JPH0752667A - Structure for switching working vehicle between two-and four-wheel drive - Google Patents

Abstract

PURPOSE:To make a transmission applicable to both two- and four-wheel drive by providing at a four-wheel drive shaft a switching clutch which connects power to a differential gear, and designing a switching-clutch-enclosing support case as a member by which a rear axle case is supported in such a manner as to be able to roll. CONSTITUTION:In a front-mount riding lawn mower, engine power is transmitted to an HST 7 via a transmission shaft 6 and then to a first differential gear 8 for front wheels and to a four-wheel drive shaft 9a via a transmission Tm. A rear-wheel drive 9 is drivingly connected to the rear of the four-wheel drive shaft 9a to rotate the rear wheels which are supported by a support mechanism 27 in such a way as to be freely rolling. In this case, a switching clutch A, which connects and disconnects the four-wheel drive shaft 9a to and from a pinion shaft 13 connected by a bevel gear to a second differential gear 12 for the rear wheels, is mounted in the casing 11 of the rear-wheel drive 9, and the support mechanism 27 is formed by fitting into a support case 11b the front projecting portion 19a of a rear axle case 19 which surrounds the second differential gear 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 2WD / 4WD switching structure for working machines such as lawn mowers and rice transplanters, and more particularly to a rationalized structure in which the switching means and rolling support means are integrated.

[0002]

2. Description of the Related Art In a work machine capable of driving four wheels, it is common to support either one of the front and rear wheels in a rolling manner in order to obtain an effective driving force by reliable grounding of the four wheels. For example, in the lawnmower disclosed in Japanese Utility Model Laid-Open No. 4-71305, it is convenient in that the lawn is less likely to be damaged by surely dispersing the four ground loads.

[0003]

A four-wheel drive machine has a switching clutch for switching between two-wheel drive, which is usually disclosed in Japanese Patent Laid-Open No.
Like the tractor disclosed in Japanese Patent Publication No. 3-291723,
The changeover clutch is arranged on the transmission case side to centralize the functions. However, basically, it is desirable to set it for two-wheel drive and to additionally equip a four-wheel drive machine with a switching clutch outside the transmission from the viewpoint of generalization while reducing the size of the transmission. . An object of the present invention is to provide a generalized structure of a 2 / 4-wheel drive switching clutch as a mission exterior and a rolling support means for a drive switching target wheel, and to provide a rational structure in which these are organically combined. There is a point to let.

[0004]

In order to achieve the above object, the present invention is a four-wheel system in which a transmission for transmitting the power of a drive source to one of the front and rear drive wheels and a differential mechanism for the other wheel can be transmission-coupled. A four-wheel drive shaft portion is provided with a switching clutch for connecting and disconnecting power to the diff mechanism, and a support case accommodating the switching clutch is provided for supporting the other wheel in a rolling manner. Is configured as a member that supports a rear axle case accommodating the same so as to be swingable around a longitudinal axis.

[0005]

In other words, by providing a two-wheel drive and four-wheel drive switching clutch in the four-wheel drive shaft portion, the two-wheel drive machine can use the transmission without waste of the unnecessary switching clutch. By providing a four-wheel drive shaft, a four-wheel drive machine can be equipped with a necessary switching clutch. Further, in the four-wheel drive machine, the support case, which incorporates a necessary switching clutch, serves as a member for rollingly supporting the drive switching target wheel, so that a dedicated supporting member can be omitted.

[0006]

Therefore, the four-wheel drive is necessary only for the four-wheel drive machine.
By providing a switching clutch on the wheel drive shaft and using the clutch case as a rolling support member, it is possible to obtain a desired function with a rational structure with a reduced number of parts. We were able to provide a transmission that could be generalized.

[0007]

Embodiments of the present invention will be described below with reference to the drawings in the case of a lawnmower which is an example of a working machine. FIG. 1 shows a front-mounted riding lawn mower, and FIG. 2 shows a main part of its transmission system. 1 is a control section, 2 is a drive section, and 3 is a drive section.
Are front wheels for driving, 4 are rear steering wheels, and 5 are mowers. The power of the engine 2a is transmitted to the HST 7 via the transmission shaft 6,
The output shaft 7a and the first differential mechanism 8 for the front wheels are gear-interlocked via the transmission Tm of the transmission case M, and are also transmitted to a four-wheel drive shaft 9a described later. Further, the output shaft 7c obtained by extending the input shaft 7b of the HST 7 and the mower 5 are linked by the transmission shaft 10.

The steering rear wheel 4 is provided at the rear of the four-wheel drive shaft 9a.
A rear-wheel drive device 9 that can drive the vehicle and a support mechanism 27 that supports the rear wheel 4 in a freely rolling manner are configured. As shown in FIGS. 2 and 3, the rear wheel drive device 9 includes a casing 11 formed by integrating a cover case 11a and a support case 11b into a four-wheel drive shaft 9a and a second differential mechanism 12 for the rear wheel. A switching clutch A for connecting and disconnecting the bevel-operated pinion shaft 13 is internally provided. The drive side shifter 15 is attached to the intermediate shaft 14 that is interlocked with the four-wheel drive shaft 9a.
A shift clutch A is formed by externally fitting a spline and supporting a shift fork 16 and a fork shaft 17 for slidingly operating the drive side shifter 15 on a cover case 11a. In other words, shift the drive side shifter 15 to the rear,
Driven side shifter 18 splined on pinion shaft 13
The four-wheel drive state is set when the gears are engaged with each other, and the two-wheel drive state is set when the front side shifter releases the engagement with the driven side shifter 18.

The support mechanism 27 is constructed by fitting the front protruding portion 19a of the rear axle case 19 surrounding the second differential mechanism 12 into the support case 11b and the rear protruding portion 19b into the bearing portion 20. Thus, the rear axle case 19 is supported so as to be rotatable around the axis P in the front-rear direction. The casing 11 and the bearing portion 20 are fixedly supported by the machine body, and the support case 11b is a member having a cover function of the rear wheel drive device 9 and a support function of the rear axle case 19.

FIG. 4 shows a support structure for the rear wheel 4.
A steering case 21 supporting the rear wheels 4 and a rear axle case 19
The bearing case 22 mounted on the end is pivotally connected to the diagonal transmission shaft 23 so as to be transmittable and steerable around the axis of the transmission shaft 23. At the lower end of the steering case 21, a seal cap 2 for a bearing 24 for the transmission shaft 23 is provided.
5 is provided, but is fitted and mounted at a position slightly above the lower end of the steering case 21 for the purpose of reducing the risk of contact with an obstacle. Reference numeral 26 is a groove formed at the lower end of the steering case 21 for removing the seal cap 25 (see FIG. 5).

[Other Embodiments] The rear wheels are always driving wheels, and
The front wheels may be steering wheels, and a two-wheel drive or four-wheel drive switching structure may be configured for the front wheels.

It should be noted that although reference numerals are given in the claims for convenience of comparison with the drawings, the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

[Figure 1] Side view of a lawn mower

FIG. 2 is a partially cutaway side view showing a transmission system.

FIG. 3 is a sectional view showing the structure of a switching clutch.

FIG. 4 is a sectional view of an essential part showing a rear wheel support structure.

FIG. 5 is a bottom view of the lower end of the steering case.

[Explanation of symbols]

 3 Drive Wheel 4 Wheel 9a 4 Wheel Drive Shaft 11b Support Case 12 Differential Mechanism 19 Rear Axle Case A Switching Clutch Tm Transmission

Claims (1)

[Claims] 1. A transmission (Tm) for transmitting power of a drive source to one of front and rear drive wheels (3), (3).
And the differential mechanism (1) for the other wheels (4), (4)
2) equipped with a four-wheel drive shaft (9a) that can be power-coupled to
A switching clutch (A) for connecting and disconnecting power to the differential mechanism (12) is provided at the portion for driving the four-wheel drive shaft (9a), and the other wheels (4), (4) are supported in a freely rolling manner. The support case (11b) accommodating the switching clutch (A) is configured as a member that supports the rear axle case (19) accommodating the differential mechanism (12) so as to be swingable around a longitudinal axis. 2/4 of working machine which is done
Drive switching structure.