JPS62113951A - Automatic transmission for vehicle - Google Patents

Abstract

PURPOSE:To improve the shock of gear shift on a driver when a non- continuously variable transmission is shifted so that it becomes a more pleasant one for the driver by providing, between an engine and the non-continuously variable transmission, the No.2 clutch which is allowed to be in a partially engaged state during the transmission is being shifted. CONSTITUTION:Between the crankshaft 16 of an engine 10 and the input shaft 18 of a non-continuously variable transmission 14 are provided in parallel both the No.1 clutch 22 which is being engaged all the time during the normal running of a vehicle, and is disengaged during the period the transmission 14 is being shifted, and the No.2 clutch 24 which is being always disengaged during the vehicle is in normal running and is allowed to be in a partially engaged state during the period the transmission 14 is being shifted. Hereby, even during the period the transmission 14 is being shifted, the power output of the engine 10 can be transmitted by means of the No.2 clutch 24, and accordingly, the shock of gear shift on the driver when the transmission 14 is shifted can be improved so as to become a more pleasant one for the driver.

Description

Detailed Description of the Invention Technical Field The present invention relates to an automatic transmission for a vehicle, and more particularly to a technique for improving the shift feel during upshifting in a low gear of a stepped transmission having a synchronous mesh gear train. It is.

BACKGROUND OF THE INVENTION 2. Related Art and Problems An automatic transmission for a vehicle has been proposed in which an actuator switches the gear stages of a stepped transmission having a synchronous mesh gear train. According to this type of automatic transmission, it is possible to obtain fuel efficiency equivalent to that of a manual transmission.

However, during automatic shift operation of such an automatic transmission, the throttle valve opening etc. are changed and the engine output is temporarily reduced according to a predetermined operating sequence, and at the same time, the stepped transmission is After the clutch connecting the input shaft and the engine is released, the actuator changes the gear stage of the stepped transmission, and the clutch is again engaged. Therefore, during the clutch release period, that is, during the period in which power transmission from the engine is interrupted, there is a problem in that the shift feeling is impaired. especially,
When shifting in a low gear, such as upshifting from 1st gear to 2nd gear, or vice versa, downshifting from 1st gear to 2nd gear, or vice versa, the transmission input shaft is This inconvenience is significant because the difference between the drive torque and the drive torque of the output shaft is large.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The gist is that an automatic transmission for a vehicle is equipped with a stepped transmission having a synchronous mesh gear train, and the gears of the stepped transmission are switched and shifted by an actuator.(1) a first clutch provided between the engine and the input shaft of the stepped transmission, which is always engaged while the vehicle is running, but released during a shift period of the stepped transmission; 2) A shaft provided between the engine and the output shaft of the stepped transmission, which is always disengaged while the vehicle is running, but is semi-engaged during a shift period of the stepped transmission. 2
This is because a clutch is provided.

Operation and Effect of the Invention In this way, in addition to the first clutch which is always engaged while the vehicle is running but is released during the shift period of the stepped transmission; A second crunch, which is always released but is semi-engaged during the shift period of the stepped transmission, is provided between the engine and the output shaft of the stepped transmission, so that the gear shift Engine power is transmitted through the second clutch even during a shift period of the machine.

Therefore, even during the shift period of the transmission, where power transmission from the engine to the drive wheels was interrupted in the past, the second
Since an appropriate amount of power is transmitted by the half-engaged state of the clutch, driving torque is obtained even during the shift period, and the speed change during shifting of the transmission is suitably improved.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, power from a vehicle engine 10 is transmitted to drive wheels via a clutch device 12, a stepped transmission 14, a differential device (not shown), and the like.

The clutch device 12 is provided between the crankshaft 16 of the engine 10 and the input shaft 18 of the transmission 14, and includes a first clutch 22 provided between the crankshaft 16 and the input shaft 18, 16 and a second clutch 24 provided between the output shaft 56 and the output shaft 56 in parallel.

That is, as shown in detail in FIG.
includes a first clutch 22, a second clutch 24, and a human power shaft 18.
and a clutch case 26 that accommodates the shaft end of the output shaft 56
is fixed. The output shaft 56 passes vertically through the input shaft 18, and the human power shaft 18 and the output shaft 56 are provided so as to be relatively rotatable. The output shaft 56 has a 20th motor 3.
A second hub 32 supporting 0 is spline-fitted.

In addition, a tenth damper 38 is connected to the input shaft 18, and a first damper 36 is connected to the input shaft 18.
A first hub 34 is spline-fitted. Inside the clutch case 26, a tenth motor 38 is provided.
An annular friction plate 40 is fixedly located between the 20th holder 30 and the 20th holder 30, and a pressing plate 4 for pinching the 10th holder 38 between the friction plate 40 and the 10th holder 38.
2 is provided so as to be movable in the axial direction. In addition, a first piston 46 is provided in a portion of the clutch case 26 on the side of the transmission 14, and is moved in the axial direction when hydraulic pressure supplied from a hydraulic control circuit 130 (described later) through an oil passage 44 is applied. The pressing plate 42 is pressed by this first piston 46.

Furthermore, a second piston 5o is disposed in the engine 10 side portion of the clutch case 26, and is moved in the axial direction when the hydraulic pressure supplied through another oil passage 48 is applied. 50 and friction plate 4
0, and the 20th-tater 3o is compressed between the two. Note that 52 is a bearing, and 54 is an oil seal.

Returning to FIG. 1, the transmission 14 is provided with a counter shaft 58 parallel to its input shaft 18 and output shaft 56, which is rotationally driven by the input shaft 18 via coupling gears 60, 62. The counter shaft 58 includes a first gear 64, a second gear 66, and a third gear that are relatively rotatably provided on the output shaft 56.
Gears 70, 72, and 74 that mesh with the gear 68, respectively, are fixed, and the rotational speeds of the third gear 68, second gear 66, and first gear 64 are lower than that of the input shaft 18, and are sequentially lower than each other. Rotationally driven.

The output shaft 56 is connected to the second gear 66 or the first gear 6.
4, a first synchronizer 78 actuated by a first hydraulic cylinder 76 to connect with the third gear 68, or a second synchronizer 82 actuated by a second hydraulic cylinder 80 to connect with the input shaft 18, respectively. It is provided. Therefore, in the first synchronizer 78, when the sleeve 86 is moved to the right in the figure by the first hydraulic cylinder 76 and the output shaft 56 and the first gear 64 are connected, the transmission 14 is shifted to the first speed. However, when the sleeve 86 is moved to the left in the figure and the output shaft 56 and the second gear 66 are connected, the transmission 14 is shifted to the second gear. Further, in the second synchronizer 82, the second hydraulic cylinder 80 moves the sleeve 87 to the right in the figure, so that the output shaft 5
6 and the third gear 68 are connected, the transmission 14 is shifted to the third gear stage, but by moving the sleeve 87 to the left in the figure, the output shaft 56 and the input shaft 18 are connected. Then, the transmission 14 is shifted to the fourth gear.

The synchronizers 78 and 82 have well-known structures, and the first synchronizer 78 includes a hub 84 fixedly attached to the output shaft 56, as shown in FIG.
A sleeve 86 that is movable in the axial direction with respect to the hub 84 but not rotatable relative to the shaft and driven by the first hydraulic cylinder 76; a key 88 that is movable with the sleeve 86 on the inner peripheral side of the sleeve 86; That key 88
The clutch gear 92 is formed on the first gear 64, and the synchronizing ring 94 is provided between the sleeve 86 and the clutch gear 92. When the sync ring 94 is pressed through the sync ring 88, the sync ring 94 and the first
The rotations of the hub 84 and clutch gear 92 are synchronized by friction with a cone portion 96 formed on the gear 64, and then the sleeve 86 is further moved to mesh with the clutch gear 92.

The engine 10 is provided with an engine rotation sensor 100 for detecting its rotation speed.
A rotation signal SE corresponding to a rotation speed Ne of 0 is supplied to the controller 102. The accelerator pedal 104 of the vehicle includes an accelerator sensor 1 for detecting the operation amount Acc of the accelerator pedal 104.
06 is provided, and an accelerator signal SA representing the amount of accelerator operation is supplied to the controller 102. A vehicle speed sensor 108 is provided near the output shaft 56.
A signal S■ corresponding to the rotational speed of the output shaft 56, that is, the vehicle speed ■ is supplied to the controller 102. An input shaft rotation sensor 110 is provided near the input shaft 18, and a signal Sl corresponding to the rotation speed Ni of the input shaft 18 is supplied to the controller 102. The transmission 14 is provided with a gear position sensor 112 for detecting the actual gear position, and a signal SG representing the actual gear position is supplied to the controller 102. Further, the shift lever 114 of the vehicle is provided with an operating position sensor 116 for detecting the operating position thereof, and a signal SL representing the operating position of the shift lever 114 is supplied to the controller 102.

The controller 102 includes RAMI 18 and ROM 120.
, a CPU 122, an input interface 124, an output interface 126, etc., it processes input signals according to a program stored in advance in the ROM 120 while utilizing the storage function of the RAM 118, and sends a drive signal to the throttle actuator 128. While outputting BD, the clutch device 1
2 and transmission 14, drive signals are supplied to solenoid valves 132, 134, 136, and 138 of hydraulic control circuit 130, respectively. This hydraulic control circuit 130 includes a hydraulic pump driven by the engine 10 or the like,
In response to the operation of the solenoid valves 132, 134, 136, 138, hydraulic pressure is supplied to the first hydraulic cylinder 76, the second hydraulic cylinder 80, the first clutch 22, and the second clutch 24, respectively.

Throttle valve 14 provided in the intake pipe of engine 10
0 is adapted to be driven by the throttle actuator 128, and is normally driven in accordance with the drive signal BD from the controller 102 so that the throttle valve opening θ corresponds to the accelerator operation amount. The solenoid valves 132 and 134 are connected to the first hydraulic cylinder 7, respectively.
6 and the second hydraulic cylinder 80, and when in operation, supplies hydraulic pressure for obtaining a predetermined gear stage of the transmission 14 to the corresponding hydraulic cylinder. Further, the electromagnetic valves 136 and 138 are connected to the first clutch 2, respectively.
2 and the second clutch 24, and when activated, supplies hydraulic pressure to keep the clutches engaged.

The operation of this embodiment will be explained below.

In the controller 102, the CPU 22 selects a control mode such as start control, neutral control, shift control, engine brake control, etc. according to vehicle condition parameters. When the shift control mode is selected while the vehicle is running, the CPU 122 always operates the electromagnetic valve 136 to engage the first clutch 22 and disengage the second clutch 24.
8 is inactive. In this shift control, CPU2
2 selects a shift pattern corresponding to the current gear stage from among a plurality of shift patterns stored in advance in the ROM 120;
Based on the shift pattern, a shift command is issued to obtain the required gear based on the vehicle speed, accelerator operation amount, etc.

In such a case, shifts are automatically performed from each gear to a commanded predetermined gear in a predetermined order. For example, if an upshift command is issued while the vehicle is running in the second gear, the shift to the third gear is automatically executed according to the steps shown in FIG.

That is, by first executing step S1,
At the same time as the electromagnetic valve 136 is deactivated and the first clutch 22 begins to be disengaged, the electromagnetic valve 138 is activated and the second clutch 24 begins to be partially engaged. Point a in FIG. 5 shows this state. In the above state, the first
When the transmission torque of the clutch 22 reaches zero, step S2 is executed, a hydraulic cylinder for driving the synchronizer is operated, and half-engagement control of the second clutch 24 is started. Point b in FIG. 5 shows this state.

After this point, the first hydraulic cylinder 76
After the solenoid valve 132 is activated to move the sleeve 87 to the neutral position, the solenoid valve 134 is activated so that the second hydraulic cylinder 80 moves the sleeve 87 toward the third gear, and the transmission 14 is activated. Shifted to third gear. During this period, the rotation speed Ni of the input shaft 18 is reduced by the operation of the second synchronizer 82, and the rotation speed N of the input shaft 18 is reduced.
i is lowered from, for example, 4000 rpm to 20QQrpm, and the connection between the output shaft 56 and the third gear 68 is completed. Point 0 in FIG. 5 indicates the starting point of the synchronizing action of this second synchronizer 82. In addition, during the above period, the actual rotational speed Ne of the engine 10 approaches the rotational speed N a (target value) of the engine 10 after the shift, which is calculated from the gear ratio of the gear after the shift and the current vehicle speed. In order to obtain a constant transmission torque Tos determined in advance, the hydraulic pressure stored in the ROM 11B in advance is transmitted from the hydraulic control circuit 130 to the second clutch 2 in correspondence with the constant transmission torque Tos.
4, and the second clutch 24 is brought into a semi-engaged state. The transmission torque Tos is determined in advance for each gear stage of the transmission 14, and a plurality of types of oil pressures corresponding thereto are also stored in advance. In this way, the controller 102 also functions as a transmission torque control means for the second clutch 24.

When the gear shift of the transmission 14 is completed as shown at time d in FIG. 5, step S3 is executed, and the solenoid valve 13
At the same time, the electromagnetic valve 138 is made inactive and the second clutch 22 starts to engage.
Clutch 24 begins to be released. This allows the first
When the clutch 22 is engaged, the second clutch 2
4 is released to complete the series of shift operations. Fifth
Point e in the figure shows this state.

In this way, during the upshift period of the transmission 14, the power of the engine 10 is transmitted by the second clutch, so that the power transmission from the engine 10 is interrupted, that is, the feeling of acceleration is lost during acceleration. This eliminates this problem and improves the feeling of shifting.

Also, during the upshift period of the transmission 14, the rotational speed Ne of the engine 10 is lowered by the half-engagement of the second clutch 24 and brought closer to the rotational speed NY, so the synchronization action time by the synchronizer is reduced. The time is shortened, and the shifting feeling is further improved.

On the other hand, when shift control is selected as described above,
For example, if a downshift command is issued while driving in the third gear, the transmission of power from the engine 10 is automatically shifted to the second gear without interruption, following the same steps as shown in FIG. can be switched. That is, first, the first clutch 22 is released and the second clutch 24 is brought into a semi-engaged state. In this state, the second hydraulic cylinder 8
0, the sleeve 87 that had been on the right side and meshed with the third gear is moved to the neutral position, and then
The sleeve 86, which was previously in the neutral position, is moved to the left by the hydraulic cylinder 76 and is brought into mesh with the second gear. During this period, the transmission torque Tor determined in advance is obtained so that the actual rotational speed Ne of the engine 10 approaches (increases) toward the rotational speed NT that should be obtained when the second gear is switched. The second clutch 24 is controlled to be in a half-engaged state so that the second clutch 24 is in a half-engaged state. Then, the first clutch 22 is engaged again and the second clutch 24 is released. In this way, as in the case of upshifting, even during the downshifting period, the second clutch 24
Since the power of the engine 10 is transmitted to the driving wheels,
Effects such as a suitably improved shift feeling can be obtained. Figure 6 shows the changes in the throttle valve opening θ, the transmission torque of each clutch, the rotational speed Ni of the input shaft 8, the rotational speed No of the output shaft 56, and the torque of the output shaft 56 in the case of this downshift. , and in the figure a
Points B, B, 0, D, and E indicate the same points as in FIG. 5, respectively.

In the above embodiment, the second clutch 24 is provided to directly connect the crankshaft 16 and the output shaft 56, but as shown in the transmission of FIG.
is provided between the first man's blade shaft 146 and the crankshaft 16, and the second clutch 24 is provided between the second man's blade shaft 148 and the crankshaft 1.
It may be provided between 6 and 6. In this case, the output of the second clutch 24 is connected to the second blade shaft 148, the connecting gear 150.
152, counter shaft 154, and final reducer 156 to the output shaft 158, 160, so that
4 is indirectly provided between the crankshaft 16 and the output shaft 158,160. In the figure, the connection between the first gear 162 and the counter shaft 154 leads to the first gear stage, the connection between the second gear 164 and the counter shaft 154 leads to the second gear stage, and the third gear 166 and the first mandrel shaft. 146, the first blade shaft 146 and the second blade shaft are connected to the third gear stage.
The transmission 14 can be switched to the fourth gear by connection with the man-made blade shaft 148, and to the fifth gear by the connection between the fifth gear 168 and the first man-made blade shaft 146.

Although one embodiment of the present invention has been described above, the present invention is also applicable to other aspects.

For example, the transmission torque T is realized by half-engagement control of the second clutch 24 during the shift period.

With S and Tor, even if the actual rotational speed Ne of the engine 10 is not a value that approaches the target value NT, power transmission can be obtained during the shift period in which power transmission would conventionally be interrupted. A certain effect can be obtained in terms of improving sensation.

Furthermore, the transmission torque T o s and Tor realized by half-engagement control of the second clutch 24 during the shift period are as follows:
The actual rotational speed Ne of the engine 10 may not only be brought close to the target value NA, but also be set to a value that substantially coincides with it during the shift period. In this way, the synchronization period by the synchronizer is further shortened.

Further, during the half-engagement period of the second clutch 24, the C
The PU 122 may perform feedbank control to adjust the transmitted torque so as to eliminate the deviation between the actual rotational speed Ne of the engine 10 and its target value N.

Further, the engine 10 of the above embodiment may be a diesel engine. In this case, the throttle actuator 128 moves a control lever provided on the fuel injection valve to adjust the amount of fuel supplied.

Note that the above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an automatic transmission for a vehicle according to an embodiment of the present invention. FIG. 2 is a sectional view showing the clutch device of FIG. 1 in detail. FIG. 3 is a diagram illustrating the synchronization device of FIG. 1. FIG. 4 is a flowchart illustrating the shift operation of the device shown in FIG. FIG. 5 is a time chart explaining the upshift operation of the device shown in FIG.
The figure is a time chart illustrating the downshift operation of the apparatus shown in FIG. FIG. 7 is a schematic diagram showing the main parts of another embodiment of the present invention. 10: Engine J4: Stepped transmission 22: First clutch 24: Second clutch

Claims (1)

[Scope of Claims] An automatic transmission for a vehicle, which includes a stepped transmission having a synchronous mesh gear train, and in which gear stages of the stepped transmission are switched and shifted by an actuator, comprising: an engine of a vehicle; It is installed between the input shaft of the stepped transmission and is always engaged while the vehicle is running.
a first clutch that is disengaged during a shift period of the stepped transmission; and a first clutch that is provided between the engine and the output shaft of the stepped transmission and is disengaged at all times while the vehicle is running; An automatic transmission for a vehicle, comprising: a second clutch that is in a semi-engaged state during a shift period of a gear transmission.