JPH02199360A - Shift device for transmission - Google Patents

Abstract

PURPOSE:To prevent the breakage of a transfer mechanism when an excessive force is applied to a shift lever by inserting a clutch having a torque limiter function between the support section of the shift lever and an operation main shaft. CONSTITUTION:The support tube 42 of a shift lever 25 is coupled with one end of the operation main shaft 41 of a link mechanism 40 via a clutch 54 having a torque limiter function. A ball 56 held by a triangular groove 55 extended in the surface axis direction of the operation main shaft 41 and the support tube 42 is excited by a spring 57 to constitute this clutch 54. The breakage of a transfer mechanism can be prevented when an excessive force is applied to the shift lever 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a shift device for a transmission, and more particularly to a shift device suitable for a hydraulic transmission used in a working machine such as a riding lawn mower.

[Prior art]

2. Description of the Related Art Some working machines, such as riding lawn mowers, are equipped with a so-called hydraulic transmission as a transmission for transmitting power from an engine to wheels. This hydraulic transmission is generally operated using the shift lever.
By inputting forward and reverse rotation from this shift lever, the transmission direction can be changed to forward, neutral, or
The configuration is such that each can be switched to reverse.

However, when an excessive input is applied to the shift lever when rotating the shift lever as described above, excessive force is applied to the transmission mechanism, which may damage the mechanism. In particular, if there is a resin part such as a bushing in the middle of the transmission mechanism, the resin part will be damaged.

In order to prevent such damage, it is possible to increase the strength of these transmission mechanisms, but a stronger amplifier than necessary will inevitably lead to an increase in weight and cause an increase in cost.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a shift device for a transmission that does not damage the transmission mechanism even if an excessive input is applied to the shift lever. An object of the present invention is to provide a shift device suitable for a transmission.

[Failure to solve the problem]

To achieve the above object, the present invention provides a shift device that converts rotational operation of a shift lever into rotation of a main operating shaft, and transmits the rotation of the main operating shaft to a transmission via a transmission mechanism. The present invention is characterized in that a clutch having a torque limiter function is interposed between the support portion of - and the main operating shaft.

The present invention will be explained below with reference to embodiments shown in the figures.

FIG. 5 schematically shows a riding lawn mower equipped with a transmission shifting device according to the invention.

In the figure, ■ is the vehicle body, 2 is the engine mounted on the front of the vehicle body 1, 3 is the front wheel, 4 is the rear wheel, 5 is the handle,
6 is a sheet. Between the front wheel 3 and the rear wheel 4, a cutter housing 8 housing the cutter 7 is connected to the front and rear links 9.
, 9, and can be raised and lowered via a link mechanism 11 by operating an elevator lever 10.

The engine 2 is provided with a crankshaft 12 extending in the vertical direction, and two pulleys 13 and 14 are fixed to the ends of the crankshaft 12 that project downward. A belt 16 is wound between the lower pulley 14 and a pulley 15 provided on the cutter housing 8.
Further, a belt 19 is wound between pulleys 17 and 18 to drive the cutter 7. A belt 22 is wound between the upper pulley 13 and a pulley 21 of a hydraulic transmission 20 at the rear of the vehicle body, so that power is input to the hydraulic transmission 20°. The hydraulic transmission 20 transmits the input power to the rear wheels 4 via a reduction gear in a gear case 23. A fan 24 for cooling the hydraulic transmission is attached to the boot IJ21.

The hydraulic transmission 20 has a shift lever 25
By inputting the rotation operation through the transmission mechanism (linkage mechanism 40), the output to the rear wheels 4 is rotated in the normal direction (forward direction),
It is designed to switch between neutral (stop) and reverse (reverse).

Further, the vehicle body 1 is provided with a foot brake 26.

When this foot brake 26 is depressed, the lever 27 moves to the shaft 2.
The rear wheels 4 are braked by rotating a rod 29 connected to this lever 27 forward. Further, another rod 30 is connected to the lever 27, and two pairs of arms 31a, 31b; 32a, 32b (see FIGS. 2 and 3) attached to the rear end are actuated in a scissor-like manner, and the lever of the link mechanism 40 is actuated. 45
The link mechanism 40 is forced to return to the neutral position by sandwiching the bottle 33 at the end of the link mechanism 40 and moving it to the middle position.

1 to 3 show the link mechanism 40 part from the shift lever 25 to the hydraulic transmission 20, and the first
The figure shows the back, FIG. 2 shows the side, and FIG. 3 shows the top.

The main operating shaft 41 of the link mechanism 40 is rotatably supported by a bracket 1a fixed on the vehicle body 1. A support tube 42 of the shift lever 25 is fitted to one end of the operating main shaft 41 via a clutch 54 having a torque limiter function, and is urged in the axial direction by a spring 50 so as to be pressed against the bracket 1a. . The shift lever 25 is attached to a bracket 4 fixed on this support tube 42.
3, and is supported by a spring 44 so as to maintain a vertical posture.

The clutch 54 has a triangular groove 55 extending in the axial direction on the surface of the operating main shaft 410, holds a ball 56 on the support tube 42 side, and urges this pawl 56 with a spring 57 to engage the triangular groove 55. It is configured as follows. More specifically, as shown in the enlarged view of Figure 4,
The ball 56 is held by a ball holder 58, and the ball holder 58 is biased by the spring 57, thereby causing the ball 56 to engage with the triangular groove 55. Further, an adjustment bolt 59 is provided as a stopper for the ball holder 58, and the biasing force of the spring 57 can be adjusted by screwing the adjustment bolt 59 back and forth.

The clutch 54 has a clutch function that connects the operating main shaft 41 and the support tube 42 by engagement between the triangular groove 55 and the ball 56. Also, when an excessive torque of a certain level or more is applied between the two at the same time, the triangular groove 55
6 into the support tube 42 to disengage the two,
It also has a torque limiter function to release the excessive torque mentioned above.

Further, a lever 45 is fixed to the other end of the main operating shaft 41 so as to rotate integrally therewith. A vertical rod 46 is connected to the end of this lever 45, and the rod 46 is attached to a lever rotatably supported on the hydraulic transmission 20 side.
It is connected to a shaping bar 47. L-shaped bar 47 4t
he4 is provided with a bin 47a, which is slidably fitted into a groove 48a of a rotary lever 48, and the rotary lever 48 is fixed to a control shaft 60 of the hydraulic transmission 20.

Therefore, when the shift lever 25 is shifted to the side of the arrow F, the operating main shaft 41 rotates, the lever 45 rotates, the rod 46 is pulled up, and the L-shaped bar 47 is rotated. This L-shaped bar 47 rotates the rotary lever 48 in the F direction through engagement between the pin 47a and the groove 48a. This rotation of the rotary lever 48 causes the control shaft 60 to rotate in the F direction,
The hydraulic transmission 20 transmits engine power input from the pump shaft 52 so that the motor shaft 53 rotates in the forward direction. Furthermore, when the shift lever 25 is shifted in the direction of arrow R, the main operating shaft 41, lever 45, rod 46, L-shaped bar 47, and rotary lever 4 move in the opposite direction to the above.
8 rotates, the control shaft 6o rotates in the R direction, and the hydraulic transmission 2o transmits the engine power input to the pump shaft 52 so that the motor shaft 53 reversely moves in the reverse direction.

49f and 49r provided on the transmission body are stoppers that restrict the rotation of the rotary lever 48.

The stopper 49f regulates the rotation limit in the forward direction' (F direction), and the stopper 49r regulates the rotation limit in the reverse direction (R direction). The amount of protrusion of both stoppers can be finely adjusted using screws.

When the shift lever 25 is centered in the front-rear shift direction, the hydraulic transmission 20 becomes neutral and no longer transmits power.

This neutral position is also automatically set via the rod 3o when the foot brake 26 is depressed as described above.

As described above, in the shift device, the shift lever 25
When an excessive force is applied to the shift lever 25 during operation, the clutch 54 between the support tube 42 and the operating main shaft 41
will come off, allowing the excessive force mentioned above to escape. Therefore, due to the release of this excessive force, no excessive force is applied to the transmission mechanisms from the operating main shaft 41 to the hydraulic transmission 20, and damage to these transmission mechanisms will not occur. Furthermore, since there is no need to forcibly increase the strength of the link mechanism 40 to prevent damage, there is no need to increase the weight of these transmission mechanisms. 55 can be easily engaged, so a normal shift operation can be performed.

In the above-described embodiment, the case of a hydraulic transmission applied to a lawn mower has been described, but the present invention can be similarly applied to a hydraulic transmission applied to a vehicle other than a lawn mower. Further, in the embodiment, the case of a hydraulic transmission has been described, but the invention is not limited to this hydraulic transmission, and a shift device that converts the shift lever into rotation of the operating main shaft and transmits it to the transmission via a transmission mechanism can be used. If applicable, it can also be applied to other general transmissions.

(Effects of the Invention) As described above, the present invention provides a shift device that converts rotational operation of a shift lever into rotation of a main operating shaft, and transmits the rotation of the main operating shaft to a transmission via a transmission mechanism. , a clutch with a torque limiter function is interposed between the support part of the shift lever and the main operating shaft, so if an excessive input is applied to the shift lever, the torque limiter function of the clutch will absorb this excessive force. This will not cause damage to the transmission mechanism. Moreover, since there is no need to increase the strength unnecessarily, no increase in weight is caused.

On the other hand, after the excessive input is released, the clutch can be easily engaged again, allowing normal shifting operations.

[Brief explanation of the drawing]

Figures 1 to 3 show the link mechanism from the shift lever to the hydraulic transmission in the lawn mower shown in Figure 5, with Figure 1 being a rear view, Figure 2 being a side view, and Figure 3 being a plan view. . FIG. 4 is a view taken along the line IV-IV in FIG. 1. FIG. 5 is a schematic side view of a lawn mower equipped with a transmission shift device according to the present invention. 2... Engine, 20... Hydraulic transmission, 25... Shift lever-140... Link mechanism, 4
1... Operating main shaft, 42... Support tube (support part), 52
... pump shaft, 53 ... motor shaft, 54 ... clutch, 55 ... triangular groove, 56 ... ball, 57 ...
・Spring, 58...Ball holder root.

Claims (1)

[Claims] In a shift device that converts a rotational operation of a shift lever into rotation of an operating main shaft and transmits the rotation of the operating main shaft to a transmission via a transmission mechanism, there is provided a space between a support portion of the shift lever and the operating main shaft. A transmission shift device in which a clutch with a torque limiter function is interposed.