Planetary gear assembly, HMT device and transmission structure

Abstract

To provide a planetary gear assembly capable of reducing the size of the entire device, while expanding a shift range of an HMT device formed in cooperation with an HST.SOLUTION: A planetary gear assembly comprises: a transmission shaft; first and second planetary gear mechanisms in which a sun gear is supported on the transmission shaft so as not to be relatively rotatable around an axial line; and a connection member externally fitted on the transmission shaft so as to be relatively rotatable around the axial line. The connection member connects planetary elements other than the sun gear and a planetary element forming a reference rotational speed power input part of the first planetary gear mechanism, and planetary elements other than the sun gear and the planetary element forming the reference rotational speed power input part of the second planetary gear mechanism so as not be relatively rotatable with each other around the axial line.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a planetary gear assembly having two planetary gear mechanisms, a hydrostatic-mechanical continuously variable transmission (HMT device) including the planetary gear assembly, and a transmission structure including the HMT device. [Background technology]

[0002] Various HMT devices that combine a hydrostatic continuously variable transmission (HST) and a planetary gear mechanism have been proposed and are suitable for use in the transmission structures of work vehicles such as combine harvesters and tractors.

[0003] For example, Patent Document 1 below discloses an HMT device (hereinafter referred to as the first conventional example) that includes an HST in which a pump shaft is operatively connected to a drive source and a motor shaft is arranged parallel to the pump shaft, a drive shaft coaxially connected to the pump shaft so as to be non-rotatable relative to the pump shaft, a first transmission shaft coaxially connected to the motor shaft so as to be non-rotatable relative to the pump shaft, a second transmission shaft arranged parallel to both the drive shaft and the first transmission shaft, a first planetary gear mechanism having a first sun gear, a first carrier, and a first internal gear and arranged coaxially with the first transmission shaft, a second planetary gear mechanism having a second sun gear, a second carrier, and a second internal gear and arranged coaxially with the second transmission shaft, an output shaft arranged coaxially and rotatable relative to the second transmission shaft, and first to fourth clutch mechanisms.

[0004] The first sun gear is supported on the first transmission shaft so as to be unable to rotate relative to it around its axis, the first carrier is operatively connected to the first transmission shaft (i.e., the motor shaft) via the first clutch mechanism and to the drive shaft (i.e., the pump shaft) via the second clutch mechanism, and the first internal gear is operatively connected to the output shaft.

[0005] In addition, the second internal gear is operatively connected to the drive shaft (i.e., the pump shaft) via the third clutch mechanism, the second carrier is operatively connected to the first transmission shaft (i.e., the motor shaft) via the fourth clutch mechanism, the second sun gear is supported on the second transmission shaft so as not to be able to rotate relative to it around its axis, and the second transmission shaft is operatively connected to the output shaft.

[0006] The first conventional example can selectively produce a first transmission state in which the first clutch mechanism is engaged and the second to fourth clutch mechanisms are released, a second transmission state in which the second clutch mechanism is engaged and the first, third and fourth clutch mechanisms are released, and a third transmission state in which the third and fourth clutch mechanisms are engaged and the first and second clutch mechanisms are released.

[0007] In the first transmission state, the HST output from the motor shaft is input to both the first sun gear and the first carrier, and rotational power is output from the first internal gear to the output shaft.

[0008] In the second transmission state, the reference rotational speed power from the drive source is input to the first carrier and the HST output from the motor shaft is input to the first sun gear, and the resultant rotational power by the first planetary gear mechanism is output from the first internal gear to the output shaft.

[0009] In the third transmission state, the reference rotational speed power from the drive source is input to the second internal gear and the HST output from the motor shaft is input to the second carrier, and the resultant rotational power by the second planetary gear mechanism is output from the second sun gear to the second transmission shaft and operatively transmitted to the output shaft.

[0010] The first conventional example having such a configuration is useful in that it can expand the range of speed changes that can be made to the rotational speed of the output shaft. However, it requires three shafts (the drive shaft, the first transmission shaft, and the second transmission shaft) that are arranged in an overlapping state in the axial direction, and further requires a gear train to transmit power between the three shafts. Therefore, there is room for improvement in terms of installation space, transmission efficiency, and cost.

[0011] Furthermore, the following Patent Document 2 discloses an HST including a drive shaft operatively connected to a drive source, a pump shaft operatively connected to the drive shaft with the drive shaft disposed parallel to the drive shaft, and a motor shaft disposed parallel to the drive shaft and the pump shaft at positions displaced from the drive shaft and the pump shaft, a first transmission shaft disposed parallel to the drive shaft, the pump shaft, and the motor shaft at positions displaced from the drive shaft, a first planetary gear mechanism having a first sun gear, a first carrier, and a first internal gear and disposed coaxially with the first transmission shaft, and a first planetary gear mechanism disposed coaxially with the first planetary gear mechanism. An HMT device (hereinafter referred to as the second conventional example) is disclosed which includes an intermediate shaft, a second transmission shaft coaxially connected to the motor shaft so as to be unable to rotate relative to the motor shaft about its axis, a second planetary gear mechanism having a second sun gear, a second carrier, and a second internal gear and arranged coaxially with the second transmission shaft, a second intermediate shaft arranged coaxially with the second planetary gear mechanism, an output shaft, a first clutch mechanism which engages and disengages power transmission from the first intermediate shaft to the output shaft, and a second clutch mechanism which engages and disengages power transmission from the second intermediate shaft to the output shaft (see, for example, Figure 1 of Patent Document 2).

[0012] The second conventional example requires many shafts, including the drive shaft, the first transmission shaft, the second transmission shaft, the first intermediate shaft, and the second intermediate shaft, which is very disadvantageous in terms of installation space, transmission efficiency, and cost.

[0013] Furthermore, Patent Document 2 also discloses an HMT device (hereinafter referred to as a third conventional example) that includes an HST and first and second planetary gear mechanisms arranged in series (see, for example, Figure 5 of Patent Document 2).

[0014] In the third conventional example, three shafts are arranged in an overlapping manner in the axial direction, including a drive shaft that is coaxially connected to the pump shaft and unable to rotate relative to it around its axis, a transmission shaft that is coaxially connected to the motor shaft and unable to rotate relative to it around its axis and supports the first and second planetary gear mechanisms and the first to third clutch mechanisms, and an output shaft that is operatively connected to the transmission shaft via a gear train, and there is room for improvement in terms of installation space, transmission efficiency, and cost. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Patent No. 4194709 [Patent Document 2] International Publication No. WO2020 / 097650 Summary of the Invention [Problem to be solved by the invention]

[0016] The present invention has been made in consideration of the above-mentioned conventional technology, and has as its first object to provide a planetary gear assembly that cooperates with an HST to form an HMT device, which can increase the speed range of the HMT output while reducing the size of the entire HMT device.

[0017] A second object of the present invention is to provide an HMT device including an HST and first and second planetary gear mechanisms, which can be made smaller while widening the speed change range of the HMT output.

[0018] A third object of the present invention is to provide a transmission structure equipped with an HMT device including an HST and first and second planetary gear mechanisms, which can reduce the size of the HMT device while widening the speed change range of the HMT output, and which can output the HMT output with good controllability. [Means for solving the problem]

[0019] In order to achieve the first object, a first aspect of the present invention is a planetary gear assembly that forms an HMT device in cooperation with an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between, for example, a first HST speed, which is the maximum speed on the reverse side, and a second HST speed, which is the maximum speed on the forward side, and outputs the HST output after speed change from a motor shaft, the planetary gear assembly having a transmission shaft and three planetary elements including a first sun gear, a first carrier, and a first internal gear, the first sun gear being supported on the transmission shaft so as not to rotate relatively about its axis, one of the first carrier and the first internal gear forming a reference rotational speed power input section that can input the reference rotational speed power, and the first planetary gear assembly including a second sun gear, a second carrier, and a second internal gear. Provided is a planetary gear assembly comprising: a second planetary gear mechanism having three planetary elements, in which a second sun gear is supported on the transmission shaft so as to be non-rotatable relative to the second carrier and the second internal gear, and in which a planetary element different from the planetary element that forms the reference rotational speed power input portion in the first planetary gear mechanism forms a reference rotational speed power input portion to which reference rotational speed power can be input; and a connecting member extrapolated to the transmission shaft so as to be rotatable relative to the first sun gear and the planetary element that forms the reference rotational speed power input portion, in which the connecting member connects the planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary element that forms the reference rotational speed power input portion to the planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary element that forms the reference rotational speed power input portion so as not to be rotatable relative to the second carrier and the second internal gear.

[0020] In one mode of the first aspect, the transmission shaft is capable of operatively inputting an HST output. In this case, the connecting member has a connecting body that connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion, and planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion, and an output body that can output the rotational power of the connecting body to the outside.

[0021] In another mode of the first aspect, the connecting member is capable of operatively inputting an HST output. In this case, the transmission shaft is capable of outputting rotational power around its own axis to the outside.

[0022] In yet another form of the first aspect, the transmission shaft is a cylindrical shaft to which HST output can be operatively input, and the planetary gear assembly is provided with an output shaft onto which the transmission shaft is externally inserted so as to be relatively rotatable about its axis. In this case, the connecting member comprises a connecting body that connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion, and planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion, and an output body that can output the rotational power of the connecting body to the outside, and the output body is coaxial with the output shaft and cannot rotate relatively around the axis.

[0023] In order to achieve the first object, a second aspect of the present invention is a planetary gear assembly that forms an HMT device in cooperation with an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between, for example, a first HST speed that is set as the maximum speed on the reverse side and a second HST speed that is set as the maximum speed on the forward side, and outputs the HST output after the speed change from a motor shaft, and that includes a transmission shaft to which the HST output can be operatively input, a first element supported on the transmission shaft so as not to rotate relatively about its axis, a second element to which the reference rotational speed power can be input, and a combination of the rotational power input to the first and second elements. a second planetary gear mechanism having a first element supported on the transmission shaft so as not to be rotatable relative to the first element about its axis, a second element to which a reference rotational speed power can be input, and a third element that outputs a resultant rotational power obtained by combining the rotational powers input to the first and second elements; and a connecting member extrapolated onto the transmission shaft so as to be rotatable relative to the first element about its axis, wherein the connecting member has a connecting body that connects the third elements of the first and second planetary gear mechanisms together, and an output body that can output the rotational power of the connecting body to the outside.

[0024] The planetary gear assembly according to the second aspect may preferably include an input member connected to the second element of the second planetary gear mechanism in a state in which the input member is rotatable relative to the transmission shaft about its axis. The input member has first and second input gear portions to which a reference rotational speed power can be input, and the pitch diameter of the second input gear portion is smaller than the pitch diameter of the first input gear portion.

[0025] In a first form of the second aspect, the first planetary gear mechanism has a first sun gear acting as a first element, a first carrier acting as a third element, and a first internal gear acting as a second element, and the second planetary gear mechanism has a second sun gear acting as a first element, a second carrier acting as a second element, and a second internal gear acting as a third element.

[0026] In this case, the gear ratio of the first planetary gear mechanism is set so that, under a transmission state, the first carrier rotates at an increased speed in a first rotational direction, which is one side around the axis, as the HST output changes from the first HST speed side to the second HST speed side, and when the HST output is set to a predetermined HST speed for the first gear stage maximum speed, the first carrier rotates in the first rotational direction at the predetermined first gear stage maximum speed.

[0027] The gear ratio of the second planetary gear mechanism is set so that, under a transmission state, when the HST output is set to the HST speed for the first gear stage maximum speed, the second internal gear rotates in the first rotational direction at the first gear stage maximum speed, and as the HST output is changed from the HST speed for the first gear stage maximum speed toward the first HST speed to a predetermined HST speed for the second gear stage maximum speed, the rotational speed of the second internal gear increases from the first gear stage maximum speed to the second gear stage maximum speed.

[0028] In a first form of the second aspect, the connecting body may preferably have a cylindrical portion extending in the axial direction, a first flange extending radially outward from a first axial side of the cylindrical portion and connected to the first carrier, and a second flange extending radially outward from a second axial side of the cylindrical portion and connected to the second internal gear.

[0029] More preferably, the output body may have a connecting flange that is arranged on the axially opposite side of the connecting body across the first planetary gear supported by the first carrier and is connected to a first axial side of the connecting body so as not to rotate relative to the connecting body around the axis, and a shaft portion that extends from the connecting flange toward the first axial side.

[0030] Preferably, the planetary gear assembly according to the second aspect may include a transmission gear member that is fitted onto the shaft portion so as to be relatively rotatable about the axis. The transmission gear member has an input gear portion that receives a reference rotational speed power operatively input from the drive source, and an output gear portion that meshes with the first internal gear.

[0031] Preferably, the planetary gear assembly according to the second aspect may include an HST driven gear that is supported on the transmission shaft on a second axial side of a portion that supports the second planetary gear mechanism so as not to rotate relative to the transmission shaft, and that can receive HST output.

[0032] In the second aspect, preferably, the gear ratio of the first planetary gear mechanism is set so that, under a transmission state, the third element becomes zero speed when the HST output is set to a predetermined HST speed for zero speed.

[0033] More preferably, the zero speed HST speed is a speed shifted from the first HST speed toward the second HST speed by a predetermined speed.

[0034] In order to achieve the first object, a third aspect of the present invention is a planetary gear assembly that forms an HMT device in cooperation with an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between, for example, a first HST speed that is set as the maximum speed on the reverse side and a second HST speed that is set as the maximum speed on the forward side, and outputs the HST output after the speed change from a motor shaft, the first planetary gear assembly having a transmission shaft, a first element supported on the transmission shaft so as not to be rotatable relative to the transmission shaft about its axis, a second element to which the reference rotational speed power can be input, and a third element to which the HST output can be input. a second planetary gear mechanism having a first element supported on the transmission shaft so as not to be rotatable relative to the first element about its axis, a second element to which a reference rotational speed power can be input, and a third element to which an HST output can be input; and a connecting member extrapolated onto the transmission shaft so as to be rotatable relative to the first element about its axis, wherein the connecting member is capable of operatively inputting the HST output and is configured to connect the third elements of the first and second planetary gear mechanisms, and the transmission shaft acts as an HMT output member common to both the first and second planetary gear mechanisms.

[0035] In order to achieve the second object, a fourth aspect of the present invention is a pump drive system including an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between, for example, a first HST speed set as the maximum speed on the reverse side and a second HST speed set as the maximum speed on the forward side, and outputs the HST output after the speed change from a motor shaft; a drive shaft to which the reference rotational speed power is operatively transmitted from the drive source; a transmission shaft; and three planetary elements including a first sun gear, a first carrier, and a first internal gear; a first planetary gear mechanism having a sun gear supported on the transmission shaft so as not to be rotatable relative to the transmission shaft about its axis, and one of a first carrier and a first internal gear forming a reference rotational speed power input section to which a reference rotational speed power can be input; and a second planetary gear mechanism having three planetary elements including a second sun gear, a second carrier, and a second internal gear, and the second sun gear is supported on the transmission shaft so as not to be rotatable relative to the transmission shaft about its axis, and one of the second carrier and the second internal gear forms a reference rotational speed power input section to which a reference rotational speed power can be input. a second planetary gear mechanism forming a reference rotational speed power input section to which a planetary element different from the planetary element forming the power section can input a reference rotational speed power; a first transmission gear train capable of operatively transmitting the reference rotational speed power from the drive shaft to the reference rotational speed power input section of the first planetary gear mechanism; a first clutch mechanism for engaging and disengaging power transmission by the first transmission gear train; and a second transmission gear train capable of operatively transmitting the reference rotational speed power from the drive shaft to the reference rotational speed power input section of the second planetary gear mechanism. the first planetary gear mechanism, other than the planetary elements that form the first sun gear and the reference rotational speed power input portion, and the second planetary gear mechanism, other than the planetary elements that form the second sun gear and the reference rotational speed power input portion, so that they cannot rotate relative to each other about the axis.

[0036] In one mode of the fourth aspect, the transmission shaft is capable of operatively inputting an HST output. In this case, the connecting member has a connecting body that connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion, and planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion, and an output body that can output the rotational power of the connecting body to the outside.

[0037] In another embodiment of the fourth aspect, the connecting member is capable of operatively inputting an HST output. In this case, the transmission shaft is capable of outputting rotational power around its own axis to the outside.

[0038] In yet another form of the fourth aspect, the transmission shaft is a cylindrical shaft to which HST output can be operatively input, and the HMT device is provided with an output shaft onto which the transmission shaft is externally inserted so as to be relatively rotatable about its axis. In this case, the connecting member comprises a connecting body that connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion, and planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion, and an output body that can output the rotational power of the connecting body to the outside, and the output body is coaxial with the output shaft and cannot rotate relatively around the axis.

[0039] In order to achieve the second object, a fifth aspect of the present invention provides an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between, for example, a first HST speed set as a maximum speed on the reverse side and a second HST speed set as a maximum speed on the forward side, and outputs the HST output after the speed change from a motor shaft; a drive shaft to which the reference rotational speed power is operatively transmitted from the drive source; a transmission shaft to which the HST output is operatively transmitted from the motor shaft; a first planetary gear mechanism having a first element supported on the transmission shaft so as not to rotate relatively about its axis, a second element to which the reference rotational speed power can be input, and a third element that outputs a combined rotational power obtained by combining the rotational powers input to the first and second elements; a first transmission gear train that can operatively transmit the reference rotational speed power from the drive shaft to the second element of the first planetary gear mechanism; and a first clutch mechanism that engages and disengages power transmission by the first transmission gear train. the second planetary gear mechanism having a first element supported on the transmission shaft so as to be non-rotatable relative to the first element around its axis, a second element to which a reference rotational speed power can be input, and a third element which outputs a resultant rotational power obtained by combining the rotational powers input to the first and second elements; a second transmission gear train which can operatively transmit the reference rotational speed power from the drive shaft to the second element of the second planetary gear mechanism; a second clutch mechanism which engages and disengages power transmission by the second transmission gear train; and a connecting member which connects the third elements of the first and second planetary gears to each other so as to be non-rotatable relative to the first element around its axis, wherein the connecting member is extrapolated onto the transmission shaft so as to be rotatable relative to the first element around its axis, and has a connecting body whose first axial side is connected to the third element of the first planetary gear mechanism and whose second axial side is connected to the third element of the second planetary gear mechanism; and an output body which can output the rotational power of the connecting body to the outside.

[0040] In a first form of the fifth aspect, the first planetary gear mechanism has a first sun gear acting as a first element, a first carrier acting as a third element, and a first internal gear acting as a second element, and the second planetary gear mechanism has a second sun gear acting as the first element, a second carrier acting as the second element, and a second internal gear acting as a third element.

[0041] In this case, the gear ratio of the first planetary gear mechanism is set so that, under transmission conditions, when the HST output is set to a predetermined HST speed for zero speed, the first carrier reaches zero speed, and as the HST output changes from the first HST speed side to the second HST speed side, the first carrier rotates at an increased speed in a first rotational direction, which is one side around the axis, and when the HST output is set to a predetermined HST speed for the first gear stage maximum speed, the first carrier rotates in the first rotational direction at the predetermined first gear stage maximum speed.

[0042] The gear ratio of the second planetary gear mechanism is set so that, under a transmission state, when the HST output is set to the HST speed for the first gear stage maximum speed, the second internal gear rotates in the first rotational direction at the first gear stage maximum speed, and as the HST output is changed from the HST speed for the first gear stage maximum speed toward the first HST speed to a predetermined HST speed for the second gear stage maximum speed, the rotational speed of the second internal gear increases from the first gear stage maximum speed to the second gear stage maximum speed.

[0043] In a first form of the fifth aspect, the connecting body preferably has a cylindrical portion extending in the axial direction, a first flange extending radially outward from a first axial side of the cylindrical portion and connected to the first carrier, and a second flange extending radially outward from a second axial side of the cylindrical portion and connected to the second internal gear.

[0044] In a first form of the fifth aspect, preferably, the drive shaft is coaxially connected to the pump shaft so as to be non-rotatable relative to the pump shaft about its axis, the transmission shaft is disposed parallel to the drive shaft, the first transmission gear train includes a first drive gear supported on the drive shaft so as to be rotatable relative to the pump shaft about its axis, and a first driven gear operatively meshed with the first drive gear and connected to a first internal gear so as to be non-rotatable relative to the pump shaft about its axis, and supported directly or indirectly on the transmission shaft so as to be rotatable relative to the pump shaft about its axis, the first clutch mechanism is provided on the drive shaft so as to engage and disengage power transmission from the drive shaft to the first drive gear, and the second transmission gear train includes a second drive gear supported on the drive shaft so as to be rotatable relative to the pump shaft about its axis, and a second driven gear operatively meshed with the second drive gear and connected to a second carrier so as to be non-rotatable relative to the pump shaft about its axis, The second clutch mechanism is provided on the drive shaft to engage and disengage power transmission from the drive shaft to the second drive gear.

[0045] More preferably, the first and second clutch mechanisms are arranged between the first and second flanges of the connecting body in the axial direction so that portions of the first and second clutch mechanisms enter the space defined between the outer peripheral surface of the cylindrical portion and the opposing surfaces of the first and second flanges.

[0046] The HMT device according to the first form of the fifth aspect may preferably include a third transmission gear train capable of operatively transmitting reference rotational speed power from the drive shaft to the second carrier, and a third clutch mechanism that engages and disengages power transmission by the third transmission gear train.

[0047] The third transmission gear train includes a third drive gear supported on the drive shaft so as to be rotatable relative to the drive shaft around its axis, and a third driven gear operatively meshed with the third drive gear and connected to the second carrier so as not to be rotatable relative to the drive shaft around its axis, and is supported on the transmission shaft directly or indirectly so as to be rotatable relative to the drive shaft around its axis, and the gear ratio is set so as to rotate the second carrier at a higher speed than the second transmission gear train. The third clutch mechanism is provided on the drive shaft to engage and disengage power transmission from the drive shaft to the third drive gear.

[0048] More preferably, the HMT device according to the first mode of the fifth aspect may include an input member connected to the second element of the second planetary gear mechanism in a state in which the input member is rotatable relative to the transmission shaft about its axis. The second and third driven gears are provided on the input member.

[0049] In order to achieve the third object, a sixth aspect of the present invention provides an HMT device according to any of the various configurations of the first aspect of the fifth aspect, a speed change operating member that can be manually operated within a speed change operating range between a zero speed position and a maximum speed position, an operating position sensor that detects the operating position of the speed change operating member, a first clutch operating member that switches the engagement and disengagement operation of the first clutch mechanism, a second clutch operating member that switches the engagement and disengagement operation of the second clutch mechanism, an HST operating member that operates an output adjustment member of the HST, and a rotational speed sensor that directly or indirectly detects the rotational speed of the connecting member. and a control device that governs operation control of the first and second clutch operating members and the HST operating member, wherein the speed change operation range is divided into a first gear stage operation region on the low speed side, which is set in a range from a zero speed position to a first gear stage maximum speed position, and a second gear stage operation region on the high speed side, which is set in a range from the first gear stage maximum speed position to a second gear stage maximum speed position, and the control device controls the first clutch mechanism to be engaged and the second clutch mechanism to be disengaged when the speed change operation member is operated in the first gear stage operation region. When the speed change operating member is positioned at the first gear position, one of the first and second clutch mechanisms is engaged and the other is disengaged. When the speed change operating member is operated in the second gear operating range, the first and second clutch operating members are actuated so that the first clutch mechanism is disengaged and the second clutch mechanism is engaged. In response to operation of the speed change operating member to the zero gear position, the HST output becomes an HST speed for zero gear. When the speed change operating member is moved to the speed increasing side within the first gear operating range, the first and second clutch operating members are actuated so that the first clutch mechanism is disengaged and the second clutch mechanism is engaged. Provided is a transmission structure that operates the HST operating member so that, in response to operation, the HST output is shifted from the first HST speed side to the second HST speed side, and the HST output becomes the HST speed for the first gear stage maximum speed in response to operation of the speed change operating member to the first gear stage maximum speed position, and the HST output is shifted from the second HST speed side to the first HST speed side in response to operation of the speed change operating member to the speed increasing side within the second gear stage operating range, and the HST output becomes the HST speed for the second gear stage maximum speed in response to operation of the speed change operating member to the maximum speed position.

[0050] In one embodiment, the transmission structure includes a forward / reverse switching mechanism that can selectively take a forward output state in which the HMT power operatively input from the output body is output without changing the rotation direction and a reverse output state in which the HMT power is output by reversing the rotation direction; replacement and a forward / reverse actuating member that actuates the conversion mechanism.

[0051] In this case, the speed change operation range of the speed change operating member includes a forward operation range from the zero speed position to the forward maximum speed position, and a reverse operation range from the zero speed position to the reverse maximum speed position, and the control device operates the forward / reverse operating member so that the forward / reverse switching mechanism is in a forward rotation output state when the speed change operating member is positioned in the forward operation range, and so that the forward / reverse switching mechanism is in a reverse rotation output state when the speed change operating member is positioned in the reverse operation range.

[0052] Preferably, the transmission structure may include an auxiliary transmission mechanism capable of changing the HMT power operatively input from the output body to a plurality of speed stages including a low speed stage and a high speed stage. [Effects of the Invention]

[0053] The planetary gear assembly according to the present invention can increase the speed range of the HMT output in the HMT device formed in cooperation with the HST, while also reducing the size of the entire HMT device. According to the HMT device of the present invention, it is possible to increase the speed range of the HMT output while achieving miniaturization. The transmission structure according to the present invention makes it possible to reduce the size of the HMT device while widening the speed range of the HMT output, and further improve the controllability of the HMT output. [Brief explanation of the drawings]

[0054] [Figure 1] FIG. 1 is a schematic diagram of a transmission structure of a working vehicle to which a planetary gear assembly according to a first embodiment of the present invention is applied. [Figure 2] FIG. 2 is a hydraulic circuit diagram of the transmission structure. [Figure 3] FIG. 3 is a partial vertical cross-sectional view of an HMT device including the planetary gear assembly according to the first embodiment. [Figure 4] FIG. 4 is a vertical cross-sectional view of the planetary gear assembly according to the first embodiment. [Figure 5] FIG. 5 is an exploded vertical cross-sectional view of a connecting member in the planetary gear assembly according to the first embodiment. [Figure 6] FIG. 6 is a graph showing the relationship between the HST output and the HMT output in an HMT device including the planetary gear assembly according to the first embodiment. [Figure 7] FIG. 7 is a graph showing the relationship between the HST output and the HMT output in a modified example of an HMT device including the planetary gear assembly according to the first embodiment. [Figure 8] FIG. 8 is a schematic diagram of a transmission structure of a working vehicle to which a planetary gear assembly according to the second embodiment of the present invention is applied. [Figure 9] FIG. 9 is a graph showing the relationship between the HST output and the HMT output in an HMT device including the planetary gear assembly according to the second embodiment. [Figure 10] FIG. 10 is a schematic diagram of another transmission structure to which the planetary gear assembly according to the first embodiment is applied. [Figure 11] FIG. 11 is a graph showing the relationship between the HST output and the output of the auxiliary transmission mechanism in the transmission structure shown in FIG. [Figure 12] FIG. 12 is a schematic diagram of a transmission structure of a working vehicle to which a planetary gear assembly according to the fourth embodiment of the present invention is applied. [Figure 13] FIG. 13 is a partial schematic diagram of a transmission structure of a working vehicle to which a planetary gear assembly according to a fifth embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE INVENTION

[0055] Embodiment 1 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a planetary gear assembly according to the present invention will now be described with reference to the accompanying drawings. 1 and 2 respectively show a transmission schematic diagram and a hydraulic circuit diagram of a transmission structure 200A in a working vehicle to which a planetary gear assembly 1A according to this embodiment is applied.

[0056] As shown in Fig. 1, the work vehicle includes a drive source 410, main drive wheels 420, and the transmission structure 200A interposed in a traveling system power transmission path from the drive source 410 to the main drive wheels 420. Note that reference numeral 411 in Figs. 1 and 2 denotes a flywheel included in the drive source 410.

[0057] The planetary gear assembly 1A cooperates with a hydrostatic continuously variable transmission (HST) 110, which continuously changes the speed of a reference rotational speed power operatively input from the drive source 410 and outputs it, to form an HMT device (hydrostatic-mechanical continuously variable transmission) 100A, and is used as one component of the transmission structure 200A.

[0058] That is, as shown in FIG. 1, the transmission structure 200A includes the HMT device 100A including the HST 110 and the planetary gear assembly 1A.

[0059] In this embodiment, as shown in FIG. 1, the transmission structure 200A includes, in addition to the HMT device 100, a forward / reverse switching mechanism 220 that can switch the rotation direction of the output (HMT output) of the HMT device 100A between a forward direction and a reverse direction, and a differential mechanism 230 that differentially transmits the output of the forward / reverse switching mechanism 220 to a pair of left and right main drive wheels 320.

[0060] The transmission structure 200A further includes a traveling brake mechanism 240 that selectively applies braking force to the pair of main drive wheels 320, a differential lock mechanism 235 that forcibly drives the pair of main drive wheels 320 synchronously, and a drive force take-off mechanism 250 for auxiliary drive wheels that can selectively output the output of the forward / reverse switching mechanism 220 to the auxiliary drive wheels.

[0061] The transmission structure 200A also has a PTO shaft 260 that outputs rotational power to the outside, and a PTO multi-stage transmission mechanism 270 that includes a PTO clutch 265 interposed in the PTO transmission path from the drive source 410 to the PTO shaft 260. The transmission structure 200A, the differential mechanism 230, the auxiliary drive wheel drive force takeoff mechanism 250, and the PTO multi-stage speed change mechanism 270 are housed in a transmission case (not shown).

[0062] The HST 110 is configured to continuously change the speed of the reference rotational speed power from the drive source 410 between a first HST speed and a second HST speed, and to output an HST output after the speed change.

[0063] Specifically, as shown in FIGS. 1 and 2, the HST 10 includes a pump shaft 112 that operatively inputs reference rotational speed power from the drive source 410, a hydraulic pump 114 that is supported on the pump shaft 112 so as not to be rotatable relative to the pump shaft 112, a hydraulic motor 118 that is fluidly connected to the hydraulic pump 114 via a pair of hydraulic oil lines 115 and is hydraulically driven to rotate by the hydraulic pump 114, a motor shaft 116 that supports the hydraulic motor 118 so as not to be rotatable relative to the hydraulic motor, and an output adjustment member 120 that changes the volume of at least one of the hydraulic pump 114 and the hydraulic motor 118.

[0064] The output adjustment member 120 operates within an operable range defined by first and second operating end positions, and the HST 10 is capable of continuously changing the ratio of the rotational speed of the HST output output from the motor shaft 116 to the reference rotational speed input to the pump shaft 112 (i.e., the speed ratio of the HST 110) between a first HST speed and a second HST speed depending on the operating position of the output adjustment member 120 within the operable range. In this embodiment, the output adjusting member 120 is configured to change the volume (discharge amount) of the hydraulic pump 114.

[0065] In this embodiment, the HST 110 is capable of switching the rotation direction of the HST output between forward and reverse.

[0066] That is, in the HST 110, when the rotation direction of the reference rotation speed power is set to a first rotation direction (e.g., forward rotation direction), the rotation speed of the HST output (first HST speed) when the output adjustment member 120 is positioned at the first operating end position is set to the maximum speed (-max) in a second rotation direction (e.g., reverse direction) opposite to the first rotation direction, and the rotation speed of the HST output (second HST speed) when the output adjustment member 120 is positioned at the second operating end position is set to the maximum speed (+max) in the first rotation direction (e.g., forward rotation direction).

[0067] In this case, when the output adjusting member 120 is positioned at a neutral position between the first and second operating end positions, the rotational speed of the HST output becomes neutral speed (zero speed).

[0068] The HST 110 can take a variety of forms, including axial piston and radial piston types. When the HST 110 is an axial piston type, the output adjustment member 120 may be a movable swash plate. When the HST 110 is a radial piston type, the output adjustment member 120 may be a movable cam ring.

[0069] The output adjusting member 120 can be operated in response to a human operation. That is, as shown in FIG. 1, the transmission structure 200A is provided with a gearshift operating member 310 that can be manually operated within a gearshift operating range between a zero speed position and a maximum speed position, an operating position sensor 315 that detects the operating position of the gearshift operating member 310, an HST operating member 320 that operates the output adjustment member 120, and a control device 300 that controls the operation of the HST operating member 320 in accordance with the operating position of the gearshift operating member 310. In this embodiment, the gear shift operating member 310 is a lever type.

[0070] The HST operating member 320 can take various forms, such as a hydraulic actuator or an electric actuator, including a hydraulic servomechanism and an electromagnetic valve that switches the supply and discharge of pressure oil to the hydraulic servomechanism, as long as it can operate the output adjustment member 120 by a control signal from the control device 300.

[0071] FIG. 3 shows a partial vertical cross-sectional view of the HMT device 100A including the planetary gear assembly 1A. FIG. 4 shows a vertical cross-sectional view of the planetary gear assembly 1A.

[0072] As shown in FIGS. 1 to 4, the planetary gear assembly 1A includes a transmission shaft 10, and first and second planetary gear mechanisms 20, 30 supported by the transmission shaft 10.

[0073] In this embodiment, the transmission shaft 10 is adapted to operatively receive the HST output. Specifically, the transmission shaft 10 operatively receives HST output from the motor shaft 116 via an HST transmission gear train 130 .

[0074] The HST transmission gear train 130 includes an HST drive gear 132 connected to the motor shaft 116 so as not to rotate relative to it about its axis, and an HST driven gear 134 operatively meshed with the HST drive gear 132.

[0075] As shown in Figures 1 and 3, the transmission shaft 10 is arranged parallel to the motor shaft 116, and supports the first planetary gear mechanism 20 on a first axial side (the side away from the motor shaft 116 in the axial direction, the right side in Figures 1 and 3), and supports the second planetary gear mechanism 30 on a second axial side (the side closer to the motor shaft 116 in the axial direction, the left side in Figures 1 and 3).

[0076] The transmission shaft 10 supports the HST driven gear 134 on the second axial side of the portion supporting the second planetary gear mechanism 30 so as to be unable to rotate relatively about the axis.

[0077] As shown in Figures 3 and 4, the first planetary gear mechanism 20 has a first sun gear 22, a first planetary gear 24 meshing with the first sun gear 22, a first internal gear 26 meshing with the first planetary gear 24, and a first carrier 28 that supports the first planetary gear 24 so as to be rotatable about its axis and rotates about the axis of the first sun gear 22 in conjunction with the revolution of the first planetary gear 24 about the first sun gear 22, and the first sun gear 22, first carrier 28 and first internal gear 26 form three planetary elements.

[0078] As shown in FIGS. 3 and 4, a first sun gear 22, which is the first element of the three planetary elements, is supported by the transmission shaft 10 so as to be non-rotatable relative to the transmission shaft 10. As described above, in this embodiment, the HST output is input to the transmission shaft 10. Therefore, in this embodiment, first sun gear 22 acts as a variable power input section that inputs the HST output.

[0079] The second element of the three planetary elements acts as a reference power input section that inputs a reference rotational speed power. In this embodiment, the first internal gear 26 is the second element of the first planetary gear mechanism 20 .

[0080] In this embodiment, the HMT device 100A is provided with a drive shaft 125 to which a reference rotational speed power is operatively transmitted from the drive source 410, and the reference rotational speed power is operatively input to the first internal gear 26 from the drive shaft 125 to which the reference rotational speed power is operatively transmitted from the drive source 410.

[0081] More specifically, in this embodiment, as shown in FIG. 3, the drive shaft 125 is connected coaxially with the pump shaft 112 so as to be unable to rotate relative to the pump shaft 112 about the axis, and the HMT device 100A is provided with the drive shaft 125, a first transmission gear train 135(1) capable of operatively transmitting reference rotational speed power from the drive shaft 125 to the first internal gear 26, and a first clutch mechanism 140(1) that engages and disengages power transmission by the first transmission gear train 135(1).

[0082] The first transmission gear train 135(1) includes a first drive gear 136(1) supported on the drive shaft 125 so as to be rotatable relative to the drive shaft 125 about its axis, and a first driven gear 137(1) operatively meshed with the first drive gear 136(1) and connected to the first internal gear 26 so as not to be rotatable relative to the drive shaft 125 about its axis, and supported on the transmission shaft 10 directly or indirectly so as to be rotatable relative to the drive shaft 125 about its axis.

[0083] That is, in this embodiment, the first internal gear 26 is configured to be able to input reference rotational speed power from the drive shaft 125 via the first clutch mechanism 140(1) and the first transmission gear train 135(1).

[0084] In the first planetary gear mechanism 20, the third element acts as a planetary output portion that outputs a combined rotational power obtained by combining the rotational powers input to the first and second elements. In this embodiment, the first carrier 28 is the third element.

[0085] As shown in Figures 3 and 4, the second planetary gear mechanism 30 has a second sun gear 32, a second planetary gear 34 meshing with the second sun gear 32, a second internal gear 36 meshing with the second planetary gear 34, and a second carrier 38 that supports the second planetary gear 34 so as to be rotatable about its axis and rotates about the axis of the second sun gear 32 in conjunction with the revolution of the second planetary gear 34 about the second sun gear 32, and the second sun gear 32, second carrier 38 and second internal gear 36 form three planetary elements.

[0086] As shown in FIGS. 3 and 4, a second sun gear 32, which is the first element of the three planetary elements, is supported by the transmission shaft 10 so as to be non-rotatable relative to the transmission shaft 10. As described above, in this embodiment, the HST output is input to the transmission shaft 10. Therefore, in this embodiment, second sun gear 32 acts as a variable power input section that inputs the HST output.

[0087] The second element of the three planetary elements acts as a reference power input section that inputs a reference rotational speed power. In this embodiment, the second carrier 38 is the second element of the second planetary gear mechanism 30 .

[0088] In this embodiment, the second carrier 38 receives a reference rotational speed power from the drive shaft 125 in an operational manner.

[0089] More specifically, in this embodiment, as shown in FIG. 3, the HMT device 100A is provided with a second transmission gear train 135(2) that can operatively transmit reference rotational speed power from the drive shaft 125 to the second carrier 38, and a second clutch mechanism 140(2) that engages and disengages power transmission by the second transmission gear train 135(2).

[0090] The second transmission gear train 135(2) has a second drive gear 136(2) supported on the drive shaft 125 so as to be rotatable relative to the drive shaft 125 about its axis, and a second driven gear 137(2) operatively meshed with the second drive gear 136(2) and connected to the second carrier 38 so as not to be rotatable relative to the drive shaft 125 about its axis, and supported directly or indirectly on the transmission shaft 10 so as to be rotatable relative to the drive shaft 125 about its axis.

[0091] That is, in this embodiment, the second carrier 38 is adapted to receive reference rotational speed power from the drive shaft 125 via the second clutch mechanism 140(2) and the second transmission gear train 135(2).

[0092] In the second planetary gear mechanism 30, the third element acts as a planetary output portion that outputs a combined rotational power obtained by combining the rotational powers input to the first and second elements. In this embodiment, the second internal gear 36 is the third element.

[0093] As shown in Figures 1 to 4, the planetary gear assembly 1A further includes a connecting member 40 that connects the third elements of the first and second planetary gear mechanisms 20, 30 together so that they cannot rotate relatively around their axes, while being extrapolated onto the transmission shaft 10 so as to be rotatable relative to each other around their axes.

[0094] As described above, in this embodiment, the third element (first carrier 28) of the first planetary gear mechanism 20 acts as a composite output part of the first planetary gear mechanism 20, and the third element (second internal gear 36) of the second planetary gear mechanism 30 acts as a composite output part of the second planetary gear mechanism 30, and therefore the connecting member 40 acts as an HMT output member common to both the first and second planetary gear mechanisms 20, 30.

[0095] In detail, as shown in Figures 3 and 4, when the first planetary gear mechanism 20 is in a power transmission state and the second planetary gear mechanism 30 is in a power interruption state, the connecting member 40 outputs the combined rotational power (HMT output) by the first planetary gear mechanism 20, and when the first planetary gear mechanism 20 is in a power interruption state and the second planetary gear mechanism 30 is in a power transmission state, the connecting member 40 outputs the combined rotational power (HMT output) by the second planetary gear mechanism 30.

[0096] FIG. 5 shows an exploded vertical cross-sectional view of the connecting member 40. As shown in Figures 3 to 5, the connecting member 40 is inserted onto the transmission shaft 10 so as to be rotatable relative to the transmission shaft 10 about its axis, and has a connecting body 41 whose first axial side is connected to the third element of the first planetary gear mechanism 20 and whose second axial side is connected to the third element of the second planetary gear mechanism 30, and an output body 45 capable of outputting the rotational power of the connecting body 41 to the outside.

[0097] As described above, in this embodiment, the first carrier 28 acts as the third element (planetary output part) of the first planetary gear mechanism 20, and the second internal gear 36 acts as the third element (planetary output part) of the second planetary gear mechanism 30.

[0098] Therefore, the connecting body 41 is extrapolated onto the transmission shaft 10 so as to be rotatable relative to the transmission shaft 10 about its axis, and the first axial side is connected to the first carrier 28 so as not to be rotatable relative to the transmission shaft 10 about its axis, and the second axial side is connected to the second internal gear 36 so as not to be rotatable relative to the transmission shaft 10 about its axis.

[0099] More specifically, as shown in Figures 4 and 5, the connecting body 41 has a cylindrical portion 42 extending in the axial direction, a first flange 43 extending radially outward from a first axial side of the cylindrical portion 42 and connected to the first carrier 28, and a second flange 44 extending radially outward from a second axial side of the cylindrical portion 42 and connected to the second internal gear 36.

[0100] In this embodiment, the output body 45 is a separate body from the connecting body 41 . In detail, the output body 45 has a connecting flange 46 that is arranged on the opposite side of the connecting body 41 in the axial direction across the first planetary gear 24 supported by the first carrier 28, and is detachably connected to the first axial side of the connecting body 41 via a fastening member 49 such as a bolt so as to be unable to rotate relatively around the axis, and a shaft portion 47 that extends from the connecting flange 46 toward the first axial side.

[0101] As shown in FIG. 5, in this embodiment, the first carrier 28 has a first carrier pin 28a that supports the first planetary gear 24 so that it can rotate freely around its axis.

[0102] The first carrier pin 28a has a first axial side engaged with an engagement hole 46a formed in the connecting flange 46, and a second axial side engaged with an engagement hole 43a formed in the first flange 43, and the connecting flange 46 and the first flange 43 form the first carrier 28 that rotates around the axis of the first sun gear 22 together with the first carrier pin 28a.

[0103] In this embodiment, the output body 45 is detachably connected to the connecting body 41, but instead, it is also possible to provide an output gear (not shown) that acts as an output body on the outer surface of the tubular portion 42 of the connecting body 41.

[0104] In this embodiment, as shown in FIG. 4, the first driven gear 137(1) is connected to the first drive gear 136(1) (see FIG. 3) at an input gear portion 137a(1) and is connected to the first internal gear 26 at an output gear portion 137b(1) in a state in which the first driven gear 137(1) is supported by being externally inserted onto the shaft portion 47 of the output body 45 so as to be relatively rotatable about its axis.

[0105] As shown in Figure 4, in this embodiment, the second carrier 38 has a second carrier pin 38a that supports the second planetary gear 34 so as to be rotatable about its axis, and a second carrier body 38b that is supported on the transmission shaft 10 so as to be rotatable relative to the transmission shaft 10 about its axis so as to rotate together with the second carrier pin 38a about the axis of the second sun gear 32. The second driven gear 137(2) is supported by the second carrier body 38b so as to be unable to rotate relatively about its axis.

[0106] As shown in FIGS. 1 to 3, in this embodiment, the first and second clutch mechanisms 140 ( 1 ), 140 ( 2 ) are both supported by the drive shaft 125 .

[0107] That is, the first clutch mechanism 140(1) is provided on the drive shaft 125 so as to engage and disengage the power transmission from the drive shaft 125 to the first drive gear 136(1), and the second clutch mechanism 140(2) is provided on the drive shaft 125 so as to engage and disengage the power transmission from the drive shaft 125 to the second drive gear 136(2).

[0108] As shown in FIGS. 1 to 3, in this embodiment, the first and second clutch mechanisms 140(1), 140(2) are hydraulic multi-plate clutches.

[0109] In detail, the first clutch mechanism 140(1) has a first clutch housing 141(1) supported on the drive shaft 125 so as not to be rotatable relative to the drive shaft 125, a friction plate group 142(1) including a first driving side friction plate supported on the first clutch housing 141 so as not to be rotatable relative to the drive shaft 125, and a first driven side friction plate supported on the first driving gear 136(1) so as not to be rotatable relative to the drive shaft 125 and facing the first driving side friction plate, and a first piston 143(1) that frictionally engages the first friction plate group 142(1).

[0110] The second clutch mechanism 140(2) has a second clutch housing 62 supported on the drive shaft so as not to rotate relative to the drive shaft, a two-friction plate group 142(2) including a second driving-side friction plate supported on the second clutch housing 62 so as not to rotate relative to the drive shaft, and a second driven-side friction plate supported on the second driving gear 136(2) so as not to rotate relative to the drive gear 136(2) while facing the second driving-side friction plate, and a second piston 143(2) that frictionally engages the second friction plate group 142(2). As shown in FIG. 3, the first and second clutch housings 141(1) and 141(2) are integrally formed.

[0111] As shown in FIG. 3, in this embodiment, the first and second clutch mechanisms 140(1), 140(2) are arranged between the first and second flanges 43, 44 of the connecting body 41 in the axial direction, and a portion of the first and second clutch mechanisms 140(1), 140(2) enters a space S (see FIG. 4) defined between the outer peripheral surface of the tubular portion 42 and the opposing surfaces of the first and second flanges 43, 44.

[0112] According to such a configuration, it is possible to reduce the size of the structure including the drive shaft 125, the first and second clutch mechanisms 140(1), 140(2), the first and second transmission gear trains 135(1), 135(2), and the planetary gear assembly 1A.

[0113] The first and second clutch mechanisms 140(1), 140(2) are configured to engage and disengage power transmission by first and second clutch operating members 145(1), 145(2), respectively, whose operation is controlled by the control device 300.

[0114] That is, the transmission structure 200A further includes the first clutch operating member 145(1) that switches the engagement and disengagement operation of the first clutch mechanism 140(1) and the second clutch operating member 145(2) that switches the engagement and disengagement operation of the second clutch mechanism 140(2), and the control device 300 is configured to control the operation of the first and second clutch operating members 145(1), 145(2) in addition to controlling the operation of the HST operating member 320.

[0115] In this embodiment, the first and second clutch operating members 145(1), 145(2) are hydraulic actuators.

[0116] In detail, as shown in FIG. 2, the first clutch actuating member 145(1) includes a pressure oil supply line 146 whose upstream side is fluidly connected to a hydraulic pressure source 430 such as a hydraulic pump, a drain line 147, a first supply / discharge line 148(1) that supplies / discharges pressure oil to / from the first clutch mechanism 140(1), and a first clutch solenoid valve 150(1).

[0117] The first clutch solenoid valve 150(1) is configured to selectively take a clutch engagement position in which the first supply / discharge line 148(1) is fluidly connected to the pressure oil supply line 146 and a clutch disengagement position in which the first supply / discharge line 148(1) is fluidly connected to the drain line 147 in response to a signal from the control device 300.

[0118] The second clutch operating member 145(2) includes the pressure oil supply line 146, the drain line 147, a second supply / discharge line 148(2) that supplies / discharges pressure oil to / from the second clutch mechanism 140(2), and a second clutch solenoid valve 150(2).

[0119] The second clutch solenoid valve 150(2) is configured to selectively take a clutch engagement position in which the second supply / discharge line 148(2) is fluidly connected to the pressure oil supply line 146 and a clutch disengagement position in which the second supply / discharge line 148(2) is fluidly connected to the drain line 147 in response to a signal from the control device 300.

[0120] 2 denotes a hydraulic oil relief valve that sets the clutch hydraulic pressure in the hydraulic oil supply line 146.

[0121] In this embodiment, the first and second clutch solenoid valves 150(1), 150(2) are proportional pressure valves, but instead, they may be ON-OFF valves.

[0122] Furthermore, in this embodiment, the first and second clutch operating members 145(1), 145(2) are hydraulic actuators that operate hydraulic multi-plate clutches. However, for example, if the first and second clutch mechanisms 140(1), 140(2) are dog clutches, the first and second clutch operating members 145(1), 145(2) can also be electric actuators such as electric motors that shift the dog clutches.

[0123] As described above, in this embodiment, the transmission structure 200A has the forward / reverse switching mechanism 220. In this case, the transmission structure 200A further includes the forward / reverse shift replacement A forward / reverse operating member 155 is provided to operate mechanism 220, and the speed change operating member 310 can be manually operated within a forward operation range from the zero speed position to the maximum forward speed position, and within a reverse operation range from the zero speed position to the maximum reverse speed position.

[0124] The control device 300 then operates the forward / reverse operating member 155 so that the forward / reverse switching mechanism 220 is in a forward output state (forward output state) when the speed change operating member 310 is positioned in the forward side operating range, and so that the forward / reverse switching mechanism 220 is in a reverse output state (reverse output state) when the speed change operating member 310 is positioned in the reverse side operating range.

[0125] It is also possible to provide the transmission structure 200A with a dedicated forward / reverse switching operation member for manually operating the forward / reverse switching mechanism 220. In this case, the forward / reverse switching operation member can have various configurations, such as a lever mechanically operably connected to the forward / reverse switching mechanism 220 or an electric switch type. When the forward / reverse switching operation member is provided, the speed change operation member 310 is, for example, a pedal-type member that can be operated from a zero speed position to a maximum speed position, and the transmission structure 200A is configured to output driving force from zero speed to maximum forward speed and from zero speed to maximum reverse speed in response to manual operation of the speed change operation member 310 and the forward / reverse switching operation member.

[0126] The forward / reverse actuation member 155 may take various forms, such as a hydraulic actuator or an electric actuator, as long as it can actuate the forward / reverse switching mechanism 220 in response to a control signal from the control device 300 .

[0127] In this embodiment, as shown in FIG. 2, the forward / reverse operating member 155 is also a hydraulic actuator.

[0128] As shown in FIG. 1, the forward / reverse switching mechanism 220 is configured to switch the rotation direction of the HMT output between the forward direction and the reverse direction between the intermediate drive shaft 210, which operatively inputs the HMT output from the connecting member 40, and the traveling output shaft 215, which is operatively connected to the differential mechanism 230.

[0129] In the present embodiment, the forward / reverse switching mechanism 220 includes a forward gear train 330F including a forward drive gear 331F supported by the intermediate drive shaft 210 and a forward driven gear 332F supported by the traveling output shaft 215 and meshed with the forward drive gear 331F, a reverse gear train 330R including a reverse drive gear 331R supported by the intermediate drive shaft 210 and a reverse driven gear 332R supported by the traveling output shaft 215 and meshed with the reverse drive gear 331R via an idle gear 333, a forward clutch mechanism 340F that engages and disengages power transmission of the forward gear train 330F, and a reverse clutch mechanism 340R that engages and disengages power transmission of the reverse gear train 330R.

[0130] As shown in FIG. 2, the forward / reverse operating member 155 includes the pressure oil supply line 146, the drain line 147, a forward supply / discharge line 156F that supplies / discharges pressure oil to / from the forward clutch mechanism 330F, a reverse supply / discharge line 156R that supplies / discharges pressure oil to / from the reverse clutch mechanism 330R, a forward solenoid valve 157F, and a reverse solenoid valve 158R.

[0131] The forward solenoid valve 157F is configured to selectively take a clutch engagement position that fluidly connects the forward supply / discharge line 156F to the pressure oil supply line 146 and a clutch disengagement position that fluidly connects the forward supply / discharge line 156F to the drain line 147 in response to a signal from the control device 300.

[0132] Similarly, the reverse solenoid valve 157R is configured to selectively take a clutch engaged position in which the reverse supply / discharge line 156R is fluidly connected to the pressure oil supply line 146 and a clutch disengaged position in which the reverse supply / discharge line 156R is fluidly connected to the drain line 147 in response to a signal from the control device 300.

[0133] In this embodiment, the transmission structure 200A is provided with a lubricating oil supply structure. As shown in Figures 2 to 4, the lubricating oil supply structure includes a lubricating oil supply line 161 that receives oil discharged from the hydraulic oil relief valve 146a after pressure adjustment, a planetary gear lubricating oil line 162 that guides the oil received from the lubricating oil supply line 161 through an axial oil passage formed in the intermediate drive shaft 210 (not shown in Figures 2 to 4) and then through an axial oil passage 162a (see Figure 4) formed in the transmission shaft 10 to desired lubrication locations of the first and second planetary gear mechanisms 20, 30, and a clutch lubricating oil line 163 that guides the oil received from the lubricating oil supply line 161 through an axial oil passage 163a (see Figure 3) formed in the drive shaft 125 to desired lubrication locations of the first and second clutch mechanisms 140(1), 140(2).

[0134] 2 denotes a lubricating oil relief valve that sets the oil pressure of the lubricating oil supply line 161.

[0135] Here, the set gear ratios of the first and second planetary gear mechanisms 20, 30 will be explained. FIG. 6 shows a graph showing the relationship between the HST output and the HMT output in the HMT device 100A.

[0136] As shown in Figure 6, the gear ratio of the first planetary gear mechanism 20 is set so that in the first planetary transmission state (first gear transmission state) in which the HST output is input to the first sun gear 22 and the reference rotational speed power is input to the first internal gear 26, when the HST output is set to the HST speed for zero speed, the HMT output presented to the first carrier 28 (i.e., the connecting member 40) becomes zero speed, and as the HST output changes from the first HST speed side to the second HST speed side, the HMT output presented to the first carrier 28 rotates at an increased speed in the first rotational direction, which is one side around the axis, and when the HST output is set to the HST speed for a predetermined first gear maximum speed, the HMT output presented to the first carrier 28 rotates in the first rotational direction at the predetermined first gear maximum speed.

[0137] In this embodiment, the zero speed HST speed is a speed shifted by a predetermined speed from the first HST speed, which is one end of the variable range of the HST output, toward the second HST speed.

[0138] This is due to the following reasons. In other words, in theory, it is possible to set the zero speed HST speed to the first HST speed, but in this case, depending on the running load of the work vehicle, etc., it is possible that the HST output will not reach the first HST speed even if the output adjustment member 120 is positioned at the first operating end position corresponding to the first HST speed. Taking this into consideration, the control device 300 sets the zero speed HST speed to a speed that is a predetermined speed away from the first HST speed, which is one speed end of the variable range of the HST output, toward the second HST speed.

[0139] For the same reason, in this embodiment, the control device 300 sets the speed shifted from the second HST speed, which is the other speed end of the variable range of the HST output, to the first HST speed by a predetermined speed as the HST speed for the first gear stage maximum speed. That is, in this embodiment, the "highest speed HST speed" refers to the adjusted output value by the control device 300, not the mechanical limit output value of the HST 110.

[0140] As shown in Figure 6, the second planetary gear mechanism 30 has a gear ratio set so that in the second planetary transmission state (second gear transmission state) in which the HST output is input to the second sun gear 32 and the reference rotational speed power is input to the second carrier 38, when the HST output is set to the HST speed for the first gear maximum speed, the HMT output appearing at the second internal gear 36 (i.e., the connecting member 40) becomes the first gear maximum speed, and as the HST output changes from the second HST speed side to the first HST speed side, the HMT output appearing at the second internal gear 36 rotates at an increased speed in the first rotation direction, which is one side around the axis, and when the HST output is set to the predetermined HST speed for the second gear maximum speed, the HMT output appearing at the second internal gear 36 rotates in the first rotation direction at the predetermined second gear maximum speed.

[0141] In this embodiment, the HST speed for the second gear stage maximum speed is also set to a speed shifted from the first HST speed, which is one end of the variable range of the HST output, to the second HST speed by a predetermined speed.

[0142] If the maximum vehicle speed that can be output in the second planetary transmission state (second gear stage transmission state) is too fast for the specifications of the work vehicle, the control device 300 can be adjusted to set the speed that is shifted significantly from the first HST speed toward the second HST speed (preferably to the neutral position N or close to the neutral position) as the HST speed for the second gear stage maximum speed, as shown in FIG.

[0143] In this embodiment, the control device 300 is configured to perform the following control to produce the HMT output shown in FIG.

[0144] That is, the transmission structure 200A further includes an output sensor 50 (see FIG. 1) that directly or indirectly detects the rotational speed of the connecting member 40. The output sensor 50 is arranged to detect the rotation speed of the connecting member 40 or the intermediate drive shaft 210, for example.

[0145] As shown in FIG. 6, the speed change operation range of the speed change operation member 310 is divided into a first speed operation region on the low speed side and a second speed operation region on the higher speed side than the first speed operation region. The first gear stage operation region is set in a range from a zero speed position to a first gear stage maximum speed position, and the second gear stage operation region is set in a range from a first gear stage maximum speed position to a second gear stage maximum speed position.

[0146] The control device 300 executes the following operation control for the first and second clutch operating members 145(1), 145(2).

[0147] That is, the control device 300: When it is determined that the gear shift operating member 310 is operated in the first gear stage operating range based on a signal from the operating position sensor 315, the first and second clutch operating members 145(1), 145(2) are operated so that the first clutch mechanism 140(1) is engaged and the second clutch mechanism 140(2) is disengaged, When it is determined that the speed change operating member 310 is positioned at the first gear maximum position based on a signal from the operating position sensor 315, the first and second clutch operating members 145(1) and 145(2) are operated so that one of the first and second clutch mechanisms 140(1) and 140(2) is in an engaged state and the other is in a disengaged state, When it is determined that the gear shift operating member 310 is being operated in the second gear operating range based on a signal from the operating position sensor 315, the first and second clutch operating members 145(1), 145(2) are operated so that the first clutch mechanism 140(1) is in a disengaged state and the second clutch mechanism 140(2) is in an engaged state.

[0148] Furthermore, the control device 300 executes the following operation control for the HST operating member 320.

[0149] That is, the control device 330: When it is determined that the gear shift operating member 310 has been operated to the zero speed position based on a signal from the operating position sensor 315, the HST operating member 320 is operated so that the HST output becomes an HST speed for zero speed, When it is determined that the gear shift operating member 310 is being operated to increase the speed within the first gear stage operating range based on a signal from the operating position sensor 315, the HST operating member 320 is operated so that the HST output is shifted from the first HST gear side to the second HST gear side, When it is determined that the gearshift operating member 310 has been operated to the first gear maximum speed position based on a signal from the operating position sensor 315, the HST operating member 320 is operated so that the HST output becomes the HST speed for the first gear maximum speed, When it is determined that the gear shift operating member 310 is being operated to increase the speed within the second gear stage operating range based on a signal from the operating position sensor 315, the HST operating member 320 is operated so that the HST output is shifted from the second HST gear side to the first HST gear side, When it is determined that the gearshift operating member 310 has been operated to the highest speed position based on a signal from the operating position sensor 315, the HST operating member 320 is operated so that the HST output becomes the HST speed for the second gear stage highest speed.

[0150] Furthermore, the control device 300 executes the following operation control for the forward / reverse operation member 155.

[0151] That is, the control device 300: When it is determined that the speed change operating member 310 is positioned in the forward operation range based on a signal from the operating position sensor 315, the forward / reverse operating member 155 is actuated so that the forward / reverse switching mechanism 220 is in a normal rotation output state; When it is determined that the speed change operating member 310 is positioned in the reverse operation range based on a signal from the operating position sensor 315, the forward / reverse operating member 155 is operated so that the forward / reverse switching mechanism 220 is in a reverse output state.

[0152] Embodiment 2 Hereinafter, another embodiment of the planetary gear assembly according to the present invention will be described with reference to the accompanying drawings. FIG. 8 shows a schematic diagram of a transmission structure 200B for a working vehicle to which the planetary gear assembly 2 according to this embodiment is applied. In the drawings, the same members as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0153] As shown in FIG. 8, the planetary gear assembly 1B according to this embodiment further includes an input member 60, as compared with the planetary gear assembly 1 according to the first embodiment.

[0154] The input member 60 is connected to a second element (in the illustrated embodiment, the second carrier 36) of the second planetary gear mechanism 30 that inputs the reference rotational speed power, while being rotatable relative to the transmission shaft 10 around its axis, and further has first and second input gear portions 61, 62 that can input the reference rotational speed power. The pitch diameter of the second input gear portion 62 is smaller than the pitch diameter of the first input gear portion 61 .

[0155] The HMT device 100B formed by the planetary gear assembly 1B in cooperation with the HST 10 is different from the HMT device 100A in that it further includes a third transmission gear train 135(3) that can operatively transmit reference rotational speed power from the drive shaft 125 to the second element (second carrier 38) of the second planetary gear mechanism 30, and a third clutch mechanism 140(3) that engages and disengages power transmission by the third transmission gear train 135(3).

[0156] The gear ratio of the third transmission gear train 135(3) is set so as to rotate the second carrier 38 at a higher speed than the second transmission gear train 135(2).

[0157] In this embodiment, the third transmission gear train 135(3) includes a third drive gear 136(3) supported on the drive shaft 125 so as to be rotatable relative to the drive shaft 125 about its axis, and a third driven gear 137(3) operatively meshed with the third drive gear 136(3) and connected to the second carrier 38 so as not to be rotatable relative to the drive shaft 125 about its axis, and supported directly or indirectly on the transmission shaft 10 so as to be rotatable relative to the drive shaft 125 about its axis.

[0158] The first and second input gear portions 61, 62 of the input member 60 act as the second driven gear 137(2) and the third driven gear 137(3), respectively.

[0159] The third clutch mechanism 140(3) is configured to engage and disengage power transmission by a third clutch operating member (not shown) whose operation is controlled by the control device 300.

[0160] FIG. 9 shows a graph showing the relationship between the HST output and the HMT output in the HMT device 100B.

[0161] As shown in FIG. 9, in the HMT device 100B, the second planetary transmission state includes a second speed stage transmission state and a third speed stage transmission state.

[0162] The second speed transmission state is a transmission state that is achieved when the first clutch mechanism 140(1) is disengaged, the second clutch mechanism 140(2) is engaged, and the third clutch mechanism 140(3) is disengaged.

[0163] The third speed transmission state is a transmission state that is achieved when the first clutch mechanism 140(1) is disengaged, the second clutch mechanism 140(2) is disengaged, and the third clutch mechanism 140(3) is engaged.

[0164] In this case, the gear shift operation range of the gear shift operation member 310 includes, as shown in FIG. 9, a first gear operation region from the zero speed position to the first gear maximum speed position, a second gear operation region from the first gear maximum speed position to the second gear maximum speed position, and a third gear operation region from the second gear maximum speed position to the third gear maximum speed position.

[0165] When the speed change operating member 310 is operated within a range from the zero speed position to the second gear maximum speed position, the control device 300 executes the same operation control as in the first embodiment for the HST operating member 320 and the first and second clutch operating members 145(1), 145(2).

[0166] On the other hand, when the speed change operating member 310 is positioned in the third gear operating region, the control device 300 operates the first to third clutch operating members so that the first and second clutch mechanisms 140(1), 140(2) are disengaged and the third clutch mechanism 140(3) is engaged, thereby realizing a third gear transmission state.

[0167] In this embodiment, the control device 300 executes the following operational control to prevent a sudden speed change from occurring in the HMT output when transitioning between the second speed transmission state and the third speed transmission state.

[0168] That is, when the speed change operating member 310 is operated to increase the speed to the second gear maximum speed position within the second gear operating range, the control device 300 operates the HST operating member 320 so that the HST output becomes the HST speed for the second gear maximum speed, and the HMT output becomes the second gear maximum speed.

[0169] Here, in the third speed transmission state, the reference rotational speed power is input to the second element (the second carrier 38 in the illustrated embodiment) of the second planetary gear mechanism 30 via the third transmission gear train 135(3) which has a higher speed ratio than the second transmission gear train 135(2).

[0170] Therefore, when the HST output is maintained at the HST speed for the second-speed maximum speed and the transmission state is shifted from the second-speed transmission state to the third-speed transmission state, a large speed change occurs in the HMT output.

[0171] Taking this into consideration, in this embodiment, when the gear change operating member 310 is operated from the second gear operating range to the third gear operating range, the control device 300 operates the second and third clutch operating members so that the second clutch mechanism 140(2) is disengaged and the third clutch mechanism 140(3) is engaged, thereby transitioning from the second gear transmission state to the third gear transmission state, while operating the HST operating member 320 so that the HST output changes from the second gear highest speed HST speed to the third gear lowest speed HST speed, thereby preventing or reducing speed changes in the HMT output when transitioning between the second gear transmission state and the third gear transmission state.

[0172] The HST speed for the lowest speed in the third gear stage is set to a speed that makes the HMT output the highest speed in the second gear stage under the third gear stage transmission condition.

[0173] Embodiment 3 In this embodiment, the planetary gear assembly 1A according to the first embodiment is applied to a transmission structure 200C that is different from the transmission structure 200A. FIG. 10 shows a schematic diagram of a transmission structure 200C in a working vehicle to which the planetary gear assembly 1A is applied. In the drawings, the same members as those in the first and second embodiments are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0174] As shown in FIG. 10, the transmission structure 200C is different from the transmission structure 200A in the first embodiment in that it includes an auxiliary transmission mechanism 280 that can change the output of the HMT device 100A in multiple stages.

[0175] In this embodiment, the sub-transmission mechanism 280 is disposed between the HMT device 100A and the forward / reverse switching mechanism 220 in terms of the power transmission direction, and is capable of shifting between two stages: low speed L and high speed H.

[0176] The sub-transmission mechanism 280 is configured to switch between the low speed stage L and the high speed stage H via a mechanical link mechanism or via a sub-transmission operating member such as a hydraulic actuator or an electric actuator whose operation is controlled by the control device 300, in response to manual operation of a sub-transmission operating member (not shown) configured as a lever or an electric switch.

[0177] FIG. 11 is a graph showing the relationship between the HST output and the output of the auxiliary transmission mechanism.

[0178] The transmission structure 200C is provided with an auxiliary transmission sensor 285 that can detect the transmission state of the auxiliary transmission mechanism 280 and transmit a detection signal to the control device 300. The auxiliary transmission sensor 285 can take various forms, such as a sensor that detects the operating position of the auxiliary transmission operating member, a sensor that detects the operating state of the auxiliary transmission mechanism 280, or a sensor that detects the movement of the auxiliary transmission operating member.

[0179] In this embodiment, as shown in FIG. 11 , the control device 300 is configured so that, in the auxiliary L-stage engaged state, the HST output is set to an HST speed for second gear maximum speed when auxiliary L-stage is engaged in response to operation of the gearshift operating member 310 to the second gear maximum speed position, while in the auxiliary H-stage engaged state, the HST output is set to an HST speed for second gear maximum speed when auxiliary H-stage is engaged, which is a predetermined speed lower than the HST speed for second gear maximum speed when auxiliary L-stage is engaged, in response to operation of the gearshift operating member 310 to the second gear maximum speed position.

[0180] The HST speed for second gear maximum speed when auxiliary transmission L stage is engaged and the HST speed for second gear maximum speed when auxiliary transmission H stage is engaged are set appropriately according to the specifications of the working vehicle.

[0181] Embodiment 4 Hereinafter, still another embodiment of the planetary gear assembly according to the present invention will be described with reference to the accompanying drawings. FIG. 12 is a partial schematic diagram of a transmission structure 200D in a working vehicle to which a planetary gear assembly 1D according to this embodiment is applied. In the drawings, the same members as those in the first to third embodiments are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0182] As shown in FIG. 12, the planetary gear assembly 1D is different from the planetary gear assembly 1A according to the first embodiment in that it includes a connecting member 70 instead of the connecting member 40.

[0183] That is, the planetary gear assembly 1D includes the transmission shaft 10, the first and second planetary gear mechanisms 20, 30, and the connecting member .

[0184] The planetary gear assembly 1D according to this embodiment has: The first sun gear 22 is supported on the transmission shaft 10 so as to be unable to rotate relatively about its axis, and one of the first carrier 28 and the first internal gear 26 acts as a reference rotational speed power input portion to which reference rotational speed power can be input. The second sun gear 32 is supported on the transmission shaft 10 so as to be unable to rotate relatively about its axis, and one of the second carrier 38 and the second internal gear 36, which is different from the planetary element acting as the reference rotational speed power input portion in the first planetary gear mechanism 20, acts as a reference rotational speed power input portion to which reference rotational speed power can be input, The connecting member 70 connects the planetary elements of the first planetary gear mechanism 20 other than the first sun gear 22 and the planetary elements acting as the reference rotational speed power input portion to the planetary elements of the second planetary gear mechanism 30 other than the second sun gear 32 and the planetary elements acting as the reference rotational speed power input portion so as to be unable to rotate relative to each other about their axes. The planetary gear assembly 1A according to the first embodiment has the same structure as the planetary gear assembly 1A according to the first embodiment.

[0185] That is, in the planetary gear assembly 1A according to the first embodiment, the first sun gear 22 is supported on the transmission shaft 10 so as to be non-rotatable relative to the first carrier 28 and the first internal gear 26, which is one of the first carrier 28 and the first internal gear 26, acts as a reference rotational speed power input portion, the second sun gear 32 is supported on the transmission shaft 10 so as to be non-rotatable relative to the first carrier 28 and the second internal gear 36, which is a planetary element (first internal gear 26) that acts as a reference rotational speed power input portion in the first planetary gear mechanism 20, A planetary element (second carrier 38) different from the first sun gear 22 and the planetary element (first internal gear 26) acting as the reference rotational speed power input portion acts as a reference rotational speed power input portion, and the connecting member 40 connects the planetary elements (first carrier 28) of the first planetary gear mechanism 20 other than the first sun gear 22 and the planetary element (first internal gear 26) acting as the reference rotational speed power input portion to the planetary elements (second internal gear 36) of the second planetary gear mechanism 30 other than the second sun gear 32 and the planetary element (second carrier 38) acting as the reference rotational speed power input portion so that they cannot rotate relative to each other around the axis.

[0186] In the planetary gear assembly 1D according to the present embodiment, the first sun gear 22 is supported on the transmission shaft 10 so as to be non-rotatable relative to the first carrier 28, and the first carrier 28, which is one of the first carrier 28 and the first internal gear 26, acts as a reference rotational speed power input portion. The second sun gear 32 is supported on the transmission shaft 10 so as not to be rotatable relative to the first carrier 28, and the second carrier 38 and the second internal gear 36 act as a planetary element (first carrier 28) which acts as a reference rotational speed power input portion in the first planetary gear mechanism 20. A different planetary element (second internal gear 36) acts as the reference rotational speed power input portion, and the connecting member 70 connects the planetary elements (first internal gear 26) of the first planetary gear mechanism 20 other than the first sun gear 22 and the planetary element (first carrier 28) acting as the reference rotational speed power input portion to the planetary elements (second carrier 38) of the second planetary gear mechanism 30 other than the second sun gear 32 and the planetary element (second internal gear 36) acting as the reference rotational speed power input portion so that they cannot rotate relative to each other around the axis.

[0187] On the other hand, in the planetary assembly 1A according to the first embodiment, the connecting member 40 acts as the HMT output member, whereas in the planetary gear assembly 1D according to the present embodiment, the transmission shaft 10 acts as the HMT output member, which is a difference between the planetary gear assembly 1D according to the present embodiment and the planetary gear assembly 1A according to the first embodiment.

[0188] More specifically, in the planetary gear assembly 1D, the first carrier 28 inputs the reference rotational speed power from the drive shaft 125 via the first transmission gear train 135(1), and the second internal gear 36 inputs the reference rotational speed power from the drive shaft 125 via the second transmission gear train 135(2).

[0189] The connecting member 70 is inserted onto the transmission shaft 10 so as to be rotatable relative to the transmission shaft 10 about its axis, and connects the first internal gear 26 and the second carrier 38, and is also capable of operatively inputting the HST output.

[0190] That is, in this embodiment, the first internal gear 26 acts as a variable power input part that inputs the HST output in the first planetary gear mechanism 20, and the second carrier 38 acts as a variable power input part that inputs the HST output in the second planetary gear mechanism 30.

[0191] In this embodiment, the connecting member 70 receives the HST output from the motor shaft 116 via the HST transmission gear train 130 .

[0192] In this way, in the first planetary gear mechanism 20, the first carrier 28 receives the reference rotational speed power and the first internal gear 26 receives the HST output, and the first sun gear 22, which is supported on the transmission shaft 10 so as not to be able to rotate relatively around its axis, functions as a planetary output section that outputs the resultant rotational power.

[0193] In the second planetary gear mechanism 30, the second internal gear 36 receives the reference rotational speed power and the second carrier 38 receives the HST output, and the second sun gear 32, which is supported on the transmission shaft 10 so as not to be able to rotate relatively around its axis, functions as a planetary output section that outputs the resultant rotational power.

[0194] The transmission shaft 10 is capable of outputting its own rotational power to the outside, and acts as an HMT output member common to both the first and second planetary gear mechanisms 20, 30.

[0195] Fifth embodiment Hereinafter, still another embodiment of the planetary gear assembly according to the present invention will be described with reference to the accompanying drawings. FIG. 13 is a partial schematic diagram of a transmission structure 200E in a working vehicle to which a planetary gear assembly 1E according to this embodiment is applied. In the drawings, the same members as those in the first to fourth embodiments are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0196] The planetary gear assembly 1E of this embodiment differs from the planetary gear assembly 1A of the first embodiment in that it has a cylindrical transmission shaft 15 instead of the transmission shaft 10, a connecting member 80 instead of the connecting member 40, and an output shaft 90.

[0197] Both ends of the output shaft 90 are supported by bearings on support walls of a transmission case (not shown), and one end is provided with a joint for connection to the intermediate drive shaft 210 described above.

[0198] The transmission shaft 15 is supported by being inserted around the output shaft 90 so as to be relatively rotatable about its axis, and the HST output can be input from the motor shaft via the HST transmission gear train 130 .

[0199] The connecting member 80 has a connecting body 81 that connects planetary elements of the first planetary gear mechanism 20 other than the first sun gear 22 and the planetary elements that form the reference rotational speed power input portion, and planetary elements of the second planetary gear mechanism 30 other than the second sun gear 32 and the planetary elements that form the reference rotational speed power input portion.

[0200] As shown in FIG. 13, in this embodiment, the first internal gear 26 acts as a reference rotational speed power input portion for the first planetary gear mechanism 20, and the second carrier 38 acts as a reference rotational speed power input portion for the second planetary gear mechanism 30. Therefore, the connecting body 81 connects the first carrier 28 and the second internal gear 36 so that they cannot rotate relative to each other about their axes.

[0201] As shown in FIG. 13, the connecting member 80 further includes an output body 85 that can output the rotational power of the connecting body 81 to the outside. In this embodiment, the output body 85 is connected to the output shaft 90 coaxially and non-rotatably about the axis of the output shaft 90 .

[0202] As shown in FIG. 13, the HMT device 100E equipped with the planetary gear assembly 1E is different from the HMT device 100A in that it has first and second clutch mechanisms 180(1) and 180(2) instead of the first and second clutch mechanisms 140(1) and 140(2).

[0203] The first and second drive gears 136(1) and 136(2) are connected to the drive shaft 125, which is connected to the pump shaft 112, so as to be unable to rotate relative to each other about their axes, and the first and second clutch mechanisms 180(1) and 180(2) are arranged coaxially with the transmission shaft 15.

[0204] In detail, the first clutch mechanism 180(1) is configured to engage and disengage power transmission from the first driven gear 137(1) to the reference rotational speed power input portion of the first planetary gear mechanism 20 (the first internal gear 26 in this embodiment).

[0205] The second clutch mechanism 180(2) is configured to engage and disengage power transmission from the second driven gear 137(2) to the reference rotational speed power input portion of the second planetary gear mechanism 30 (the second carrier 36 in this embodiment).

[0206] In the first embodiment (FIG. 1), the first clutch mechanism 140(1) is disposed between the drive shaft 125 and the first drive gear 136(1), and the second clutch mechanism 140(2) is disposed between the drive shaft 125 and the second drive gear 136(2). Therefore, when one of the clutch mechanisms (for example, the first clutch mechanism 140(1)) is engaged, the drive gear on the non-engagement side (in this example, the second drive gear 136(2)) is reversely driven by the driven gear (in this example, the second driven gear 137(2)) that receives the rotation of the connecting member 40. In this case, if the relative rotation difference between the drive gear on the non-engagement side (in this example, the second drive gear 136(2)) and the drive shaft 125 exceeds a tolerance, abnormal wear or seizure may occur.

[0207] In contrast to this, in the present embodiment (FIG. 13), the first clutch mechanism 180(1) is disposed between the transmission shaft 15 and the first driven gear 137(1), and the second clutch mechanism 180(2) is disposed between the transmission shaft 15 and the second driven gear 137(2) in a state in which the first and second drive gears 136(1), 136(2) are unable to rotate relative to the drive shaft 125 about their axes. Therefore, when one of the clutch mechanisms (for example, the first clutch mechanism 140(1)) is engaged, the rotation of the connecting member 80 is not transmitted to the non-engaged driven gear (in this example, the second driven gear 137(2)), which has the advantage of allowing for more efficient design around the drive shaft 125. [Explanation of symbols]

[0208] 1A~1E Planetary gear assembly 10, 15 Transmission shaft 20. First planetary gear mechanism 22 First sun gear 26 1st internal gear 28 First Carrier 30 Second planetary gear mechanism 32 Second sun gear 36 Second internal gear 38 Second Carrier 40, 70, 80 connecting members 41, 81 Concatenation 42 Cylinder part 43 First flange 44 Second flange 45, 85 output body 46 Connecting flange 47 Shaft 50 Output Sensor 60 Input member 61 First input gear section 62 Second input gear section 85 output shaft 100A~100E HMT device 110 HST 112 Pump shaft 116 Motor shaft 100A~100D HMT device 125 drive shaft 134 HST driven gear 135(1) First transmission gear train 136(1) First drive gear 137(1) First driven gear (transmission gear member) 137a(1) Input gear section 137b(1) Output gear section 135(2) Second transmission gear train 136(2) Second drive gear 137(2) Second driven gear 135(3) Third transmission gear train 136(3) Third drive gear 137(3) Third driven gear 140(1), 180(1) First clutch mechanism 140(2), 180(2) Second clutch mechanism 140(3) Third clutch mechanism 200A~200E Transmission Structure 220 Forward / reverse switching mechanism 280 Sub-transmission mechanism 300 control device 310 Gear shift operating member 315 Operation position sensor 320 HST operating member 410 Drive source

Claims

1. A planetary gear assembly that forms an HMT device in cooperation with an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between a first HST speed and a second HST speed, and outputs the changed HST output from a motor shaft, A transmission shaft; a first planetary gear mechanism having three planetary elements including a first sun gear, a first carrier, and a first internal gear, the first sun gear being supported on the transmission shaft so as not to be rotatable relative to the transmission shaft about its axis, and one of the first carrier and the first internal gear forming a reference rotational speed power input section to which a reference rotational speed power can be input; a second planetary gear mechanism having three planetary elements including a second sun gear, a second carrier, and a second internal gear, the second sun gear being supported on the transmission shaft so as to be unable to rotate relatively about its axis, and one of the second carrier and the second internal gear, which is different from a planetary element that forms a reference rotational speed power input portion in the first planetary gear mechanism, forms a reference rotational speed power input portion to which reference rotational speed power can be input; a connecting member fitted onto the transmission shaft so as to be relatively rotatable about the axis thereof, a planetary gear assembly characterized in that the connecting member connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion to planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion so that they cannot rotate relative to each other around their axes.

2. The transmission shaft is capable of operatively inputting an HST output, 2. The planetary gear assembly according to claim 1, wherein the connecting member has a connecting body that connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion to planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion, and an output body that can output the rotational power of the connecting body to the outside.

3. the connecting member is capable of operatively inputting an HST output; 2. The planetary gear assembly according to claim 1, wherein the transmission shaft is capable of outputting rotational power around its own axis to the outside.

4. the transmission shaft is a cylindrical shaft to which the HST output can be operatively input, The planetary gear assembly is provided with an output shaft on which the transmission shaft is externally fitted so as to be relatively rotatable about an axis line, the connecting member includes a connecting body that connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion, and planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion, and an output body that can output the rotational power of the connecting body to the outside, 3. The planetary gear assembly according to claim 2, wherein the output body is coaxial with the output shaft and is not rotatable relative to the output shaft about its axis.

5. A planetary gear assembly that forms an HMT device in cooperation with an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between a first HST speed and a second HST speed, and outputs the changed HST output from a motor shaft, a transmission shaft to which the HST output can be operatively input; a first planetary gear mechanism including a first element supported on the transmission shaft so as to be unable to rotate relatively about an axis, a second element to which a reference rotational speed power can be input, and a third element that outputs a composite rotational power obtained by combining the rotational powers input to the first and second elements; a second planetary gear mechanism including a first element supported on the transmission shaft so as to be unable to rotate relatively about an axis, a second element to which a reference rotational speed power can be input, and a third element that outputs a composite rotational power obtained by combining the rotational powers input to the first and second elements; a connecting member fitted onto the transmission shaft so as to be relatively rotatable about the axis thereof, a planetary gear assembly characterized in that the connecting member has a connecting body that connects the third elements of the first and second planetary gear mechanisms to each other, and an output body that can output the rotational power of the connecting body to the outside.

6. an input member connected to a second element of the second planetary gear mechanism in a state in which the input member is rotatable about an axis of the transmission shaft relative to the transmission shaft; the input member has first and second input gear portions to which a reference rotational speed power can be input, 6. The planetary gear assembly according to claim 5, wherein the pitch diameter of said second input gear portion is smaller than the pitch diameter of said first input gear portion.

7. the first planetary gear mechanism has a first sun gear acting as a first element, a first carrier acting as a third element, and a first internal gear acting as a second element; the second planetary gear mechanism has a second sun gear acting as a first element, a second carrier acting as a second element, and a second internal gear acting as a third element; the first planetary gear mechanism has a gear ratio set so that, under a transmission state, as the HST output is changed from the first HST speed side to the second HST speed side, the first carrier rotates at an increased speed in a first rotation direction which is one side about the axis, and when the HST output is set to a predetermined HST speed for first gear stage maximum speed, the first carrier rotates in the first rotation direction at a predetermined first gear stage maximum speed; 7. The planetary gear assembly according to claim 5 or 6, wherein the gear ratio of the second planetary gear mechanism is set so that, in a transmission state, when the HST output is set to an HST speed for first gear maximum speed, the second internal gear rotates in a first rotational direction at the first gear maximum speed, and as the HST output is changed from the HST speed for first gear maximum speed toward the first HST speed to a predetermined HST speed for second gear maximum speed, the rotational speed of the second internal gear increases from the first gear maximum speed to the second gear maximum speed.

8. 8. The planetary gear assembly according to claim 7, wherein the connecting body has a cylindrical portion extending in the axial direction, a first flange extending radially outward from a first axial side of the cylindrical portion and connected to the first carrier, and a second flange extending radially outward from a second axial side of the cylindrical portion and connected to the second internal gear.

9. 9. The planetary gear assembly according to claim 7, wherein the output body has a connecting flange arranged on the opposite side of the connecting body in the axial direction with respect to the first planetary gear supported by the first carrier, and connected to a first axial side of the connecting body so as not to rotate relatively about the axis, and a shaft portion extending from the connecting flange toward the first axial side.

10. a transmission gear member fitted onto the shaft portion so as to be relatively rotatable about the axis; 10. The planetary gear assembly according to claim 9, wherein the transmission gear member has an input gear portion that receives a reference rotational speed power operatively input from the drive source, and an output gear portion that meshes with the first internal gear.

11. 11. A planetary gear assembly according to claim 5, further comprising an HST driven gear that is supported on the transmission shaft on a second axial side of a portion that supports the second planetary gear mechanism so as not to be rotatable relative to the second planetary gear mechanism, and that can receive HST output.

12. 12. A planetary gear assembly according to claim 5, wherein the gear ratio of the first planetary gear mechanism is set so that, under a transmission state, the third element is at zero speed when the HST output is set to a predetermined HST speed for zero speed.

13. 13. The planetary gear assembly according to claim 12, wherein the zero speed HST speed is a speed shifted from the first HST speed by a predetermined speed toward the second HST speed.

14. A planetary gear assembly that forms an HMT device in cooperation with an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between a first HST speed and a second HST speed, and outputs the changed HST output from a motor shaft, A transmission shaft; a first planetary gear mechanism including a first element supported on the transmission shaft so as to be unable to rotate relatively about an axis, a second element to which a reference rotational speed power can be input, and a third element to which an HST output can be input; a second planetary gear mechanism including a first element supported on the transmission shaft so as to be unable to rotate relatively about an axis, a second element to which a reference rotational speed power can be input, and a third element to which an HST output can be input; a connecting member that is fitted onto the transmission shaft so as to be relatively rotatable about the axis, the connecting member is capable of operatively inputting an HST output and connects third elements of the first and second planetary gear mechanisms together; a transmission shaft acting as an HMT output member common to both the first and second planetary gear mechanisms;

15. an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between a first HST speed and a second HST speed, and outputs the changed HST output from a motor shaft; a drive shaft to which a reference rotational speed power is operatively transmitted from the drive source; A transmission shaft; a first planetary gear mechanism having three planetary elements including a first sun gear, a first carrier, and a first internal gear, the first sun gear being supported on the transmission shaft so as not to be rotatable relative to the transmission shaft about its axis, and one of the first carrier and the first internal gear forming a reference rotational speed power input section to which a reference rotational speed power can be input; a second planetary gear mechanism having three planetary elements including a second sun gear, a second carrier, and a second internal gear, the second sun gear being supported on the transmission shaft so as to be unable to rotate relatively about its axis, and one of the second carrier and the second internal gear, which is different from a planetary element that forms a reference rotational speed power input portion in the first planetary gear mechanism, forms a reference rotational speed power input portion to which reference rotational speed power can be input; a first transmission gear train capable of operatively transmitting a reference rotational speed power from the drive shaft to a reference rotational speed power input portion of the first planetary gear mechanism; a first clutch mechanism that engages and disengages power transmission by the first transmission gear train; a second transmission gear train capable of operatively transmitting a reference rotational speed power from the drive shaft to a reference rotational speed power input portion of the second planetary gear mechanism; a second clutch mechanism that engages and disengages power transmission by the second transmission gear train; a connecting member fitted onto the transmission shaft so as to be relatively rotatable about the axis thereof, an HMT device characterized in that the connecting member connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion to planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion so that they cannot rotate relative to each other around their axes.

16. The transmission shaft is capable of operatively inputting an HST output, 16. The HMT device according to claim 15, wherein the connecting member includes a connecting body that connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion to planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion, and an output body that can output the rotational power of the connecting body to the outside.

17. the connecting member is capable of operatively inputting an HST output; 16. The HMT device according to claim 15, wherein the transmission shaft is capable of outputting rotational power around its own axis to the outside.

18. the transmission shaft is a cylindrical shaft to which the HST output can be operatively input, The HMT device is provided with an output shaft that is externally fitted onto the transmission shaft so as to be relatively rotatable about an axis line, the connecting member includes a connecting body that connects planetary elements of the first planetary gear mechanism other than the first sun gear and the planetary elements that form the reference rotational speed power input portion, and planetary elements of the second planetary gear mechanism other than the second sun gear and the planetary elements that form the reference rotational speed power input portion, and an output body that can output the rotational power of the connecting body to the outside, 16. The HMT device according to claim 15, wherein the output body is coaxial with the output shaft and is not rotatable relative to the output shaft about its axis.

19. an HST that continuously changes the speed of a reference rotational speed power operatively input from a drive source to a pump shaft between a first HST speed and a second HST speed, and outputs the changed HST output from a motor shaft; a drive shaft to which a reference rotational speed power is operatively transmitted from the drive source; a transmission shaft to which the HST output is operatively transmitted from the motor shaft; a first planetary gear mechanism including a first element supported on the transmission shaft so as to be unable to rotate relatively about an axis, a second element to which a reference rotational speed power can be input, and a third element that outputs a composite rotational power obtained by combining the rotational powers input to the first and second elements; a first transmission gear train operatively transmitting a reference rotational speed power from the drive shaft to a second element of the first planetary gear mechanism; a first clutch mechanism that engages and disengages power transmission by the first transmission gear train; a second planetary gear mechanism including a first element supported on the transmission shaft so as to be unable to rotate relatively about an axis, a second element to which a reference rotational speed power can be input, and a third element that outputs a composite rotational power obtained by combining the rotational powers input to the first and second elements; a second transmission gear train operatively capable of transmitting a reference rotational speed power from the drive shaft to a second element of the second planetary gear mechanism; a second clutch mechanism that engages and disengages power transmission by the second transmission gear train; a connecting member that connects the third elements of the first and second planetary gears to each other so that they cannot rotate relatively about the axis, the connecting member is fitted onto the transmission shaft so as to be rotatable relative to the transmission shaft about its axis, and has a connecting body whose first axial side is connected to the third element of the first planetary gear mechanism and whose second axial side is connected to the third element of the second planetary gear mechanism, and an output body capable of outputting the rotational power of the connecting body to the outside.

20. the first planetary gear mechanism has a first sun gear acting as a first element, a first carrier acting as a third element, and a first internal gear acting as a second element; the second planetary gear mechanism has a second sun gear acting as a first element, a second carrier acting as a second element, and a second internal gear acting as a third element; The first planetary gear mechanism has a gear ratio set so that, under a transmission state, when the HST output is set to a predetermined HST speed for zero speed, the first carrier reaches zero speed, and as the HST output is changed from the first HST speed side to the second HST speed side, the first carrier rotates at an increased speed in a first rotation direction which is one side about the axis, and when the HST output is set to a predetermined HST speed for first gear stage maximum speed, the first carrier rotates in the first rotation direction at the predetermined first gear stage maximum speed, 20. The HMT device according to claim 19, wherein the gear ratio of the second planetary gear mechanism is set so that, in a transmission state, when the HST output is set to an HST speed for first gear stage maximum speed, the second internal gear rotates in a first rotational direction at the first gear stage maximum speed, and as the HST output is changed from the HST speed for first gear stage maximum speed toward the first HST speed to a predetermined HST speed for second gear stage maximum speed, the rotational speed of the second internal gear increases from the first gear stage maximum speed to the second gear stage maximum speed.

21. 21. The HMT device according to claim 20, wherein the connecting body has a cylindrical portion extending in an axial direction, a first flange extending radially outward from a first axial side of the cylindrical portion and coupled to the first carrier, and a second flange extending radially outward from a second axial side of the cylindrical portion and coupled to the second internal gear.

22. the drive shaft is coaxially connected to the pump shaft so as to be non-rotatable relative to the pump shaft about its axis; The transmission shaft is disposed parallel to the drive shaft, the first transmission gear train includes a first drive gear supported on the drive shaft so as to be relatively rotatable about its axis, and a first driven gear operatively meshed with the first drive gear and connected to a first internal gear so as not to be relatively rotatable about its axis, and supported on the transmission shaft directly or indirectly so as to be relatively rotatable about its axis, the first clutch mechanism is provided on the drive shaft to engage and disengage power transmission from the drive shaft to the first drive gear, the second transmission gear train includes a second drive gear supported on the drive shaft so as to be relatively rotatable about its axis, and a second driven gear operatively meshed with the second drive gear and connected to a second carrier so as not to be relatively rotatable about its axis, and supported directly or indirectly on the transmission shaft so as to be relatively rotatable about its axis, 22. The HMT device according to claim 21, wherein the second clutch mechanism is provided on the drive shaft to engage and disengage power transmission from the drive shaft to the second drive gear.

23. the first and second clutch mechanisms are disposed between the first and second flanges of the connecting body in the axial direction, 23. The HMT device according to claim 22, wherein a portion of the first and second clutch mechanisms is disposed within a space defined between an outer peripheral surface of the cylindrical portion and opposing surfaces of the first and second flanges.

24. a third transmission gear train capable of operatively transmitting a reference rotational speed power from the drive shaft to the second carrier; a third clutch mechanism that engages and disengages power transmission by the third transmission gear train, the third transmission gear train includes a third drive gear supported on the drive shaft so as to be relatively rotatable about its axis, and a third driven gear operatively meshed with the third drive gear and connected to the second carrier so as not to be relatively rotatable about its axis, and supported on the transmission shaft directly or indirectly so as to be relatively rotatable about its axis, and a gear ratio is set so as to rotate the second carrier at a higher speed than the second transmission gear train, 24. The HMT device according to claim 22 or 23, wherein the third clutch mechanism is provided on the drive shaft so as to engage and disengage power transmission from the drive shaft to the third drive gear.

25. an input member connected to a second element of the second planetary gear mechanism in a state in which the input member is rotatable about an axis of the transmission shaft relative to the transmission shaft; 25. The HMT device of claim 24, wherein the second and third driven gears are provided on the input member.

26. An HMT device according to any one of claims 19 to 25; a speed change operation member that can be manually operated within a speed change operation range between a zero speed position and a maximum speed position; an operation position sensor that detects the operation position of the gear shift operation member; a first clutch actuating member that switches between an engagement and disengagement operation of the first clutch mechanism; a second clutch actuating member that switches between an engagement and disengagement operation of the second clutch mechanism; an HST operating member that operates an output adjusting member of the HST; an output sensor that directly or indirectly detects the rotational speed of the connecting member; a control device that controls the operation of the first and second clutch operating members and the HST operating member, The speed change operation range is divided into a first gear operation region on the low speed side, which is set in a range from a zero speed position to a first gear maximum speed position, and a second gear operation region on the high speed side, which is set in a range from the first gear maximum speed position to a second gear maximum speed position, The control device operates the first and second clutch operating members so that, when the speed change operating member is operated in the first gear stage operating range, the first clutch mechanism is engaged and the second clutch mechanism is disengaged, when the speed change operating member is positioned at the first gear stage maximum speed position, one of the first and second clutch mechanisms is engaged and the other is disengaged, and when the speed change operating member is operated in the second gear stage operating range, the first clutch mechanism is disengaged and the second clutch mechanism is engaged, a transmission structure in which the HST operating member is operated so that, in response to operation of the speed change operating member to the zero speed position, the HST output becomes an HST speed for zero speed; in response to operation of the speed change operating member to the speed increasing side within a first gear stage operation range, the HST output is shifted from the first HST speed side to the second HST speed side; in response to operation of the speed change operating member to the first gear stage maximum speed position, the HST output becomes an HST speed for first gear stage maximum speed; in response to operation of the speed change operating member to the speed increasing side within a second gear stage operation range, the HST output is shifted from the second HST speed side to the first HST speed side; and in response to operation of the speed change operating member to the maximum speed position, the HST output becomes an HST speed for second gear stage maximum speed.

27. a forward / reverse switching mechanism that can selectively take a normal rotation output state in which the rotation direction of the HMT power operatively input from the output body is not changed and is output, and a reverse rotation output state in which the rotation direction of the HMT power is reversed and is output; a forward / reverse operating member that operates the forward / reverse switching mechanism, the speed change operation range of the speed change operation member includes a forward operation range from a zero speed position to a forward maximum speed position, and a reverse operation range from the zero speed position to a reverse maximum speed position, 27. The transmission structure according to claim 26, wherein the control device operates the forward / reverse operating member so that the forward / reverse switching mechanism is in a forward rotation output state when the speed change operating member is positioned in a forward side operation range, and so that the forward / reverse switching mechanism is in a reverse rotation output state when the speed change operating member is positioned in a reverse side operation range.

28. 28. The transmission structure according to claim 26 or 27, further comprising an auxiliary transmission mechanism capable of changing the HMT power operatively input from the output body to a plurality of speed stages including a low speed stage and a high speed stage.

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