Drum-type transmission

Abstract

To improve reliability of a park lock mechanism in a drum-type transmission of an electric shift type with a simple constitution.SOLUTION: A drum-type transmission device 1 includes a park lock mechanism 500 having a park pole 510 that engages with and disengages from a parking concave-convex portion 112P of a park gear provided on a transmission shaft 810 in a relatively non-rotatable manner, a park pole operation member 530 that engages the park pole 510 with the parking concave-convex portion 112P when a drum member 140 is in a park position and releases the engagement when the drum member 140 is out of the park position, and an assist cam 156 that urges the park pole 510 to move in a direction of disengaging from the parking concave-convex portion 112P when the drum member 140 rotates from the park position toward a shift position or a neutral position. The assist cam 156 is provided at one end part 150a of one end portion of an assist operation shaft 150 which is rotated by power branched from a shift operation gear train 200.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a drum-type transmission equipped with a parking lock mechanism. [Background technology]

[0002] As a transmission used in the traveling power transmission paths of work vehicles such as utility vehicles and tractors, an electric gear shift type drum type transmission device in which gear shifting is performed by driving an electric motor has been proposed (see, for example, Patent Document 1).

[0003] Such a drum-type transmission device includes a speed change gear supported on the counter shaft so as to be rotatable relative to the counter shaft, a transmission gear supported on the main shaft so as not to be rotatable relative to the main shaft and meshed directly or indirectly with the speed change gear, a shifter member supported on the counter shaft so as not to be rotatable relative to the counter shaft but so as to be movable in the axial direction, a drum member having a fork guide groove and adapted to rotate about its axis, a fork shaft parallel to the drum member, and a shift fork having a boss portion supported on the fork shaft so as to be movably axially, an engagement pin portion which engages with the fork guide groove, and a fork portion which engages with the shifter member.

[0004] Specifically, the opposing end faces of the shifter member and the transmission gear are provided with gear-shifting concave and convex portions. By rotating the drum member about its axis, the shift fork, whose axial position is restricted by the fork guide groove, moves axially, causing the shifter member to engage with the transmission gear. This places the gear train, including the transmission gear and the power transmission gear, in a power transmission state, and power is transmitted between the main shaft and the counter shaft at the gear ratio of the gear train.

[0005] The drum member is rotated by driving an electric motor. In such an electric gear shift drum-type transmission, a shift operation gear train having multiple reduction stages is provided to transmit power between the output shaft of the electric motor and the drum shaft of the drum member.

[0006] In addition to the power transmission state via the gear train, it is desirable for a drum-type transmission device to reliably enter a parking lock state, which forcibly stops rotation. In this regard, a proposal has been made to engage a park pawl, which is supported on a countershaft so as not to rotate relative to the countershaft, with the park gear in response to rotation of the drum toward the park position, thereby forcibly stopping rotation of the countershaft (see, for example, Patent Document 2). This drum-type transmission device has an assist cam at one end of a shift operation shaft that rotates the drum, which urges the park pawl in a direction away from the park gear when the drum rotates from the park position toward the shift position, thereby enabling the parking lock state to be released forcefully. Another example has also been disclosed in which an assist cam is provided that urges the park pawl in a direction to engage with the park gear when the drum rotates from the shift position or neutral position toward the park position, thereby enabling the parking lock state to be strongly maintained. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5909400 [Patent Document 2] Japanese Patent Publication No. 2020-173010 Summary of the Invention [Problem to be solved by the invention]

[0008] When electrifying gear shifting operations in the drum-type transmission of Patent Document 2, the rotational speed of the high-speed electric motor must be significantly reduced before it is transmitted to the drum shaft, so a multi-stage shift operation gear train is required to transmit power between the output shaft of the electric motor and the shift operation shaft.This increases the number of parts and also requires the coexistence of an assist cam to improve the reliability of the parking lock mechanism, leaving room for improvement.

[0009] The present invention has been made in consideration of the above-mentioned conventional technology, and aims to provide a compact drum-type transmission that performs shifting operations using the driving force of an electric motor while improving the reliability of the parking lock mechanism with a simple configuration. [Means for solving the problem]

[0010] One aspect of the drum-type transmission of the present invention is a drum-type transmission including a transmission shaft having a plurality of transmission gears, a drum member that can rotate about the drum shaft to shift to a park position, a neutral position, or a shift position, and a shift operation gear train that transmits the driving force of an electric motor to the drum shaft, and is equipped with a park pawl that engages and disengages with a park gear that is attached to the transmission shaft so as not to rotate relative to the transmission shaft, a park pawl operation member that engages the park pawl with the park gear when the drum member is in the park position and disengages the park gear when the drum member is out of the park position, and an assist cam that assists the movement of the park pawl in a direction that disengages the park gear when the drum member rotates from the park position toward the shift position or the neutral position, or in a direction that engages the park pawl with the park gear when the drum member rotates from the park position toward the shift position or the neutral position toward the park position, and the assist cam is provided at one end of an assist operation shaft that rotates by power branched off from the shift operation gear train. is.

[0011] According to one aspect of the drum-type transmission of the present invention, a separate path is provided that branches off from the main path (which locks the park pole) connecting the electric motor to the drum shaft and releases the park pole. This allows the park pole to be forcibly moved and reliably released via the separate path even if the park pole remains engaged with the park gear and does not return from the parking lock state, thereby improving the reliability of the parking lock mechanism. Furthermore, the assist cam is provided at one end of the assist operating shaft that rotates using power (the separate path) that branches off from the shift operating gear train (the main path), allowing the assist cam to be operated with a simple configuration.

[0012] In the drum-type transmission of one aspect described above, an intermediate gear shaft may be provided between the assist operating shaft and the drum shaft and positioned parallel to each other, and the shift operating gear train may include a first shift operating gear train that transmits power between the intermediate gear shaft and an output shaft of the electric motor, and a second shift operating gear train that transmits power between the intermediate gear shaft and the drum shaft, and an assist gear train that transmits power between the intermediate gear shaft and the assist operating shaft.Furthermore, the first shift operating gear train may include a plurality of gears supported for free rotation on each of the assist operating shaft and the intermediate gear shaft.

[0013] According to this aspect, a shift operation gear train connecting the electric motor to the drum shaft can be formed using an assist operation shaft with an assist cam attached to one end thereof. This makes it possible to provide an assist operation shaft with an assist cam without increasing the number of parts, and improves the reliability of the parking lock mechanism in a drum-type transmission with a low-cost, compact configuration without significantly increasing manufacturing costs.

[0014] In the drum-type transmission of one embodiment described above, an end of the drum shaft may extend to the outside of a cover that covers the shift operation gear train, and a manual shift operation unit may be provided on the end of the drum shaft so as to be unable to rotate relative to the drum shaft.

[0015] According to this aspect, if the electric motor becomes inoperable, the operator can manually operate the manual shift operation unit to rotate the drum shaft and perform gear shifting. Also, even if the driving force of the electric motor is insufficient to release the parking lock state and the vehicle does not return to the parking lock state, the operator can manually operate the manual shift operation unit to rotate the assist operation shaft via the drum shaft and operate the assist cam, thereby forcibly releasing the parking lock state. [Effects of the Invention]

[0016] The present invention can improve the reliability of a parking lock mechanism in a drum-type transmission in which shifting operations are performed using the driving force of an electric motor, with a simple configuration. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic plan view, partially in skeleton form, of a power transmission mechanism of a vehicle to which an embodiment of a drum-type transmission mechanism is applied; [Figure 2] 2 is a schematic cross-sectional view of the embodiment, developed along a speed change shaft, a power input shaft, a rear wheel output shaft, and a front wheel output shaft. FIG. [Figure 3] 5 is a schematic cross-sectional view showing a cross section developed along the transmission shaft, the fork shaft, and the drum shaft together with the shift operation gear train in the same embodiment, and corresponds to the CC position in FIG. 4. [Figure 4] FIG. 4 is a schematic cross-sectional view corresponding to the AA position in FIG. 3, showing the parked state. [Figure 5] FIG. 4 is a schematic cross-sectional view corresponding to the AA position in FIG. 3, showing a parking lock state. [Figure 6] FIG. 5 is a schematic cross-sectional view showing a cross section developed along the power input shaft, the reverse idle shaft, the assist operation shaft, and the drum shaft, together with the shift operation gear train, and corresponds to the DD position in FIG. 4. [Figure 7] FIG. 4 is a schematic cross-sectional view showing a detent mechanism corresponding to the BB position in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic diagram of a power transmission of a work vehicle 1000 to which a drum-type transmission 1 according to this embodiment is applied. The drum-type transmission 1 is suitable for use in the traveling power transmission path of a work vehicle such as a tractor or utility vehicle. First, the general configuration of the work vehicle 1000 will be described with reference to FIG. 1.

[0019] The work vehicle 1000 comprises a body 8, an engine 2 as a drive source supported by the body 8, rear wheels 4 and front wheels 6 supported by the body 8, and a drum-type transmission 1 interposed in a power transmission mechanism 3 that runs from the engine 2 to which of the rear wheels 4 and front wheels 6 acts as a drive wheel.

[0020] The power transmission mechanism 3 transmits the power of the engine 2 via a drum-type transmission 1 in a transmission 800 located behind the engine 2 to a front axle drive unit 7 located in front of the engine 2 and to a rear axle drive unit 5 located in the transmission 800 together with the drum-type transmission 1.

[0021] The power transmission mechanism 3 is equipped with a belt transmission 21 driven by the engine 2, and a transmission 800 having a drum transmission 1 and a rear axle 5, both of which are driven by the belt transmission 21. The rear axle 5 drives a pair of left and right rear wheels 4 and a rear axle 4a. In addition, a front axle 7 is provided in front of the engine 2, which drives a pair of left and right front wheels 6 and a front axle 6a. The output of the drum transmission 1 is distributed and transmitted to the rear axle 5 and the front axle 7.

[0022] As shown in Fig. 1, the belt transmission 21 includes a drive pulley 22 and a driven pulley 23 arranged in a front-to-rear direction, and an endless belt 24 is wound around the drive pulley 22 and the driven pulley 23. The drive pulley 22 is attached to a power output shaft 30 of the engine 2 extending in the left-to-right direction of the vehicle body so as to be non-rotatable relative to the drive pulley 22, and the driven pulley 23 is attached to a power input shaft 820 of the transmission 800 extending in the left-to-right direction of the vehicle body so as to be non-rotatable relative to the drive pulley 22. The power output shaft 30 serves as the rotational axis (pulley shaft) of the drive pulley 22, and the power input shaft 820 serves as the rotational axis (pulley shaft) of the driven pulley 23. The belt transmission 21 is a continuously variable transmission (CVT) configured to continuously change the output / input rotational speed ratio by changing the width of the pulley grooves of both pulleys 22, 23 in accordance with changes in the rotational speed of the engine 2. The power input shaft 820 of the transmission 800 constitutes the power input shaft of the drum type transmission 1 provided inside the transmission 800.

[0023] Rear transaxle 5 is provided in transmission 800 and includes a rear wheel differential gear mechanism 830 to which the output of drum transmission 1 is input, and a pair of left and right rear wheel output shafts 840 extending in the left-right direction. Each rear wheel output shaft 840 protrudes outward to the left and right from mission housing 805, and is interlocked with rear axles 4a of each of the left and right rear wheels 4 via universal joints and transmission shafts. Rear wheel differential gear mechanism 830 is housed within mission housing 805, and left and right rear wheel output shafts 840 are connected to each other via rear wheel differential gear mechanism 830 so that they can be differentially rotated.

[0024] Front transaxle 7 has a front transaxle housing 70, which serves as its housing, supporting an input shaft 71 that extends in the fore-and-aft direction of the vehicle body in a plan view, and a pair of left and right output shafts 73 that extend in the left-right direction. Each output shaft 73 of front transaxle 7 protrudes outward to the left and right from front transaxle housing 70 and is operatively connected to a front axle 6a of each of the left and right front wheels 6 via a universal joint and a transmission shaft. A front-wheel differential mechanism (not shown) is housed within front transaxle housing 70, and the left and right output shafts 73 are differentially connected to each other via the front-wheel differential mechanism. The rear end of input shaft 71 protrudes rearward from front transaxle housing 70 and is connected, from the front side, to a front end of a front-wheel output shaft 850 that protrudes forward from a transmission housing 805 of transmission 800 via a universal joint 91, a front power transmission shaft 92, a universal joint 93, a rear power transmission shaft 94, and a shaft coupling 95.

[0025] In this embodiment, the work vehicle 1000 has both rear wheels 4 and front wheels 6 that function as drive wheels. Specifically, the work vehicle 1000 has a pair of left and right rear wheels 4 that function as main drive wheels, and a pair of left and right front wheels 6 that function as auxiliary drive wheels and also as steering wheels, and rotational power that has been changed in speed by the drum type transmission 1 is operatively transmitted to the rear wheels 4 and front wheels 6.

[0026] Next, the drum type transmission 1 will be described with reference to Figures 1 to 3. Figure 2 is a cross-sectional view taken along the transmission shaft 810, power input shaft 820, rear wheel output shaft 840, and front wheel output shaft 850. Figure 3 is a cross-sectional view taken along the transmission shaft 810, fork shaft 120, and drum shaft 148.

[0027] The drum type transmission 1 is capable of transmitting rotational power at variable speeds between a transmission shaft 810 and a power input shaft 820 that are arranged in parallel to each other. In detail, as shown in Figures 1 to 3, the drum type transmission 1 includes a transmission gear 10 that is supported on the transmission shaft 810 so as to be relatively rotatable, a transmission gear 20 that is supported on (or formed integrally with) the power input shaft 820 so as not to be relatively rotatable and that is directly or indirectly meshed with the transmission gear 10, and a drum type speed change operation mechanism 100 that selectively places the transmission gear 10 in a power transmitting state.

[0028] In this embodiment, the transmission gear 10 has a forward high-speed transmission gear 10H, a forward low-speed transmission gear 10L, and a reverse transmission gear 10R. The transmission gear 20 has a transmission gear 20H that meshes with the transmission gear 10H to form a forward high-speed gear train together with the transmission gear 10H, a transmission gear 20L that meshes with the transmission gear 10L to form a forward low-speed gear train together with the transmission gear 10L, and a transmission gear 20R that meshes with the transmission gear 10R via a reverse idle gear 15 (see FIG. 6) to form a reverse gear train together with the transmission gear 10R and the reverse idle gear 15.

[0029] In this embodiment, the power input shaft 820 acts as a transmission input shaft that operatively inputs rotational power from a drive source such as the engine 2, and the transmission shaft 810 acts as a transmission output shaft that outputs the rotational power after gear shifting to the drive wheels. A transmission output gear 11 that meshes with a final gear 831 of a rear-wheel differential gear mechanism 830 is fixedly provided to the transmission shaft 810, and the transmission shaft 810 rotates together with the rear wheels 4. A drive bevel gear 832 is attached to one end (the right end in this embodiment) of the transmission shaft 810 via a torque limiter 40, and meshes with a driven bevel gear 833 that is attached to the rear end of the front-wheel output shaft 850 so as not to rotate relative to it, and the rotational power of the transmission shaft 810 is also transmitted to the front-wheel output shaft 850.

[0030] That is, as shown in Figures 1 and 2, transmission 800 comprises a mission housing 805, a power input shaft 820 that acts as a transmission input shaft and is supported on mission housing 805 so as to be rotatable about its axis with one end extending outward so as to be operatively connected to engine 2 as a drive source, a transmission shaft 810 that is supported on mission housing 805 so as to be rotatable about its axis and acts as a transmission output shaft, and a drum-type transmission device 1 that transmits rotational power from power input shaft 820 to transmission shaft 810 at multiple speeds.

[0031] Transmission 800 further includes rear axle drive device 5 having a pair of left and right rear wheel output shafts 840, and a rear wheel differential gear mechanism 830 that differentially transmits rotational power operatively input from transmission output shafts (transmission shafts 810) to the pair of left and right rear wheel output shafts 840. Transmission 800 also includes a front wheel output shaft 850 that outputs the rotational power of transmission shafts 810 to a transmission path separate from rear wheel output shafts 840.

[0032] The drum type speed change operation mechanism 100 is configured to selectively place the plurality of speed change gears 10 in a power transmission state, thereby placing the drum type transmission 1 in a desired speed stage engagement state.

[0033] More specifically, as shown in Figures 1 to 3, the drum-type speed change operation mechanism 100 is provided with a shifter member 110 that is supported on the speed change shaft 810 so as to be non-rotatable relative to the speed change shaft 810 but movable axially, and that selectively engages with the speed change gear 10 in a concave-convex manner by axial movement, a fork shaft 120 that is parallel to the speed change shaft 810, a shift fork 130 that is supported on the fork shaft 120 so as to be movable axially, and a drum member 140 that is rotated about an axis that is parallel to the speed change shaft 810.

[0034] In detail, the opposing end faces of the shifter member 110 and the transmission gear 10 are provided with gear-shifting uneven portions 112, 12, respectively, and by moving the shifter member 110 along the axial direction in a direction approaching the transmission gear 10, the gear-shifting uneven portion 112 of the shifter member 110 engages with the gear-shifting uneven portion 12 of the transmission gear 10, thereby establishing a power transmission state in which the transmission gear 10 rotates integrally with the transmission shaft 810 via the shifter member 110.

[0035] As shown in FIGS. 1 to 3, in this embodiment, a transmission gear 10H, a transmission gear 10R, and a transmission gear 10L are arranged on a transmission shaft 810 in this order from left to right in the axial direction.

[0036] The drum-type shift operation mechanism 100 has, as its shifter members 110, a first shifter member 110HR that is supported on the shift shaft 810 between the shift gear 10H and the shift gear 10R so as to be non-rotatable relative to the shift gear shaft 810 but movable axially, and that engages with the shift gear 10H and the shift gear 10R in a concave-convex manner as the shift gear moves to the left and right in the axial direction, and a second shifter member 110L that is supported on the shift shaft 810 at a position opposite the shift gear 10L so as to be non-rotatable relative to the shift gear 10L but movable axially, and that engages with the shift gear 10L in a concave-convex manner as the shift gear moves to the side closer to the shift gear 10L in the axial direction (to the left axial direction in this embodiment).

[0037] The first shifter member 110HR has, on its left axial end face facing the transmission gear 10H, a high-speed concave-convex portion 112H that can be engaged with the transmission concave-convex portion 12H of the transmission gear 10H, and, on its right axial end face facing the transmission gear 10R, a reverse concave-convex portion 112R that can be engaged with the transmission concave-convex portion 12R of the transmission gear 10R.

[0038] The second shifter member 110L has, on its left axial end face facing the transmission gear 10L, a low speed concave-convex portion 112L that can be engaged with the transmission concave-convex portion 12L of the transmission gear 10L.

[0039] As shown in FIG. 3, the drum type gear change operation mechanism 100 also has, as the shift fork 130, first and second shift forks 130HR, 130L that move the first and second shifter members 110HR, 110L in the axial direction, respectively.

[0040] As shown in Figure 3 etc., the first shift fork 130HR has a first boss portion 132HR supported on the fork shaft 120 so as to be axially movable, a first engagement pin portion 134HR that engages with a first fork guide groove 142HR formed in the drum member 140, and a first fork portion 136HR that engages with the first shifter member 110HR, and is configured to move the first shifter member 110HR in the axial direction on the transmission shaft 810 in response to the axial movement of the first shift fork 130HR on the fork shaft 120.

[0041] More specifically, the first shift fork 130HR and the first shifter member 110HR can take three axial positions: a reference position where the first shifter member 110HR is not engaged with either the transmission gear 10H or the transmission gear 10R; a high-speed position where the first shifter member 110HR is engaged with the transmission gear 10H; and a reverse position where the first shifter member 110HR is engaged with the transmission gear 10R. Note that Fig. 3 shows a state where the first shift fork 130HR and the first shifter member 110HR are positioned at the reference positions.

[0042] The second shift fork 130L has a second boss portion 132L supported on the fork shaft 120 so as to be axially movable, a second engagement pin portion 134L that engages with a second fork guide groove 142L formed in the drum member 140, and a second fork portion 136L that engages with the second shifter member 110L, and is configured to move the second shifter member 110L in the axial direction on the transmission shaft 810 in accordance with its own axial movement on the fork shaft 120.

[0043] Specifically, the second shift fork 130L and the second shifter member 110L can take two axial positions: a reference position where the second shifter member 110L is not engaged with the transmission gear 10L, and a low-speed position where the second shifter member 110L is engaged with the transmission gear 10L. Note that Fig. 3 shows a state where the second shift fork 130L and the second shifter member 110L are positioned at the reference position.

[0044] The drum member 140 is adapted to rotate about the axis of a drum shaft 148 in response to a gear shift operation. The drum member 140 and the drum shaft 148 are supported by a transmission housing 805 so as to be rotatable about their axes.

[0045] 3 and 6, the drum-type gear shift operation mechanism 100 is provided with an electric motor 190 that is driven in response to gear shift operations. The drum member 140 is operatively connected to a shift drive gear 191 that is made up of a pinion gear fixed to the output shaft of the electric motor 190.

[0046] The electric motor 190 is attached to the outer wall of a shift gear chamber cover 806 provided on the transmission housing 805 so that the shift drive gear 191 is disposed to extend in the left-right direction of the vehicle parallel to the drum shaft 148. In this embodiment, the shift drive gear 191 is operatively connected to the drum member 140 via a shift operation gear train 200.

[0047] As shown in FIG. 3, the drum member 140 has a drum main body 141 in which fork guide grooves (in this embodiment, first and second fork guide grooves 142HR, 142L) are formed, and a drum shaft 148 that supports the drum main body 141 coaxially with the drum main body 141.

[0048] As shown in FIG. 3, the drum-type gear change operation mechanism 100 further includes a first shift fork pushing spring 160HR that pushes the first boss portion 132HR to the left in the axial direction, a slider member 170 that is extrapolated and supported on the fork shaft 120 on the left side of the first boss portion 132HR so as to be axially movable, and a slider member pushing spring 180 that pushes the slider member 170 to the right in the axial direction.

[0049] When the first shift fork 130HR is free, the first shift fork pushing spring 160HR is set to push the first boss portion 132HR to the left in the axial direction with a spring force that can move the first shifter member 110HR to a high-speed position where it engages with the transmission gear 10H.

[0050] More specifically, the first shift fork pushing spring 160HR has an axial right end which is a fixed end that is engaged with a locking member 126 provided on the fork shaft 120, and an axial left end which is a movable end that engages with the axial right end face of the first boss portion 132HR.

[0051] The slider member 170 is supported on the fork shaft 120 so as to be movable in the axial direction, with the end of its movement to the right in the axial direction being defined by a stop portion 133 provided on the first boss portion 132HR, and its axial position is further regulated by a slider guide groove 144 provided on the drum member 140.

[0052] More specifically, the slider member 170 has a slider main body 172 fitted onto the first boss portion 132HR so as to be movable in the axial direction, and a slider engaging pin portion 174 which is fitted into the slider guide groove 144.

[0053] Slider member pushing spring 180 is configured to push slider member 170 to the right in the axial direction with a biasing force greater than that of first shift fork pushing spring 160HR.

[0054] That is, when the first shift fork 130HR and the slider member 170 are free, the slider member pushing spring 180 is set to push the first boss portion 132HR to the right in the axial direction via the slider member 170 with a force sufficient to move the first shifter member 110HR to the reverse position where it engages with the transmission gear 10R, against the biasing force of the first shift fork pushing spring 160HR that biases the first shift fork 130HR toward the first axial side.

[0055] In detail, the slider member pushing spring 180 has a fixed end at its left axial end that is engaged with a locking member 127 provided on the fork shaft, and a movable end at its right axial end that is engaged with the left axial end face of the slider member 170.

[0056] In this embodiment, as shown in FIG. 3, the drum-type gear change operation mechanism 100 further includes a second shift fork pushing spring 160L that pushes the second boss portion 132L in a direction that presses the second shifter member 110L toward the gear change gear 10L.

[0057] As described above, in this embodiment, the transmission gear 10L is located on the axial left side of the second shifter member 110L, and therefore the second shift fork pushing spring 160L pushes the second boss portion 132L leftward in the axial direction.

[0058] More specifically, the second shift fork pushing spring 160L has an axial right end which is a fixed end that is engaged with a locking member 128 provided on the fork shaft 120, and an axial left end which is a movable end that engages with the axial right end face of the second boss portion 132L.

[0059] The second shift fork pushing spring 160L is set to push the second boss portion 132L with a spring force that can move the second shifter member 110L to a low-speed position where it engages with the transmission gear 10L in a concave-convex manner when the second shift fork 130L is free.

[0060] In the drum type transmission 1, the drum member 140 is configured to take operation positions around the axis corresponding to the gear stages (including the neutral stage) that the drum type transmission 1 can take.

[0061] In this embodiment, the drum-type transmission 1 is configured to be able to assume a neutral position, a forward high-speed position, a forward low-speed position, and a reverse position, and therefore the drum member 140 is configured to assume a neutral position, a high-speed position, a low-speed position, and a reverse position around the axis.

[0062] More specifically, in this embodiment, the drum member 140 is configured to assume a high-speed position when rotated from the neutral position to one side about the axis, to assume a low-speed position when rotated further from the high-speed position to one side about the axis, and to assume a reverse position when rotated from the neutral position to the other side about the axis.

[0063] The drum-type transmission 1 can also have a park position, and the drum member 140 can have a park position in addition to the above-mentioned operating positions. In this embodiment, the drum member 140 is configured to assume the park position when it is further rotated from the reverse position to the other side around the axis. The configuration for achieving this parking lock state will be described later.

[0064] The drum-type gear shift operation mechanism 100 further includes a detent mechanism 700 that locks the drum member 140 in each of the operating positions. FIG. 7 is a schematic cross-sectional view illustrating the detent mechanism, corresponding to the BB position in FIG. 3. As shown in FIGS. 3 and 7, the detent mechanism 700 includes a detent plate 710 that is supported on one end 148a (the left end in this embodiment) of a drum shaft 148 of the drum member 140 so as not to rotate relative to the drum member 140, a detent arm 720 that is supported so as to be rotatable about a detent shaft 725 that is parallel to the drum member 140, and a detent spring 730. As shown in FIG. 3, an angle sensor 146 is attached to one end 148a of the drum shaft 148 to detect the position of the drum member 140 about its axis.

[0065] The detent plate 710 has a plurality of detent recesses 712 corresponding to the above-mentioned operating positions that the drum member 140 can take. These detent recesses 712 include a neutral position recess 712N, a high speed position recess 712H, a low speed position recess 712L, a reverse position recess 712R, and a parking position recess 712P. Figure 7 shows the state in which the drum member 140 is positioned in the neutral position N.

[0066] The detent arm 720 has a base end rotatably supported on a detent shaft 725 and a free end having an engagement portion 722 that can be engaged with the detent recess 712. In this embodiment, the detent arm 720 has a roller at its free end that can rotate about a rotation axis parallel to the detent shaft 725, and this roller acts as the engagement portion 722.

[0067] The detent spring 730 biases the detent arm 720 around the detent shaft 725 so that the engagement portion 722 of the detent arm 720 is pressed toward the detent plate 710. The provision of the detent mechanism 700 effectively prevents the drum member 140 and the drum shaft 148 from unintentionally rotating from the operating position.

[0068] In the drum-type transmission 1, the intermittent rotation of the drum member 140 causes the shift forks 130HR, 130L to feed in increments that correspond to the groove shapes of the fork guide grooves 142HR, 142L and the slider guide groove 144. This sets the drum-type transmission 1 in one of a low-speed forward state, a high-speed forward state, a reverse drive state, a neutral state, and a parking lock state. A configuration similar to the drum-type transmission 1 of this embodiment is disclosed in, for example, Japanese Patent Application Laid-Open No. 2018-91376.

[0069] As is clear from FIG. 3 , the drum member 140 rotates about the axis of the drum shaft 148 in response to the drive of the electric motor 190 operatively connected thereto via a shift operation gear train 200. A shift drive gear 191 is attached to the output shaft of the electric motor 190 so as not to rotate relative to the drum shaft 148. The electric motor 190 rotates the shift drive gear 191 in conjunction with the operation of a speed change operation device (lever, pedal, dial, etc.) not shown. A shift driven gear 222 is attached to the other end 148b (the right end in this embodiment) of the drum shaft 148 so as not to rotate relative to the drum shaft 148. The shift operation gear train 200 transmits power between the shift drive gear 191 and the shift driven gear 222.

[0070] In this embodiment, the shift operation gear train 200 has four reduction stages and one speed increase stage. The shift operation gear train 200 is equipped with two gear shafts: an assist operation shaft 150 and an intermediate gear shaft 201. The assist operation shaft 150 and the intermediate gear shaft 201 are disposed parallel to the drum shaft 148.

[0071] In the shift operation gear train 200, a first large diameter gear 211 rotatably supported on the assist operation shaft 150 meshes with a shift drive gear 191 of the electric motor 190 to form a first reduction stage. A first small diameter gear 212, which has a smaller diameter than the first large diameter gear 211, is rotatably supported on the assist operation shaft 150. The first large diameter gear 211 and the first small diameter gear 212 are provided so as not to rotate relative to each other.

[0072] The first small diameter gear 212 meshes with a second large diameter gear 213 rotatably supported on the intermediate gear shaft 201 to form a second reduction stage. A second small diameter gear 214 having a diameter smaller than the second large diameter gear 213 is rotatably supported on the intermediate gear shaft 201. The second large diameter gear 213 and the second small diameter gear 214 are provided so as not to rotate relative to each other. The second small diameter gear 214 meshes with a third large diameter gear 215 rotatably supported on the assist operating shaft 150 to form a third reduction stage. A third small diameter gear 216 having a diameter smaller than the third large diameter gear 215 is rotatably supported on the assist operating shaft 150. The third large diameter gear 215 and the third small diameter gear 216 are provided so as not to rotate relative to each other.

[0073] The third small diameter gear 216 meshes with a fourth large diameter gear 217 that is journalled on the intermediate gear shaft 201 so as not to rotate relative to the fourth gear, thereby constituting a fourth reduction stage. A fifth large diameter gear 221 that meshes with a shift driven gear 222 of the drum shaft 148 to constitute a speed increasing stage is journalled on the intermediate gear shaft 201 so as not to rotate relative to the fifth large diameter gear. As the electric motor 190 is driven, the gears 211 to 217, the intermediate gear shaft 201 and the gear 221 rotate, and in conjunction with this, the shift driven gear 222 and the drum shaft 148 rotate.

[0074] In this embodiment, the shift operation gear train 200 includes a first shift operation gear train 210 that transmits power between an intermediate gear shaft 201 that is parallel to the assist operation shaft 150 and the shift drive gear 191 of the electric motor 190, and a second shift operation gear train 220 that transmits power between the intermediate gear shaft 201 and the drum shaft 148. The first shift operation gear train 210 includes four reduction stages having a plurality of gears 211 to 217 that are rotatably supported on the assist operation shaft 150 and the intermediate gear shaft 201, respectively. The second shift operation gear train 220 includes an increase speed stage that is configured from a fifth large diameter gear 221 and a shift driven gear 222.

[0075] The rotation of the shift drive gear 191 of the electric motor 190 is reduced in speed by the first shift operation gear train 210 and transmitted to the intermediate gear shaft 201. The rotation of the intermediate gear shaft 201 is increased in speed by the second shift operation gear train 220 and transmitted to the shift driven gear 222, and then transmitted to the drum shaft 148 and drum member 140 which rotate integrally with the shift driven gear 222. The first shift operation gear train 210 may have one to three reduction stages, or may have five or more stages. Alternatively, the second shift operation gear train 220 may be configured with a reduction gear train or a constant speed gear train, or may be configured with a gear train of multiple stages.

[0076] 3, an assist small-diameter gear 231 is journaled on the intermediate gear shaft 201 so as to be non-rotatable relative to the intermediate gear shaft 201. The assist small-diameter gear 231 meshes with an assist large-diameter gear 232 journaled on the assist operation shaft 150 so as not to be rotatable relative to the intermediate gear shaft 201, thereby forming an assist gear train 230. In this embodiment, the assist gear train 230 is formed of a reduction gear train, but it may also be formed of a speed-up gear train or a constant speed gear train, or may be formed of a multi-stage gear train.

[0077] Here, the right end of the drum shaft 148, the assist operating shaft 150, and the shift operating gear train 200 are housed in a shift gear chamber 805a provided on the outer surface (right surface in this embodiment) of the transmission housing 805. The shift gear chamber 805a is isolated by a partition wall 805b from the internal space of the transmission housing 805 that houses the drum body 141, the speed change gear 10, the transmission gear 20, etc. The shift gear chamber 805a is covered with a removable shift gear chamber cover 806.

[0078] The assist operating shaft 150 and the intermediate gear shaft 201 are rotatably supported by the partition wall 805b and the shift gear chamber cover 806. The assist operating shaft 150 is disposed by passing through the partition wall 805b, with one end 150a (the left end in this embodiment) disposed inside the transmission housing 805 and the other end 150b (the right end in this embodiment) supported by the shift gear chamber cover 806.

[0079] The other end 148b of the drum shaft 148 is inserted from the transmission housing 805 through a partition wall 805b and disposed within a shift gear chamber cover 806. A manual shift operation unit 147 is attached to the other end 148b of the drum shaft 148 so as not to be rotatable relative to the other end 148b. The manual shift operation unit 147 is attached to the shift gear chamber cover 806 which covers the shift operation gear train 200, and is operable from outside the transmission 800. Note that a configuration in which the other end 148b of the drum shaft 148 is inserted through the shift gear chamber cover 806 and the manual shift operation unit 147 is attached to the other end 148b may also be used.

[0080] An example of the parking structure of the drum-type transmission 1 will now be described. Figures 4 and 5 show cross-sectional views corresponding to the position AA in Figure 3. Figure 4 shows the parked state, and Figure 5 shows the parking locked state.

[0081] As shown in Figures 3 to 5, in the drum-type transmission 1, a park uneven portion 112P facing radially outward is provided on a shifter member (second shifter member 110L) that is moved axially by a shift fork (second shift fork 130L) and engages with a corresponding transmission gear (transmission gear 10L) to bring the transmission gear into a power transmission state.

[0082] In addition, the drum-type transmission 1 is provided with a parking lock mechanism 500 that engages with the parking uneven portion 112P to forcibly stop the rotation of the shifter member (second shifter member 110L). In this embodiment, the second shifter member 110L having the parking uneven portion 112P also serves as a park gear.

[0083] In this way, the drum-type transmission 1 is configured so that the shifter member (second shifter member 110L), which engages and disengages power transmission by the corresponding transmission gear (transmission gear 10L), also serves as a park gear, thereby reducing the number of parts, thereby lowering costs and making the device smaller in the axial direction.

[0084] It is also possible to provide a park gear, which is a separate member from the shifter member, on the speed change shaft 810 so as to be non-rotatable relative to the shifter member, and to provide the park uneven portion 112P on the park gear.

[0085] As shown in Figures 3 to 5, the parking lock mechanism 500 has a park pole 510 that is capable of swinging around a swing axis 505 parallel to the transmission shaft 810 that supports the second shifter member 110L and has an engagement portion 515 at its free end that can engage with the parking uneven portion 112P, a park release spring 520 that urges the park pole 510 in the park release direction around the swing axis 505, and a pole pushing member 530 (park pole operating member).

[0086] The park pole 510 can take a locked position (see Figure 5) around the swing axis 505 in which the engagement portion 515 engages with the parking uneven portion 112P to forcibly stop rotation of the second shifter member 110L, and an unlocked position (see Figure 4) in which the engagement portion 515 is moved radially outward from the parking uneven portion 112P.

[0087] The pole pushing member 530 uses the rotational movement of the drum member 140 about its axis toward the park position to push the park pole 510 toward the lock position against the biasing force of the park release spring 520 .

[0088] In this embodiment, as shown in Figures 3 to 5, the pole pushing member 530 has a pushing member main body 532 supported by the drum member 140, and a cam pushing portion 535 extending radially outward from the pushing member main body 532.

[0089] As shown in FIG. 4, the cam pushing portion 535 does not act on the park pole 510 when the drum member 140 is in the shift position or the neutral position (the reverse position in the illustrated embodiment), and as shown in FIG. 5, the cam pushing portion 535 is configured to use the rotational movement of the drum member 140 toward the park position to push the park pole 510 toward the lock position against the biasing force of the park release spring 520 (see FIG. 3).

[0090] 3 to 5, the parking pole 510 has a boss portion 512 that is fitted onto a pivot shaft 506 that defines a swing axis 505 so as to be relatively rotatable, and an arm portion 514 that extends radially outward from the boss portion 512. An engagement portion 515 is provided on the free end of the arm portion 514 on the side facing the parking uneven portion 112P, and a sliding roller 516 that the pushing member main body portion 532 abuts on is provided on the side of the arm portion 514 opposite the parking uneven portion 112P.

[0091] 3, in this embodiment, the reverse idle shaft 16 that supports the reverse idle gear 15 that forms the reverse gear train is used as a pivot shaft 506 that swingably supports the park pole 510. In other words, the axis of the reverse idle shaft 16 forms the swing axis 505 of the park pole 510.

[0092] As shown in Figure 3, the park release spring 520 is a coil spring that is inserted around the pivot shaft 506, with one end operatively connected to the park pole 510 and the other end operatively connected to the pivot shaft 506 (in this embodiment, via a pin 522).

[0093] In this embodiment, as described above, the drum member 140 is adapted to assume the reverse position when rotated from the neutral position to the other side around the axis, and to assume the park position when further rotated from the reverse position to the other side around the axis.

[0094] Therefore, the cam pushing portion 535 does not come into contact with the sliding roller 516 when the drum member 140 is positioned in the reverse position R, the neutral position N, the high speed position (high speed forward position) H, or the low speed position (low speed forward position) L, and comes into contact with the sliding roller 516 when the drum member 140 is rotated from the reverse position R toward the park position P, and pushes the park pole 510 toward the lock position against the biasing force of the park release spring 520.

[0095] In this manner, in this embodiment, the pole pushing member 530 is supported by the drum member 140, which makes it possible to make the park lock mechanism 500 more compact by utilizing the rotation of the drum member 140 to the park position to push the park pole 510 toward the lock position.

[0096] The drum type transmission 1 according to this embodiment further comprises the following configuration in order to provide a standby function during a gear shift operation to the park stage.

[0097] That is, in this embodiment, the pushing member main body 532 of the pole pushing member 530 is fitted onto the drum member 140 so as to be relatively rotatable.

[0098] Furthermore, as shown in FIG. 3, the pole pushing member 530 and the drum member 140 are connected via a parking coil spring 540 that is inserted around the drum member 140, with one end operatively connected to the pole pushing member 530 and the other end operatively connected to the drum member 140 (via a pin in this embodiment).

[0099] The parking coil spring 540 is configured to connect the cam pushing portion 535 and the pawl pushing member 530 so as to prevent relative rotation between them, so that the pawl pushing member 530 rotates integrally with the drum member 140 as the drum member 140 rotates about its axis when the circumferential load applied to the cam pushing portion 535 is equal to or less than a predetermined value, and to elastically deform when the circumferential load applied to the cam pushing portion 535 exceeds the predetermined value, allowing the drum member 140 to rotate ahead of the pawl pushing member 530 about its axis.

[0100] In this embodiment, the parking coil spring 540 is configured to be elastically deformed in the diameter-reducing direction when the drum member 140 is rotated relative to the pawl pushing member 530 in advance.

[0101] With this configuration, a standby action can be obtained during the shift operation to the park gear. That is, when the cam pushing portion 535 swings the park pole 510 toward the lock position in response to the rotation of the drum member 140 to the park position, the engaging portion 515 of the park pole 510 abuts against the convex portion of the park uneven portion 112P of the second shifter member 110L, and the park pole 510 cannot swing to the lock position.

[0102] In this case, a circumferential load exceeding a predetermined value is applied to the cam pushing portion 535. Therefore, the drum member 140 rotates ahead of the pawl pushing member 530 about its axis to the park position while elastically deforming the parking coil spring 540.

[0103] The park coil spring 540 in this elastically deformed state possesses an elastic force that urges the pawl pushing member 530 in a direction that causes it to follow the drum member 140. When the engagement portion 515 and the park uneven portion 112P are aligned, the elastic force causes the park pole 510 to swing to the locked position against the urging force of the park release spring 520, and the engagement portion 515 and the park uneven portion 112P engage with each other, completing the shift operation to the park gear (see FIG. 5).

[0104] In this embodiment, as shown in FIG. 5, when the cam pushing portion 535 positions the park pole 510 in the lock position and the drum-type transmission 1 is in the park stage engagement state, the direction of the reaction force acting on the cam pushing portion 535 from the sliding roller 516 is configured to be approximately opposite to the direction in which the cam pushing portion 535 extends radially outward with respect to the axis of the drum member 140 (hereinafter referred to as a "jamming" configuration by the cam pushing portion 535).

[0105] By providing a "blocking" configuration using the cam pushing portion 535, it is possible to effectively prevent or reduce the possibility of the engagement between the engagement portion 515 of the parking pole 510 and the parking uneven portion 112P being unintentionally released.

[0106] In more detail, when the drum-type transmission 1 is used in the traveling system transmission path of a work vehicle, it is assumed that the work vehicle is positioned on a slope and the drum member 140 is positioned in the park position, thereby putting the drum-type transmission 1 into the park gear engagement state.

[0107] In this situation, the gravity acting on the work vehicle is transmitted back from the drive wheels to the speed change shaft 810, and a rotational driving force acts on the speed change shaft 810 about its axis.

[0108] Generally, the cross-sectional shape of the recess of the concave-convex engagement structure (in this embodiment, the recess of the parking concave-convex portion 112P) is tapered so that it narrows radially inward, and the cross-sectional shape of the convex portion that engages with the recess (in this embodiment, the engagement portion 515 of the park pole 510) is tapered to correspond to the concave, thereby ensuring the "ease" of concave-convex engagement.

[0109] On the other hand, if the cross-sectional shape of the recess and engagement portion 515 of the parking uneven portion 112P is tapered, when a reverse driving force from the drive wheel is transmitted to the transmission shaft 810, this reverse driving force will act as a force to swing the park pole 510 in the park release direction, and the park pole 510, which is positioned in the locked position, may be swung in the park release direction against its will, causing the uneven engagement between the park pole 510 and the parking uneven portion 112P to be released.

[0110] In this regard, if the cam pushing portion 535 is provided with a "blocking" configuration, it is possible to effectively prevent or reduce the occurrence of the park pole 510 swinging unintentionally from the locked position in the unlocked direction.

[0111] In addition, in this embodiment, as shown in FIG. 4 etc., when the cam pushing portion 535 is not engaged with the park pole 510, that is, when the drum member 140 is positioned in an operating position from the low speed position to the reverse position, the pushing member main body 532 of the pole pushing member 530 is configured to come into contact with the park pole 510 which is biased in the park release direction around the swing axis 505 by the park release spring 520, thereby defining the swing end of the park pole 510 in the park release direction.

[0112] 3 to 5, the assist operating shaft 150 is provided so as to penetrate a partition wall 805b of the transmission housing 805 and the shift gear chamber cover 806, and one end 150a (the left end in this embodiment) of the assist operating shaft 150 is disposed adjacent to the park pole 510 inside the transmission housing 805. In this embodiment, the assist operating shaft 150 is provided at a position overlapping with the park pole 510 when viewed from the axial direction of the assist operating shaft 150. An assist cam 156 provided at the one end 150a of the assist operating shaft 150 is inserted into an engagement hole 517 provided in an arm portion 514 of the park pole 510.

[0113] 4, the assist cam 156 is provided on the end face of one end 150a of the assist operating shaft 150, and protrudes in the axial direction of the assist operating shaft 150 so as to be offset from the axis of the assist operating shaft 150. In this embodiment, the assist cam 156 is formed by cutting out a portion of the peripheral wall of one end 150a of the assist operating shaft 150, and has a generally fan-shaped columnar shape.

[0114] The assist cam 156 is provided at one end of the assist operating shaft 150, which rotates by power branched off from the shift operating gear train 200. The drum-type transmission 1 is provided with an assist gear train 230 that branches off and transmits power from the intermediate gear shaft 201 to the assist operating shaft 150. Therefore, the rotation of the shift drive gear 191 caused by driving of the electric motor 190 is transmitted to the intermediate gear shaft 201 by the first shift operating gear train 210 of the shift operating gear train 200. The rotation of the intermediate gear shaft 201 is transmitted to the drum shaft 148 by the second shift operating gear train 220, and is also transmitted to the assist operating shaft 150 by the assist gear train 230. In other words, the assist operating shaft 150 rotates in response to the rotation of the drum member 140.

[0115] 4, in a park released state in which the park pole 510 is located at the unlocked position, the park pole 510 is configured not to interfere with the rotation of the assist operating shaft 150 (rotational displacement of the assist cam 156). In this embodiment, the engagement hole 517 of the park pole 510 has the form of a circular through-hole with a diameter slightly larger than the shaft diameter of the assist operating shaft 150, and is provided so as to roughly overlap the outline of the assist operating shaft 150 when viewed from the axial direction of the assist operating shaft 150 in the park released state. This prevents the assist cam 156 from contacting the inner circumferential wall of the engagement hole 517 when the drum member 140 rotates and displaces between the reverse position R and the low speed position L, thereby preventing an increase in the operating resistance of the drum member 140.

[0116] 5, in the parking lock state where the park pole 510 is in the locked position, the engagement hole 517 is positioned closer to the second shifter member 110L (park gear) than the position in the park release state (see FIG. 4). When viewed from the axial direction of the assist operating shaft 150, a portion of the inner peripheral wall of the engagement hole 517 intersects with the movement locus of the assist cam 156 when the drum shaft 148 is rotated between the park position and the reverse position.

[0117] The assist cam 156 is configured to come into contact with the inner peripheral wall of the engagement hole 517 when the drum member 140 rotates from the park position P toward the reverse position R, thereby urging the park pole 510 toward the unlocked position.

[0118] The drum-type transmission 1 of this embodiment is provided with an unlocking mechanism that uses the spring force of the park release spring 520 when the drum member 140 rotates from the park position toward the shift position or the neutral position (reverse position R in this embodiment), and an unlocking mechanism that uses the assist cam 156 provided on the assist operating shaft 150. As a result, even if the parking state cannot be released solely by the spring force of the park release spring 520 and the reaction force that the park pole 510 receives from the second shifter member 110L (park gear), the parking lock state can be reliably released by the action of the assist cam 156. This improves the reliability of the park lock mechanism 500 in the drum-type transmission 1.

[0119] Furthermore, by providing the assist cam 156 on the assist operating shaft 150, which is interlocked and connected to the drum member 140 and the pawl pushing member 530, it is possible to operate two lock release mechanisms with one operating system (operation of the assist operating shaft 150). In other words, it is possible to provide a lock release mechanism using the assist cam 156 without adding a separate operating system to the operating system that uses the assist operating shaft 150 to operate the rotation of the drum member 140 and the pawl pushing member 530, and it is possible to improve the reliability of the parking lock mechanism 500 in the drum-type transmission 1 with a simple configuration and at low cost.

[0120] Furthermore, the assist cam 156 is provided on the assist operating shaft 150, which is located upstream of the transmission path of the rotational force that rotates the drum member 140. Therefore, when rotating the drum member 140 from the park position toward the shift position or the neutral position, the release operating force input to the assist operating shaft 150 can be transmitted to the park pole 510 without reduction, and a significant increase in the release operating force can be suppressed.

[0121] Furthermore, in the drum-type transmission 1 of this embodiment, the assist cam 156 is formed by cutting out one end 150a of the assist operating shaft 150, so the assist cam 156 can be provided on the assist operating shaft 150 without increasing the number of parts.This means that the reliability of the parking lock mechanism 500 in the drum-type transmission 1 can be improved with a low-cost, compact configuration without incurring a significant increase in manufacturing costs.

[0122] In addition, the assist cam 156 may be configured to always urge the park pole 510 toward the unlocked position when the parking lock is released, or may be configured to urge the park pole 510 toward the unlocked position only when the cam pushing portion 535 of the pole pushing member 530 moves away from the park pole 510 but the park pole 510 does not move away from the parking uneven portion 112P.

[0123] Furthermore, the shape of the assist cam 156 is not limited to a substantially sectorial columnar shape, and may be other shapes, such as a cylindrical shape. Furthermore, instead of the assist cam 156 formed by cutting out a portion of the assist operating shaft 150, it is also possible to configure an assist cam by attaching a separate member to one end 150a of the assist operating shaft 150, which can urge the park pole 510 toward the unlocked position when the drum member 140 is moved from the park position to the shift position or the neutral position.

[0124] Furthermore, the engagement hole 517 in the park pole 510 with which the assist cam 156 comes into contact is not limited to a circular shape, and may have another shape, such as an L-shaped groove, or may be open to the outer circumferential side surface of the park pole 510. Furthermore, the location of the park pole 510 with which the assist cam 156 comes into contact may be provided in a portion of the outer circumferential side surface of the park pole 510 that faces the second shifter member 110L, with the assist cam 156 being disposed between the park pole 510 and the second shifter member 110L (park gear).

[0125] The drum-type transmission 1 of this embodiment includes a transmission shaft 810 having a plurality of transmission gears 10H, 10L, and 10R, a drum member 140 that rotates around a drum shaft 148 and can be shifted to a park position, a neutral position, or a shift position, and a shift operation gear train 200 that transmits the driving force of an electric motor 190 to the drum shaft 148. The drum-type transmission 1 also includes a parking lock mechanism 500 having a park pole 510 that engages with and disengages from the parking uneven portion 112P of the second shifter member 110L (park gear) that is non-rotatable relative to the transmission shaft 810, a pole pushing member 530 (park pole operating member) that engages the park pole 510 with the parking uneven portion 112P when the drum member 140 is in the park position and disengages the park pole 510 when the drum member 140 is out of the park position, and an assist cam 156 that assists movement in a direction that disengages the park pole 510 from the parking uneven portion 112P when the drum member 140 rotates from the park position toward the shift position or the neutral position, or in a direction that engages the park pole 510 with the parking uneven portion 112P when the drum member 140 rotates from the park position toward the shift position or the neutral position toward the park position. The assist cam 156 is provided at one end 150 a of an assist operation shaft 150 that rotates by power branched from the shift operation gear train 200 .

[0126] The drum-type transmission 1 is provided with a separate path that branches off from the main path (which locks the park pole 510) that connects the electric motor 190 to the drum shaft 148 and that unlocks the park pole 510. This allows the park pole 510 to be forcibly moved via the separate path and reliably unlocked even if the park pole 510 remains engaged with the parking uneven portion 112P and does not return from the parking lock state, thereby improving the reliability of the parking lock mechanism 500. Furthermore, the assist cam 156 is provided at one end 150a of the assist operating shaft 150 that rotates using power (separate path) that branches off from the shift operating gear train 200 (main path), so the assist cam 156 can be operated with a simple configuration.

[0127] An intermediate gear shaft 201 is provided between the assist operation shaft 150 and the drum shaft 148 and in a parallel orientation to each other, and the shift operation gear train 200 includes a first shift operation gear train 210 that transmits power between the intermediate gear shaft 201 and the output shaft of the electric motor 190, and a second shift operation gear train 220 that transmits power between the intermediate gear shaft 201 and the drum shaft 148. An assist gear train 230 is also provided that branches off and transmits the power of the intermediate gear shaft 201 to the assist operation shaft 150. Furthermore, the first shift operation gear train 210 includes a plurality of gears 211 to 217 that are supported on the assist operation shaft 150 and the intermediate gear shaft 201 so as to be able to rotate freely, respectively.

[0128] The drum type transmission 1 can form a shift operation gear train 200 that connects the electric motor 190 to the drum shaft 148 by utilizing an assist operation shaft 150 that has an assist cam 156 attached to one end 150a. This makes it possible to provide the assist operation shaft 150 that has the assist cam 156 without increasing the number of parts, and can improve the reliability of the parking lock mechanism 500 in the drum type transmission 1 with a low-cost, compact configuration without incurring a significant increase in manufacturing costs.

[0129] In the drum type transmission 1, the other end 148b of the drum shaft 148 extends to the outside of the shift gear chamber cover 806 that covers the shift operation gear train 200, and a manual shift operation unit is provided on the other end 148b of the drum shaft 148 so as not to rotate relative to the other end 148b. The manual shift operation unit 147 may have a shape such as a hexagonal nut, for example.

[0130] As a result, if the electric motor 190 becomes inoperable, the operator can manually operate the manual shift operation unit 147 with a wrench or the like to rotate the drum shaft 148 and perform gear shifting. Furthermore, even if the driving force of the electric motor 190 is insufficient to release the parking lock state and the vehicle does not return to the parking lock state, the operator can manually operate the manual shift operation unit 147 to rotate the assist operation shaft 150 via the drum shaft 148 and the assist gear train 230 and operate the assist cam 156, thereby forcibly releasing the parking lock state.

[0131] The manual speed change operation unit 147 may be provided at one end 148a of the drum shaft 148. In this case, it is preferable to attach the angle sensor 146 to the other end 148b of the drum shaft 148.

[0132] Furthermore, in the drum-type transmission 1, the electric gear shift module including the assist operating shaft 150, the electric motor 190, the shift operating gear train 200, and the shift gear chamber cover 806 can be changed to a manual gear shift module shown in Patent Document 2. In this case, an angle sensor 146 may be attached to the other end 148b of the drum shaft 148.

[0133] Furthermore, in this embodiment, the assist cam 156 is configured to urge the park pole in the direction away from the park gear, but in another embodiment, the assist cam may be configured to urge the park pole in the direction of engaging with the park gear when the drum member rotates from the shift position or neutral position toward the park position, thereby making it possible to strongly maintain the parking lock state. The present invention is not limited to the above-described embodiment, but can be embodied in various forms. The configuration of each part is not limited to the illustrated embodiment, and various modifications are possible within the scope of the spirit of the present invention. For example, the configurations described in the above-described embodiment and modified examples (notes, etc.) may be combined, and additions, omissions, substitutions, and other modifications of the configurations are possible. [Explanation of symbols]

[0134] 1 Drum-type transmission 10, 10H, 10L, 10R gears 110L Second shifter part (an example of a park gear) 112P Park uneven part 140 Drum parts 147 Manual gear shift operation unit 148 Drum shaft 150 Assist operation axis 150a One end of the assist operating shaft 156 Assist Cam 190 Electric Motor 191 Shift drive gear 200 Shift operation gear train 201 Intermediate gear shaft 210 1st shift operation gear train 220 Second shift operation gear train 230 Assist Gear Train 500 Park Lock Mechanism 510 Park Pole 530 Pole pushing member (park pole operating member) 810 Speed ​​change shaft

Claims

1. A drum-type transmission device including a speed change shaft having a plurality of speed change gears, a drum member that rotates around a drum shaft and can be shifted to a park position, a neutral position, or a speed change position, and a shift operation gear train that transmits the driving force of an electric motor to the drum shaft, a park pole that engages with and disengages from a park gear that is provided on the speed change shaft so as not to rotate relative to the speed change shaft; a park pole operating member that engages the park pole with the park gear when the drum member is in the park position and disengages the park pole when the drum member is out of the park position; a park lock mechanism having an assist cam that assists the movement of the drum member in a direction to disengage the park pole from the park gear when the drum member rotates from the park position toward the shift position or the neutral position, or in a direction to engage the park pole with the park gear when the drum member rotates from the shift position or the neutral position toward the park position, The assist cam is provided at one end of an assist operation shaft that rotates by power branched from the shift operation gear train. Drum type transmission.

2. an intermediate gear shaft is provided between the assist operating shaft and the drum shaft, the intermediate gear shaft being parallel to each other; the shift operation gear train includes a first shift operation gear train that transmits power between the intermediate gear shaft and an output shaft of the electric motor, and a second shift operation gear train that transmits power between the intermediate gear shaft and the drum shaft, an assist gear train is provided to transmit power between the intermediate gear shaft and the assist operation shaft; 2. The drum-type transmission according to claim 1.

3. The first shift operation gear train includes a plurality of gears rotatably supported on the assist operation shaft and the intermediate gear shaft, respectively.

3. The drum-type transmission according to claim 2.

4. An end of the drum shaft extends to the outside of a cover that covers the shift operation gear train, and a manual gear shift operation unit is provided on the end of the drum shaft so as to be unable to rotate relative to the drum shaft.

4. The drum-type transmission according to claim 1.

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