JP2635974B2 - Operation structure for working vehicle traveling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a mechanical linkage mechanism for linking a traveling hydraulic stepless transmission that is biased to return to a neutral state with an operating tool, A friction mechanism that frictionally holds the operating tool at an arbitrary position against the neutral return biasing force of the hydraulic continuously variable transmission,
The present invention relates to a traveling operation structure for an operator such as a tractor provided in a state of applying a frictional force to one of the hydraulic continuously variable transmission, the operating tool, and the link mechanism.

[Conventional technology]

In this type of operation structure for traveling of a work vehicle, the operation tool can be held at an arbitrary operation position against the return biasing force of the hydraulic continuously variable transmission by the friction mechanism. It is possible to easily and accurately perform constant speed traveling without troublesome holding.

However, when the traveling brake is applied during such constant-speed traveling, there is a problem that it is difficult to obtain a desired braking performance if the position of the operating tool is maintained by the friction mechanism.

Therefore, conventionally, an operation mechanism for forcibly canceling the position holding state of the operation tool by the friction mechanism is provided,
When the traveling brake is applied, the hydraulic continuously variable transmission is returned to a neutral state by its urging force, thereby cutting off the traveling driving force to ensure the braking (for example,
See Japanese Patent Application No. 62-103947).

[Problems to be solved by the invention]

However, according to the conventional structure, when the friction mechanism is switched to the frictional force released state in conjunction with the brake operation of the brake pedal, the hydraulic continuously variable transmission instantaneously returns to the neutral state with its urging force, Since the traveling driving force is cut off almost simultaneously with the start of the brake operation of the brake pedal, especially when a sudden brake is applied, the traveling speed is rapidly reduced, and there is a problem that a braking shock occurs.

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to gently stop braking from constant-speed running in which an operating tool of a hydraulic continuously variable transmission is frictionally held at an arbitrary position via a friction mechanism.

[Means for solving the problem]

In order to achieve the above object, the traveling operation structure of the working vehicle according to the present invention is characterized by a mechanical linkage mechanism for linking the traveling hydraulic continuously variable transmission device which is urged back to the neutral state and the operating tool. A friction mechanism that frictionally holds the operating tool at an arbitrary position against the neutral return biasing force of the hydraulic continuously variable transmission, and the friction mechanism can be any one of the hydraulic continuously variable transmission, the operating tool, and the linkage mechanism. In the operation structure for traveling of a work vehicle provided in a state of applying a crab friction force, the friction mechanism, by changing the position of a pressing tool that applies a pressing force to a friction plate,
The hydraulic tool is configured to be switchable from an operation state in which the operation tool is frictionally held to a frictional force reduction state in which a small frictional force is applied so that the neutral return operation of the hydraulic continuously variable transmission is permitted, and the friction of the friction mechanism is changed. A force changing mechanism for switching the force between a state in which the operating tool is frictionally held and a state in which the frictional force is reduced is biased by the urging force of the pushing tool in accordance with the rotation of the cam operating shaft rotated around the axis. The present invention is characterized in that it comprises a cam mechanism for changing the position in the increasing / decreasing direction, and an operating mechanism for rotating the cam machine to the biasing force decreasing side in conjunction with the braking operation of the traveling brake pedal.

(Operation)

The effects of taking the above technical means are as follows.

In other words, when releasing the position of the operating tool in conjunction with the brake operation of the brake pedal, instead of switching the frictional force by the friction mechanism to a completely released state, the frictional force is switched to a reduced frictional force state, so that the hydraulic stepless Resistance can be applied to the neutral return biasing force of the transmission, and when the brake is applied, the return operation of the hydraulic continuously variable transmission is performed slowly, and a sudden change in the traveling speed is prevented.

In addition, a cam mechanism for changing the position of the pressing tool in the direction of increasing or decreasing the urging force in accordance with the rotation operation of the cam operation shaft for rotating the frictional force changing mechanism for switching the frictional force to the reduced state around the axis. The cam mechanism is configured to rotate to the biasing force decreasing side in conjunction with the brake operation of the traveling brake pedal, so that the frictional force can be reliably changed by mechanical operation. The entire structure can be made compact with a structure that occupies a small space such that the cam operation shaft and the cam mechanism are used, and also has a small operation space enough to rotate the cam operation shaft.

〔The invention's effect〕

As described above, the present invention provides a hydraulic stepless transmission in which the operation tool of the hydraulic stepless transmission is frictionally held at an arbitrary position via the friction mechanism, and the hydraulic stepless transmission is gradually stopped in the neutral state when braking is stopped from the constant speed traveling. The traveling driving force is cut off by automatically returning to the normal state, and the transition from constant-speed traveling to braking stop can be smoothly performed.

In addition, a mechanism for controlling the neutral return is constructed in order to perform a gradual neutral return of the hydraulic continuously variable transmission when control is stopped using the friction mechanism originally provided for constant speed traveling. There is an advantage that it can be easily configured.

Also, the mechanism for changing the frictional force can reliably and mechanically configure the entire mechanical structure compactly by the operation of the cam mechanism operated by rotation about the axis and the operation structure thereof.

In particular, as will be described in the following embodiments, a first friction plate that applies the small friction force is provided as a friction mechanism, and the hydraulic continuously variable transmission is maintained in a transmission state in cooperation with the first friction plate. If the second friction plate is provided so as to be freely switchable between a frictional force applying state and a frictional force releasing state,
1, Since the friction force of the second friction plate can be adjusted independently, the small friction force in the reduced friction force state can be set easily and accurately,
The operation of returning the hydraulic continuously variable transmission to the neutral state when the friction mechanism is switched to the frictional force decreasing state can be easily stabilized.

〔Example〕

 Next, examples of the present invention will be described.

As shown in FIG. 11, a lawn mowing device (2) transmitted from the traveling body is mounted on a wheel traveling type traveling body, and is mounted between a front wheel and a rear wheel so as to be operable up and down via a link mechanism (1). A riding lawn mower as an example of a work vehicle is configured.

The traveling body is provided with a traveling hydraulic continuously variable transmission (5) that is interlocked with an engine (3) via a transmission shaft (4) and is interlocked with a rear wheel transmission.

The hydraulic continuously variable transmission (5) includes the rear wheel transmission and is mounted on a transmission case (6) that supports the rear wheel (8). The transmission case (6) includes: And a traveling brake (7) acting on a rear wheel transmission.

The hydraulic continuously variable transmission (5) is biased to return to a neutral state, and the neutral return biasing means is configured to rotate the hydraulic continuously variable transmission (5) as shown in FIG. Shaft (5a)
The cam plate (13) is integrally mounted on the cam plate (13), and swings around the axis (P2) to press the V-shaped cam surface (13a) of the cam plate (13) with the roller portion (14a). An arm (14) for swinging (13) to the neutral position is attached to the transmission case (6), and a spring (15) for swinging the arm (14) to the pressing side is provided.

The operation unit of the hydraulic continuously variable transmission (5) includes a speed change pedal (11) swingable around a left-right lateral axis (P1) and a manual lever (16). The gear shift operation can be performed by any of them.
A link mechanism (B) for linking the manual lever (16) with the operating tool (A) as the operating tool (A) capable of frictionally holding the shift operation position and the hydraulic continuously variable transmission (5). ) And the operation guide (35) of the manual lever (16)
, A friction mechanism (C), and a mechanism for changing the frictional force of the friction mechanism (C).

The speed change pedal (11) is attached to the foot of a control unit (12) of the traveling body, and has the operation unit (11a) and the rear operation unit (11b) as shown in FIG. .

As shown in FIGS. 1 and 2, the manual lever (16) is supported by a support shaft (18) on the side of the body frame portion (19) so as to be swingable around the support shaft (18). For the member (17),
It is mounted so as to swing integrally with the support member (17) and to be slidable in a direction parallel to the support shaft (18).

The linkage mechanism (B) is mounted on a rotary operation shaft (5a) of the hydraulic stepless transmission (5) such that an interlocking tool (9) rotates integrally with the rotary operation shaft (5a), and When the pedal (11) is depressed by operating the front operation section (11a), the hydraulic continuously variable transmission (5) is switched from the neutral state to the forward side, and the transmission pedal (11) is moved to the rear operation section (11).
b) When the stepping operation is performed, the hydraulic continuously variable transmission (5) switches from the neutral state to the reverse side, and the stepping stroke of the speed change pedal (11) is increased in each of the forward side and the reverse side. An interlock rod (10) for interlocking the transmission pedal (11) and the interlock device (9) is provided so that the hydraulic continuously variable transmission (5) is on the high speed side, and the manual lever (16) is connected to the interlock device ( The clutch mechanism (20) is provided so as to be operable to switch between a state in which it is linked to 9) and a state in which it is disconnected.

As shown in FIGS. 1 and 2, the clutch mechanism (20) includes an airframe portion (1) of the manual lever (16).
9) a clutch pin (22) attached to a place that has entered the inside of the fuselage through the elongated hole (21) formed on the support shaft (18);
A clutch device (24) attached to a boss portion (19a) fixed to the body frame portion (19) so as to hold the clutch device so as to swing around the boss portion (19a), and the clutch device (24). And a rod (23) linked to the linking tool (9).

The clutch device (24) includes first and second plate portions (24a) and (24b) juxtaposed in the sliding direction of the manual lever (16), that is, in the axial direction of the support shaft (18). ing.

As shown in FIGS. 3 and 5, the first plate portion (24a) disengages the clutch pin (22) by swinging the manual lever (16) to the first position (P1). Notch (25) and clutch pin (22) in the notch (25)
When the manual lever (16) is pivoted to the forward side (F) in a state in which is inserted, the direction in which the clutch pin (22) is pressed by the clutch pin (22) to pivot the interlock (9) to the forward side (arrow) (the direction of f).

As shown in FIGS. 4 and 6, the second plate portion (24b) disengages the clutch pin (22) by sliding the manual lever (16) to the second position (P2). Notch (27) and its notch (27) with clutch pin (22)
When the manual lever (16) is operated to swing backward (R) in a state in which is inserted, the clutch pin (22) is pressed to swing the interlock (9) backward. (In the direction of arrow r).

The notch (25) of the first plate portion (24a)
When the shift petal (11) is operated to the forward side with the clutch pin (22) inserted therein, the first pedal portion (24a) avoids contact with the clutch pin (22) to prevent the shift pedal from moving. The first plate portion (24a) is formed to have a length (1) sufficient to allow the forward movement of the first plate portion (24a), and the notch (27) of the second plate portion (24b) is When the shift pedal (11) is operated to the reverse side with the clutch pin (22) engaged therein, the second plate portion (24
The length (1 ') is short enough to allow the second plate portion (24b) to swing backward in accordance with the operation of the speed change pedal by avoiding contact with the clutch pin (22) of (b). Have been.
The manual lever (16) is connected to the clutch pin (2
Slide 2) through the spring (29) to the third position (P3) which does not enter the notches (25) and (27) of the first and second plate portions (24a) and (24b). Being energized.

Thus, by moving the manual lever (16) to the first position (P1), the clutch mechanism (20) transmits only the forward operation of the manual lever (16) to the interlocking tool (9). And the manual lever (16) is in the second position (P2).
When the manual lever (16) is moved to the third position (P3) by sliding the manual lever (16) to the third position (P3). The interlock between the manual lever (16) and the interlock (9) is cut off.

Only when the manual lever (16) is at the neutral position (N) as shown in FIG. 8, the operation guide (35) moves the manual lever (16) to the first, second, and third positions ( P1),
Only when the manual lever (16) is at the first position (P1) and only when the manual lever (16) is at the first position (P1), is the forward side (F) of the manual lever (16) allowed to slide over (P2) and (3). ) And a manual lever (1).
6) has a reverse guide groove (36c) for allowing the manual lever (16) to swing to the reverse side (R) only when the manual lever (16) is at the second position (P2). The shift state is indicated by the position in the groove. The movement of the clutch pin (22) is regulated by the operation guide (35). To ensure the regulation of the movement of the clutch pin (22), as shown in FIG. Further, a pin guide (30) directly acting on the clutch pin (22) is attached to the body frame portion (19).

The friction mechanism (C) applies a friction force for holding the operation tool (A) at an arbitrary operation position against the neutral return biasing force of the hydraulic continuously variable transmission (5) by the manual operation. To the support member (17) of the lever (16),
Acting on an arm portion (17a) connected to the support member (17) to apply a small frictional force that allows the hydraulic continuously variable transmission (5) to move to a neutral state by the adjusting force of the hydraulic continuously variable transmission (5). The first friction mechanism (C1) acts on the boss portion (17b) of the support member (17) which is fitted to the support shaft (18).
It is divided into a second friction mechanism (C2) for maintaining the hydraulic continuously variable transmission (5) in a transmission state in cooperation with 1).

As shown in FIG. 12, the first friction mechanism (C1)
A first spring (33a) for pressing the arm portion (17a) toward the body frame portion (19), and the arm portion (17a)
A first friction plate (32a) interposed between the first frame (19a) and the first friction plate (32a) which is pressed against the arm portion (17a) so as to apply frictional resistance against swing to the arm portion (17a) by the pressing action of the first spring (33a). ). The first spring (33
The receiver (33A) of a) penetrates through the body frame portion (19) in a state of being prevented from being pulled out to the arm portion (17a) side,
The pin (P) penetrating the first friction plate (32a) and the arm portion (17a) is detachably attached to a penetrating end of the pin (P). Of course, the body frame part (1
The hole 9) is an arc-shaped long hole along the periphery of the support shaft (18) so as to allow the support member (17) to swing around the support shaft (18).

The second friction mechanism (C2) includes a second spring (33b) for pressing the boss portion (17b) toward the body frame portion (19) via a pressing tool (31), a boss portion (17b) and a body. Between the frame part (19), the boss part (17b) and the pressing tool (3
1) and the second spring (3
A pair of second friction plates (3) that are pressed against each other so as to impart frictional resistance to swing to the boss (17b) by the pressing action of 3b).
2b), the support shaft (18) and the pressing tool (31) are moved from the first swing position (PS1) of the support shaft (18) to the second swing position (PS1).
Each cam surface (18a, 31a) of the cam mechanism (18a, 31a) for separating the pressing tool (31) from the boss (17b) against the pressing force of the second spring (33b) with the rotation to 2). 18a), (31a)
Are formed in a distributed manner.

As the cam mechanism (18a, 31a), the pivoting movement of the support shaft (18) from the first swing position (PS1) to the second swing position (PS2) is performed, and the pressing tool (31) is a boss. Any type may be used as long as it converts the motion into a linear motion in the direction away from (17b). For example, a pair of well-known ones such as a pair of front cams whose cam surfaces are inclined with respect to the rotation axis are arranged facing each other. A structure may be adopted in which the cam surfaces (18a) and (31a) are formed.

That is, the second friction mechanism (C2) is connected to the cam mechanism (18a,
The rotation of the support shaft (18), which also serves as the cam operation shaft of 31a),
It is configured to be switchable between a frictional force applying state and a frictional force releasing state. Receiving (33B) of the second spring (33b)
Is mounted on the end of the support shaft (18) so as to prevent the second spring (33b) from pressing by changing the position of the support (33B). The lock nut (NA) and the lock nut (LN), which are screwed to the support, can be adjusted.

Thus, the friction mechanism (C) switches the second friction mechanism (C2) to the frictional force released state, thereby preventing the operation of the hydraulic continuously variable transmission (5) to the neutral state from a large frictional force state. Only the first friction mechanism (C1) is configured to apply a frictional force and switch to a frictional force decreasing state in which the operation of the hydraulic continuously variable transmission (5) to the neutral state is braked.

A friction push change mechanism that switches the friction force of the friction mechanism (C) between a state in which the operation tool (A) is frictionally held and a state in which the friction force is reduced, includes a support shaft (18) serving as the cam operation shaft.
A cam mechanism (18a, 31a) for changing the position of the pressing tool (31) in the direction of increasing or decreasing the urging force in accordance with the rotation of the cam, and a brake operation of the traveling brake pedal (40) using the cam mechanism (18a, 31a) And an operating mechanism (D) for rotating the urging force in a reduced direction in conjunction with the operation.

As shown in FIG. 7, the operating mechanism (D) is interlocked with the oscillating operating arm (7a) of the brake (7) via interlocking rods (37) and (39) and a rotating shaft (38). When the brake pedal (40) pivotally supported to swing freely around the horizontal axis (P3) at the foot of the control unit (12), the support as the cam operation shaft is actuated. Axis (1
8) is rotated to switch the friction mechanism (C) to the frictional force decreasing state. Specifically, as shown in FIG. 10, a drive arm (41) is integrally fixed to the rotating shaft (38) for linking the brake pedal (40) with the brake (7), and The drive arm (4
When 1) swings with the brake operation of the brake pedal (40), the drive arm (41) pushes the support shaft (18) from the first swing position (PS1) to the second swing position. (P
Attach the driven arm (12) to be rotated to S2) integrally,
Thus, the second friction mechanism (C2) is switched to the frictional force released state in conjunction with the braking operation of the brake pedal (40).

Therefore, according to the operation unit, the clutch mechanism (20)
, The hydraulic continuously variable transmission (5) interlocks with the manual lever (16), which has been prevented from swinging by the friction mechanism (C), and the manual lever (16) does not interlock. The manual lever (1
The hydraulic continuously variable transmission (5) is maintained in the transmission state instructed by (6), and the vehicle enters the constant speed traveling state. Of course, of the operations of the speed change pedal (11) in the constant speed traveling state, the operation on the deceleration side is an operation against the frictional force by the friction mechanism (C), but the operation on the speed increase side is performed by the clutch. In the mechanism (20), the clutch device (24) is allowed to swing independently to the speed increasing side irrespective of the clutch pin (22). When the increasing / decreasing operation of the shift pedal (11) is released, the hydraulic continuously variable transmission (5) automatically returns to the transmission state instructed by the manual lever (16) by the urging force,
The above-mentioned constant speed running state is established.

When the brake pedal (40) is operated in the above-mentioned constant speed traveling state, the friction mechanism (C) is switched to a frictional force decreasing state by the braking operation of the brake pedal (40), and the hydraulic continuously variable transmission (5) operates to return to the neutral state against the frictional force reduced by the urging force, and as a result, braking and stopping from the constant speed running state are performed gradually.

Of course, if the clutch mechanism (20) is operated in the disengaged state, the hydraulic continuously variable transmission (5) of the manual lever (16) can be used.
And the frictional force of the friction mechanism (C) is not applied to the operation of the hydraulic continuously variable transmission (5) by the transmission pedal (11). The operation of the continuously variable transmission (5) can be performed lightly.

(Another embodiment)

 Hereinafter, another embodiment of the present invention will be described.

[1] In the above embodiment, the clutch mechanism (20) for intermittently interlocking the friction mechanism (C) with the hydraulic stepless transmission (5) is provided, and the hydraulic stepless (11) alone is used. The transmission (5) can now be operated, but the manual lever (1
6) may be implemented such that it is always linked to the hydraulic continuously variable transmission (5).

[2] The friction mechanism (C) and the frictional force changing mechanism described in the above embodiment can be applied to various works such as an agricultural tractor, a combine, or a transport vehicle in addition to the lawnmower.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the structure shown in the attached drawings.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of a traveling operation structure of a work vehicle according to the present invention, and FIG. 1 is a partially cutaway front view of a transmission operation structure.
2 is a side view of the transmission operating structure, FIGS. 3 and 4 are cross-sectional views of the clutch mechanism, FIGS. 5 and 6 are side views of the clutch mechanism, and FIG. 7 is a perspective view of the brake operating structure. , FIG. 8 is a plan view of a lever guide, FIG. 9 is a plan view of a pin guide, FIG. 10 is a cross-sectional view taken along line XX of FIG. 1, and FIG. 11 is a side view of a riding lawn mower. FIG. 12 is a side view of a main part. (A) Operating tool, (B) Linking mechanism, (C) Friction mechanism, (D) Operating mechanism, (5) Hydraulic continuously variable transmission, (18) Cam Operating shaft, (18a, 31a) ... cam mechanism, (31) ... pressing tool, (32a) ... first friction plate, (3
2b) Second friction plate, (40) Brake pedal.

Claims (1)

(57) [Claims] A mechanical linking mechanism (B) for linking an operating tool (A) with a traveling hydraulic stepless transmission (5) which is urged to return to a neutral state; In a traveling operation structure for a working vehicle provided with a friction mechanism (C) for frictionally holding the operation tool (A) at an arbitrary position against a neutral return biasing force of a transmission (5), the friction mechanism ( C) the hydraulic stepless transmission (5)
A first friction plate (32a) for applying a small frictional force to the extent that the neutral return operation is permitted, and the hydraulic continuously variable transmission (5) is transmitted in cooperation with the first friction plate (32a). A second friction plate (32b) for maintaining the second friction plate (32b).
The second friction plate (32b) is switched between a frictional force applying state and a frictional force releasing state by changing the position of a pressing tool (31) for applying a pressing force to the operating tool (A). And the friction mechanism is configured to be switchable between an operation state in which friction is maintained and a frictional force decreasing state in which a small frictional force is applied to such an extent that the neutral return operation of the hydraulic continuously variable transmission (5) is permitted. The frictional force changing mechanism for switching the frictional force of (C) between the operation state in which the operating tool (A) is frictionally held and the frictional force decreasing state is provided by a cam operating shaft (18) rotated around an axis. A cam mechanism (18a, 31a) for changing the position of the pressing tool (31) in the direction of increasing or decreasing the urging force in accordance with the rotation operation, and a brake pedal (4) for driving the cam mechanism (18a, 31a).
An operation mechanism for traveling of a working vehicle, comprising: an operation mechanism (D) for rotating the urging force in a reduced direction in conjunction with the brake operation of (0).