AUTOMATIC TRANSMISSION

Abstract

Automatic transmission (1) in an engine compartment (100A) of a motor vehicle (100) having an onboard component (51) within the engine compartment (100A), the automatic transmission (1) comprising: a transmission housing unit (2) spaced rearwardly from the onboard component (51) in a direction along the longitudinal axis of the motor vehicle (100) and having an outer wall (4c) including a front wall (4A) at the front end, the transmission housing unit (2) accommodating at least one gearshift actuating element (5, 10) for performing a gearshift operation; and a gearshift unit (30) for automatically actuating the gearshift actuating element (5, 10) to shift gears, wherein the gearshift unit (30) includes a hydraulic fluid storage device (36), a hydraulic pressure generating device (32) for pressing the hydraulic fluid from the hydraulic fluid storage device (36), an actuating device (33) that is actuable with the hydraulic fluid pressed by the hydraulic pressure generating device (32) to actuate the gearshift actuating element (5, 10), and a base plate (35) that supports the hydraulic fluid storage device (36), the hydraulic pressure generating device (32), and the actuating device (33) for attaching the hydraulic fluid storage device (36), the hydraulic pressure generating device (32), and the actuating device (33) to the outer wall (4c) of the transmission housing unit (2), wherein the base plate (35) has an outwardly extending portion (35a), wherein the outwardly extending portion (35a) extends more forward in a direction along the longitudinal axis of the motor vehicle (100) than the front wall (4A) at the front end of the transmission housing unit (2), wherein the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) are mounted on the outwardly extending portion (35a) of the base plate (35) such that the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) are opposite the onboard component (51) but spaced apart from the onboard component (51) in the rearward direction, and that the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) are mounted vertically such that the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) overlap with each other in the vertical direction when a front end surface (36a) of the hydraulic fluid storage device (36) and a front end surface (37a) of the hydraulic pressure generating device (32) lie in the same vertical plane (53), wherein the hydraulic pressure generating device (32) includes a motor (37), a hydraulic fluid pump (38) for conveying a hydraulic fluid from the hydraulic fluid storage device (36), and a pressure accumulating device (39) for accumulating a hydraulic pressure of the hydraulic fluid conveyed by the hydraulic fluid pump (38); and wherein the pressure accumulation device (39) is attached to the outwardly extending portion (35a) of the base plate (35) such that the pressure accumulation device (39) is located on the lateral side of the hydraulic fluid storage device (36), and is mounted behind a vertical plane in contact with a front end surface (38a) of the hydraulic fluid pump (38), but in front of a vertical plane in contact with the front wall (4A) at the front end of the transmission housing unit (2).

Description

[Technical field]

[0001] This invention relates to an automatic transmission, more particularly to an automatic transmission mounted within an engine compartment behind an onboard component. [State of the art]

[0002] An automatic transmission is mounted in the engine compartment of a motor vehicle behind an onboard component, such as a radiator. The automatic transmission includes a pump. The pump is located opposite the radiator but is spaced rearward from the radiator, so the radiator is likely to exert a force on the pump after its rearward displacement caused by a frontal collision.

[0003] JP 2005-98338 A discloses an arrangement for protecting an electric pump unit from the impact load caused by a frontal collision. The electric pump unit is mounted near a converter housing of a transmission housing unit such that a space is provided to allow displacement of the electric pump unit during a frontal collision.

[0004] This arrangement mitigates the impact on the electric pumping unit by allowing the electric pumping unit to move within the space during a frontal collision. [State of the art]

[0005] DE 41 33 737 A1 discloses a gearshift unit with a hydraulic fluid storage device and a hydraulic pressure generating device for forcing the hydraulic fluid from the hydraulic fluid storage device. An actuating device can be actuated with the hydraulic fluid. The hydraulic fluid is forced through the hydraulic pressure generating device to actuate a gearshift actuating element. The hydraulic pressure storing device and the hydraulic pressure generating device are integrated into a single assembly such that they overlap when a front end surface of the hydraulic fluid storage device and a front end surface of the hydraulic pressure generating device lie in the same vertical plane. [Summary of the invention][Technical problem]

[0006] The above-mentioned known arrangement is effective in protecting the electric pump unit from the impact, but it is not effective in preventing the application of excessive force to the transmission case unit after the electric pump unit comes into contact with the torque converter case.

[0007] An object of the present invention is to provide an automatic transmission capable of preventing the application of excessive force to the transmission case unit in the case where a motor vehicle is subjected to the impact caused by a frontal collision. [Solution to the problem]

[0008] In the present embodiment according to a first variant, an automatic transmission is provided in an engine compartment of a motor vehicle, having an onboard component within the engine compartment. The automatic transmission includes: a transmission housing unit spaced rearwardly along the longitudinal axis of the motor vehicle from the onboard component and having an outer wall including a wall at the front end, the transmission housing unit accommodating at least one gearshift operating element for performing a gearshift operation; and a gearshift unit for automatically actuating the gearshift operating element to shift gears.The gearshift unit includes a hydraulic fluid storage device, a hydraulic pressure generating device for forcing the hydraulic fluid from the hydraulic fluid storage device, an actuator that can be actuated with the hydraulic pressure exerted by the hydraulic pressure generating device to actuate the gearshift actuator, and a base plate that supports the hydraulic fluid storage device, the hydraulic pressure generating device, and the actuator for attaching the hydraulic fluid storage device, the hydraulic pressure generating device, and the actuator to the outer wall of the transmission housing unit. The base plate has an outwardly extending portion.The outwardly extending portion extends further forward in a direction along the longitudinal axis of the motor vehicle than the wall of the transmission housing unit at the front end.The hydraulic fluid storage device and the hydraulic pressure generating device are mounted on the outwardly extending portion of the base plate such that the hydraulic fluid storage device and the hydraulic pressure generating device are opposed to the onboard component but spaced apart from the onboard component in the rearward direction, and the hydraulic fluid storage device and the hydraulic pressure generating device are mounted vertically such that the hydraulic fluid storage device and the hydraulic pressure generating device overlap with each other in the vertical direction when a surface at the front end of the hydraulic fluid storage device and a surface at the front end of the hydraulic pressure generating device lie in the same vertical plane.The hydraulic pressure generating device includes a motor, a hydraulic fluid pump for supplying hydraulic fluid from the hydraulic fluid storage device, and a pressure accumulating device for accumulating hydraulic pressure of the hydraulic fluid supplied by the hydraulic fluid pump. The pressure accumulating device is attached to the outwardly extending portion of the base plate such that the pressure accumulating device is located on the lateral side of the hydraulic fluid storage device, and is mounted rearward of a vertical plane in contact with a front end surface of the hydraulic fluid pump, but forward of a vertical plane in contact with the front end wall of the transmission housing unit.

[0009] In the present embodiment according to a second variant, an automatic transmission is provided in an engine compartment of a motor vehicle, having an onboard component within the engine compartment. The automatic transmission includes: a transmission housing unit spaced rearwardly along the longitudinal axis of the motor vehicle from the onboard component and having an outer wall including a wall at the front end, the transmission housing unit accommodating at least one gearshift operating element for performing a gearshift operation; and a gearshift unit for automatically operating the gearshift operating element to shift gears.The gearshift unit includes a hydraulic fluid storage device, a hydraulic pressure generating device for forcing the hydraulic fluid from the hydraulic fluid storage device, an actuator that can be actuated with the hydraulic pressure exerted by the hydraulic pressure generating device to actuate the gearshift actuator, and a base plate that supports the hydraulic fluid storage device, the hydraulic pressure generating device, and the actuator for attaching the hydraulic fluid storage device, the hydraulic pressure generating device, and the actuator to the outer wall of the transmission housing unit. The base plate has an outwardly extending portion.The outwardly extending portion extends further forward in a direction along the longitudinal axis of the motor vehicle than the wall of the transmission housing unit at the front end.The hydraulic fluid storage device and the hydraulic pressure generating device are mounted on the outwardly extending portion of the base plate such that the hydraulic fluid storage device and the hydraulic pressure generating device are opposed to the onboard component but spaced apart from the onboard component in the rearward direction, and the hydraulic fluid storage device and the hydraulic pressure generating device are mounted vertically such that the hydraulic fluid storage device and the hydraulic pressure generating device overlap with each other in the vertical direction when a surface at the front end of the hydraulic fluid storage device and a surface at the front end of the hydraulic pressure generating device lie in the same vertical plane.The hydraulic pressure generating device includes a motor, a hydraulic fluid pump for supplying hydraulic fluid from the hydraulic fluid storage device, and a pressure accumulating device for accumulating hydraulic pressure of the hydraulic fluid supplied by the hydraulic fluid pump. The hydraulic pressure storing device, the hydraulic pressure generating device, and the pressure accumulating device are mounted on the outwardly extending portion of the base plate such that the front end surface of the hydraulic fluid storing device, the front end surface of the hydraulic pressure generating device, and a front end surface of the pressure accumulating device are located on the same vertical plane. [Advantageous effect of the invention]

[0010] The above configuration can prevent the application of excessive force to the transmission case unit in the case where the motor vehicle is subjected to the impact caused by a frontal collision. [Brief description of the drawings] Fig. 1 is a top plan view of a frontal end portion of a motor vehicle, illustrating an engine compartment in which an onboard component (i.e., a radiator) and an automatic transmission are mounted; Fig. 2 is a fragmentary plan view of Fig. 1 from above after a 90 degree clockwise rotation, illustrating the relationship between the radiator and the automatic transmission; Fig. 3 is a front elevation of the automatic transmission when viewing the automatic transmission in Fig. 1 from the front of the motor vehicle when the radiator is removed; Fig. 4 is a side view of the automatic transmission and the radiator when viewing the automatic transmission and the radiator in Fig. 1 from the right side of the motor vehicle; Fig. 5 is a side view of the automatic transmission and the radiator when viewing the automatic transmission and the radiator in Fig. 1 from the left side of the motor vehicle; Fig. 6 is a similar view to Fig. 5, if a gearbox housing is removed; Fig. 7 is a section through the line VII-VII in Fig. 3; Fig. 8 is a block diagram illustrating the configuration of a hydraulic pressure generating device and a gear shift actuator as well as the direction of a flow of the hydraulic fluid; Fig. 9 is a perspective view of a base plate of the automatic transmission; Fig. 10 is a view similar to Fig. 4, which illustrates the radiator in contact with the automatic transmission after its rearward displacement caused by a frontal collision of the motor vehicle; Fig. 11 is a view similar to Fig. 5, which illustrates the radiator in contact with the automatic transmission after its rearward displacement caused by the frontal collision of the motor vehicle; Fig. 12 is a view similar to Fig. 6, which illustrates a modification; Fig. 13 is a view similar to Fig. 3, which illustrates a further modification. [Embodiment of the invention]

[0011] In the present embodiment, an automatic transmission is provided in an engine compartment of a motor vehicle, having an onboard component within the engine compartment. The automatic transmission includes: a transmission housing unit spaced rearwardly along the longitudinal axis of the motor vehicle from the onboard component and having an outer wall including a wall at the front end, the transmission housing unit housing at least one gearshift operating member for performing a gearshift operation; and a gearshift unit for automatically operating the gearshift operating member to shift gears.The gearshift unit includes a hydraulic fluid storage device, a hydraulic pressure generating device for forcing the hydraulic fluid from the hydraulic fluid storage device, an actuator that can be actuated with the hydraulic fluid forced by the hydraulic pressure generating device to actuate the gearshift actuator, and a base plate that supports the hydraulic fluid storage device, the hydraulic pressure generating device, and the actuator for attaching the hydraulic fluid storage device, the hydraulic pressure generating device, and the actuator to the outer wall of the transmission housing unit. The base plate has an outwardly extending portion.The outwardly extending portion extends further forward in a direction along the longitudinal axis of the motor vehicle than the wall of the transmission housing unit at the front end.The hydraulic fluid storage device and the hydraulic pressure generating device are mounted on the outwardly extending portion of the base plate such that the hydraulic fluid storage device and the hydraulic pressure generating device are opposed to the onboard component but spaced apart from the onboard component in the rearward direction, and the hydraulic fluid storage device and the hydraulic pressure generating device are mounted vertically such that the hydraulic fluid storage device and the hydraulic pressure generating device overlap with each other when a surface at the front end of the hydraulic fluid storage device and a surface at the front end of the hydraulic pressure generating device lie in the same vertical plane.

[0012] This can prevent the action of excessive force on the transmission case unit in the event that the motor vehicle is subjected to the impact caused by a frontal collision. [Embodiments]

[0013] The present embodiment is described in detail with reference to the accompanying drawings. Fig. 1 to 7 and 9 to 13, the terms "top", "front" and "left" are used throughout with reference to a vehicle occupant in a driver's seat of a motor vehicle in which the automatic transmission according to the embodiment is mounted laterally forward to show the projection of each of the views.

[0014] First, the configuration is described.

[0015] Referring to Fig. 1, a motor vehicle, e.g., a passenger car, is designated by 100. The motor vehicle 100 has an engine compartment 100A. Arranged in the engine compartment 100A are an automatic transmission 1 in the form of an automated manual transmission (AMT), an internal combustion engine 50, and a radiator 51. The radiator 51 and the automatic transmission 1 are aligned along the longitudinal axis of the motor vehicle 100 such that the automatic transmission 1 is located behind the radiator 51, and the automatic transmission 1 and the radiator 51 overlap with respect to the longitudinal axis of the motor vehicle 100. In the present embodiment, the radiator 51 forms an onboard component, as claimed.

[0016] Referring to the Fig. 1 to 3, the automatic transmission 1 includes a transmission housing unit 2. The transmission housing unit 2 includes a clutch housing 3 and a transmission housing 4 that is adjacent to the clutch housing 3.

[0017] As indicated by the dashed line with two short dashes or dots in Fig. 4, there is a starting clutch 5 inside the clutch housing 3.

[0018] Referring to Fig. 6 Inside the transmission housing 4 there is a drive shaft 6, a first countershaft 7, a second countershaft 8 and a differential gear 9. The drive shaft 6, the first countershaft 7 and the second countershaft 8 are fixed in such a way that their axes become parallel.

[0019] When the starting clutch 5 is engaged, the power is transmitted from the internal combustion engine 50 to the drive shaft 6. Specifically, the radiator 51 is designed to cool the coolant circulating through the internal combustion engine 50. The radiator 51 is equipped with a cooling fan (not shown) for forcing air into the radiator core, as well as a fan shroud 51A.

[0020] Switchable drive gears 6A are mounted on the drive shaft 6. The drive gears 6A, which correspond in number to the number of forward and reverse gears, are separated in an axial direction of the drive shaft 6. Switchable first counter gears 7A are mounted on the first countershaft 7, and switchable second counter gears 8A are mounted on the second countershaft 8. Each of the first and second counter gears 7A and 8A meshes with the corresponding one of the drive gears 6A.

[0021] The dashed line in Fig. 5 shows a final drive gear 7B mounted on the first countershaft 7 and another final drive gear 8B mounted on the second countershaft 8. The final drive gears 7B and 8B mesh with a final drive gear 9A of the differential gear 9.

[0022] The differential gear 9 includes the final drive gear 9A, a differential gear case 9B to which the final drive gear 9A is mounted, and differential gears, not shown, within the differential gear case 9B.

[0023] The transmission housing 4 accommodates a shift and selection shaft 10. The shift and selection shaft 10 is supported by a gearshift housing 4C attached to the top of the transmission housing 4. The shift and selection shaft 10 has an axis lying in a plane whose normal vector runs along the axis of the drive shaft 6. The shift and selection shaft 10 is supported such that the shift and selection shaft 10 can be moved axially along its axis and can be rotated about its axis.

[0024] Referring to Fig. 6, the first countershaft 7, the second countershaft 8, and the final drive gear 9A are located on one side of an imaginary vertical plane with respect to the motor vehicle, in which the axis of the drive shaft 6 lies, and the shift and selection shaft 10 is located on the opposite side of the vertical plane. The shift and selection shaft 10 has two inner levers 10A and 10B, one located axially remote from the other. The inner lever 10A and a selected one of two shift pieces 12A and 12B can mesh with each other, and the inner lever 10B and a selected one of two shift pieces 12C and 12D can mesh with each other.

[0025] The shift pieces 12A, 12B, 12C, and 12D are coupled to shift shafts 13A, 13B, 13C, and 13D, respectively. The shift shafts 13A, 13B, 13C, and 13D are mounted on the transmission housing 4 such that the shift shafts 13A to 13D can move axially parallel to the axis of the drive shaft 6.

[0026] Shift forks 14A, 14B, 14C, and 14D are fixedly attached to the shift shafts 13A, 13B, 13C, and 13D, respectively. The shift forks 14A, 14B, 14C, and 14D are coupled to their respective dog clutches, not shown. The two dog clutches to which the shift forks 14A and 14B are coupled are mounted on the first countershaft 7 such that these dog clutches can be moved in one and the opposite axial direction along the axis of the first countershaft 7. The other two dog clutches to which the shift forks 14C and 14D are coupled are mounted on the second countershaft 8 such that these dog clutches can be moved in one and the opposite axial direction along the axis of the second countershaft 8.

[0027] In the present embodiment, the switching and selecting shaft 10 moves (or moves vertically) in one and the opposite axial directions along its axis to perform a selecting operation, and rotates around the axis at the selected position to perform a switching operation.

[0028] In detail, after the switching and selection shaft 10 has moved along its axis to a selected position at which the inner lever 10A engages one of the switching pieces 12A and 12B or the inner lever 10B engages one of the switching pieces 12C and 12D, the switching and selection shaft 10 rotates about its axis to cause one of the switching shafts 13A, 13B, 13C and 13D to move axially parallel to the axis of the drive shaft 6.

[0029] In response to the axial movement of the shift shaft 13A or 13B or 13C or 13D, the shift fork 14A or 14B or 14C or 14D, which is fixedly attached to the shift shaft 13A or 13B or 13C or 13D, moves its dog clutch in one or the opposite axial direction along the axis of the corresponding one of the first countershaft 7 and the second countershaft 8 to couple the engaged one of the first countershaft gears 7A and the second countershaft gears 8A to the corresponding countershaft 7 or 8.

[0030] This causes the gear to form a pair by means of the counter gear 7A or 8A and the corresponding one of the drive gears 6A to become active to establish a gear or speed.

[0031] When the gear pair 6A / 7A (or 7B) is engaged by the coupling of the counter gear 7A or 7B with the countershaft 7 or 8, the power of the internal combustion engine 50 is transmitted from the drive shaft 6 via the engaged, switchable gear pair 6A / 7A (or 6A / 8A) to the first countershaft 7 or the second countershaft 8 when the starting clutch 51 is engaged.

[0032] Now, when the power is transmitted from the first countershaft 7 or the second countershaft 8 to the axle output gear 9A via the corresponding axle output gear 7B and 8B, the differential gears inside the differential gear case 9B transmit the power to the left and right drive wheels 102L and 102R via the left and right drive axles 101L and 101R (see Fig. 1), while controlling a difference in rotation between the left and right wheels 102L and 102R. It is possible for the left and right drive wheels 102L and 102R to rotate at different speeds.

[0033] The clutch 5 and the shift and selector shaft 10 form gearshift actuating elements, as claimed. The transmission housing 4 forms a transmission housing, as claimed. The first counter gear 7A forms a counter gear of a first switchable gear pair (6A / 7A), and the second counter gear 8A forms a counter gear of a second switchable gear pair (6A / 8A). The final drive gear 9A forms a final drive gear, as claimed.

[0034] The drive gear 6A and the first counter gear 7A form the first switchable gear pair 6A / 7A, as claimed. The drive gear 6A and the second counter gear 8A form the second switchable gear pair 6A / 8A, as claimed.

[0035] On the other hand, the combustion engine contains 50 (see Fig. 1) a crankshaft and a flywheel (not shown) fixedly attached to the crankshaft. The clutch 5 includes a clutch plate (not shown) attached to the drive shaft 6.

[0036] In the initial state, in which the clutch 5 is engaged, leaving the clutch plate in contact with the flywheel, the power is transmitted from the crankshaft to the drive shaft 6. When the clutch 5 is disengaged to separate the clutch plate from the flywheel, the transmission of power from the crankshaft to the drive shaft 6 is interrupted.

[0037] Referring to Fig. 4, a clutch release element 20 is located inside the clutch housing 3. The clutch release element 20 includes a release bearing 21 and a release cylinder 22. The release bearing 21 and the release cylinder 22 are mounted on the drive shaft 6.

[0038] The hydraulic fluid is supplied to the release cylinder 22 through a hydraulic pressure line 23. The release bearing 21 is operable with the hydraulic pressure supplied to the release cylinder 22 and functions to bring the clutch plate of the clutch 5 into contact with the flywheel or to separate it from the flywheel. This enables the transmission of power from the internal combustion engine 50 to the drive shaft 6 or an interruption of the power transmission. In the present embodiment, the clutch release element 20 and the hydraulic pressure line 23 form a clutch control system 31 as claimed.

[0039] Referring to the Fig. 1 and Fig. 2, a hydraulic pressure generating device 32, a gear shift actuator 33, and a control unit 34 are located on the top side of the transmission housing unit 2 on the outside of the transmission housing unit 2. The hydraulic pressure generating device 32, the gear shift actuator 33, and the control unit 34 are attached to a base plate 35. The base plate 35 is attached to an upper wall 4c of the transmission housing 4 (see Fig. 6). A gearshift housing 4C forms a portion of the transmission case 4, so that the upper wall 4c includes an upper surface of the gearshift housing 4C.

[0040] Referring to Fig. 3, the hydraulic pressure generating device 32 includes a reservoir 36, a motor 37, a hydraulic fluid pump 38, and an accumulator 39. In the present embodiment, the reservoir 36 constitutes a hydraulic fluid storage device as claimed, and the accumulator 39 constitutes a pressure accumulation device.

[0041] The reservoir 36 stores the hydraulic fluid. The reservoir 36 is provided above the motor 37 such that the reservoir 36 extends laterally to straddle the motor 37. The hydraulic fluid pump 38, when supplied with power by the motor 37, supplies the hydraulic fluid stored in the reservoir 36 to the accumulator 39 via an unillustrated hydraulic fluid passage with which the base plate 35 is formed. The accumulator 39 accumulates the pressure of the hydraulic fluid and supplies the hydraulic pressure to the gearshift actuator 33 through an unillustrated hydraulic fluid passage with which the base plate 35 is formed.

[0042] Referring to Fig. 9, the base plate 35 is formed in a planar shape lying in a horizontal plane with respect to the motor vehicle. The base plate 35 includes an accumulator mount 35A to which the accumulator 39 is mounted, and a motor mount 35B to which the motor 37 is mounted. The base plate 35 is formed with connecting holes 35C. The connecting holes 35C form hydraulic fluid passages through which the reservoir 36 and the hydraulic fluid pump 38 communicate with each other.

[0043] The base plate 35 has a gearshift actuator mount 35E to which the gearshift actuator 33 is attached. The gearshift actuator mount 35E is formed with an opening 35e.

[0044] The shift and select shaft 10 passes through the opening 35e such that the upper part of the shift and select shaft 10 protrudes upward through the opening 35 from the top of the base plate 35. A select lever and a shift lever, not shown, are provided on the shift and select shaft 10.

[0045] Referring to Fig. 8, the gearshift actuator 33 has a clutch actuation solenoid 40, a selection actuation solenoid 41, a shift actuation solenoid 42, a selection actuator 43 and a shift actuator 44.

[0046] To Fig. 3, the base plate 35 is formed with a hydraulic fluid supply 35D. One end of the hydraulic pressure piping 23 is attached to the hydraulic fluid supply 35D. The hydraulic fluid supply 35D is formed with a hydraulic fluid passage 35d. The hydraulic fluid passage 35d communicates with the accumulator 39 via a hydraulic fluid passage (not shown) with which the base plate 35 is formed. This configuration allows the high hydraulic pressure of the accumulator 39 to be supplied to the release cylinder 22 through the hydraulic fluid passage 35d of the hydraulic fluid supply 35D and the hydraulic pressure piping 23.

[0047] The clutch actuating solenoid 40 supplies the high hydraulic pressure generated by the accumulator 39 from the hydraulic fluid passage 35d of the hydraulic fluid supply 35D to the release cylinder 22 via the hydraulic pressure pipe 23 to actuate the clutch 5.

[0048] The select actuation solenoid 41 adjusts the high hydraulic pressure generated by the accumulator 39 to supply the set pressure to the select actuator 43. The shift actuation solenoid 42 adjusts the high hydraulic pressure generated by the accumulator 39 to supply the set pressure to the shift actuator 44.

[0049] The selection actuator 43 urges the shift and select shaft 10 against the bias of the coil spring 17 in response to the hydraulic pressure supplied from the selection actuation solenoid 41 to linearly actuate the shift and select shaft 10 in a selection direction along its axis.

[0050] When the shift and select shaft 10 is in the selected gear selection position, the shift actuator 44 actuates the shift lever of the shift and select shaft 10 in response to the hydraulic pressure supplied by the shift actuation solenoid 42 to angularly actuate the shift and select shaft 10 about its axis in one or the opposite shift direction. In the present embodiment, the gear shift actuator 33 constitutes an actuating device.

[0051] The control unit 34 consists of a computer unit that includes, but is not limited to, a central processing unit (CPU), a read-only memory (ROM), and a random access memory (RAM). The control unit 34 determines an appropriate shift point in response to a range position input from a transmission range sensor (not shown) that detects a range selected by a transmission range selector (not shown), in response to a vehicle speed input from a vehicle speed sensor (not shown), and in response to an accelerator pedal position input from an accelerator pedal position sensor (not shown).

[0052] After determining the shift point, the control unit 34 causes the clutch actuation solenoid 40 to operate to enable the supply of hydraulic pressure to the release cylinder 22. The supply of hydraulic pressure to the release cylinder 22 causes the release bearing 21 to separate the clutch plate of the clutch 5 from the flywheel, thereby interrupting the transmission of power from the crankshaft to the drive shaft 6.

[0053] Discharge of the hydraulic fluid from the release cylinder 22 after termination of the supply of hydraulic pressure to the release cylinder 22 causes the release bearing 21 to bring the clutch plate of the clutch 5 into contact with the flywheel, thereby resuming the transmission of power from the crankshaft to the drive shaft 6.

[0054] The control unit 34 performs control of the selection actuation solenoid 41 and the shift actuation solenoid 42 while the clutch 5 is disengaged, so that the selection actuation solenoid 41 and the shift actuation solenoid 42 supply power to the selection actuator 43 and the shift actuator 44, respectively, to actuate the shift and selection shaft 10 in the axial direction along its axis and in the shifting direction around its axis to perform gear shifting.

[0055] Referring to Fig. 4, a clutch stroke sensor 24 is mounted on the drive shaft 6. The clutch stroke sensor 24 is connected to the control unit 34 via a wiring line 24a. The clutch stroke sensor 24 detects the cylinder position assumed by the release cylinder 22 and provides a cylinder position input to the control unit 34. The control unit 34 determines the status of the clutch 5, e.g., slipping of the clutch 5, in response to the cylinder position input from the clutch stroke sensor 24.

[0056] In the present embodiment, the clutch control system 31, the hydraulic pressure generating device 32, the gear shift actuator 33, the control unit 34, and the base plate 35 constitute the gear shift unit 30. The hydraulic pressure generating device 32, the gear shift actuator 33, and the base plate 35 constitute a gear shift unit 30 as claimed.

[0057] Referring to Fig. 6, it is readily apparent that, when the automatic transmission 1 is viewed in the direction along the axis of the drive shaft 6, the clutch housing 3 is formed with an outwardly projecting portion 3A. The outwardly projecting portion 3A projects more outwardly than the vertically extending front wall 4A of the transmission housing 4.

[0058] The base plate 35 has or is formed with an outwardly extending portion 35a. The outwardly extending portion 35a is arranged such that the end of the base plate 35 is defined with respect to the direction in which the base plate 35 extends. The outwardly extending portion 35a extends outwardly from the front wall 4A of the transmission housing 4. The upper wall 4c of the transmission housing 4 forms part of an outer wall of the transmission housing unit 2 as claimed. The front wall 4A of the transmission housing 4 forms a front wall of the outer wall of the transmission housing unit 2 as claimed.

[0059] Referring to the Fig. 5 and Fig. 6, the outwardly extending portion 35a of the base plate 35 supports the hydraulic pressure generating device 32 such that the outwardly extending portion 35a has the reservoir 36 and the motor 37 on its upper surface side and has the hydraulic fluid pump 38 and the accumulator 39 on its lower surface side.

[0060] Referring to the Fig. 1 and Fig. 3, the accumulator 39 is located on the lateral side (in the example shown on the left side) of the collection tank 36. As best seen in FIG: 4, the accumulator 39 is arranged such that the accumulator 39 is located rearward of a vertical plane in contact with the front end surface 38a of the hydraulic fluid pump 38, but forward of a vertical plane in contact with the front wall 4A at the front end of the transmission housing 4. The collection tank 36, the motor 37, the hydraulic fluid pump 38 and the accumulator 39 are opposite the radiator 51, but are spaced from the radiator 51 in the rearward direction along the longitudinal axis of the motor vehicle 100.

[0061] How best to Fig. As can be seen in Fig. 5, the collecting tank 36, the motor 37, and the hydraulic fluid pump 38 are mounted on the base plate 35. When the front end surface 36a of the collecting tank 36 and the front end surface 37a of the motor 37 lie in the same vertical plane 53, the collecting tank 36 and the motor 37 are mounted vertically such that the collecting tank 36 overlaps the motor 37.

[0062] Of the occupancy areas of the hydraulic pressure generating device 32 on the base plate 35, the occupancy area of ​​the hydraulic pressure generating device 32 on the upper surface side of the outwardly extending portion 35a is the largest. Specifically, the occupancy area of ​​the reservoir 36 and the motor 37 on the upper surface side of the outwardly extending portion 35 is the largest.

[0063] Becomes Fig. 3, the hydraulic fluid supply 35D is mounted on the lower surface side of the outwardly extending portion and extends downward from the lower surface side of the outwardly extending portion 35a. The clutch housing 3 is formed with an opening 3B. The opening 3B is located below the outwardly extending portion 35a. The opening 3B is arranged and sized to allow insertion of the hydraulic pressure conduit 23. The hydraulic pressure conduit 23 is inserted into the clutch housing 3 through the opening 3B.

[0064] Becomes Fig. 7, the hydraulic fluid supply 35D is arranged between the hydraulic fluid pump 38 spaced laterally with respect to the motor vehicle and the accumulator 39 and spaced rearwardly from the front end surface 38a of the hydraulic fluid pump 38.

[0065] Next, the operation is described.

[0066] A transmission of the impact of a frontal collision of the motor vehicle 100 to the rear causes a displacement of the radiator 51 to the rear towards the automatic transmission 1.

[0067] In the present embodiment, the automatic transmission 1 includes the gearshift unit 30 for automatically operating the clutch 5 and the shift and select shaft 10 to shift gears. The gearshift unit 30 includes the reservoir 36, the motor 37, and the hydraulic fluid pump 38. Furthermore, the gearshift unit 30 includes the gearshift actuator 33 and the base plate 35. The base plate 35 supports the reservoir 36, the motor 37, the hydraulic fluid pump 38, and the gearshift actuator 33 to be fixed to the upper wall 4c of the transmission case 4.

[0068] The base plate 35 has the outwardly extending portion 35a. The outwardly extending portion 35a extends further forward in the direction along the longitudinal axis of the motor vehicle 100 than the front wall 4A of the transmission case 4. The reservoir 36, the motor 37, and the hydraulic fluid pump 38 are mounted on the outwardly extending portion 35a of the base plate 35 such that the reservoir 36, the motor 37, and the hydraulic fluid pump 38 face the radiator 51 but are spaced rearward from the radiator 51, and the reservoir 36, the motor 37, and the hydraulic fluid pump 38 are mounted such that the front end surface 36a of the reservoir 36 and the front end surface 37a of the motor 37 lie in the same vertical plane.

[0069] With the configuration mentioned above, as shown in the Fig. 10 and Fig. 11, the header tank 36 and the motor 37 cooperate during the displacement of the radiator 51 rearward toward the automatic transmission 1 and accommodate the radiator 51 after the radiator 51 comes into contact with the front end surface 36a of the header tank 36 and the front end surface 37a of the motor 37.

[0070] The reservoir 36 stores the hydraulic fluid. The reservoir 36 is mounted above the motor 37 such that the reservoir 36 extends laterally beyond the motor 37. With this configuration, the reservoir 36 and the motor 37 can accommodate the cooler 51.

[0071] Furthermore, the motor 37 and the hydraulic fluid pump 38 are more rigid than the reservoir 36, so the motor 37 and the hydraulic fluid pump 38 can prevent the rearward displacement of the radiator 51 caused by a frontal collision. This configuration can prevent the impact energy from being concentrated by the radiator 51 on any one of the reservoir 36, the motor 37, and the hydraulic fluid pump 38 by distributing the impact energy among the reservoir 36, the motor 37, and the hydraulic fluid pump 38.

[0072] The above configuration can reduce deformation of the base plate 35, preventing excessive force from being transmitted from the base plate 35 to the transmission case unit 2. This can protect the automatic transmission 1 from an impact caused by a frontal collision.

[0073] In the present embodiment, the hydraulic pressure generating device 32 includes the accumulator 39 for accumulating the hydraulic pressure of the hydraulic fluid supplied by the hydraulic fluid pump 38 and for supplying the hydraulic fluid under pressure to the gear shift actuator 33 and the release cylinder 22.

[0074] The accumulator 39 is attached to the outwardly extending portion 35a of the base plate 35 such that the accumulator 39 is located on the lateral side of the reservoir 36, and is mounted rearward of a vertical plane in contact with the front end surface 38a of the hydraulic fluid pump 38, but forward of a vertical plane in contact with the front wall 4A at the front end of the transmission case 4.

[0075] This configuration allows the cooler 51 to contact the accumulator 39 after contact with the reservoir 36, the motor 37, and the hydraulic fluid pump 38. This arrangement of the accumulator 39, in addition to the reservoir 36, the motor 37, and the hydraulic fluid pump 38, between the cooler 51 and the transmission housing unit 2 allows for a more dispersed impact distribution by the cooler 51.

[0076] The accumulator 39 can effectively absorb the impact load from the radiator 51 due to its cover case having a high rigidity and its dimension being larger than the motor 37 or the hydraulic fluid pump 38.

[0077] This results in increasing effectiveness in reducing deformation of the base plate 35, while increasing effectiveness in preventing transmission of excessive force from the base plate 35 to the gear housing unit 2.

[0078] In the present embodiment, the reservoir 36 and the motor 37 are mounted on the upper surface side of the outwardly extending portion 35a, while the hydraulic fluid pump 38 and the accumulator 39 are mounted on the lower surface side of the outwardly extending portion 35a.

[0079] This configuration allows the reservoir 36 and motor 37, as well as the hydraulic fluid pump 38 and accumulator 39, to hold the base plate 35 vertically. The base plate 35, reservoir 36, motor 37, hydraulic fluid pump 38, and accumulator 39 are mounted together so that they can distribute the impact load from the radiator 51 after absorbing the impact load.

[0080] This results in increasing effectiveness in reducing deformation of the base plate 35, while increasing effectiveness in preventing transmission of excessive force from the base plate 35 to the gear housing unit 2.

[0081] In the present embodiment, the transmission case unit 2 accommodates the input shaft 6 which transmits the power from the engine 50, the clutch 5 which engages or disengages a power transmission between the engine 50 and the input shaft 6, and the shift and select shaft 10 which performs a gear shifting operation.

[0082] The clutch release element 20 is mounted on the drive shaft 6, the clutch release element 20 being operable with the hydraulic pressure exerted by the hydraulic fluid pump 38 to actuate the clutch 5, and the clutch release element 20 and the accumulator 39 are connected by means of the hydraulic pressure pipe 23.

[0083] The base plate 35 includes the hydraulic fluid supply 35D, to which the hydraulic pressure piping 23 is connected, for supplying the hydraulic fluid from the accumulator 39 to the hydraulic pressure piping 23. The hydraulic fluid supply 35D is located between the motor 37 and the hydraulic fluid pump 38 and the accumulator 39, which are laterally spaced apart, and the hydraulic fluid supply 35D is mounted behind the front end surface 37a of the motor 37 and the front end surface 38a of the hydraulic fluid pump 38.

[0084] This configuration allows the cooler 51 to contact the reservoir 36, the engine 37, and the hydraulic fluid pump 38 before the cooler 51 comes into contact with the hydraulic fluid supply 35D after the cooler 51 is displaced rearward. This mitigates the impact acting on the hydraulic fluid supply 35D and protects the hydraulic fluid supply 35D from the impact load from the cooler 51, preventing hydraulic fluid leakage.

[0085] In the present embodiment, the transmission housing unit 2 accommodates the first countershaft 7, which is to be coupled to the input shaft 6 via the first switchable gear pair (6A / 7A), and the second countershaft 8, which is to be coupled to the input shaft 6 via the second switchable gear pair (6A / 8A). The transmission housing unit 2 accommodates the final drive gear 9A, to which the power from the first countershaft 7 or the second countershaft 8 is transmitted.

[0086] To meet the need for space within the transmission housing unit 2 for mounting the first countershaft 7 and the second countershaft 8, an unavoidable conclusion is that the shift and select shaft 10 mounted on the transmission housing unit 2 is located in front of the first countershaft 7 and the second countershaft 8. In this case, the shift and select shaft 10 is likely to be subjected to a high impact upon collision of the radiator 51 with the transmission housing unit 2.

[0087] In the present embodiment, the shift and select shaft 10 is protected by bringing the cooler 51 into contact with the reservoir 36, the motor 37, the hydraulic fluid pump 38 and the accumulator 39 to prevent the transmission case unit 2 from being subjected to excessive impact.

[0088] Moreover, in the present embodiment, the countershaft is configured as a double countershaft including the first and second countershafts 7 and 8, so that the automatic transmission 1 can be downsized and protected from the impact caused by a frontal collision without any difficulty.

[0089] Referring to a modification made in Fig. 12, a reservoir 36, a motor 37, a hydraulic fluid pump 38 and an accumulator 39 may be mounted on a base plate 35 such that the front end surfaces 36a, 37a, 38a and 39a of the reservoir 36, the motor 37, the hydraulic fluid pump 38 and the accumulator 39 are in the same vertical plane.

[0090] With this configuration, during the rearward displacement of the radiator 51 caused by a frontal collision of the motor vehicle 100, the reservoir 36, the motor 37, the hydraulic fluid pump 38, and the accumulator 39 simultaneously absorb the impact from the radiator 51 and disperse the impact.

[0091] This results in increased effectiveness in reducing deformation of the base plate 35, while increasing effectiveness in preventing the transmission of excessive force from the base plate 35 to the transmission housing unit 2. Furthermore, this results in increased effectiveness in protecting the transmission housing unit 2.

[0092] Referring to a further modification which is Fig.13, a reservoir 36 and a motor 37 may be mounted on the lower surface side of an outwardly extending portion 35a, while a hydraulic fluid pump 38 and an accumulator 39 may be mounted on the upper surface side of the outwardly extending portion 35a.

[0093] This configuration allows the reservoir 36 and motor 37, as well as the hydraulic fluid pump 38 and accumulator 39, to hold the base plate 35 vertically. The base plate 35, reservoir 36, motor 37, hydraulic fluid pump 38, and accumulator 39 are mounted together, allowing them to distribute the impact load from the radiator 51 after absorbing the impact load.

[0094] This results in increasing effectiveness in reducing deformation of the base plate, while increasing effectiveness in preventing the transmission of excessive force from the base plate 35 to the gear housing unit 2.

[0095] In the above description, the automated manual transmission (AMT) is used as an example of the automatic transmission 1, but as another example of the automatic transmission 1, the normal automatic transmission (AT) as claimed may be used.

[0096] Although the disclosure relates to the present embodiment, but is not limited to it, it will be appreciated that modifications may be made by those skilled in the art without departing from the scope of the present invention. All such modifications and equivalents thereof are intended to be covered by the following claims, which are described within the scope of the claims. [Description of reference symbols] 1 automatic transmission 2 Gearbox housing unit 3 clutch housing 3A outwardly protruding section (of the clutch housing) 3B Opening (of the clutch housing) 4 Gearbox housing 4A front wall (or front end surface of the transmission housing unit) 4C gearshift housing 4c upper wall (or outer wall of the gearbox housing unit) 5 Clutch 6 Drive shaft 6A Drive gears (or drive gear of the first switchable gear pair and drive gear of the second switchable gear pair) 7 first countershaft 7A first counter gear (first counter gear of the first switchable gear pair) 7B first axle output gear 8 second countershaft 8A second counter gear (second counter gear of the second switchable gear pair) 8B second axle output gear 9 differential gears 9A third axle output gear 9B Differential gear housing 10 Shift and selection shaft (gear shift operating element) 10A, 10B Inner levers 12A, 12B, 12C, 12D contact pieces 13A, 13B, 13C, 13D shift shafts 14A, 14B, 14C, 14D shift forks 17 Coil spring 20 Clutch release element (of the clutch control system) 21 Release bearing (of the clutch release element) 22 Release cylinder (of the clutch release element) 23 Hydraulic pressure pipe (of the clutch control system) 24 Clutch stroke sensor 24a wiring cable 30 gearshift unit 31 Clutch control system (of the gearshift unit) 32 Hydraulic pressure generating device (of the gearshift unit) 33 Gearshift actuator (actuating device or gearshift unit) 34 Control unit 35 Base plate (of the gearshift unit) 35A battery mounting (of the base plate) 35a outwardly extending section (of the base plate) 35B Motor mounting (of the base plate) 35C Connection holes (of the base plate) 35D Hydraulic fluid supply (of the base plate) 35d Hydraulic fluid passage (of the hydraulic fluid supply) 35E Gearshift actuator mounting (of the base plate) 35e Opening (of the gearshift actuator mount) 36 collection tanks (hydraulic fluid storage device) 36a, 37a, 38a, 39a front end surfaces 37 Motor (of the hydraulic pressure generating device) 38 Hydraulic fluid pump (of the hydraulic pressure generating device) 39 Accumulator (pressure accumulation device of the hydraulic pressure generating device) 40 clutch actuation solenoid switches 41 Selection actuation magnetic switch 42 switching actuation magnetic switches 43 Selection actuator 44 Switch actuator 50 combustion engine 51 cooler (onboard component) 51A fan cover 53 vertical plane (of the end surfaces 36a and 37a) 100 motor vehicles 100A engine compartment 101L left drive axle 101R right drive axle 102L left drive wheel 102R right drive wheel

Claims

[1] Automatic transmission (1) in an engine compartment (100A) of a motor vehicle (100) having an onboard component (51) within the engine compartment (100A), the automatic transmission (1) comprising: a transmission housing unit (2) spaced rearwardly from the onboard component (51) in a direction along the longitudinal axis of the motor vehicle (100) and having an outer wall (4c) including a front wall (4A) at the front end, the transmission housing unit (2) accommodating at least one gearshift actuating element (5, 10) for performing a gearshift operation; and a gearshift unit (30) for automatically actuating the gearshift actuating element (5, 10) to shift gears, wherein the gearshift unit (30) includes a hydraulic fluid storage device (36), a hydraulic pressure generating device (32) for pressing the hydraulic fluid from the hydraulic fluid storage device (36), an actuating device (33) that is actuable with the hydraulic fluid pressed by the hydraulic pressure generating device (32) to actuate the gearshift actuating element (5, 10), and a base plate (35) that supports the hydraulic fluid storage device (36), the hydraulic pressure generating device (32), and the actuating device (33) for attaching the hydraulic fluid storage device (36), the hydraulic pressure generating device (32), and the actuating device (33) to the outer wall (4c) of the transmission housing unit (2), wherein the base plate (35) has an outwardly extending portion (35a), wherein the outwardly extending portion (35a) extends more forward in a direction along the longitudinal axis of the motor vehicle (100) than the front wall (4A) at the front end of the transmission housing unit (2), wherein the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) are mounted on the outwardly extending portion (35a) of the base plate (35) such that the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) are opposite the onboard component (51) but spaced apart from the onboard component (51) in the rearward direction, and that the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) are mounted vertically such that the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) overlap with each other in the vertical direction when a front end surface (36a) of the hydraulic fluid storage device (36) and a front end surface (37a) of the hydraulic pressure generating device (32) lie in the same vertical plane (53), wherein the hydraulic pressure generating device (32) includes a motor (37), a hydraulic fluid pump (38) for conveying a hydraulic fluid from the hydraulic fluid storage device (36), and a pressure accumulating device (39) for accumulating a hydraulic pressure of the hydraulic fluid conveyed by the hydraulic fluid pump (38); and wherein the pressure accumulation device (39) is attached to the outwardly extending portion (35a) of the base plate (35) such that the pressure accumulation device (39) is located on the lateral side of the hydraulic fluid storage device (36), and is mounted behind a vertical plane in contact with a front end surface (38a) of the hydraulic fluid pump (38), but in front of a vertical plane in contact with the front wall (4A) at the front end of the transmission housing unit (2). [2] Automatic transmission (1) in an engine compartment (100A) of a motor vehicle (100) having an onboard component (51) within the engine compartment (100A), the automatic transmission (1) comprising: a transmission housing unit (2) spaced rearwardly from the onboard component (51) in a direction along the longitudinal axis of the motor vehicle (100) and having an outer wall (4c) including a front wall (4A) at the front end, the transmission housing unit (2) accommodating at least one gearshift actuating element (5, 10) for performing a gearshift operation; and a gearshift unit (30) for automatically actuating the gearshift actuating element (5, 10) to shift gears, wherein the gearshift unit (30) includes a hydraulic fluid storage device (36), a hydraulic pressure generating device (32) for pressing the hydraulic fluid from the hydraulic fluid storage device (36), an actuating device (33) that is actuable with the hydraulic fluid pressed by the hydraulic pressure generating device (32) to actuate the gearshift actuating element (5, 10), and a base plate (35) that supports the hydraulic fluid storage device (36), the hydraulic pressure generating device (32), and the actuating device (33) for attaching the hydraulic fluid storage device (36), the hydraulic pressure generating device (32), and the actuating device (33) to the outer wall (4c) of the transmission housing unit (2), wherein the base plate (35) has an outwardly extending portion (35a), wherein the outwardly extending portion (35a) extends more forward in a direction along the longitudinal axis of the motor vehicle (100) than the front wall (4A) at the front end of the transmission housing unit (2), wherein the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) are mounted on the outwardly extending portion (35a) of the base plate (35) such that the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) are opposite the onboard component (51) but spaced apart from the onboard component (51) in the rearward direction, and that the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) are mounted vertically such that the hydraulic fluid storage device (36) and the hydraulic pressure generating device (32) overlap with each other in the vertical direction when a front end surface (36a) of the hydraulic fluid storage device (36) and a front end surface (37a) of the hydraulic pressure generating device (32) lie in the same vertical plane (53), wherein the hydraulic pressure generating device (32) includes a motor (37), a hydraulic fluid pump (38) for transporting a hydraulic fluid from the hydraulic fluid storage device (36), and a pressure accumulating device (39) for accumulating a hydraulic pressure of the hydraulic fluid transported by the hydraulic fluid pump (38); and wherein the hydraulic pressure storage device (36), the motor (37) and the pressure accumulation device (39) are mounted on the outwardly extending portion (35a) of the base plate (35) such that the front end surface (36a) of the hydraulic fluid storage device (36), the front end surface (37a, 38a) of the hydraulic pressure generating device (32) and a front end surface (39a) of the pressure accumulation device (39) lie in the same vertical plane. [3] Automatic transmission (1) according to claim 1 or 2, wherein the outwardly extending portion (35a) has an upper surface side and a lower surface side; and the hydraulic fluid storage device (36) and the motor (37) are mounted on one of the upper surface side and the lower surface side of the outwardly extending portion (35a), while the hydraulic fluid pump (38) and the pressure accumulation device (39) are mounted on the other of the upper surface side and the lower surface side of the outwardly extending portion (35a). [4] Automatic transmission (1) according to one of claims 1 to 3, wherein the transmission housing unit (2) accommodates a drive shaft (6) to which the power from an internal combustion engine (50) is transmitted; the gearshift operating element (5, 10) accommodated by the transmission housing unit (2) includes a clutch (5) that engages and disengages a power transmission between the internal combustion engine (50) and the drive shaft (6), and a shift and select shaft (10) that performs a gearshift operation; a clutch release element (20) is mounted on the drive shaft (6), the clutch release element (20) being operable with the hydraulic force exerted by the hydraulic pressure generating device (32) to actuate the clutch (5); the clutch release element (20) and the hydraulic pressure generating device (32) are connected to the hydraulic pressure pipeline (23); the base plate (35) includes a hydraulic fluid supply (35D) to which the hydraulic pressure pipe (23) is connected in order to supply the hydraulic fluid from the hydraulic pressure generating device (32) to the hydraulic pressure pipe (23); the hydraulic fluid supply (35D) is located between the hydraulic fluid pump (38) and the pressure accumulation device (39), which are laterally spaced apart, the hydraulic fluid supply (35D) is mounted behind the front end surface (37a, 38a) of the hydraulic pressure generating device (32). [5] Automatic transmission (1) according to claim 4, wherein the transmission housing unit (2) accommodates a first countershaft (7) which is to be coupled to the drive shaft (6) via a first switchable gear pair (6A / 7A), and a second countershaft (8) which is to be coupled to the drive shaft (6) via a second switchable gear pair (6A / 8A).

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