 142 is also directed to actuator 109 of forward clutch 27, which
7. The select valve 103 has a port b leading to the pressure line 101 in one position;
passes through line 112 to the 1-2 shift valve 110, and further passes through line 113 to the rear brake 36.
is connected to the actuator 114 of. When the solenoid valves SL1 and SL2 are de-energized by a predetermined signal, the 1-2 shift valve 110 and the 2-3 shift valve 120 move the spool to switch the line, thereby switching a predetermined brake or clutch. is activated, and the 1-2 and 2-3 speed change operations are performed, respectively. In addition, the hydraulic control circuit includes a cutback valve 115 that stabilizes the hydraulic pressure from the pressure regulating valve 102, and a pressure regulating valve 115 that stabilizes the hydraulic pressure from the pressure regulating valve 102.
A vacuum throttle valve 116 for changing the line pressure from the engine, and a throttle backup valve (hereinafter simply referred to as a backup valve) 117 for assisting the throttle valve 116 are provided. Furthermore, the hydraulic control circuit of this example is provided with a 3-4 shift valve 130 and an actuator 132 to control the clutch 54 and brake 56 of the overdrive planetary gear transmission mechanism 50. The engagement side pressure chamber of the actuator 132 is connected to the pressure line 101.
The brake 56 is pushed in the engaging direction by the pressure. This 3-4 shift valve is also 1-2, 2-3 above.
Like the shift valves 110 and 120, it is a normally open valve,
The solenoid valve SL3 is in a de-energized state
30 spool 131 moves downward, pressure line 101 and line 122 are cut off, and line 12
2 is drained. As a result, the brake 56
The hydraulic pressure acting on the release side pressure chamber of the actuator 132 disappears, and the brake 56 is actuated in the engaging direction, and the actuator 132 of the clutch 54 acts to release the clutch 54. Further, the hydraulic control circuit of this example is provided with a lock-up control valve 133, which is connected to the select valve 1 via a line L4.
It is connected to port a of 03. This line L
A drain line D4 is branched from the drain line D4 and is provided with a solenoid valve SL4, similar to the drain lines D1, D2, and D3. Lockup control valve 13
3, the solenoid valve SL4, which is a normally open valve, is energized, the drain line D4 is closed, and the line L4 is closed.
When the pressure inside increases, the spool cuts off line 123 and line 124, and also cuts off line 1.
24 is drained to move the lock-up clutch 15 in the connecting direction. The backup valve 117 is connected to the port 117.
a, 117b and 117c, and drain port 1
17d and is biased downward by a spring 117e to be in the lower position in the normal state, and when in the lower position, the port 117c is communicated with the drain port 117d, while when in the upper position, the drain port 117c is in communication with the drain port 117d. A spool 117f that cuts off communication is provided. The spool 117 is connected to the port 117a.
When hydraulic pressure is supplied to the ports 117a and 117b, it moves to the above-mentioned upper position, and when hydraulic pressure is supplied to the ports 117a and 117b, it is positioned at the above-mentioned lower position. The throttle valve 116 has a port 116
a, 116b, and 116c, when in the upper position shown in the figure, the port 116c is communicated with the port 116a, and when moving to the lower position, the communication between the port 116c and the port 116a is cut off, and the port 116c is connected to the port 116b. The spool 116d is provided with a spool 116d for communication. A diaphragm device 118 is operatively connected to the spool 116d.
has an operating chamber 118b that is partitioned by a diaphragm 118a and communicated with a portion of an intake pipe (not shown) downstream of a throttle valve. This diaphragm device 118 moves the working chamber 11 when the accelerator is depressed and the intake negative pressure becomes low.
The pressure inside 8b increases, and the diaphragm 118a lowers according to the degree of increase in pressure, and the spool 11
It is designed to lower 6d. A line 102 leading to the lower part of the pressure regulating valve 102 is connected to the port 116c of the throttle valve 116. In the pressure regulating valve 102, the spool 116d of the throttle valve 116 is located above it, the port 116c communicates with the port 116a,
As a result, the port 117c of the backup valve 117
When communicating with the drain port 117d via the spool, the spool is located downward and does not increase the line pressure, but when the accelerator is depressed, the spool 116d lowers as described above and the port 116c connects to the port 116b. When the line 102a receives pressurized oil from the pump 100 through the line 102a, the spool rises and the line pressure increases according to the height of the rise. A backup control valve (hereinafter simply referred to as a control valve) BV for controlling the operation of the backup valve 117 is connected to the backup valve 117. This control valve BV has ports P1, P2, P
3, P4, a drain port P5, and a spool S. Port P1 is connected to line L3, the line pressure of which is controlled by third solenoid SL3. Port P2 is communicated with port d of select valve 103, which communicates with pressure line 101 when the P, R, 2, 1 range is selected. Port d of select valve 103 is also communicated with port 117a of backup valve 117. Port P3 communicates with port 117b of backup valve 117. and port P
4 is the pressure line 10 when the D range is selected.
The port c of the select valve 103 communicates with the port c of the select valve 103. The spool S is biased to the right by a spring B, and therefore is located at the right position shown in the figure in a normal state. Spool S is
When in this right position, ports P2 and P3 are communicated with each other, and drain port P5 is closed. on the other hand,
When the spool S moves to the right against the force of the spring B, the spool S communicates the port P3 with the drain port P5 and closes the port P2. The select valve 103 has this select valve 1
A range sensor 140 is provided that detects when 03 is switched from the D range to the 2,1 range, which is the engine brake range, and outputs a detection signal S. This range sensor 140 includes
A control circuit 141 is connected, and when receiving the detection signal S from the range sensor 140, the control circuit 141 temporarily puts the solenoid valve SL3 in an inactive state, that is, a closed state, for a predetermined period of time, and thereby controls the solenoid valve SL3. The spool S of the valve BV is moved to the left, the spool 117f of the backup valve 117 is raised, and the drain port 117d is closed. It's starting to take control. In the above configuration, the operational relationship between each gear position, lockup, and each solenoid, and the operational relationship between each gear position, clutch, and brake are shown in the following table.

【table】

【table】

【table】

[Table] Electronic control circuit using a microcomputer Next, referring to FIG. 2, an electronic control circuit 200 for controlling the operation of the hydraulic control circuit will be described. The electronic control circuit 200 includes an input/output device 201, a random access memory 202 (hereinafter referred to as RAM), and a central processing unit 203 (hereinafter referred to as CPU). The input/output device 201 includes a load sensor 207 that detects the engine load from the opening degree of a throttle valve 206 provided in the intake passage 205 of the engine 204 and outputs a load signal SL, and a load sensor 207 whose range is from D to 2, Range sensor 208 detects that the range has been switched to 1 range and outputs a range signal S _R , and detects the rotation speed of converter output shaft 14 and outputs a turbine rotation speed signal.
Sensors that detect running conditions, such as a turbine rotation speed sensor 209 that outputs ST, are connected, and the above-mentioned signals and the like are input from these sensors. The input/output device 201 processes the load signal SL and turbine rotation speed signal ST received from the sensor, and
Supplied to RAM202. The RAM 202 stores these signals SL and ST, and also stores the signals SL and ST.
These signals SL, ST in response to commands from 203
Or other data is supplied to the CPU 203.
The CPU 203 outputs the turbine rotation speed signal ST according to a program that is compatible with the speed change control of the present invention.
With reference to the shift-up shift line and shift-down shift line determined based on the turbine rotation speed-engine load characteristics read in response to the load signal SL,
Calculation is performed to determine whether or not to change gears. The calculation results of the CPU 203 are sent to the input/output device 201
and the 1-2 shift valve 110, which is the speed change control valve described with reference to FIG. 1, via the drive circuit 210;
It is given as a signal to control the excitation of the solenoid valve group 211 that operates the 2-3 shift valve 120, the 3-4 shift valve 130, and the lock-up control valve 133. This solenoid valve group 211 includes solenoid valves SL1, SL2, SL3, and SL4 of a 1-2 shift valve 110, a 2-3 shift valve 120, a 3-4 shift valve 130, and a lock-up control valve 133. When the electronic control circuit 200 receives the detection signal S _R from the range sensor 208, it supplies a signal for inactivating the solenoid valve SL3 to the drive circuit 210 for a predetermined period of time, thereby causing the above-described operation to occur. In this way, the solenoid valve SL3 is temporarily deactivated to create a temporary backup state. An example of control of an automatic transmission by the electronic control circuit 200 will be described below. Electronic control circuit 200
It is preferable that the electronic control circuit 200 is configured by a microcomputer, and a program installed in the electronic control circuit 200 is executed, for example, according to the flowchart shown in FIG. 3 and subsequent figures. FIG. 3 shows an overall flowchart of the shift control, and as can be seen from this figure, the shift control is first performed from initialization settings. This initialization setting is performed by first initializing the ports of each control valve that switches the hydraulic control circuit of the automatic transmission and the necessary counters, and then starting the gear transmission mechanism 20.
is set to first gear, and the lock-up clutch 15 is set to released. Thereafter, various working areas of the electronic control circuit 200 are initialized to complete the initialization settings. After this initialization setting, a step is performed to read the position of the select valve 103, that is, the shift range. Next, it is determined whether the read shift range is the D range. When the determination as to whether the vehicle is in the D range is YES, a shift and lockup map including a shift change control line and a lockup control line is set. Next, shift-up speed change control, shift-down speed change control, and lock-up speed change control including shift-up determination are performed. On the other hand, when the determination as to whether the range is in the D range is NO, backup control is performed. This backup control is performed by determining whether the range is P, R, or N, as shown in FIG. If this determination is YES, the timer is reset, and then the timer is set to several seconds to complete the control. On the other hand, if the above judgment is NO, 2,
Since the range is 1, the timer is read, and then it is determined whether the time is 0 or not.
When the determination is YES, the backup is canceled and the control is completed, while when the determination is NO, the backup is kept activated until the determination that the time is 0 becomes YES. In the main routine shown in Figure 3, D
When the range determination is NO, the following control is performed in parallel with the lockup control described above. In this control, first, it is determined whether the shift range is the 2nd range. When this determination is YES, that is, when the shift range is the 2nd range, a signal is generated to control the shift valve so as to release the lockup and fix the gear transmission mechanism 20 at the 2nd speed. On the other hand, when the above judgment of 2nd range is NO, the shift range is 1st range, so first release the lockup, then calculate whether or not the engine will overrun when downshifting to 1st gear. . After this, based on this calculation, it is determined whether or not overrun occurs, and if this determination is NO, the gear is shifted to 1st gear, and if this determination is YES, the gear is shifted to 2nd gear.
Shift to high speed, complete the main routine, and repeat the above steps again.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a cross section of a mechanical part and a hydraulic control circuit of an electronically controlled automatic transmission according to an embodiment of the present invention, FIG. 2 is a diagram showing an electronic control circuit of the automatic transmission, and FIG. and FIG. 4 is a flowchart of shift control and backup control according to the present invention. 10...Torque converter, 11...Pump,
12...Turbine, 100...Hydraulic pump, 10
3...Select valve, 200...Electronic control circuit, 2
07...Load sensor, 209...Turbine rotation speed sensor, SL1, SL2, SL3, SL4...Solenoid valve, 102...Pressure regulating valve, 103...Select valve, 117...Backup valve, 118...Backup slot Tutle valve, BV...backup control valve, 140...range sensor, 141...control circuit.

Claims (1)

[Claims] 1 A select lever allows one range to be selected from a plurality of ranges with different shift zones, a transmission gear mechanism connected to the output shaft of the engine, and a power transmission path for this transmission gear mechanism. and a plurality of shift valves that switch the supply of pressure fluid to hydraulic actuators that operate these friction elements. In an automatic transmission configured to be able to create two gears, a back-up means for increasing the fluid pressure supplied to the hydraulic actuator, when the range is set to the engine brake range by the select lever; and a range sensor that detects and outputs a detection signal, and when receiving the detection signal from the range sensor, temporarily operates the backup means only for a period corresponding to completion of engagement of the friction element. Automatic transmission with control means for temporarily increasing fluid pressure.