JPH0346698B2 - - Google Patents

Description

[Detailed description of the invention]

(1) Technical field The present invention relates to an automatic transmission with an overdrive, particularly when the manual valve is set to the drive range and the overdrive gear is selected, and the manual valve is switched to the 2nd speed range for engine braking. This relates to technology for reducing shock. (2) Prior art An automatic transmission with an overdrive has a manual valve that is in the first drive range.
It is common that the transmission gears are automatically selected from speed, second speed, third speed, and overdrive.
Usually, the second gear is selected by operating a band brake, and this band brake applies braking in the leading direction of the band during normal driving of the vehicle (while the engine is driving the vehicle drive wheels). While the vehicle is running under engine braking (while the engine is being reversely driven by the vehicle drive wheels)
Brake action is applied in the trailing direction of the band. By the way, as is well known, the leading and trailing characteristics of band brakes are different.
The braking force due to the former characteristic is greater than the braking force due to the latter characteristic. Therefore, if the line pressure for operating the band brake is the same during normal driving in 2nd gear and engine braking, the braking force of the band brake may be insufficient during engine braking in 2nd gear. Therefore, due to the slippage here, sufficient engine braking cannot be expected. On the other hand, the line pressure is determined by the solid line in Figure 3 according to the engine throttle opening that approximately corresponds to the output torque, since the operating force of the band brake, etc. that is activated by this must correspond to the output torque of the engine. It is normal to change it as shown by α, and since the throttle opening is naturally kept at the minimum during engine braking, the line pressure is also at its lowest. In this respect as well, the above-mentioned slippage of the band brake is further exacerbated, and it is inevitable that the effectiveness of the engine brake becomes worse while the vehicle is running under engine brake in the second gear. Therefore, when engine braking is desired and the manual valve is switched from the drive range to the 2nd speed range, the line pressure is increased to a constant high value as shown by the dashed line β in Figure 3, and the band Measures have been taken to ensure the effectiveness of engine braking by generating sufficient braking force without any slippage when the brakes perform a braking action in the trailing direction. By the way, in the case of an automatic transmission with an overdrive, when the manual valve is switched to the 2nd gear range in order to perform engine braking while driving in the overdrive gear, when shifting from the overdrive gear to the 2nd gear, In this case, not only the band brake is operated, but the clutch is also operated, and the clutch is operated using the increased line pressure. Thus, the clutch does not have the leading and trailing characteristics of a band brake, and when actuated by the increased line pressure, the clutch capacity becomes too large. Therefore, when driving with the overdrive gear selected and attempting to apply engine braking by switching the manual valve from the drive range to the 2nd gear range, a vehicle equipped with an overdrive automatic transmission will not be able to maintain the clutch capacity above. Excessive amount will cause a large shock. (3) Purpose of the Invention Therefore, the present invention delays the above-mentioned increase in line pressure that is carried out when switching such a manual valve until the above-mentioned clutch has completed its operation, and thereby controls the operation of the clutch to be either excessive or insufficient. The purpose of this invention is to prevent the occurrence of the above-mentioned shock by properly increasing the line pressure before increasing the pressure, and then to prevent the band brake from slipping as usual by increasing the line pressure properly. . (4) Structure of the Invention For this purpose, the automatic transmission with overdrive of the present invention delays the increase in line pressure, which is performed by the backup pressure when the manual valve is set to the 2nd speed range, until the operation of the clutch is completed. Additionally, a pressure increase control valve is provided which cuts off the backup pressure supply circuit in response to the actuation pressure of the clutch until the actuation of the clutch is completed. (5) Examples Hereinafter, the present invention will be explained in detail with reference to illustrated examples. FIG. 1 shows a skeleton diagram of a speed change gear mechanism of an automatic transmission with an overdrive, which is composed of a torque converter section 1, an overdrive gear train section 2, and a third speed gear train section 3. The torque converter 4 with a lock-up mechanism of the torque converter section 1 receives torque from an engine (not shown) from a rotating shaft 4a, and receives torque from a rotating shaft 4b.
Torque is output to the overdrive gear train section 2 by. The torque converter 4 with a lock-up mechanism has a lock-up clutch 4c, which allows the rotating shafts 4a and 4b to be mechanically connected.
The overdrive gear train section 2 has a planetary gear set 5, a direct clutch 6, and an overdrive brake 7. Carrier 5a of planetary gear set 5
is connected to a torque converter 4 with a lockup mechanism via a rotating shaft 4b, and an internal gear 5b is connected to a third speed gear train 3 via a rotating shaft 8. The sun gear 5c and the internal gear 5b can be connected by a direct clutch 6, and the sun gear 5c can be fixed to a stationary part by an overdrive brake 7. When the direct clutch 6 is activated and the overdrive brake 7 is deactivated, the carrier 5a, which is a component of the planetary gear set 5,
Internal gear 5b and sun gear 5c rotate integrally, and rotating shaft 4b and rotating shaft 8 are in a connected state (that is, the gear ratio is 1). vice versa,
When the direct clutch 6 is deactivated and the overdrive brake 7 is activated, the rotational speed of the internal gear 5b becomes faster than that of the carrier 5a, and the rotation of the rotating shaft 8 is accelerated more than the rotation of the rotating shaft 4b ( In other words, the gear ratio is smaller than 1, resulting in an overdrive state). The 3rd speed gear train section 3 is a well-known gear train with 3 forward speeds and 1 reverse speed.
planetary gear sets 9 and 10, two clutches 11
and 12, two brakes 13 and 14 (13 is a band brake), and a one-way clutch 15
By operating the brakes 13, 14, one-way clutch 15, and clutches 11, 12 in appropriate combinations, three forward speeds and one reverse speed can be obtained as shown in the table below.

[Table] FIG. 2 shows the concept of the present invention applied to a well-known shift control circuit that automatically shifts the gears of the transmission mechanism shown in FIG. 1. It is constructed by adding a control valve 17. Therefore, in this specification, only this control valve and its related parts will be mainly explained, and the other parts will be described only by their names. In other words, in Fig. 2, 18 is a manual valve, which the driver controls to set the parking (P) range, reverse drive (R) range, neutral (N) range, and drive (D) range.
By manually operating the range, 2nd speed 2 ranges, and 1st speed 1 range, the line pressure in the line pressure circuit 19 is switched to be distributed to various circuits. A pressure regulator valve 20 regulates the pressure of the hydraulic oil from the oil pump 21 to a line pressure, and outputs this to the line pressure circuit 19 while adjusting it to an optimum value depending on the running condition of the vehicle. In addition, 22 is a 1-2 shift valve, 23 is a 2-3 shift valve, 24 is a pressure modifier valve, 25 is a vacuum throttle valve, and 26
27 is a solenoid downshift valve, 28 is a second lock valve, 29 is a 2-3 timing valve, and 30 is a governor valve. When the manual valve 18 is in the D range, the line pressure circuit 19 is connected to the circuit 31, and line pressure is supplied to the clutch 12 to actuate it.
The first speed can be selected as shown in the table. At this time, the one-way clutch 15 acts as a reaction brake and enables power transmission at the first speed.
The governor valve 30 outputs governor pressure according to the vehicle speed to the circuit 32, and the 1-2 shift valve 22 is set to the upper half position when the governor pressure reaches a predetermined value and the valve spool is moved to the upper half position. Passes between 33 and 34. Thus, the line pressure supplied to circuit 31 is transferred to circuits 33, 34, second lock valve 28 (the valve spool is located in the right half of the figure), and circuit 3.
5 to the operating side of the band brake 13, and the operation of the band brake and the operation of the clutch 12 select the second speed as shown in Table 1 above. When the vehicle speed further increases, the valve spool of the 2-3 shift valve 23 is also moved to the upper half position in the figure by the governor pressure from the circuit 32, and the valve spool is moved between the circuits 36 and 37. By the way, circuit 36 is manual valve 18
Since the corresponding D range is connected to line pressure circuit 19 and is supplied with line pressure, circuit 3
Line pressure is output to 7. This line pressure is circuit 3
7 to the inoperative side of the band brake 13 to deactivate it, and to the clutch 11 on the other hand.
As a result, the third speed is selected as shown in Table 1 above. 44 is a 3-4 shift valve, 45 is an overdrive release valve, 46 is an overdrive release solenoid, and 47 is a lockup control valve. When the solenoid 46 is energized by the operator, the downstream orifice 49 of the orifices 48 and 49 in the line pressure circuit 19 is activated.
from the drain port 50, and the solenoid 46
The orifice 49 is communicated with the drain port 50 when the drain port 50 is deenergized. In the former state of the solenoid 46, the pressure between the orifices 48 and 49 becomes equal to the line pressure, and the overdrive release valve 45 has its valve spool in the lower half position in the figure to connect the circuit 51 to the line pressure circuit 19, and the solenoid In the latter state of 46, no pressure is generated between orifices 48 and 49, and overdrive release valve 45 has its valve spool in the upper half position in the figure, allowing circuit 51 to communicate with circuit 52. The 3-4 shift valve 44 receives governor pressure (corresponding to vehicle speed) from the governor pressure circuit 32 and throttle pressure (corresponding to throttle opening) from the throttle pressure circuit 42 at both ends thereof, and the valve spool receives the following pressure from the throttle pressure circuit 42. React as follows. That is, as mentioned above, D
3-3 under governor and throttle pressures such that 1st, 2nd, or 3rd gear is selected in the range.
The valve spool of the 4-shift valve 44 maintains the lower half position in the figure and connects the circuit 52 to the line pressure circuit 19 to supply line pressure to the circuit 52. Here, if the driver does not wish to release the overdrive and deactivates the solenoid 46 and sets the valve spool of the lock-up release valve 45 to the upper half position in the figure, the line pressure led to the circuit 52 will decrease. Direct clutch 6 via circuit 51 and one-way orifice 53
It is supplied to the accumulator 59 and also to the release chamber 7a of the overdrive brake 7 via the circuit 51 and the one-way orifice 54. Thus, even though the line pressure from the circuit 19 is constantly guided to the apply chamber 7b, the overdrive brake 7 is inactivated due to the pressure receiving area due to the line pressure in the release chamber 7a, and the direct clutch 6 is inactivated by the accumulator. 59, the engine rotation reaches the shaft 8 (see FIG. 1) as it is if the engine speed increases as described above. Therefore, the above-described first, second, and third speed selection states in the D range are obtained, but when the vehicle speed increases in the third speed selection state and the governor pressure output to the circuit 32 increases, the 3rd speed selection state is obtained. The valve spool of the -4 shift valve 44 is in the upper half position in the figure and communicates the circuit 52 to the drain port 55. At this time, line pressure is no longer supplied to the circuit 52, and the direct clutch 6
is deactivated, and overdrive brake 7
is operated by the line pressure in the apply chamber 7b. As a result, the engine rotation reaches the accelerated shaft 8 (see Figure 1) as described above, and an overdrive gear stage with a smaller reduction ratio (speed increase ratio) than 3rd gear can be selected. . If the driver does not desire this overdrive and moves the valve spool of the overdrive release valve 45 to the lower half position in the figure by energizing the solenoid 46, the line pressure from the circuit 19 is supplied to the circuit 51. Therefore, the overdrive can be released as desired by deactivating the overdrive brake 7 and activating the direct clutch 6. Lockup control valve 47 is responsive to governor pressure from governor pressure circuit 32 and pressure from circuit 51. As is clear from the above, line pressure is always guided to the circuit 51 except in the overdrive selection state, and the valve spool of the lockup control valve 47 is connected to the upper half of the figure regardless of the governor pressure from the circuit 32. kept in position. At this time, the circuit 5 leading to the lock-up clutch 4c
6 is connected to a circuit 57 leading to a circuit portion equal to the internal pressure of the torque converter 4, which releases the lock-up clutch 4c and causes the torque converter 4 to function in a so-called converter state for power transmission. By the way, in the overdrive selection state, as is clear from the above, the circuit 51 is in a non-pressure state, so when the governor pressure from the circuit 32 reaches a certain value, that is, in the overdrive selection state, the vehicle speed increases. When the vehicle speed exceeds the lockup speed, the valve spool of the lockup control valve 47 is moved to the lower half position in the figure by the governor pressure. At this time, the circuit 56 communicates with the drain port 58 and engages the lock-up clutch 4c, thereby causing the torque converter 4 to function to transmit power in a so-called lock-up state. Furthermore, when engine braking is desired and the manual valve 18 is changed from the D range to the 2nd speed 2nd range while driving in overdrive, the second lock valve 28 is operated as a result of the line pressure being supplied from the manual valve 18 via the circuit 38 disappearing. , the valve spool is moved from the right half position to the left half position, and the line pressure supplied from the manual valve 18 through the circuit 39 is passed through the circuit 35 to the band brake 13.
Supplied to the operating side of the On the other hand, manual valve 1
Since no line pressure is output to the circuit 38 in these two ranges of 8, no line pressure is output to the circuit 36 either, and the clutch 11 is naturally deactivated. On the other hand, at the time of range switching, line pressure is output from the manual valve 18 to the circuit 40, and this line pressure reaches the actuator 60 and causes its piston rod to protrude, thereby causing the valve spool of the 3-4 shift valve 44 to move. Switch to the lower half position in the figure. In this case, as described above, the overdrive brake 7 is deactivated and the direct clutch 6 is activated, and automatic gear shifting is achieved by the activation of the direct clutch, the aforementioned activation of the band brake 13, and the operation and maintenance of the clutch 12. The aircraft is shifted from overdrive to second gear and remains locked in second gear, allowing engine braking in second gear. By the way, the pressure increase control valve 17 provided in the present invention
The valve spool 61 is slidably inserted into a valve body 62, and the valve spool is provided with two lands 61a and 61b. And land 61a
facing the chamber 63, and the valve spool 61 facing this chamber.
is biased by a spring 64. One end of the circuit 65 is connected so as to constantly communicate with the chamber between the lands 61a and 61b, and the other end of the circuit is connected to the back-up pressure (described later) inlet port 2 of the vacuum throttle valve 25.
Connect to 5a. A drain port 66 is formed in the valve body 62 to communicate with the circuit 65 at the right half position of the valve spool 61 in the figure, and a vacuum port is further formed in this valve body so that the valve spool 61 communicates with the circuit 65 at the left half position in the figure. The backup pressure circuit 41 from the throttle valve 26 is connected. Also, room 63
conducts the actuating pressure of the direct clutch 6 through a circuit 67, which pressure causes the valve spool 61 to respond against the spring 64. In the automatic transmission of the present invention equipped with such a pressure increase control valve 17, line pressure is controlled as follows. First, in the D range of the manual valve 18, the drain port of the manual valve 18 is connected to the circuit 40, and the throttle backup valve 26 connects the backup pressure circuit 41 to the circuit 40.
1 is kept in an unpressurized state. Therefore, regardless of the position of the valve spool 61 of the pressure increase control valve 17, the circuit 65 is maintained in a pressure-free state by communicating with the pressure-free circuit 41 or the drain port 66, and the vacuum throttle valve 25 is maintained in a pressure-free state. The port 25a is made to function as a drain port. On the other hand, the vacuum throttle valve 25 responds to the engine suction negative pressure (throttle opening degree), connects the throttle pressure circuit 42 to the circuit 43 that communicates with the line pressure circuit 19 and the port 25a in the drain state, and disconnects the throttle pressure circuit 42 from the circuit 43. The line pressure is regulated to a throttle pressure according to the engine throttle opening and output to the throttle pressure circuit 42.
This throttle pressure is supplied from the circuit 42 to the pressure regulator valve 20, which adjusts the line pressure generated in the circuit 19 to a predetermined pressure according to the throttle opening as shown by α in FIG. can. Thus, in the two ranges of the manual valve, it supplies line pressure from line pressure circuit 19 to circuit 40, and throttle backup valve 26 supplies a constant backup pressure to circuit 41, which is a value below this line pressure. It is output and supplied to the pressure increase control valve 17. Here, we will explain the line pressure control action when the manual valve 18 is switched to the 2nd range with the manual valve 18 set to the D range while driving in the overdrive gear position with the manual valve 18 set to the D range in order to perform engine braking. As the direct clutch 6 and band brake 13 are activated by line pressure, the gear is shifted from overdrive to second gear, and this state is maintained, making it possible to drive with engine braking in second gear. do. However, until the operation of the direct clutch 6, which is gradually performed by the action of the accumulator 59 as described above, is completed, the direct clutch pressure toward the direct clutch 6 is low because the reaction force is small, and this pressure is transferred to the chamber 63 through the circuit 67. Even if the valve spool 61 reaches the position shown in FIG. Circuit 65 therefore communicates with drain port 66 to maintain port 25a of vacuum throttle valve 25 in the drain condition. Therefore, the vacuum throttle valve 25 outputs the throttle pressure corresponding to the throttle opening to the circuit 42 as before.
Continue supplying pressure regulator valve 20. Thus, the pressure regulator valve 20
The line pressure is regulated to an appropriate value according to the throttle opening as shown by α in Fig. 3, and the tightening force of the direct clutch 6 that is being operated by this line pressure is not excessive, and the shock during the range switching is maintained. can be prevented from occurring. After that, when the operation of the direct clutch 6 is completed, the direct clutch pressure becomes the same value as the line pressure under a large reaction force. This pressure reaches the chamber 63 from the circuit 67, pushes the valve spool 61 against the spring 64 to the left half position in the figure, and connects the circuit 65 to the circuit 41. By the way, as mentioned above, since backup pressure is supplied to the range switching circuit 41,
This backup pressure reaches port 25a of vacuum throttle valve 25 via circuit 65.
Therefore, the vacuum throttle valve 25 outputs a constant high throttle pressure to the throttle pressure circuit 42 by supplying backup pressure to the port 25a which has been drained until now. The throttle pressure reaches the pressure regulator valve 20 and is regulated thereby to maintain the line pressure generated in the circuit 19 at a high constant value as shown by β in FIG. The line pressure increased in this way is used to maintain the operation of the direct clutch 6, but since the direct clutch 6 has already completed its operation and is in a steady state, it does not cause a shock. Moreover, while the band brake 13 is kept in the operating state by the range switching as described above, this increased line pressure slightly reduces its operating force when it operates in the trailing direction (for engine braking). If this is sufficient, the effectiveness of engine braking can be improved. (6) Effects of the Invention Thus, the present invention provides the first speed, second speed, and
3rd speed and overdrive gears are automatically selected, and when the manual valve 18 is switched to 2nd speed and 2 ranges with the overdrive gear selected, the band brake 13 is activated by line pressure, and the line pressure The clutch (direct clutch) 6 is also operated to select and hold the second gear, and the line pressure is increased by the backup pressure generated at the second gear range position of the manual valve 18 (β in Fig. 3). In the automatic transmission with an overdrive, a pressure increase control valve 17 is provided which responds to the operating pressure of the clutch 6, thereby cutting off the backup pressure supply circuit and increasing the line pressure until the clutch 6 completes operation. Since the above-mentioned pressure increase is delayed, the clutch 6 is actuated with the appropriate line pressure before pressure increase, as described above, and the shock caused by the operation of the clutch 6 at the time of range switching is suppressed. Occurrence can be prevented. Further, after that, the band brake 13 is prevented from slipping as usual by increasing the line pressure, and the engine braking effect can be made sufficient.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram illustrating the power transmission gear train of the automatic transmission with overdrive of the present invention, and Fig. 2 is a shift control hydraulic circuit of the automatic transmission with overdrive of the present invention configured to control the shift of the same gear train. figure,
FIG. 3 is a line pressure change characteristic diagram of the automatic transmission of the present invention. 1... Torque converter section, 2... Overdrive gear train section, 3... 3rd speed gear train section, 6... Direct clutch, 7... Overdrive brake, 13... Band brake, 17... Pressure increase control Valve, 18... Manual valve, 19... Line pressure circuit, 20... Pressure regulator valve, 21... Oil pump, 22... 1-2 shift valve, 23... 2-3 shift valve, 25...
...Backup throttle valve, 26...Throttle backup valve, 28...Second lock valve, 30...Governor valve, 32...Governor pressure circuit, 40...2 range pressure circuit, 41...Throttle backup valve Pressure circuit, 42...Throttle pressure circuit, 44...3-4 shift valve, 45...
...Overdrive release valve, 46...Overdrive release solenoid, 47...Lockup control valve, 53, 54...One-way orifice, 57...Accumulator, 60...
...actuator, 61...valve spool, 62...
...valve body, 63...valve chamber, 64...spring,
65...Communication circuit, 66...Drain port, 67
...Direct clutch pressure extraction circuit.

Claims (1)

[Scope of Claims] 1. With the manual valve in the drive range, the first, second, third, and overdrive gears are automatically selected, and with the overdrive gear selected, the manual valve is in the drive range. When switching the valve to the 2nd gear range, the band brake is activated by line pressure and the clutch is also activated by the line pressure to select and hold the 2nd gear, which occurs at the 2nd gear range position of the manual valve. In an automatic transmission with an overdrive that increases the line pressure using backup pressure, a pressure increase control valve that shuts off the backup pressure supply circuit in response to the operating pressure of the clutch until operation of the clutch is completed. An automatic transmission with an overdrive, which is characterized by being provided with.