JP2003120808A - Automatic transmission - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To omit a back taper at a meshing portion between a synchro sleeve of a synchromesh mechanism and a spline,
The processing cost of this automatic transmission is reduced. SOLUTION: A partition 7a of a transmission case 7
A piston 62 supporting a steel ball 63 is fitted into the cylinder chamber 61. Further, locking ball grooves 68a to 68c that engage with the steel balls 63 are formed in the fork rod 51. When the synchromesh mechanism is driven by the shift actuator, the hydraulic pressure supplied to the cylinder chamber 61 is released, the fastening to the fork rod 51 is released, the driving load of the shift actuator is reduced, and the synchromesh mechanism drives the transmission gear train. When the state is switched to the transmission state, the hydraulic pressure is supplied to the cylinder chamber 61 to fasten the fork rod 51 to prevent the gear from slipping out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission mounted on an automobile or the like, and is particularly effective when applied to an automatic transmission having a plurality of speed change gear trains.

[0002]

2. Description of the Related Art Conventionally, an automatic transmission (Automated Manual Tra) based on the structure of a manual transmission (hereinafter referred to as MT) having a plurality of transmission gear trains is used.
nsmission. Hereinafter, abbreviated as AMT) is known.

The AMT has an input shaft that is connected to the engine and that is provided with a plurality of drive gears, and an output shaft that is provided with a plurality of driven gears that mesh with the drive gears to form a transmission gear train. Therefore, a shift mechanism such as a synchromesh mechanism is used to switch a shift gear train for transmitting power from among these shift gear trains to perform a shift operation. The synchromesh mechanism is connected to a hydraulic actuator via a fork rod reciprocally provided in the transmission case, and the hydraulic actuator automatically performs a gear shift operation, that is, a shift change.

In such an AMT, in order to prevent a so-called gear disengagement in which the synchromesh of the synchromesh mechanism and the spline are disengaged while the vehicle is traveling, for example, Japanese Unexamined Patent Publication No. 4-362314 and Japanese Utility Model Laid-Open No. 62- As shown in Japanese Patent No. 41935, the meshing portions of the synchromesh mechanism and the splines of the synchromesh mechanism are each formed in a back taper shape so as to generate a reaction force for gear disengagement. However, the processing of the back taper is complicated and the number of processing steps is increased, so that the processing cost of this automatic transmission is increased.

On the other hand, the fork rod is provided with a shift lock mechanism. This shift lock mechanism has a structure in which a spring load is applied to a steel ball that engages with a groove formed on the outer peripheral surface of the fork rod, and by applying an appropriate fastening force to the fork rod, the axial resistance force is increased. In addition, positioning and removal of gears are prevented.

[0006]

However, since the resistance force due to such a shift lock mechanism is set to a constant value according to the spring constant of the spring to be used,
If the resistance force is set to a large value to generate sufficient gear disengagement resistance, the load on the hydraulic actuator at the time of gear shifting operation will be increased. Therefore, conventional AMT
However, the resistance force cannot be set to a large value to secure sufficient gear pull-out resistance by the shift lock mechanism alone, and the back taper formed in the synchromesh mechanism cannot be omitted.

An object of the present invention is to reduce the machining cost of this automatic transmission by omitting the back taper at the meshing portion of the synchromesh mechanism and the spline.

[0008]

The automatic transmission according to the present invention comprises:
An input shaft provided with a plurality of drive gears, and an output shaft provided with a plurality of driven gears that mesh with the drive gears to form a speed change gear train, and power is transmitted by a switching mechanism driven by an actuator. Is an automatic transmission that automatically switches the transmission gear train that performs the above-mentioned operation. The automatic transmission is mounted in a transmission case accommodating the input shaft, the output shaft, and the switching mechanism so as to be axially reciprocally movable. For transmitting to the switching mechanism, a piston that is reciprocally mounted in a cylinder chamber formed in the transmission case, and applies a fastening force to the fork rod, and a fork rod when the fork rod moves in the axial direction. Release the hydraulic pressure supplied to the cylinder chamber and supply the hydraulic pressure to the cylinder chamber when fastening the fork rod. And having a hydraulic control unit that.

The automatic transmission according to the present invention is characterized in that the piston has an engaging member which engages with a groove formed on the outer peripheral surface of the fork rod.

The automatic transmission according to the present invention is characterized in that it has a shift state determining means for determining whether or not the shift gear train is in the power transmission state by the hydraulic pressure supplied to the cylinder chamber.

According to the present invention, when the transmission gear train is in the power transmission state, hydraulic pressure is supplied to the cylinder chamber to fasten the fork rod to prevent gear disengagement, and the fork rod is axially moved. When moving, the hydraulic pressure supplied to the cylinder chamber is released to reduce the load on the actuator, so the back taper at the meshing part of the switching mechanism can be omitted to reduce the processing cost of this automatic transmission. You can

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a skeleton diagram showing an automatic transmission according to an embodiment of the present invention. An engine 1 is provided with an electronically controlled throttle 2 for adjusting engine torque and engine speed, which is usually The electronic control throttle 2 is opened / closed by an output signal from an electronic control device according to the amount of depression of an accelerator pedal (not shown) to perform engine control. Further, the electronically controlled throttle 2 can be opened / closed as necessary to control the engine regardless of the depression amount of the accelerator pedal, based on a map or the like preset according to the detected operating state.

The automatic transmission for transmitting the power generated by the engine 1 to the drive wheels is connected to the input shaft 5 connected to the crankshaft 4 of the engine 1 via the torque converter 3 and to the drive wheels in parallel therewith. And an output shaft 6 which is installed in the transmission case 7 facing the traveling direction of the vehicle.

The input shaft 5 is integrally provided with first and second speed driving gears 11 and 12, and is rotatably provided with third to fifth speed driving gears 13 to 15. . Further, the output shaft 6 has a driven gear 21 for the first speed and a driven gear for the second speed,
22 is rotatably provided, and driven gears 23 to 25 from the third speed to the fifth speed are integrally provided. Each of the driving gears 11 to 15 has a corresponding driven gear 21 to 25.
To form a transmission gear train, and the gear shifting operation is performed by switching among the plurality of transmission gear trains that transmit power. Input shaft 5
Further, a drive gear 16 for retreating is integrally provided in the.

The output shaft 6 has a first mechanism as a switching mechanism between a first-speed driven gear 21 and a second-speed driven gear 22.
The synchromesh mechanism 31 is provided. The input shaft 5 has a second synchromesh mechanism 3 as a switching mechanism between the third speed drive gear 13 and the fourth speed drive gear 14.
2 is provided, and a third synchromesh mechanism 33 as a switching mechanism is provided adjacent to the fifth speed drive gear 15.

The synchromesh mechanism 31 has a synchromesh 31a fixed to the output shaft 6 and a synchromesh 31b which is constantly meshed with the synchromesh 31a.
When 1b is engaged with the spline 21a integrally formed with the first-speed driven gear 21, the gear ratio is set to the first speed, and conversely, the spline 22a integrally formed with the second-speed driven gear 22 is formed. When meshed, the second speed is set. Similarly, the other synchromesh mechanisms 32 and 33 also have the input shaft 5
Fixed to the synchro hubs 32a and 33a, and synchro sleeves 32b and 33b that mesh with them at all times.
And have splines 13 corresponding to them, respectively.
The gear ratio is set from the third speed to the fifth speed by engaging with any of a, 14a, and 15a.

A driven gear 26 for retreat is attached to the synchro sleeve 31b of the first synchromesh mechanism 31, and the idler shaft (not shown) parallel to the input shaft 5 and the output shaft 6 is retreated. An idler gear (not shown) is slidably mounted in the axial direction so as to be movable between a position where the driving gear 16 and the driven gear 26 are engaged with each other and a position where the gear is disengaged. Therefore, when the idler gear is slid under the neutral position of the synchronizing sleeve 31b, the idler gear meshes with the backward driving gear 16 and the driven gear 26, and the rotation of the input shaft 5 is changed from the first speed to the first speed. 5
It is transmitted to the output shaft 6 in the opposite direction to the case up to the speed.

The output shaft 6 is hollow, the front wheel output shaft 34 is incorporated therein, and the output shaft 6 and the front wheel output shaft 34 are included.
Are connected by a center differential device 35. The front wheel output shaft 34 is connected to a front wheel drive shaft (not shown) via a front differential device 36, and the drive shaft drives the front wheel (not shown). In addition, the center differential device 3
Reference numeral 5 is connected to a rear wheel output shaft 39 via a drive gear 37 and a driven gear 38, and the rear wheel output shaft 39 is connected to a rear wheel drive shaft (not shown) via a rear differential device (not shown). The drive shaft drives rear wheels (not shown).

A drive-side bypass gear 17 is rotatably attached to the input shaft 5, and a driven-side bypass gear 27 is integrally attached to the output shaft 6.
7, 27 are always meshed with each other at a predetermined gear ratio. In the illustrated case, these gear ratios are set to correspond to the third speed. The input shaft 5 is provided with a bypass clutch 18 composed of a hydraulic multi-plate clutch.
8 is a clutch drum 19 fixed to the bypass gear 17
And a clutch hub 20 fixed to the input shaft 5. A plurality of driving-side and driven-side clutch plates are alternately arranged on the clutch drum 19 and the clutch hub 20, respectively. When the clutch plates are pressed by hydraulic pressure, the torque of the input shaft 5 is transmitted via the bypass clutch 18 to the output shaft. 6 is transmitted.

An input clutch 41 is provided between the turbine shaft 8 of the torque converter 3 and the input shaft 5.
The input clutch 41 has a clutch drum 42 fixed to the turbine shaft 8 and a clutch hub 43 attached to the input shaft 5. By engaging a clutch plate mounted between the clutch drum 42 and the clutch hub 43, the turbine shaft 8 and the input shaft 5 are brought into the engaged state, and engine power is transmitted to the input shaft 5. On the other hand, when the engagement is released, the turbine shaft 8 and the input shaft 5 are opened, and the power transmission of the engine power to the input shaft 5 is cut off.

An oil pump 44 is mounted in the transmission case 7, and the rotor of the oil pump 44 is connected to the torque converter 3 and is rotationally driven by the crankshaft 4. The hydraulic oil discharged from the oil pump 44 is
It is supplied to the torque converter 3, the bypass clutch 18, the input clutch 41, hydraulic actuators such as a shift actuator, a select actuator, and a shift lock mechanism 60, which will be described later, and to each lubrication unit. Although the oil pump 44 is driven by the engine in the present embodiment, the present invention is not limited to this, and may be driven by an electric motor.

FIG. 2 is a perspective view showing a shift fork for driving the synchro sleeve of the synchromesh mechanism, and FIG. 3 is a sectional view showing details of the fork rod shown in FIG. FIG. 4 is a sectional view showing details of the shift lock mechanism.

As shown in FIGS. 2 and 3, the transmission case 7 of this automatic transmission is provided with fork rods 51 to 53, and each of the fork rods 51 to 53 is a partition wall 7 of the transmission case 7.
support holes 9a to 9c, 10a to 10 provided in a and 7b.
It is supported by c and can reciprocate in the axial direction.

A first shifter fork 51a for sliding a synchro sleeve 31b of the first synchromesh mechanism 31 is fixed to the fork rod 51, and a synchro sleeve of the second synchromesh mechanism 32 is fixed to the fork rod 52. A second shifter fork 52a that slides 32b is fixed. Further, a third shifter fork 53a is fixed to the fork rod 53 so as to slide a synchro sleeve 33b of the third synchromesh mechanism 33 and a reverse switching mechanism (not shown) for switching the idler shaft.

Engagement portions 51b to 53b are provided at one ends of the respective fork rods 51 to 53, and a shifter arm 54 is engaged with these engagement portions 51b to 53b. The fork rods 51 to 53 are driven by driving the shifter arm 54 in the left-right direction in the drawing by a shift actuator (not shown). Further, one of the fork rods driven by the shifter arm 54 is set by a select actuator (not shown).

As shown in FIG. 4, this automatic transmission has
A shift lock mechanism 60 is provided to prevent disengagement of the synchromesh mechanism while the vehicle is traveling. In addition, in the present embodiment, the shift lock mechanism 60 is provided for each of the fork rods 51 to 53, but each shift lock mechanism 6 is provided.
Since 0 has the same structure, in the following, fork rod 5
Only those for 1 will be described.

As shown in FIG. 4, the partition wall 7a of the transmission case 7 that supports the fork rod 51 includes:
A cylinder chamber 61 opening to the support hole 9a is formed, and a piston 62 is mounted inside the cylinder chamber 61 so as to be reciprocally movable in the axial direction. Further, a steel ball 63 as an engaging member is attached to the fork rod 51 side of the piston 62.

The cylinder chamber 61 communicates with the oil pump 44 via a hydraulic passage 64, and the hydraulic pressure from the oil pump 44 is supplied to the cylinder chamber 61. Further, a solenoid valve 65 as a hydraulic control means is provided in the hydraulic passage 64 for controlling the hydraulic pressure supplied to the cylinder chamber 61.

The inflow port 65a of the solenoid valve 65 is connected to the oil pump 44, and the oil pressure from the oil pump 44 adjusted to a predetermined value by a pressure adjusting valve (not shown) is supplied. Further, the outflow port 65b of the solenoid valve 65 communicates with the cylinder chamber 61 via the hydraulic passage 64, and further, the discharge port 65b.
c is communicated with the oil pan 66.

The solenoid valve 65 is switched by turning on / off the energization of the solenoid portion 65d. When the energization of the solenoid portion 65d is turned on, the inflow port 65a and the outflow port 65b are communicated with each other, and the oil When the hydraulic pressure from the pump 44 is supplied to the cylinder chamber 61 and the energization of the solenoid portion 65d is turned off, the outflow port 65b and the exhaust port 6 are discharged.
The hydraulic pressure in the cylinder chamber 61 is drained to the oil pan 66 by communicating with 5c.

A hydraulic pressure sensor 67 is provided in the hydraulic pressure passage 64 as a gear shift state determining means.
The hydraulic pressure of No. 4, that is, the hydraulic pressure supplied to the cylinder chamber 61 can be detected. In the present embodiment, since the shift lock mechanism 60 is provided for each of the fork rods 51 to 53, the hydraulic flow path 64, the solenoid valve 65, etc. are also provided separately. The number of the solenoid valves 65 is not limited to one, and the hydraulic flow path 64 connected to the outflow port 65b is branched so as to branch the fork rods 51 to 5 respectively.
Main constituent members may be shared by the respective cylinder chambers 61, such as supplying hydraulic pressure to the cylinder chambers 61 for the three cylinders at the same time.

On the other hand, on the outer peripheral surface of the fork rod 51, three locking ball grooves 68a, 68b are formed as grooves.
68c is formed, and the locking ball groove 68a is arranged such that the fork rod 51 moves the synchromesh mechanism 31 to the first position.
The locking ball groove 68b is arranged so as to engage with the steel ball 63 when completely meshed at high speed, and the locking ball groove 68b engages with the steel ball 63 when the fork rod 51 brings the synchromesh mechanism 31 to the neutral position. The locking ball groove 68c is arranged so as to engage with the steel ball 63 when the fork rod 51 completely engages the synchromesh mechanism 31 in the second speed.

When the shift lock mechanism 60 is engaged, the hydraulic pressure is supplied to the cylinder chamber 61 with the steel ball 63 engaged with the locking ball groove, and the piston 62
Is operated to strongly press the steel ball 63 into the rocking ball groove and apply a fastening force to the fork rod 51. When the hydraulic pressure supplied to the cylinder chamber 61 is released, the engagement between the steel ball 63 and the locking ball groove is released, and the fastening force applied to the fork rod 51 is released. In the present embodiment, when the hydraulic pressure supplied to the cylinder chamber 61 is released, the hydraulic pressure in the cylinder chamber 61 is drained to the oil pan 66 and is almost zero.
However, the present invention is not limited to this, and a predetermined hydraulic pressure lower than that at the time of fastening may be supplied to the cylinder chamber 61 even when the hydraulic pressure is released, and at that time, a fastening force smaller than that at the time of fastening. May occur on the fork rod 51.

This automatic transmission detects the running state of the vehicle by signals such as engine speed, accelerator opening, vehicle speed, input shaft speed, and gear position, and shifts based on a preset map. Is done automatically. That is, the shift operation is performed by controlling the select actuator and the shift actuator according to the running state of the vehicle.

The shift lock mechanism 60 releases the hydraulic pressure to be supplied to the cylinder chamber 61 during a gear shifting operation, that is, when the fork rod 51 is axially moved by a shift actuator (not shown) to drive the synchromesh mechanism. The fastening force on the fork rod 51 is released.

For example, when shifting from the first speed to the second speed, the fork rod 51 moves from the position where the locking ball groove 68a engages with the steel ball 63 by the shift actuator to the locking ball groove 68c moves to the steel ball 63. The hydraulic pressure supplied to the cylinder chamber 61 of the shift lock mechanism 60 is released during that time, and the steel ball 63 and the locking ball grooves 68a, 68 are released.
The engagement with b and 64c is released to reduce the drive load of the shift actuator.

As described above, when the fork rod 51 moves in the axial direction, the shift lock mechanism 60 releases the fastening force applied to the fork rod 51 to reduce the drive load of the shift actuator. By downsizing, this automatic transmission can be made smaller and lighter.

On the other hand, when the synchro sleeve driven by the shift actuator is in a state of being completely meshed with the spline of the shift stage, that is, when the synchromesh mechanism switches the shift gear train to the power transmission state, the cylinder chamber 61 The hydraulic pressure is supplied to the fork rod 51 to apply a fastening force.

That is, the fork rod 51 uses the shift actuator to move the locking ball groove 68c into the steel ball 63.
When driven to a position where it engages with, that is, the synchro sleeve 31b moves from the spline 21a side to the spline 2
When it moves to the 2a side and is completely meshed with the spline 22a, the cylinder chamber 61 of the shift lock mechanism 60 is
By supplying the hydraulic pressure to the fork rod 51, a fastening force is applied to the fork rod 51 to restrain the movement of the fork rod 51 in the axial direction so that gear disengagement does not occur.

As described above, when the synchromesh mechanism driven by the shift actuator is completely meshed with the spline of the shift stage and the synchromesh mechanism is in the power transmission state, hydraulic pressure is supplied to the cylinder chamber 61 to shift-lock. Since the mechanism 60 applies the fastening force to the fork rod 51, the shift lock mechanism 60
It is possible to obtain sufficient resistance to disengagement of gears. Therefore, it is not necessary to provide a back taper at the meshing part of the synchromesh mechanism and the spline to generate a reaction force that causes the gear to slip out, facilitating the machining of the synchromesh mechanism and reducing the machining cost of this automatic transmission. can do. Further, since it is not necessary to provide a back taper at the meshing portion between the synchro sleeve and the spline, it is possible to reduce the backlash of the synchromesh mechanism and reduce the shift shock of the automatic transmission.

Further, in the shift lock mechanism 60, the hydraulic pressure is supplied to the cylinder chamber 61 when the synchromesh mechanism is in the power transmission state, and the cylinder chamber 61 is in the gear shifting operation, that is, when the synchromesh mechanism is not in the power transmission state. Since the hydraulic pressure of 61 is released, by monitoring the hydraulic pressure of this cylinder chamber 61 with the hydraulic sensor 67, it is possible to determine whether or not the synchromesh mechanism is in the power transmission state. Therefore, the detection signal from the oil pressure sensor 67 can be used as a fail-safe signal.

It is needless to say that the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, the shift speed is 5 forward gears and 1 reverse gear. However, the present invention is not limited to this. Good.

[0044]

According to the present invention, when the transmission gear train is in the power transmission state, hydraulic pressure is supplied to the cylinder chamber to fasten the fork rod to prevent the gear from coming off, and the fork rod is axially moved. Since the hydraulic pressure supplied to the cylinder chamber is released to reduce the load on the actuator when moving to, the back taper at the meshing portion of the switching mechanism is omitted, and the processing cost of this automatic transmission is reduced. be able to. Further, by omitting the back taper at the meshing portion of the switching mechanism, the backlash of the switching mechanism can be reduced. Further, since the driving load on the actuator is reduced, the actuator can be downsized and the automatic transmission can be downsized and lightweight.

Further, since it is possible to judge whether the switching mechanism is in the power transmission state or not by detecting the oil pressure in the cylinder chamber by the gear shift state judging means, use this detection signal as a fail safe input. You can

[Brief description of drawings]

FIG. 1 is a skeleton diagram showing an automatic transmission according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a shift fork for driving a synchromesh of a synchromesh mechanism.

FIG. 3 is a sectional view showing details of the fork rod shown in FIG.

FIG. 4 is a sectional view showing details of a shift lock mechanism.

[Explanation of symbols]

1 engine 5 input axes 6 Output shaft 7 transmission case 11-15 Drive gear 21-25 Driven gear 31-33 Synchromesh mechanism 51-53 Fork rod 60 shift lock mechanism 61 cylinder chamber 62 pistons 63 steel balls 65 solenoid valve 67 Oil pressure sensor 68a-68c Rocking ball groove

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinya Asao             1-7-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Fuji             Heavy Industry Co., Ltd. F term (reference) 3J067 AC05 BA58 FA22 FA82 FA84                       FB83 GA01

Claims (3)

[Claims] 1. An input shaft provided with a plurality of drive gears,
An automatic output gear having an output shaft provided with a plurality of driven gears that mesh with the drive gear to form a transmission gear train, and automatically switches the transmission gear train for transmitting power by a switching mechanism driven by an actuator. A fork rod that is reciprocally mounted in a transmission case that accommodates the input shaft, the output shaft, and the switching mechanism, and that transmits the output of the actuator to the switching mechanism. A piston, which is reciprocally mounted in a cylinder chamber formed in the transmission case, applies a fastening force to the fork rod, and releases the hydraulic pressure supplied to the cylinder chamber when the fork rod moves in the axial direction. And a hydraulic control means for supplying hydraulic pressure to the cylinder chamber when the fork rod is fastened. Automatic transmission to be. 2. The automatic transmission according to claim 1, wherein the piston has an engaging member that engages with a groove formed on an outer peripheral surface of the fork rod. 3. The automatic transmission according to claim 1, further comprising a shift state determination means for determining whether or not the shift gear train is in a power transmission state by the hydraulic pressure supplied to the cylinder chamber. Characteristic automatic transmission.