CN110778678A - HMT structure - Google Patents

Abstract

In the HMT structure of the present invention, when the shift lever is in the zero-speed position, the output of the output element of the planetary gear mechanism becomes zero-speed, and the output of the output element increases in the forward and reverse directions as the shift lever is operated from the zero-speed position to the forward and reverse sides, respectively. The HMT structure includes a clutch mechanism for engaging and disengaging power transmission from the output element to the HMT output shaft, and the clutch mechanism is in a power transmission state when a shift operation lever is subjected to a shift operation in a 1 st operation direction and is in a power cutoff state when the shift operation lever is operated from a zero speed position to a clutch release position in a 2 nd operation direction different from the 1 st operation direction.

Description

HMT structure

Technical Field

The present invention relates to a hydrostatic mechanical continuously variable transmission structure (HMT structure) including a hydrostatic continuously variable transmission mechanism (HST) and a planetary gear mechanism.

Background

The HMT structure in which the HST and the planetary gear mechanism are combined is suitable for a travel system transmission path of a work vehicle such as a combine (combine) or a tractor (tractor).

For example, japanese patent No. 5822761 (hereinafter, referred to as patent document 1) discloses a work vehicle in which an HMT structure is applied to a travel system power transmission path, the HMT structure being configured such that an output rotational power of a planetary gear mechanism is set to a zero speed by shifting an HST to a set intermediate speed between a reverse-side highest speed and a neutral speed, the output rotational power of the planetary gear mechanism is increased to a reverse side as the HST is shifted from the set intermediate speed to the reverse-side highest speed, and the output of the planetary gear mechanism is increased to a forward side as the HST is shifted from the set intermediate speed to the normal-side highest speed via the neutral speed.

The HMT structure described in patent document 1 is useful in that the work vehicle can be driven to travel in both forward and reverse directions by the shift operation of the HST without separately providing a forward/reverse switching mechanism in the work vehicle to which the HMT structure is applied.

However, the conventional HMT configuration has the following problems: it is difficult to bring the output into a zero speed state (the output rotational power of the planetary gear mechanism is in a zero speed state), and in the case of being applied to the traveling system power transmission path, it is difficult to bring the traveling stop state of the work vehicle into existence.

That is, in order to bring the output of the conventional HMT structure to a zero-speed state, it is necessary to manufacture the HST and the link mechanism of the HST and the shift lever so that the output rotational power of the HST accurately becomes a set intermediate speed when the shift lever for performing a shift operation on the HST is located at a set intermediate speed position corresponding to the set intermediate speed of the HST, and strictly manufacture and assemble the HST and the planetary gear mechanism so that the output rotational power of the planetary gear mechanism becomes a zero-speed when the output rotational power of the set intermediate speed is input from the HST.

Further, in the work vehicle in which the HMT structure is provided in the drive train transmission path, there is a problem that it is difficult to pull the work vehicle at the time of a failure or the like.

That is, when towing a work vehicle having the HMT structure provided in a travel system transmission path, the hydraulic motor of the HST operatively connected to the travel member (i.e., the actuation of the HST) is forcibly rotated by the rotation of the travel member. Here, the hydraulic motor is connected to a drive source such as an engine by a hydraulic pump of the HST that is fluidly connected through a pair of hydraulic oil lines, and is in a state of being unable to rotate freely.

Therefore, when the hydraulic motor is forcibly rotated in accordance with the rotation of the travel member during the towing of the work vehicle, the discharge oil from the hydraulic motor flows into one of the pair of hydraulic oil lines in a state where the hydraulic pump cannot be rotated due to the operational connection with the drive source, and the rotation of the hydraulic motor is inhibited by the hydraulic pressure of the one hydraulic oil line.

Disclosure of Invention

The present invention has been made in view of the above-described conventional technology, and an object thereof is to provide an HMT structure including an HST and a planetary gear mechanism, which can output bidirectional rotational power on the forward side and the reverse side and can reliably bring about an output zero state.

In order to achieve the above object, a 1 st aspect of the present invention provides an HMT structure including: an HST that continuously shifts and outputs rotational power input from a drive source; a planetary gear mechanism that inputs rotational power from the drive source and rotational power from the HST to the 1 st and 2 nd elements, respectively, and combines the rotational power of the 1 st and 2 nd elements and outputs the resultant rotational power from the 3 rd element; an HMT output shaft; a clutch mechanism that disengages the power transmission from the 3 rd element to the HMT output shaft; and a shift lever that performs a shift operation of the HST, the shift lever being capable of a shift operation in a 1 st operation direction toward a forward side and a reverse side via a zero-speed position, and a clutch engagement/disengagement operation between a clutch engagement position and a clutch release position in a 2 nd operation direction different from the 1 st operation direction, the shift operation being capable of a shift operation in the 1 st operation direction only when the shift lever is located at the clutch engagement position, and the clutch engagement/disengagement operation in the 2 nd operation direction only when the shift lever is located at the zero-speed position, wherein the HST and the planetary gear mechanism are configured such that, when the shift lever is located at the zero-speed position, rotational power output from the 3 rd element becomes zero-speed, and the shift lever is operated toward the forward side and the reverse side from the zero-speed position, and the rotational power output from the 3 rd element is increased in speed toward the forward direction and the reverse direction, respectively, and the clutch mechanism is configured to engage and disengage power transmission to the HMT output shaft when the shift lever is at the clutch engagement position and the clutch release position, respectively.

According to the HMT structure of claim 1 of the present invention, the HMT output shaft can output bidirectional rotational power on the forward side and the reverse side, and the output zero state of the HMT output shaft can be reliably made.

Therefore, when the HMT structure is applied to the travel system power transmission path of the work vehicle, the vehicle can be advanced and retracted without separately providing the work vehicle with an advance/retraction switching mechanism, and the work vehicle can be reliably prevented from moving at a creep speed against the intention of the operator. Further, when the clutch mechanism is in the power transmission interrupted state, the traveling member of the work vehicle is in a free state in which the traveling member is rotatable with respect to the HST, and therefore the work vehicle can be easily forcibly towed.

Preferably, the HMT structure according to claim 1 may include a brake mechanism that applies a braking force to the HMT output shaft in an operative manner (japanese rotation).

In this case, the shift lever is capable of performing a brake engagement/disengagement operation between the brake engagement position and the brake release position in a 3 rd operation direction different from the 2 nd operation direction only in a state in which the shift lever is located at the clutch release position, and is capable of performing a clutch engagement/disengagement operation in the 2 nd operation direction only in a state in which the shift lever is located at the brake release position, and the brake mechanism is configured to apply and release a braking force to and from actuation of the HMT output shaft when the shift lever is located at the brake engagement position and the brake release position, respectively.

Preferably, the 3 rd operating direction is parallel to the 1 st operating direction.

In order to achieve the above object, a 2 nd aspect of the present invention provides an HMT structure including: an HST that continuously shifts and outputs rotational power input from a drive source; a planetary gear mechanism that inputs rotational power from the drive source and rotational power from the HST to the 1 st and 2 nd elements, respectively, and combines the rotational power of the 1 st and 2 nd elements and outputs the resultant rotational power from the 3 rd element; an HMT output shaft; a clutch mechanism that disengages the power transmission from the 3 rd element to the HMT output shaft; a brake mechanism operatively applying a braking force to the HMT output shaft; and a shift lever that performs a shift operation of the HST, the shift lever being capable of a shift operation in a 1 st operation direction toward a forward side and a reverse side via a zero-speed position, and a clutch engagement/disengagement operation between a clutch engagement position and a clutch release position in a 2 nd operation direction different from the 1 st operation direction, the shift operation being capable of a shift operation in the 1 st operation direction only when the shift lever is located at the clutch engagement position, and the clutch engagement/disengagement operation in the 2 nd operation direction only when the shift lever is located at the zero-speed position, wherein the HST and the planetary gear mechanism are configured such that, when the shift lever is located at the zero-speed position, rotational power output from the 3 rd element becomes zero-speed, and the shift lever is operated toward the forward side and the reverse side from the zero-speed position, the rotational power output from the 3 rd element increases in speed toward the forward side and the reverse side, respectively, and when the shift lever is in the clutch engagement position, the clutch mechanism engages the power transmission to the HMT output shaft and the brake mechanism releases the braking force for the operability of the HMT output shaft, while when the shift lever is in the clutch release position, the clutch mechanism interrupts the power transmission to the HMT output shaft and the brake mechanism applies the braking force for the operability of the HMT output shaft.

According to the HMT structure of claim 2 of the present invention, the HMT output shaft can output bidirectional rotational power on the forward side and the reverse side, and the output zero state of the HMT output shaft can be reliably made.

Therefore, when the HMT structure is applied to the travel system power transmission path of the work vehicle, the vehicle can be advanced and retracted without separately providing the work vehicle with an advance/retraction switching mechanism, and the work vehicle can be reliably prevented from moving at a creep speed against the intention of the operator.

In the aspect of claim 1 provided with the brake mechanism and in the aspect of claim 2, for example, the clutch mechanism includes: a clutch drive member supported by the HMT output shaft so as to be rotatable with respect to the HMT output shaft in a state of being operatively coupled to the 3 rd element; a clutch engagement/disengagement member that can selectively obtain an engaged state in which power transmission from the clutch drive member to the HMT output shaft is performed and a disengaged state in which the power transmission is interrupted; and a clutch switching member that switches an operating state of the clutch engagement and disengagement member, the brake mechanism having: a brake rotating member that is supported on the HMT output shaft so as to be non-rotatably relative to the HMT output shaft so as to rotate integrally with the HMT output shaft; a brake fixing member provided to be non-rotatable; a brake engagement and disengagement member that is capable of selectively achieving a braking force application state in which the brake rotation member is operatively engaged with the brake fixing member to operatively apply a braking force to the HMT output shaft and a braking force release state in which the braking force is released; and a brake switching member that switches an operating state in which the brake is engaged and disengaged.

Instead, the clutch mechanism may have: a clutch drive member supported by the HMT output shaft so as to be rotatable with respect to the HMT output shaft in a state of being operatively coupled to the 3 rd element; and a clutch engagement/disengagement member that can selectively obtain an engaged state in which power transmission from the clutch drive member to the HMT output shaft is performed and a disengaged state in which the power transmission is interrupted, the brake mechanism including: a brake rotating member that is supported on the HMT output shaft so as to be non-rotatably relative to the HMT output shaft so as to rotate integrally with the HMT output shaft; a brake fixing member provided to be non-rotatable; and a brake engagement/disengagement member that is capable of selectively obtaining a braking force application state in which the brake rotation member is operatively engaged with the brake fixing member to operatively apply a braking force to the HMT output shaft and a braking force release state in which the braking force is released.

In this case, the clutch engagement and disengagement member and the brake engagement and disengagement member are switched in operation by a single clutch/brake switching member.

In the above various configurations, the HMT structure may include a housing that houses the HST, the planetary gear mechanism, the clutch mechanism, and the brake mechanism.

The shift operating lever may include: a 1 st operation shaft, the 1 st operation shaft being supported to be rotatable around an axis; a 2 nd operation shaft, the 2 nd operation shaft being supported by the 1 st operation shaft in a state of being orthogonal to the 1 st operation shaft; a lever main body that is manually operated; and a connecting member that connects a base end portion of the lever main body to the 2 nd operation shaft, wherein the lever main body, the connecting member, the 2 nd operation shaft, and the 1 st operation shaft are integrally rotatable about an axis of the 1 st operation shaft, and the lever main body and the connecting member are rotatable about an axis of the 2 nd operation shaft.

In one aspect, a clutch engagement/disengagement operation in the 2 nd operation direction occurs by rotating the lever main body and the coupling member about the axis of the 2 nd operation shaft in a state where the lever main body, the coupling member, the 2 nd operation shaft, and the 1 st operation shaft are located at a zero speed position about the axis of the 1 st operation shaft, a shift operation in the 1 st operation direction occurs by rotating the lever main body, the coupling member, the 2 nd operation shaft, and the 1 st operation shaft about the axis of the 1 st operation shaft in a state where the lever main body and the coupling member are located at a clutch engagement position about the axis of the 2 nd operation shaft, and a shift operation in the 1 st operation direction occurs by rotating the lever main body and the coupling member about the axis of the 2 nd operation shaft in a clutch release position, The connecting member, the 2 nd operating shaft, and the 1 st operating shaft rotate about the 1 st operating shaft axis, so that a brake engagement/disengagement operation in the 3 rd operating direction occurs.

Preferably, the shift operating lever of the one aspect may include an urging member that urges the lever main body and the coupling member to a clutch engagement position about an axis of the 2 nd operating shaft.

In another aspect, the clutch engagement/disengagement operation in the 2 nd operating direction occurs by rotating the lever main body and the coupling member about the axis of the 2 nd operating shaft in a state where the lever main body, the coupling member, the 2 nd operating shaft, and the 1 st operating shaft are located at a zero speed position about the axis of the 1 st operating shaft, and the gear shift operation in the 1 st operating direction occurs by rotating the lever main body, the coupling member, the 2 nd operating shaft, and the 1 st operating shaft about the axis of the 1 st operating shaft in a state where the lever main body and the coupling member are located at a clutch engagement position about the axis of the 2 nd operating shaft.

Preferably, the shift operating lever of the other aspect may include an urging member that urges the lever main body and the coupling member to a clutch release position about an axis of the 2 nd operating shaft.

Drawings

Fig. 1 is a schematic transmission diagram of a work vehicle to which an HMT structure according to embodiment 1 of the present invention is applied.

Fig. 2 is a sectional view of an HMT structure according to embodiment 1 of the present invention.

Fig. 3 is a sectional view taken along the line III-III in fig. 2.

Fig. 4 is a hydraulic circuit diagram of the HMT configuration.

Fig. 5 (a) and (b) are a front view and a side view, respectively, of a shift lever provided in the HMT structure.

Fig. 6 is a top view of the shift operating lever.

Fig. 7 is an enlarged view of a portion VII in fig. 2.

Fig. 8 is a partial sectional view of the HMT structure according to modification 1 of embodiment 1.

Fig. 9 is a hydraulic circuit diagram of the HMT structure of modification 1.

Fig. 10 is a partial cross-sectional view of an HMT structure according to modification 2 of embodiment 1.

Fig. 11 is a front view of the shift operating lever shown in fig. 5 and 6 with a biasing member biasing the shift operating lever to a clutch engagement position.

Fig. 12 is a hydraulic circuit diagram of an HMT structure according to embodiment 2 of the present invention.

Fig. 13 is a plan view of a shift lever provided in the HMT structure according to embodiment 2.

Fig. 14 is a partial sectional view of an HMT structure according to a modification of embodiment 2.

Fig. 15 is a front view of the shift operating lever shown in fig. 13 with an urging member for urging the shift operating lever to a clutch release position.

Description of the reference numerals

5: a drive source;

10：HST；

100: a planetary gear mechanism;

110: sun gear (element 2);

130: an internal gear (1 st element);

150: a carrier (element 3);

200A to 200C, 200(2) A to 200(2) B: an HMT configuration;

210: an HMT housing;

350: an HMT output shaft;

400: a brake mechanism;

405: a brake rotating member;

410: a brake fixing member;

420: a brake engagement disengagement member;

425. 650: a brake switching member;

450: a clutch mechanism;

455: a clutch drive member;

460. 630: a clutch engagement disengagement member;

470. 640: a clutch switching member;

570. 830, 870: a clutch-brake switching member;

632: a clutch housing (brake rotating member);

700. 700 (2): a shift operating lever;

707: a clutch engagement urging member;

708: a clutch release (brake engagement) apply member;

710: 1 st operating shaft;

720: a 2 nd operation shaft;

730: a lever body;

740: a connecting member;

D1-D3: 1 st to 3 rd operating directions.

Detailed Description

Embodiment mode 1

Hereinafter, an embodiment of an HMT structure according to the present invention will be described with reference to the drawings.

Fig. 1 shows a schematic transmission diagram of a work vehicle 1 to which an HMT structure (hydrostatic mechanical continuously variable transmission structure) 200A of the present embodiment is applied.

As shown in fig. 1, the work vehicle 1 includes a drive source 5, a travel member 6, and the HMT structure 200A interposed in a travel line transmission path from the drive source 5 to the travel member 6.

The HMT construction 200A has: an HST (hydrostatic continuously variable transmission) 10 that continuously changes and outputs rotational power input from the drive source 5; a planetary gear mechanism 100, the planetary gear mechanism 100 combining rotational power operatively input from the drive source 5 and the HST10 and outputting the combined rotational power; and an HMT output shaft 350, the HMT output shaft 350 operatively inputting the combined rotational power from the planetary gear mechanism 100 and outputting the combined rotational power to a driven member (the traveling member 6 in the present embodiment).

A cross-sectional view of the HMT construction 200A is shown in fig. 2.

In addition, a cross-sectional view along the line III-III in fig. 2 is shown in fig. 3.

Also, a hydraulic circuit diagram of the HMT configuration 200A is shown in fig. 4.

As shown in fig. 1 to 4, the HST10 includes: a pump shaft 20, the pump shaft 20 being operatively driven in rotation by the drive source 5; a hydraulic pump 25, the hydraulic pump 25 being supported on the pump shaft 20 so as not to be rotatable with respect to the pump shaft 20; a hydraulic motor 35, the hydraulic motor 35 being fluidly connected to the hydraulic pump 25 via a pair of hydraulic oil lines 601, 602 and being hydraulically driven to rotate by the hydraulic pump 25; a motor shaft 30, the motor shaft 30 supporting the hydraulic motor 35 non-rotatably with respect to the hydraulic motor 35; and an output adjustment means 40, wherein the output adjustment means 40 continuously changes the ratio of the rotational speed of the HST output from the motor shaft 30 to the rotational speed of the rotational power input to the pump shaft 20 (i.e., the gear ratio of the HST 10) by changing the displacement of at least one of the hydraulic pump 25 and the hydraulic motor 35.

The output adjusting member 40 is configured to continuously shift the HST output from the motor shaft 30 in a forward and reverse bidirectional shift range in response to a manual operation of a shift lever 700 (see fig. 4) provided to the HMT structure 200A in a manually operable manner.

In the present embodiment, the HST10 includes, as the output adjustment means 40, a movable swash plate that changes the capacity of the hydraulic pump 25 by swinging about a swing axis and is capable of swinging about one side and the other side in the swing axis direction via a neutral position at which the discharge amount from the hydraulic pump 25 is zero.

When the movable swash plate is at the neutral position, the discharge of pressure oil (hydraulic oil) from the hydraulic pump 25 disappears, and the hydraulic motor 35 enters a zero speed output state.

When the movable swash plate swings from the neutral position toward one side of the swing shaft in the normal rotation direction, pressure oil is supplied from the hydraulic pump 25 to a corresponding hydraulic oil line (for example, the hydraulic oil line 601) of the pair of hydraulic oil lines 601 and 602, the corresponding hydraulic oil line 601 becomes the high pressure side, and the other hydraulic oil line 602 becomes the low pressure side.

Thereby, the hydraulic motor 35 is rotationally driven to the normal rotation side.

Conversely, when the movable swash plate swings from the neutral position to the reverse rotation side on the other side of the swing shaft, pressure oil is supplied from the hydraulic pump 25 to a corresponding one of the pair of hydraulic oil lines 601 and 602 (for example, the hydraulic oil line 602), the corresponding hydraulic oil line 602 becomes the high pressure side, and the other hydraulic oil line 601 becomes the low pressure side.

Thereby, the hydraulic motor 35 is driven to rotate in the reverse direction.

In the HST10, the hydraulic motor 35 fixes the volume by fixing a swash plate.

In the present embodiment, the HST10 further includes an auxiliary pump unit 80 and a supply (charge) mechanism 610, the auxiliary pump unit 80 includes an auxiliary pump 81 that is rotationally driven by the drive source 5, and the supply mechanism 610 supplies pressure oil from the auxiliary pump 81 to the pair of hydraulic oil lines 601 and 602.

As shown in fig. 4, the auxiliary pump 81 sucks oil from a tank (not shown) through a suction line (not shown) and discharges pressure oil to a pressure oil supply line 605.

The pressure oil supply line 605 is set to a predetermined hydraulic pressure by the relief valve 606.

As shown in fig. 4, the supply mechanism 610 includes: a pair of supply lines 611 and 612, the upstream side of the pair of supply lines 611 and 612 being fluidly connected to the pressure oil supply line 605 and the downstream side being fluidly connected to the pair of hydraulic oil lines 601 and 602, respectively; and a pair of check valves 615 and 616, the pair of check valves 615 and 616 being inserted into the pair of supply lines 611 and 612, respectively, so as to allow the pressure oil to flow from the pressure oil supply line 605 into the hydraulic oil lines 601 and 602 and prevent the reverse flow.

As shown in fig. 4, the HMT structure 200A further includes an HST shift operating mechanism 750, and the HST shift operating mechanism 750 operates the output adjusting member 40 in response to a manual operation of the shift operating lever 700.

In the present embodiment, as shown in fig. 4, the HST shift operating mechanism 750 includes a hydraulic servo 760, and the hydraulic servo 760 operates the output adjusting member 40 using pressure oil from the assist pump 81 as hydraulic oil.

The hydraulic servo 760 includes: a cylinder 761; a piston 763 that divides an internal space of the cylinder 761 into a normal rotation chamber 761F and a reverse rotation chamber 761R in a liquid-tight manner and is housed in the internal space of the cylinder 761 in a slidable manner; and a switching valve 765 for switching supply and discharge of the pressure oil to and from the normal rotation chamber 761F and the reverse rotation chamber 761R.

The switching valve 765 is capable of selectively taking a normal rotation position at which the pressure oil supply line 605 is fluidly connected to the normal rotation chamber 761F and the reverse rotation chamber 761R is fluidly connected to the drain line 609, a holding position at which the normal rotation chamber 761F and the reverse rotation chamber 761R are respectively closed, and a reverse rotation position at which the pressure oil supply line 605 is fluidly connected to the reverse rotation chamber 761R and the normal rotation chamber 761F is fluidly connected to the drain line 609.

The piston 763 is operatively coupled to the output adjustment member 40.

Specifically, when pressure oil is supplied to the normal rotation chamber 761F and pressure oil is discharged from the reverse rotation chamber 761R, the piston 763 moves in a direction to expand the normal rotation chamber 761F. Conversely, when pressure oil is supplied to the reverse rotation chamber 761R and pressure oil is discharged from the normal rotation chamber 761F, the piston 763 moves in a direction to expand the reverse rotation chamber 761R. When the forward rotation chamber 761F and the reverse rotation chamber 761R are closed, the piston 763 is held at the position at that time.

Here, the piston 763 is operatively coupled to the output adjustment member 40 in the following manner: when the piston 763 is moved in a direction to expand the normal rotation chamber 761F, the output adjustment member 40 is moved to the normal rotation side, when the piston 763 is moved in a direction to expand the reverse rotation chamber 761R, the output adjustment member 40 is moved to the reverse rotation side, and when the piston 763 is held at the position at that time, the output adjustment member 40 is held at the position at that time.

Further, when the output adjusting member 40 moves to the normal rotation side, the output of the HST10 increases in speed to the normal rotation side, and when the output adjusting member 40 moves to the reverse rotation side, the output of the HST10 increases in speed to the reverse rotation side.

The switching valve 765 is position-controlled in response to a manual operation of the shift lever 700.

Fig. 5 (a) and (b) show a front view and a side view of the shift lever 700, respectively.

Fig. 6 is a top view of the shift lever 700.

As shown in fig. 4 and 5 (b), the HST shift operating mechanism 750 includes an HST shift arm 770 coupled to the switching valve 765 so as to move the switching valve 765, and the HST shift arm 770 is operated in response to a manual operation of the shift lever 700.

As shown in fig. 4 and 5 (b), in the present embodiment, the shift operating lever 700 is operatively coupled to the HST shift arm 770 via a mechanical link 780.

Instead, the HST shift operating mechanism 750 may include an HST shift motor (shift motor) such as an electric motor that operates the HST shift arm 770, and the operation control of the HST shift motor may be performed so that the HST shift arm 770 is operated in response to a manual operation of the shift operating lever 700.

As shown in fig. 5 (b) and 6, the shift lever 700 is capable of shifting in the 1 st operating direction D1 toward the forward side F and the reverse side R with the zero position 0 interposed therebetween.

In the present embodiment, as shown in fig. 5 (a) and (b), the shift lever 700 includes a 1 st operating shaft 710 supported by a support body 705 such as an operating box so as to be rotatable about an axis, and a lever main body 730 whose base end portion is supported directly or indirectly by the 1 st operating shaft 710 so as not to be relatively rotatable about the axis with respect to the 1 st operating shaft 710, and the shift lever 700 is movable in a 1 st operating direction D1 by swinging the lever main body 730 about the axis of the 1 st operating shaft 710.

In the present embodiment, the shift operating lever 700 further includes a grip portion 735 provided at a distal end portion of the lever main body 730.

The HMT structure 200A of the present embodiment includes an operating position maintaining mechanism 790, and the operating position maintaining mechanism 790 locks the shift operating lever 700 in the 1 st operating direction D1 to a desired operating position.

As shown in fig. 5 (a), the operating position holding mechanism 790 includes a plate 792 supported by the 1 st operating shaft 710 so as to be relatively non-rotatable about an axis, a pair of pads (pads) 794 disposed to face each other with the plate 792 interposed therebetween, and an urging member 796 such as a coil spring that urges the pair of pads 794 in a pinching direction.

The operating position holding mechanism 790 locks the 1 st operating shaft 710 at an arbitrary position around the axis line by the biasing force of the biasing member 796, and allows the 1 st operating shaft 710 to rotate around the axis line when an operating force exceeding the biasing force of the biasing member 796 is applied to the shift operating lever 700.

The HMT structure 200A is configured such that when the shift lever 700 is located at the zero-speed position 0, the output of the HMT structure 200A (i.e., the combined rotational power output from the planetary gear mechanism 100) becomes zero-speed, and the rotational power output from the planetary gear mechanism 100 increases in speed toward the forward side and the reverse side, respectively, as the shift lever 700 is operated from the zero-speed position 0 toward the forward side F and the reverse side R.

That is, the HST shift operating mechanism 750 is configured such that when the shift operating lever 700 is located at the zero speed position 0, the HST10 outputs power at a predetermined rotation speed at which the output of the HMT structure 200A is zero speed.

In the present embodiment, the number of rotations of the HST output at which the output of the HMT structure 200A is zero is set to a predetermined reverse-side number of rotations R1 (see fig. 5) between the neutral speed N and the reverse-side maximum speed Rmax.

The HST shift operating mechanism 750 is further configured such that as the shift operating lever 700 is operated from the zero-speed position 0 in the 1 st operating direction D1 to the forward side, the HST output increases in speed from the reverse-rotation side predetermined rotational speed to the forward rotation side via the neutral state, and as the shift operating lever 700 is operated from the zero-speed position 0 in the 1 st operating direction D1 to the reverse side, the HST output increases in speed from the reverse-rotation side predetermined rotational speed R1 to the reverse rotation side.

The HST10 and the planetary gear mechanism 100 are configured such that the output of the HMT structure 200A increases from zero to the forward side as the HST output increases from the reverse side predetermined rotational speed in the forward direction through the neutral state, and the output of the HMT structure 200A increases from zero to the reverse side as the HST output increases from the reverse side predetermined rotational speed in the reverse direction.

In the present embodiment, as shown in fig. 5 (a) and 6, the shift operating lever 700 is configured to be capable of performing a clutch engagement/disengagement operation in the 2 nd operating direction D2 different from the 1 st operating direction D1 from the zero speed position 0 in addition to the shift operation in the 1 st operating direction D1.

This point will be described later.

The planetary gear mechanism 100 inputs the rotational power from the drive source 5 to the 1 st element and the rotational power from the HST10 to the 2 nd element, and combines and outputs the rotational powers.

Specifically, as shown in fig. 2, the planetary gear mechanism 100 includes a sun gear 110, a planetary gear 120 meshing with the sun gear 110, an internal gear 130 meshing with the planetary gear 120, and a carrier 150 supporting the planetary gear 120 rotatably about an axis and rotating about the axis of the sun gear 110 in conjunction with the revolution of the planetary gear 120 about the sun gear 110.

In the present embodiment, the internal gear 130 and the sun gear 110 function as the 1 st and 2 nd elements, respectively, and the carrier 150 functions as the 3 rd element.

The sun gear 110 is coupled to the motor shaft 30 coaxially with the motor shaft 30 so as to be non-rotatable about the axis with respect to the motor shaft 30.

The carrier 150 includes a carrier pin 160 that supports the planetary gear 120 so as to be rotatable about an axis, and a carrier body 170 that supports the carrier pin 160 so as to rotate about the axis of the sun gear 110 together with the revolution of the planetary gear 120 about the sun gear 110.

In the present embodiment, the carrier body 170 includes a 1 st carrier body 171 and a 2 nd carrier body 172 that are detachably coupled to each other.

The 1 st carrier body 171 and the 2 nd carrier body 172 define a space surrounding the sun gear 110 in a coupled state, and support one end portion in the axial direction and the other end portion in the axial direction of the carrier pin 160, respectively.

Specifically, the 1 st carrier main body 171 on the side close to the HST10 includes: a base end portion supported by a partition wall 235 provided in the below-described HMT case 210 via a bearing member so as to be rotatable with respect to the partition wall 235 and provided with a shaft hole through which the motor shaft 30 is inserted; and a radially extending portion that extends radially outward from the base end portion and is provided with a support hole that supports one end side in the axial direction of the carrier pin 160.

The 2 nd carrier body 172 on the opposite side of the HST10 is operatively coupled to the HMT output shaft 350 so as to be non-rotatable with respect to the HMT output shaft 350.

In the present embodiment, the 2 nd carrier body 172 has a base end portion and a radially extending portion that extends radially outward from the base end portion and is provided with a support hole that supports the other end side in the axial direction of the carrier pin 160.

In the present embodiment, the rotational power taken out from the transmission path from the drive source 5 to the pump shaft 20 is transmitted to the internal gear 130.

Specifically, as shown in fig. 1 and 2, the HMT structure 200A includes an HMT input shaft 310, and the HMT input shaft 310 is disposed coaxially with the pump shaft 20, and is operatively coupled to the drive source 5 on the upstream side in the transmission direction and is coupled to the pump shaft 20 on the downstream side in the transmission direction so as not to be rotatable with respect to the pump shaft 20.

In the present embodiment, the HMT input shaft 310 is a hollow shaft, and the input-side drive shaft 305 operatively coupled to the drive source 5 is spline-coupled to the upstream side in the transmission direction, and the pump shaft 20 is spline-coupled to the downstream side in the transmission direction.

The HMT input shaft 310 is also provided with a drive-side transmission gear 312 in the middle between the upstream side and the downstream side in the transmission direction so as not to be relatively rotatable.

In the present embodiment, the driving side transmission gear 312 is formed integrally with the HMT input shaft 310, but it is needless to say that the driving side transmission gear 312 and the HMT input shaft 310 may be separate bodies and may be supported in an axial direction intermediate of the HMT input shaft 310 so as not to be relatively rotatable.

The internal gear 130 has a driven-side transmission gear 135 engaged with the driving-side transmission gear 312, and the rotational power from the drive source 5 is input to the internal gear 130 through the HMT input shaft 310, the driving-side transmission gear 312, and the driven-side transmission gear 135.

In the present embodiment, the internal gear 130 includes: a base end portion supported on an outer peripheral surface of the base end portion of the 2 nd carrier body 172 via a bearing member so as to be relatively rotatable; an extension portion extending radially outward from the base end portion; and an outer end portion extending from the extension portion and provided with a gear engaged with the planetary gear 120 and the driven side transmission gear 135.

In the present embodiment, the HMT output shaft 350 is disposed parallel to the axis of the planetary gear mechanism 100.

As shown in fig. 1, 2, and 4, the HMT structure 200A of the present embodiment further includes a clutch mechanism 450 for disengaging the power transmission from the 3 rd element to the HMT output shaft 350.

The clutch mechanism 450 is configured to engage and disengage power transmission from the 3 rd element to the HMT output shaft 350 in response to the shift lever 700 being operated to a clutch engagement position and a clutch release position, respectively.

In the present embodiment, as shown in fig. 5 (a), 5 (b) and 6, the shift operating lever 700 includes the 1 st operating shaft 710, the lever main body 730, a 2 nd operating shaft 720 supported by the 1 st operating shaft 710 in a substantially orthogonal posture, and a connecting member 740 supported by the 2 nd operating shaft 720.

The connecting member 740 connects the base end portion of the lever main body 730 and the 2 nd operation shaft 720 such that the lever main body 730, the connecting member 740, the 2 nd operation shaft 720, and the 1 st operation shaft 710 integrally swing around the axis of the 1 st operation shaft 710, and the lever main body 730 and the connecting member 740 swing around the axis of the 2 nd operation shaft 720.

According to this configuration, the lever main body 730, the coupling member 740, the 2 nd operation shaft 720, and the 1 st operation shaft 710 are integrally pivoted about the axis of the 1 st operation shaft 710, whereby the shift operation of the shift operation lever 700 in the 1 st operation direction D1 is performed, and the lever main body 730 and the coupling member 740 are integrally pivoted about the axis of the 2 nd operation shaft 720, whereby the clutch engagement/disengagement operation of the shift operation lever 700 in the 2 nd operation direction D2 is performed.

As shown in fig. 5 (b), in the present embodiment, the 2 nd operation shaft 720 is supported by the 1 st operation shaft 710 so that one end portion and the other end portion extend outward and penetrate the 1 st operation shaft 710.

The connecting member 740 includes a pair of support pieces 742 respectively supported by one end and the other end of the 2 nd operating shaft 720, and a connecting piece 744 that connects the pair of support pieces 742 with a gap between the connecting member and the 1 st operating shaft 710, and a base end portion of the lever main body 730 is connected to the connecting piece 744.

The 1 st operating shaft 710 is supported by the support body 705 so as to be rotatable about an axis line, and the lever main body 730, the connecting member 740, the 2 nd operating shaft 720, and the 1 st operating shaft 710 are integrally rotatable about the axis line of the 1 st operating shaft 710.

The 2 nd operation shaft 720 is rotatable about an axis line with respect to the 1 st operation shaft 710 and/or the pair of support pieces 742 is rotatable about an axis line with respect to the 2 nd operation shaft 720, and the lever main body 730 and the coupling member 740 are swingable about the axis line of the 2 nd operation shaft 720 within a range in which the gap exists.

In the present embodiment, the shift lever 700 is operable to perform the clutch engagement and disengagement operation between the clutch engagement position and the clutch release position in the 2 nd operating direction D2 only when the shift lever is in the zero speed position 0 in the 1 st operating direction D1, and is operable to perform the shift operation in the 1 st operating direction D1 only when the shift lever is in the clutch engagement position in the 2 nd operating direction D2.

Specifically, as shown in fig. 6, the shift operating lever 700 further includes a guide plate 800, and the guide plate 800 includes a guide groove 810 through which the lever main body 730 is inserted.

The guide slot 810 has a 1 st slot 811 that guides the lever body 730 in the 1 st operating direction D1 and a 2 nd slot 812 that permits movement of the shift operating lever 700 in the 2 nd operating direction D2 only when the shift operating lever 700 is in the zero position 0 in the 1 st operating direction D1.

Further, the end position of the 2 nd groove 812 on the side close to the 1 st groove 811 (the position where the lever main body 730 is engaged with both the 2 nd groove 812 and the 1 st groove 811) is set to the clutch engagement position on the 2 nd operation direction side, and the end position of the 2 nd groove 812 on the opposite side to the 1 st groove 811 is set to the clutch release position on the 2 nd operation direction side.

According to the HMT structure 200A having this configuration, the forward-side rotational force and the reverse-side rotational force can be output from the HMT output shaft 350 by operating the shift lever 700 in the 1 st operation direction D1 to the forward side F and the reverse side R via the zero-speed position 0, and the power transmission between the 3 rd element and the HMT output shaft 350 can be cut off and the HMT output shaft 350 can be reliably brought into the output zero state by operating the shift lever 700 in the 2 nd operation direction D2 from the zero-speed position 0 to the clutch release position.

Therefore, when the HMT structure 200A is applied to the travel line power transmission path of the work vehicle 1 as in the present embodiment, forward travel and reverse travel can be performed without separately providing a forward/reverse switching mechanism, and the shift lever 700 is positioned at the clutch release position, so that it is possible to reliably prevent the work vehicle 1 from moving at the creep speed against the intention of the operator.

When the shift lever 700 is located at the clutch release position, the travel member 6 and the planetary gear mechanism 100 operatively coupled to the drive source 5 are disengaged by the clutch mechanism 450, and the travel member 6 is in a free state in which it is rotatable. Therefore, the forced traction of the work vehicle 1 can be easily performed.

Fig. 7 shows an enlarged view of a section VII in fig. 2.

As shown in fig. 2 and 7, in the present embodiment, the clutch mechanism 450 includes a clutch driving member 455, a clutch engagement/disengagement member 460, and a clutch switching member 470, the clutch driving member 455 is supported by the HMT output shaft 350 so as to be rotatable with respect to the HMT output shaft 350 in a state of being operatively coupled to the 3 rd element, the clutch engagement/disengagement member 460 is capable of selectively obtaining an engaged state in which power transmission from the clutch driving member 455 to the HMT output shaft 350 is performed and a disengaged state in which the power transmission is interrupted, and the clutch switching member 470 switches an operating state of the clutch engagement/disengagement member 460.

In the present embodiment, the transmission gear 175 is relatively non-rotatably supported by the carrier body 170 (the base end portion of the 2 nd carrier body 172), and the clutch driving member 455 is operatively coupled to the carrier body 170 functioning as the 3 rd element by meshing with the transmission gear 175.

In the present embodiment, as shown in fig. 7, the clutch engagement/disengagement member 460 includes a rolling element 462 such as a ball (ball) and a snap groove 464, the rolling element 462 is supported by the clutch driving member 455 so as to be relatively non-rotatable about the axis of the HMT output shaft 350 and movable in a radial direction with respect to the axis of the HMT output shaft 350, and the snap groove 464 is formed in the HMT output shaft 350 so as to be selectively engageable/disengageable by the rolling element 462 moving in the radial direction with respect to the axis of the HMT output shaft 350.

The clutch switching member 470 is a slider (slider) supported on the HMT output shaft 350 so as to be movable in the axial direction so as to be able to obtain a clutch engagement position on one side in the axial direction and a clutch release position on the other side in the axial direction, and is configured to press the rolling elements 462 into the engagement grooves 464 when in the clutch engagement position and to allow the rolling elements 462 to be disengaged radially outward from the engagement grooves 464 by a centrifugal force when in the clutch release position.

In fig. 2 and 7, the clutch switching member 470 is shown in a state of being located at a clutch engagement position on an upper side of the HMT output shaft 350, and the clutch switching member 470 is shown in a state of being located at a clutch release position on a lower side of the HMT output shaft 350.

The rolling bodies 462 are pressed into the engagement grooves 464 to produce a clutch engaged state in which power transmission from the clutch driving member 455 to the HMT output shaft 350 is performed, and the rolling bodies 462 are disengaged from the engagement grooves 464 to produce a clutch released state in which power transmission from the clutch driving member 455 to the HMT output shaft 350 is cut off.

As shown in fig. 4, the HMT configuration 200A also has a clutch operating mechanism 480.

The clutch operating mechanism 480 operates the clutch switching member in response to a clutch engagement/disengagement operation of the shift operating lever 700.

In the present embodiment, as shown in fig. 4, the clutch operating mechanism 480 is configured to operate the clutch switching member 470 by the action of hydraulic pressure that uses pressure oil from the assist pump 81 as hydraulic oil.

Specifically, as shown in fig. 2 and 4, the clutch operating mechanism 480 includes: a cylinder 482; a clutch piston 484 that is housed in the cylinder 482 so as to liquid-tightly partition a clutch release oil chamber (japanese language: oil chamber) 482a and be slidable; a clutch release fork (486), the clutch release fork (486) being supported by the clutch operating shaft 485 so as to be able to swing freely; an urging member 488 that urges the clutch piston 484 in a direction to contract the clutch release oil chamber 482 a; and a clutch switching valve 490, the clutch switching valve 490 switching supply and discharge of pressure oil to and from the clutch release oil chamber 482 a.

The clutch release fork 486 has: a base end portion supported to be rotatable about an axis of the clutch operating shaft 485; a 1 st arm 486a extending radially outward from a base end portion and operatively coupled to the clutch piston 484; and a 2 nd arm 486b extending radially outward from a base end portion and engaged with the clutch switching member 470.

The clutch release fork 486 is operatively coupled to the clutch piston 484 and the clutch switching member 470 such that the clutch switching member 470 is moved to the clutch engagement position on one side in the axial direction when the clutch piston 484 is pushed by the biasing member 488 in a direction to contract the clutch release oil chamber 482a, and the clutch switching member 470 is moved to the clutch release position on the other side in the axial direction when the clutch piston 484 is pushed in a direction to expand the clutch release oil chamber 482a against the biasing force of the biasing member 488.

As shown in fig. 4, the clutch switching valve 490 is configured to selectively obtain a discharge position (clutch engagement position) where pressurized oil is discharged from the clutch release oil chamber 482a and the clutch piston 484 is moved in a direction to reduce the clutch release oil chamber 482a by the biasing force of the biasing member 488, and a supply position (clutch release position) where pressurized oil from a hydraulic pressure source (the assist pump 81 in the present embodiment) is supplied to the clutch release oil chamber 482a and the clutch piston 484 is moved in a direction to expand the clutch release oil chamber 482a against the biasing force of the biasing member 488.

Further, fig. 4 shows a state where the clutch switching valve 490 is located at the clutch engagement position.

In the present embodiment, the clutch switching valve 490 is an electromagnetic valve, and is position-controlled by a control device 900 (see fig. 4) provided in the HMT structure 200A.

That is, as shown in fig. 5 (a) and 6, the clutch mechanism 450 includes a clutch release detection sensor 492 that detects that the shift lever 700 is located at the clutch release position.

The clutch switching valve 490 is biased by a biasing member so that a clutch engagement position (discharge position) is an initial position, and the controller 900 positions the clutch switching valve 490 at the clutch engagement position (discharge position) in a state where the detection signal from the clutch release detection sensor 492 is not input, and positions the clutch switching valve 490 at the clutch release position (supply position) when the detection signal from the clutch release detection sensor 492 is input.

As shown in fig. 1, 2, and 4, the HMT structure 200A of the present embodiment further includes a brake mechanism 400 that applies a braking force to the HMT output shaft 350 in an actuated manner.

As shown in fig. 2, 4 and 7, in the present embodiment, the brake mechanism 400 includes: a brake rotating member 405, the brake rotating member 405 being supported by the HMT output shaft 350 so as to be non-rotatable with respect to the HMT output shaft 350 so as to rotate integrally with the HMT output shaft 350; a brake fixing member 410, the brake fixing member 410 being provided to be non-rotatable; a brake engagement and disengagement member 420, the brake engagement and disengagement member 420 selectively obtaining a braking force application state in which the brake rotation member 405 is operatively engaged with the brake fixing member 410 and a braking force is operatively applied to the HMT output shaft and a braking force release state in which the braking force is released; and a brake switching member 425, the brake switching member 425 switching an operating state of the brake engagement and disengagement member 420.

In the present embodiment, as shown in fig. 7, the brake engagement and disengagement member 420 has: a rotary friction plate 422, the rotary friction plate 422 being supported by the brake rotating member 405 so as to be movable in an axial direction and so as not to be relatively rotatable about the axis; and a fixed friction plate 424, the fixed friction plate 424 being supported by the brake fixing member 410 so as not to be relatively rotatable about the axis.

The brake switching member 425 is a slider supported on the HMT output shaft 350 so as to be movable in the axial direction so as to be able to obtain a brake release position on one side in the axial direction and a brake engagement position on the other side in the axial direction, and is configured to allow the rotary friction plate 422 to rotate relative to the fixed friction plate 424 when located at the brake release position, and to frictionally engage the rotary friction plate 422 with the fixed friction plate 424 when located at the brake engagement position, thereby applying a braking force to the HMT output shaft 350.

The HMT configuration 200A also has a brake actuation mechanism 430.

The brake operating mechanism 430 operates the brake switching member 425 in response to a brake engagement disengagement operation of the shift operating lever 700.

In the present embodiment, as shown in fig. 4, the brake operating mechanism 430 is configured to operate the brake switching member 425 by the action of a hydraulic pressure that uses pressure oil from the assist pump 81 as hydraulic oil.

Specifically, as shown in fig. 2 and 4, the brake operating mechanism 430 includes: a cylinder 432; a brake piston 434 that is housed in the cylinder 432 in a manner that divides a brake engagement oil chamber 432a in a liquid-tight manner and is slidable; a brake release fork (brake fork) 436, the brake release fork 436 being swingably supported on the brake operating shaft 435; an urging member 438, the urging member 438 urging the brake piston 434 in a direction to contract the brake engagement oil chamber 432 a; and a brake switching valve 440, wherein the brake switching valve 440 switches supply and discharge of the pressure oil to and from the brake engagement oil chamber 432 a.

The brake release fork 436 has: a base end portion supported by the brake operating shaft 435 so as to be rotatable about an axis; a 1 st arm 436a extending radially outward from a base end portion of the 1 st arm 436a and operatively coupled to the brake piston 434; and a 2 nd arm 436b, the 2 nd arm 436b extending radially outward from a base end portion and engaging with the stopper switching member 425.

The brake release fork 436 is operatively coupled to the brake piston 434 and the brake switching member 425 such that the brake switching member 425 is moved to a brake release position on one axial side when the brake piston 434 is pushed in a direction to contract the brake engagement oil chamber 432a by the biasing member 438, and the brake switching member 425 is moved to a brake engagement position on the other axial side when the brake piston 434 is pushed in a direction to expand the brake engagement oil chamber 432a against the biasing force of the biasing member 438.

As shown in fig. 4, the brake switching valve 440 is configured to selectively obtain a discharge position (brake release position) where the pressurized oil is discharged from the brake engagement oil chamber 432a and the brake piston 434 is moved in a direction to contract the brake engagement oil chamber 432a by the biasing force of the biasing member 438, and a supply position (brake engagement position) where the pressurized oil from the hydraulic pressure source (the assist pump 81 in the present embodiment) is supplied to the brake engagement oil chamber 432a and the brake piston 434 is moved in a direction to expand the brake engagement oil chamber 432a against the biasing force of the biasing member 438.

Fig. 4 shows a state where the brake switching valve 440 is located at the brake release position.

In the present embodiment, the brake switching valve 440 is an electromagnetic valve, and the control device 900 performs position control in response to the brake engagement/disengagement operation of the shift lever 700.

As shown in fig. 6, the shift lever 700 is capable of performing a brake engagement/disengagement operation between a brake engagement position and a brake release position in a 3 rd operation direction D3 different from the 2 nd operation direction D2 only in a state of being located at the clutch release position, and is capable of performing a clutch engagement/disengagement operation in a 2 nd operation direction D2 only in a state of being located at the brake release position, in addition to a shift operation in a 1 st operation direction D1 and a clutch engagement/disengagement operation in a 2 nd operation direction D2.

Specifically, the guide groove 810 includes a 3 rd groove 813 in addition to the 1 st groove 811 and the 2 nd groove 812, and the 3 rd groove 813 allows the shift operating lever 700 to be operated in the 3 rd operating direction D3 only when the shift operating lever 700 is located at the clutch release position in the 2 nd operating direction D2.

In the present embodiment, the 3 rd groove 813 is parallel to the 1 st groove 811.

The end position of the 2 nd groove 812 opposite to the 1 st groove 811 is set to a clutch release position and a brake release position.

The end position of the 3 rd groove 813 opposite to the 2 nd groove 812 is set to a brake engagement position.

As shown in fig. 4, 5 (b) and 6, the brake mechanism 400 includes a brake operation detection sensor 442 that detects that the shift lever 700 is located at the brake engagement position.

The brake switching valve 440 is biased by a biasing member so that a brake release position (discharge position) is an initial position, and the control device 900 positions the brake switching valve 440 at a brake release position (discharge position) in a state where the detection signal from the brake operation detection sensor 442 is not input, and positions the brake switching valve 440 at a brake engagement position (supply position) when the detection signal from the brake operation detection sensor 442 is input.

As shown in fig. 2 and the like, the HMT structure 200A of the present embodiment includes an HMT case 210 that houses the HST10, the planetary gear mechanism 100, the clutch mechanism 450, and the brake mechanism 400 and supports the HMT output shaft 350.

The HMT case 210 is detachably coupled to a mounting portion (in the present embodiment, the transmission 500).

As shown in fig. 2, the HMT case 210 has a 1 st space 211 accommodating the HST10 and a 2 nd space 212 accommodating the planetary gear mechanism 100.

In the present embodiment, the HMT case 210 includes a case main body 220, and a 1 st cover member 240 and a 2 nd cover member 260 detachably coupled to the case main body 220.

The housing main body 220 includes a hollow peripheral wall 230 having first and second axial openings 231 and 232 on one side and the other side, respectively, and the partition wall 235 partitioning an inner space of the peripheral wall 230 into the first space 211 and the second space 222 at an axial intermediate position of the peripheral wall 230.

The 1 st cover member 240 is detachably coupled to the housing main body 220 so as to close the 1 st opening 231.

The 1 st cover member 240 also functions as a port block (portblock) in which the pair of hydraulic oil lines 601 and 602 are formed.

The 2 nd cover member 260 is detachably coupled to the housing main body 220 so as to close the 2 nd opening 232.

The 2 nd cover member 260 also functions as a mounting surface for a mounting portion of the HMT case 210 (in the present embodiment, the transmission case 510 of the transmission 500).

In the present embodiment, the HMT housing 210 is configured to support the HMT input shaft 310.

Specifically, the HMT input shaft 310 is supported in the 2 nd space 212 to be rotatable about the axis by the 2 nd cover member 260 and the partition wall 235.

The HMT input shaft 310 is coupled to the input-side drive shaft 305 on the upstream side in the transmission direction via an access hole (access) formed in the 2 nd cover member 260.

An upstream end of the pump shaft 20 in the transmission direction penetrates the partition 235 and is connected to a downstream side of the HMT input shaft 310 in the transmission direction.

In the present embodiment, as shown in fig. 2, the transmission direction downstream end of the pump shaft 20 extends outward through the 1 st cover member 240, and the auxiliary pump 81 is supported by this outward extending portion.

The auxiliary pump 81 is surrounded by the auxiliary pump case 83 which is detachably coupled to the HMT case 210 (the 1 st cover member 240) in a state of being supported by the pump shaft 20.

The motor shaft 30 is supported by the 1 st cover member 240 and the partition wall 235 so as to be rotatable about the axis line in a state where the downstream end in the transmission direction thereof penetrates the partition wall 235 and protrudes into the 2 nd space 212.

The HMT output shaft 350 is supported in parallel with the motor shaft 310 in the HMT housing 210.

The HMT output shaft 350 is operatively coupled to the carrier 150 on the upstream side in the transmission direction, and is supported by the extension wall of the casing main body 220 and the 2 nd cover member 260 so as to be rotatable about the axis line in a state where the downstream side in the transmission direction is accessible from the outside through an access hole formed in the 2 nd cover member 260.

As shown in fig. 1, the work vehicle 1 to which the HMT structure 200A of the present embodiment is applied includes the transmission 500 that changes the speed of the rotational power from the HMT structure 200A and outputs the power to the travel member 6.

The transmission 500 includes the transmission case 510, a transmission input shaft 515 supported by the transmission case 510, a sub-transmission drive shaft 520 and a sub-transmission driven shaft 530, and a sub-transmission mechanism 525 that performs multi-speed transmission between the sub-transmission drive shaft 520 and the sub-transmission driven shaft 530.

In the work vehicle 1, the travel members 6 are paired right and left.

Therefore, the transmission 500 further includes a pair of drive axles 545 and 545 for outputting driving forces to the pair of travel members 6 and 6, respectively; and a differential mechanism 540 that differentially transmits the rotational power of the sub-transmission driven shaft 530 to the pair of drive axles 545 and 545.

Further, reference numeral 535 in fig. 1 is a parking brake mechanism that selectively applies a braking force to the subtransmission driven shaft 530, and reference numeral 550 is a pair of service brake mechanisms that selectively apply a braking force to the pair of drive axles 545 and 545, respectively.

In the HMT structure 200A of the present embodiment, as described above, the clutch engagement and disengagement member 460 and the brake engagement and disengagement member 420 are configured to be switched between the operating states by the dedicated clutch switching member 470 and the dedicated brake switching member 425, respectively.

Instead, the operation state of the clutch engagement and disengagement member 460 and the brake engagement and disengagement member 420 may be switched by a single clutch/brake switching member 570.

Fig. 8 and 9 respectively show a partial sectional view and a hydraulic circuit diagram of an HMT structure 200B according to modification 1 of the present embodiment configured to switch the operation states of the clutch engagement/disengagement member 460 and the brake engagement/disengagement member 420 by a single clutch/brake switching member 570.

In the drawings, the same members as those in the present embodiment are denoted by the same reference numerals.

The clutch brake switching member 570 is supported by the HMT output shaft 350 so as to be movable in the axial direction, and is configured to be able to obtain a clutch engagement brake release position on one side in the axial direction, a clutch release brake engagement position on the other side in the axial direction, and a clutch release brake release position in the middle in the axial direction.

When the clutch brake switching member 570 is positioned at the clutch engagement brake release position, the rotating friction plate 422 is in a relatively rotatable state with respect to the fixed friction plate 424, and the rolling elements 462 are engaged in the engagement grooves 464, thereby generating a clutch engagement brake release state.

When the clutch brake switching member 570 is positioned at the clutch release brake releasing position, the rolling elements 462 are disengaged radially outward from the engaging grooves 464 and a clutch release brake releasing state is established, while the relative rotation state of the rotary friction plate 422 with respect to the fixed friction plate 424 is maintained.

When the clutch brake switching member 570 is positioned at the clutch release brake engagement position, the rotating friction plate 422 and the fixed friction plate 424 are frictionally engaged with each other in a state where the rolling elements 462 are radially outwardly disengaged from the engagement grooves 464, and a clutch release brake engagement state occurs.

As shown in fig. 9, the modification 200B includes a clutch brake operating mechanism 580 instead of the clutch operating mechanism 480 and the brake operating mechanism 430, as compared with the present embodiment 200A.

The clutch brake operating mechanism 580 is configured to operate the clutch brake switching member 570 by the action of hydraulic pressure using pressure oil from a hydraulic pressure source.

Specifically, as shown in fig. 9, the clutch brake actuation mechanism 580 includes: a cylinder 582; a piston 584 that divides an inner space of the cylinder 582 into a clutch engagement oil chamber 582a and a brake engagement oil chamber 582b arranged in series in an axial direction in a fluid-tight manner and is housed in the cylinder 582 in a slidable manner; a clutch brake release fork 586, and the clutch brake release fork 586 is swingably supported on the clutch brake operating shaft 585; an urging member 588 that urges the piston 584 in a direction in which the brake engagement oil chamber 582b is contracted and the clutch engagement oil chamber 582a is expanded; a 1 st switching valve 590, one end side of the 1 st switching valve 590 being fluidly connected to the pressure oil supply line 605 and the drain line 620; and a 2 nd switching valve 592, one end side of the 2 nd switching valve 592 being fluidly connected to the other end side of the 1 st switching valve 590 through 1 st and 2 nd intermediate pipes 622a, 622b, and the other end side being fluidly connected to the clutch engagement oil chamber 582a and the brake engagement oil chamber 582b through a clutch supply/discharge pipe 624a and a brake supply/discharge pipe 624b, respectively.

The clutch/brake release fork 586 includes: a base end portion supported by the clutch brake operating shaft 585 so as to be rotatable about an axis; a 1 st arm 586a extending radially outward from a base end portion and operatively coupled to the piston 584; and a 2 nd arm 586b, the 2 nd arm 586b extending radially outward from a base end portion and engaging with the clutch brake switching member 570.

The 1 st switching valve 590 is configured to selectively obtain a discharge position where the pressure oil supply line 605 is cut off and the 1 st and 2 nd intermediate lines 622a and 622b are fluidly connected to the drain line 620, and a supply/discharge position where the pressure oil supply line 605 is fluidly connected to the 2 nd intermediate line 622b and the 1 st intermediate line 622a is fluidly connected to the drain line 620.

The 2 nd switching valve 592 is configured to selectively obtain a supply/discharge position at which the 1 st and 2 nd intermediate lines 622a and 622b are fluidly connected to the clutch supply/discharge line 624a and the brake supply/discharge line 624b, respectively, and a blocking position at which the clutch supply/discharge line 624a and the brake supply/discharge line 624b are blocked.

In the present embodiment, the 1 st switching valve 590 and the 2 nd switching valve 592 are solenoid valves, and are position-controlled by the control device 900 in response to a manual operation of the shift lever 700.

Specifically, when the shift lever 700 is shifted (i.e., when the shift lever 700 is not engaged and disengaged from the clutch and the brake), the 1 st switching valve 590 is set to the discharge position and the 2 nd switching valve 592 is set to the supply/discharge position.

In the present embodiment, the 1 st switching valve 590 is biased by a biasing member so that the discharge position is set to the initial position, and the 2 nd switching valve 592 is biased by a biasing member so that the supply/discharge position is set to the initial position.

Therefore, the control device 900 sets the 1 st switching valve 590 and the 2 nd switching valve 592 to the OFF state and sets the 1 st switching valve 592 and the 2 nd switching valve 592 to the discharge position and the supply/discharge position, respectively, unless the detection signal from the clutch release detection sensor 492 is input.

In this state, the pressurized oil in the clutch engagement oil chamber 582a and the brake engagement oil chamber 528b is drained, and the piston 584 is pushed in a direction in which the brake engagement oil chamber 582b is contracted and the clutch engagement oil chamber 582b is expanded by the biasing force of the biasing member 588.

By this operation of the piston 584, the clutch brake release fork 586 causes the clutch brake switching member 570 to be positioned at the clutch engagement brake release position.

When the shift lever 700 is operated to the clutch release position and the control device 900 inputs a detection signal from the clutch release detection sensor 492, the control device 900 sets the 1 st switching valve 590 to the ON (ON) state and the 1 st switching valve 590 to the supply/discharge position, and sets the 2 nd switching valve 592 to the off state (supply/discharge position) and then sets the 2 nd switching valve 592 to the ON state (blocking position) after a predetermined time.

While the 2 nd switching valve 592 is in the off state and is in the supply/discharge position, the pressure oil from the pressure oil supply line is supplied to the brake engagement oil chamber 582b, and the pressure oil in the clutch engagement oil chamber 582a is drained.

Therefore, the piston 584 is pushed a predetermined distance in a direction to expand the brake engagement oil chamber 582b and contract the clutch engagement oil chamber 582a against the urging force of the urging member 588.

In this state, when the 2 nd switching valve 592 is switched to the on state (the blocking position), the brake engagement oil chamber 582b and the clutch engagement oil chamber 582a are blocked, and the piston 584 is held at this position.

Thus, the clutch brake release fork 586 causes the clutch brake switching member 570 to be positioned at the clutch release brake releasing position.

When the shift lever 700 is operated to the brake engagement position and the control device 900 inputs the detection signal from the brake operation detection sensor 442, the control device 900 sets the 2 nd switching valve 592 to the off state (supply/discharge position) while maintaining the on state (supply/discharge position) of the 1 st switching valve 590.

In this state, the pressure oil in the clutch engagement oil chamber 582a is drained, the pressure oil from the pressure oil supply line 605 is supplied to the brake engagement oil chamber 582b, and the piston 584 is pushed in a direction to contract the clutch engagement oil chamber 582a and expand the brake engagement oil chamber 582b against the biasing force of the biasing member 588.

By this operation of the piston 584, the clutch brake release fork 586 causes the clutch brake switching member 570 to be positioned at the clutch release brake engagement position.

In the embodiment 200A and the 1 st modification 200B, the clutch engagement/disengagement member 460 includes the rolling elements 462 and the engagement grooves 464, but the present invention is not limited to this configuration.

For example, a friction plate type clutch engagement/disengagement member 630 may be provided instead of the clutch engagement/disengagement member 460.

Fig. 10 is a partial cross-sectional view showing a variation 200C of the 2 nd embodiment including a friction plate type clutch engagement/disengagement member 630.

In the drawings, the same members as those in the embodiment 200A and the 1 st modification 200B are denoted by the same reference numerals.

As shown in fig. 10, the clutch engagement and disengagement member 630 has: a drive side friction plate 634, the drive side friction plate 634 being supported by the clutch drive member 455 so as to be relatively non-rotatable and movable in the axial direction; a clutch housing 632, said clutch housing 632 non-rotatably supported relative to said HMT output shaft 350 from said HMT output shaft 350; and a driven side friction plate 636, wherein the driven side friction plate 636 is supported by the clutch housing 632 so as to be relatively non-rotatable and movable in the axial direction while facing the driving side friction plate 634.

In the modification 2C, as compared with the present embodiment 200A, a clutch switching member 640 is provided instead of the clutch switching member 470.

The clutch switching member 640 forms a clutch engagement oil chamber 633a in a fluid-tight manner in cooperation with the clutch housing 632 and the HMT output shaft 350, and is supported by the clutch housing 632 and the HMT output shaft 350 so as to be movable in the axial direction.

The clutch switching member 640 is pushed in a clutch engagement direction in which the driving side friction plate 634 and the driven side friction plate 636 are frictionally engaged by the pressurized oil supplied to the clutch engagement oil chamber 633a, and a clutch engagement state occurs in which power is transmitted from the clutch driving member 455 to the HMT output shaft 350.

As shown in fig. 10, in the 2 nd modification 200C, the clutch switching member 640 forms a clutch release oil chamber 633b in a liquid-tight manner on the opposite side of the clutch engagement oil chamber 633a in the axial direction.

The clutch switching member 640 is pushed in a direction of separating from the driving side friction plate 634 and the driven side friction plate 636 by the pressure oil supplied to the clutch release oil chamber 633b, and thereby, a clutch release state occurs in which the power transmission from the clutch driving member 455 to the HMT output shaft 350 is cut off.

In comparison with the present embodiment 200A, the modification 2C includes a stopper switching member 650 instead of the stopper switching member 425.

In the modification 2C described above, the clutch housing 632 functions as the brake rotating member 405 supported by the HMT output shaft 350 so as to be non-rotatable with respect to the HMT output shaft 350 so as to rotate integrally with the HMT output shaft 350.

That is, the rotating friction plates 422 of the brake engagement and disengagement member 420 are supported by the clutch housing 632 functioning as the brake rotating member 405 so as to be movable in the axial direction and so as not to be relatively rotatable about the axis.

The brake switching member 650 forms a brake engagement oil chamber 635a in a fluid-tight manner in cooperation with the clutch housing 632 and the HMT output shaft 350, and is supported by the clutch housing 632 and the HMT output shaft 350 so as to be movable in the axial direction.

The brake switching member 650 is pushed by the pressure oil supplied to the brake engagement oil chamber 635a in a brake engagement direction in which the rotary friction plate 422 and the fixed friction plate 424 are frictionally engaged, and thereby a brake engagement state occurs in which a braking force is applied to the HMT output shaft 350.

Further, in modification 2C, a brake release spring 652 that biases the brake switching member 650 in a direction away from the rotating friction plate 422 and the fixed friction plate 424 is provided.

Therefore, the pressure oil supplied to the brake engagement oil chamber 635a urges the brake switching member 650 in the brake engagement direction against the urging force of the brake release spring 652.

On the other hand, when the pressure oil in the brake engagement oil chamber 635a is discharged, the brake switching member 650 is separated from the rotating friction plates 422 and the fixed friction plates 424 by the biasing force of the brake release spring 652, and the frictional engagement between the friction plates 422 and 424 is released, thereby bringing about a brake released state.

In comparison with embodiment 200A, modification 2C includes a clutch operating mechanism 660 and a brake operating mechanism 680 instead of clutch operating mechanism 480 and brake operating mechanism 430.

As shown in fig. 10, the clutch operating mechanism 660 includes a clutch engagement line 662a and a clutch release line 662b that are fluidly connected to the clutch engagement oil chamber 633a and the clutch release oil chamber 633b, respectively, and a clutch switching valve 665 interposed between the pressurized oil supply line 605 and the clutch engagement line 662a and the clutch release line 662 b.

The clutch switching valve 665 is capable of selectively taking a clutch engagement position at which the pressure oil supply line 605 is fluidly connected to the clutch engagement line 662a and the clutch release line 662b is fluidly connected to the drain line 620, and a clutch release position at which the clutch engagement line 662a is fluidly connected to the drain line 620 and the pressure oil supply line 605 is fluidly connected to the clutch release line 662 b.

As shown in fig. 10, in modification 2C, the clutch switching valve 665 is an electromagnetic valve and is biased by a biasing member so that the clutch engagement position becomes the initial position.

As shown in fig. 10, the brake operating mechanism 680 has a brake engagement line 682 fluidly connected to the brake engagement oil chamber 635a, and a brake switching valve 685 interposed between the pressurized oil supply line 605 and the brake engagement line 682.

The brake switching valve 685 is capable of selectively assuming a brake release position at which the pressure oil supply line 605 is cut off and the brake engagement line 682 is fluidly connected to the drain line 620, and a brake engagement position at which the pressure oil supply line 605 is fluidly connected to the brake engagement line 682.

As shown in fig. 10, in modification 2C, the brake switching valve 685 is an electromagnetic valve and is biased by a biasing member so that the brake release position is an initial position.

As shown in fig. 10, the clutch engagement line 662a, the clutch release line 662b, and the brake engagement line 682 each have an axial line oil passage formed in the HMT output shaft 350.

In fig. 10, reference numeral 608 denotes a lubrication line for guiding a part of the oil spilled from the supply relief valve (charge relief valve)606 to a predetermined position as lubricating oil, and reference numeral 609 denotes a relief valve for setting a hydraulic pressure of the lubrication line 608.

In the present embodiment, when the shift lever 700 is located at the end position on the side opposite to the side where the shift operation is possible (the side close to the 1 st groove 811) (the side opposite to the 1 st groove 811) with respect to the operation position along the 2 nd operation direction D2 guided by the 2 nd groove 812, the brake mechanism 400 is in the brake released state, and the clutch mechanism 450 is in the clutch released state.

In such a configuration, it is preferable that the shift operating lever 700 be provided with a biasing member 707 for biasing the lever main body and the coupling member 740 about the axis of the 2 nd operating shaft 720 to a clutch engagement position (a terminal end position of the 2 nd groove 812 on a side close to the 1 st groove 811).

Fig. 11 shows a front view of the shift operating lever 700 with the biasing member 707.

In fig. 11, the same members as those in the present embodiment are denoted by the same reference numerals.

By providing the biasing member 707, it is possible to effectively prevent the shift lever 700 from being inadvertently positioned at the clutch release position (and the brake release position) and the work vehicle 1 from being brought into a free wheel (freewheel) state against the intention of the operator.

Embodiment mode 2

Hereinafter, another embodiment of the HMT structure of the present invention will be described with reference to the drawings.

Fig. 12 shows a hydraulic circuit diagram of an HMT structure 200(2) a according to the present embodiment.

In the drawings, the same members as those in embodiment 1 are denoted by the same reference numerals, and the description thereof is appropriately omitted.

The HMT structure 200A according to embodiment 1 is configured such that the free wheel state of the applied work vehicle 1, that is, the state in which the travel member 6 of the work vehicle 1 is rotatable can be brought about by bringing the clutch mechanism 450 into the disengaged state and bringing the brake mechanism 400 into the disengaged state.

In contrast, in the HMT structure 200(2) a of the present embodiment, the clutch mechanism 450 and the brake mechanism 400 are linked so that the brake mechanism 400 is always in the engaged state when the clutch mechanism 450 is in the disengaged state.

Specifically, the HMT structure 200(2) a has a clutch/brake switching member 830 instead of the clutch switching member 640 and the brake switching member 650, and a clutch/brake operating mechanism 850 instead of the clutch operating mechanism 660 and the brake operating mechanism 680, as compared with the HMT structure 200A according to embodiment 1.

As shown in fig. 12, the clutch brake switching member 830 is a slider supported to be movable in the axial direction on the HMT output shaft 350 so as to be able to obtain a clutch engagement brake release position on one side in the axial direction and a clutch release brake engagement position on the other side in the axial direction.

The clutch brake switching member 830 presses the rolling bodies 462 into the engagement grooves 464 and allows the rotary friction plate 422 to rotate relative to the fixed friction plate 424 in a state in which the clutch brake switching member is located at the clutch engagement brake release position, thereby bringing about a clutch engagement brake release state.

On the other hand, the clutch brake switching member 830 allows the rolling elements 462 to be disengaged from the engagement grooves 464 radially outward in a state where the member is located at the clutch brake release engagement position, and causes the rotary friction plate 422 and the fixed friction plate 424 to be frictionally engaged, thereby bringing about a clutch brake release engagement state.

As shown in fig. 12, the clutch brake operating mechanism 850 has: a cylinder 852; a piston 854 which is housed in the cylinder 852 so as to partition a clutch release brake engagement oil chamber 852a in a liquid-tight manner and be slidable; a clutch brake release fork 856, the clutch brake release fork 856 being supported swingably on a clutch brake operating shaft 855; an urging member 858 that urges the piston in a direction to reduce the clutch release brake engagement oil chamber 852 a; and a clutch brake switching valve 860 for switching supply and discharge of pressure oil to and from the clutch release brake engagement oil chamber 852 a.

The clutch brake release fork 856 is operatively coupled to the piston 854 and the clutch brake switching member 830 such that when the piston 854 is pushed by the urging member 858 in a direction to contract the clutch release brake engagement oil chamber 852a, the clutch brake switching member 830 is moved to a clutch engagement brake release position on one side in the axial direction, and when the piston 854 is pushed by pressurized oil supplied to the clutch release brake engagement oil chamber 852a in a direction to expand the oil chamber 852a against the urging force of the urging member, the clutch brake switching member 830 is moved to a clutch release brake engagement position on the other side in the axial direction.

The clutch-brake switching valve 860 is configured to selectively obtain a discharge position (clutch engagement-brake release position) where pressure oil is discharged from the clutch engagement-release oil chamber 852a and the piston 854 is moved in a direction to reduce the oil chamber 852a by the biasing force of the biasing member 858, and a supply position (clutch engagement-release brake engagement position) where pressure oil from a hydraulic pressure source is supplied to the oil chamber 852a and the piston 854 is moved in a direction to expand the oil chamber 852a against the biasing force of the biasing member 858.

In the present embodiment, the clutch/brake switching valve 860 is an electromagnetic valve that is biased by a biasing member so that a discharge position (clutch engagement/brake release position) is an initial position, and is position-controlled by the control device 900.

The HMT structure 200(2) a of the present embodiment has a shift lever 700(2) instead of the shift lever 700, as compared with the HMT structure 200A of embodiment 1.

Fig. 13 shows a top view of the shift lever 700 (2).

The shift operating lever 700(2) is operable only in the 1 st operating direction D1 and the 2 nd operating direction D2, and is not operable in the 3 rd operating direction D3 (see fig. 6).

Specifically, the shift lever 700(2) has a guide plate 800(2) instead of the guide plate 800, as compared with the shift lever 700.

As shown in fig. 13, the guide plate 800(2) has a guide groove 810 (2).

The guide groove 810(2) has the 1 st groove 811 and the 2 nd groove 812, and the 3 rd groove 813 (see fig. 6) is deleted.

As shown in fig. 13, a clutch release brake engagement sensor 494 is provided in the 2 nd groove 812 at a terminal position on the opposite side of the 1 st groove 811.

In the present embodiment having this configuration, the same effects as those in embodiment 1 can be obtained.

In the present embodiment, as in modification 2C of embodiment 1, a friction plate type clutch engagement/disengagement member 630 may be provided in place of the clutch engagement/disengagement member 460.

Fig. 14 shows a partial cross-sectional view of an HMT structure 200(2) B of a modification of the present embodiment, which includes a friction plate type clutch engagement/disengagement member 630.

In the drawings, the same members as those in embodiment 1 and the present embodiment are denoted by the same reference numerals.

In the modification 200(2) B, the friction plate type clutch engagement/disengagement member 630 and the friction plate type brake engagement/disengagement member 420 are operated in conjunction with each other by a single clutch/brake switching member 870.

In detail, as shown in fig. 14, the single clutch-brake switching member 870 has: a clutch switching member 640 that partitions a clutch engagement oil chamber 633a and is housed in the clutch housing 632 in a fluid-tight slidable manner; a brake switching member 650 that partitions a brake engagement oil chamber 635a and is housed in the clutch housing 632 in a liquid-tight slidable manner; and a coupling member 872, wherein the coupling member 872 couples the clutch switching member 640 and the brake switching member 650 to each other so as to integrally move in the axial direction.

That is, when the clutch switching member 640 is pushed in a direction to frictionally engage the driving side friction plate 634 and the driven side friction plate 636 by the pressure oil supplied to the clutch engagement oil chamber 633a, the brake switching member 650 coupled to the clutch switching member 640 by the coupling member 872 moves in a direction to separate from the rotating friction plates 422 and the fixed friction plates 424.

On the other hand, when the brake switching member 650 is pushed in a direction to frictionally engage the rotary friction plates 422 with the fixed friction plates 424 by the pressurized oil supplied to the brake engagement oil chamber 635a, the clutch switching member 640 coupled to the brake switching member 650 by the coupling member 872 moves in a direction to separate from the driving side friction plates 634 and the driven side friction plates 636.

Modification 200(2) B includes a clutch brake operating mechanism 880 instead of the clutch operating mechanism 660 and the brake operating mechanism 680, as compared with modification 200C of embodiment 1.

As shown in fig. 14, the clutch brake operating mechanism 880 includes a clutch engagement line 662a fluidly connected to the clutch engagement oil chamber 635a, a brake engagement line 682 fluidly connected to the brake engagement oil chamber 635a, and a clutch brake switching valve 880 interposed between the pressurized oil supply line 605 and the clutch engagement line 662a and the brake engagement line 682.

The clutch/brake switching valve 880 is configured to be able to selectively assume a clutch engagement/brake release position at which the pressure oil supply line 605 is fluidly connected to the clutch engagement line 662a and the brake engagement line 682 is fluidly connected to the drain line 620, and a clutch release/brake engagement position at which the pressure oil supply line 605 is fluidly connected to the brake engagement line 682 and the clutch engagement line 662a is fluidly connected to the drain line 620.

As shown in fig. 14, in modification 200(2) B, the clutch/brake switching valve 880 is a solenoid valve and is biased by a biasing member so that the clutch engagement/brake release position is set to the initial position.

In the present embodiment, the brake engaged state occurs when the shift operating lever 700(2) is located at the end position on the side opposite to the side where the shift operation is possible (the side close to the 1 st groove 811) (the side opposite to the 1 st groove 811) with respect to the operating position in the 2 nd operating direction D2 guided by the 2 nd groove 812.

In such a configuration, the shift lever 700(2) may include an urging member 708, and the urging member 708 may urge the lever main body 730 and the coupling member 740 to a clutch release brake engagement position (a terminal end position on the opposite side of the 1 st groove 811 in the 2 nd groove 812) around the axis of the 2 nd operating shaft 720.

Fig. 15 shows a front view of the shift lever 700(2) including the biasing member 708.

By providing the biasing member 708, the shift lever 700(2) can automatically obtain the brake engagement state when the operation force is released in a state where the shift lever 700(2) is positioned at the zero speed position in the 1 st operation direction D1.

Claims (10)

1. An HMT construction characterized in that,

the HMT structure is provided with: an HST that continuously shifts and outputs rotational power input from a drive source; a planetary gear mechanism that inputs rotational power from the drive source and rotational power from the HST to the 1 st and 2 nd elements, respectively, and combines the rotational power of the 1 st and 2 nd elements and outputs the resultant rotational power from the 3 rd element; an HMT output shaft; a clutch mechanism that disengages the power transmission from the 3 rd element to the HMT output shaft; and a shift operation lever that performs a shift operation of the HST,

the shift lever is capable of performing a shift operation in a 1 st operation direction toward a forward side and a reverse side with a zero-speed position interposed therebetween, and a clutch engagement/disengagement operation between a clutch engagement position and a clutch release position in a 2 nd operation direction different from the 1 st operation direction, and capable of performing a shift operation in the 1 st operation direction only in a state of being located at the clutch engagement position, and capable of performing a clutch engagement/disengagement operation in the 2 nd operation direction only in a state of being located at the zero-speed position,

the HST and the planetary gear mechanism are configured such that when the shift lever is at a zero-speed position, the rotational power output from the 3 rd element becomes zero-speed, and the rotational power output from the 3 rd element increases in speed toward the forward side and the reverse side, respectively, as the shift lever is operated from the zero-speed position toward the forward side and the reverse side,

the clutch mechanism engages and disengages power transmission to the HMT output shaft when the shift operating lever is in a clutch engagement position and a clutch release position, respectively.

2. HMT construction according to claim 1,

the HMT structure includes a brake mechanism that operatively applies a braking force to the HMT output shaft,

the shift operating lever is capable of a brake engagement/disengagement operation between a brake engagement position and a brake release position in a 3 rd operating direction different from the 2 nd operating direction only in a state of being located at the clutch release position, and is capable of a clutch engagement/disengagement operation in the 2 nd operating direction only in a state of being located at the brake release position,

the brake mechanism is configured to operatively apply and release a braking force to the HMT output shaft when the shift lever is in the brake engagement position and the brake release position, respectively.

3. An HMT construction characterized in that,

the HMT structure is provided with: an HST that continuously shifts and outputs rotational power input from a drive source; a planetary gear mechanism that inputs rotational power from the drive source and rotational power from the HST to the 1 st and 2 nd elements, respectively, and combines the rotational power of the 1 st and 2 nd elements and outputs the resultant rotational power from the 3 rd element; an HMT output shaft; a clutch mechanism that disengages the power transmission from the 3 rd element to the HMT output shaft; a brake mechanism operatively applying a braking force to the HMT output shaft; and a shift operation lever that performs a shift operation of the HST,

the shift lever is capable of performing a shift operation in a 1 st operation direction toward a forward side and a reverse side with a zero-speed position interposed therebetween, and a clutch engagement/disengagement operation between a clutch engagement position and a clutch release position in a 2 nd operation direction different from the 1 st operation direction, and capable of performing a shift operation in the 1 st operation direction only in a state of being located at the clutch engagement position, and capable of performing a clutch engagement/disengagement operation in the 2 nd operation direction only in a state of being located at the zero-speed position,

the HST and the planetary gear mechanism are configured such that when the shift lever is at a zero-speed position, the rotational power output from the 3 rd element becomes zero-speed, and the rotational power output from the 3 rd element increases in speed toward the forward side and the reverse side, respectively, as the shift lever is operated from the zero-speed position toward the forward side and the reverse side,

when the shift lever is in a clutch engaged position, the clutch mechanism engages power transmission to the HMT output shaft and the brake mechanism releases operative braking force to the HMT output shaft, while when the shift lever is in a clutch released position, the clutch mechanism disconnects power transmission to the HMT output shaft and the brake mechanism operatively applies braking force to the HMT output shaft.

4. HMT construction according to claim 2 or 3,

the clutch mechanism includes: a clutch drive member supported by the HMT output shaft so as to be rotatable with respect to the HMT output shaft in a state of being operatively coupled to the 3 rd element; a clutch engagement/disengagement member that can selectively obtain an engaged state in which power transmission from the clutch drive member to the HMT output shaft is performed and a disengaged state in which the power transmission is interrupted; and a clutch switching member that switches an operating state of the clutch engagement and disengagement member,

the brake mechanism includes: a brake rotating member that is supported on the HMT output shaft so as to be non-rotatably relative to the HMT output shaft so as to rotate integrally with the HMT output shaft; a brake fixing member provided to be non-rotatable; a brake engagement and disengagement member that is capable of selectively achieving a braking force application state in which the brake rotation member is operatively engaged with the brake fixing member to operatively apply a braking force to the HMT output shaft and a braking force release state in which the braking force is released; and a brake switching member that switches an operating state in which the brake is engaged and disengaged.

5. HMT construction according to claim 2 or 3,

the clutch mechanism includes: a clutch drive member supported by the HMT output shaft so as to be rotatable with respect to the HMT output shaft in a state of being operatively coupled to the 3 rd element; and a clutch engagement/disengagement member that can selectively obtain an engaged state in which power transmission from the clutch drive member to the HMT output shaft is performed and a disengaged state in which the power transmission is interrupted,

the brake mechanism includes: a brake rotating member that is supported on the HMT output shaft so as to be non-rotatably relative to the HMT output shaft so as to rotate integrally with the HMT output shaft; a brake fixing member provided to be non-rotatable; and a brake engagement/disengagement member that is capable of selectively obtaining a braking force application state in which the brake rotation member is operatively engaged with the brake fixing member to operatively apply a braking force to the HMT output shaft and a braking force release state in which the braking force is released.

The clutch engagement and disengagement member and the brake engagement and disengagement member are switched in operation by a single clutch-brake switching member.

6. HMT construction according to claim 2 or 3,

the HMT structure includes a housing that houses the HST, the planetary gear mechanism, the clutch mechanism, and the brake mechanism.

7. HMT construction according to claim 2,

the shift operating lever includes: a 1 st operation shaft, the 1 st operation shaft being supported to be rotatable around an axis; a 2 nd operation shaft, the 2 nd operation shaft being supported by the 1 st operation shaft in a state of being orthogonal to the 1 st operation shaft; a lever main body that is manually operated; and a connecting member that connects a base end portion of the lever main body to the 2 nd operation shaft, the lever main body, the connecting member, the 2 nd operation shaft, and the 1 st operation shaft being integrally rotatable about an axis of the 1 st operation shaft, while the lever main body and the connecting member being rotatable about an axis of the 2 nd operation shaft,

a clutch engagement/disengagement operation in a 2 nd operation direction occurs by rotating the lever main body and the connecting member about the axis of the 2 nd operation shaft in a state where the lever main body, the connecting member, the 2 nd operation shaft, and the 1 st operation shaft are located at a zero speed position about the axis of the 1 st operation shaft,

the shift operation in the 1 st operating direction occurs by rotating the lever main body, the connecting member, the 2 nd operating shaft, and the 1 st operating shaft about the axis of the 1 st operating shaft in a state where the lever main body and the connecting member are located at the clutch engagement position about the axis of the 2 nd operating shaft, and the brake engagement/disengagement operation in the 3 rd operating direction occurs by rotating the lever main body, the connecting member, the 2 nd operating shaft, and the 1 st operating shaft about the axis of the 1 st operating shaft in a state where the lever main body and the connecting member are located at the clutch release position about the axis of the 2 nd operating shaft.

8. HMT construction according to claim 7,

the shift operating lever includes an urging member that urges the lever main body and the coupling member about an axis of the 2 nd operating shaft to a clutch engagement position.

9. HMT construction according to claim 3,

the shift operating lever includes: a 1 st operation shaft, the 1 st operation shaft being supported to be rotatable around an axis; a 2 nd operation shaft, the 2 nd operation shaft being supported by the 1 st operation shaft in a state of being orthogonal to the 1 st operation shaft; a lever main body that is manually operated; and a connecting member that connects a base end portion of the lever main body to the 2 nd operation shaft, the lever main body, the connecting member, the 2 nd operation shaft, and the 1 st operation shaft being integrally rotatable about an axis of the 1 st operation shaft, while the lever main body and the connecting member being rotatable about an axis of the 2 nd operation shaft,

a clutch engagement/disengagement operation in a 2 nd operation direction occurs by rotating the lever main body and the connecting member about the axis of the 2 nd operation shaft in a state where the lever main body, the connecting member, the 2 nd operation shaft, and the 1 st operation shaft are located at a zero speed position about the axis of the 1 st operation shaft,

a shifting operation in a 1 st operating direction occurs by rotating the lever main body, the connecting member, the 2 nd operating shaft, and the 1 st operating shaft about the axis of the 1 st operating shaft in a state where the lever main body and the connecting member are located at a clutch engagement position about the axis of the 2 nd operating shaft.

10. HMT construction according to claim 9,

the shift operating lever includes an urging member that urges the lever main body and the coupling member to a clutch release position about an axis of the 2 nd operating shaft.

Images