JP2006062615A - Four-wheel steering device for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a four-wheel steering device for a working vehicle capable of solving problems in the manufacturing cost, operability and maintenance by a simple configuration. <P>SOLUTION: The four-wheel steering device for a working vehicle 1 is constituted steerable by selecting a front wheel steering mode to steer front wheels of the working vehicle having right and left front wheels 2 and right and left rear wheels 3, a rear wheel steering mode to steer rear wheels, and a front-rear wheel steering mode to steer both the front and rear wheels. A full hydraulic type steering unit 14 for front wheels to feed pressurized oil to a front wheel steering cylinder 12 to steer the front wheels 2 and a full hydraulic type steering unit 15 for rear wheels to feed pressurized oil to a rear wheel steering cylinder 13 to steer the rear wheels 3 are juxtaposed below a steering wheel 11h of the working vehicle. A switching means 16 to switch the transmission system from a steering shaft 11s to both of or either of the steering units 14, 15 of the front and rear wheels is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a four-wheel steering apparatus for a work vehicle that steers front and rear wheels together or separately for traveling according to various work conditions required for a four-wheel tractor and a multi-purpose work vehicle.

  The four-wheel steering device for a work vehicle shown in Patent Document 1 is a device that steers the front and rear wheels by sending hydraulic oil to the steering cylinders of the front and rear wheels in accordance with the turning operation of the steering shaft by a fully hydraulic steering unit. The two solenoid valves for switching and controlling the hydraulic oil of the two steering cylinders for the front wheel and the rear wheel can select the steering of the front wheel and / or the rear wheel, that is, the front and rear wheel steering mode for steering both the front and rear wheels, The front wheel steering mode for steering the front wheels and the rear wheel steering mode for steering the rear wheels are arbitrarily switched to enable vehicle travel suitable for the working conditions.

However, since the four-wheel steering apparatus having the above-described configuration requires a hydraulic circuit for switching hydraulic oil including two solenoid valves and an electric circuit for controlling the hydraulic circuit, the manufacturing cost and operation associated with complication of the apparatus are required. There are problems related to performance and maintenance, and a solution is awaited.
JP-A-6-298109

  The problem to be solved is to provide a four-wheel steering device for a work vehicle that can solve problems in manufacturing cost, operability, and maintenance with a simple configuration.

According to a first aspect of the present invention, a front wheel steering mode for steering the front wheels of a work vehicle having left and right front wheels and left and right rear wheels, a rear wheel steering mode for steering the rear wheels, and steering the front and rear wheels together. A four-wheel steering device for a work vehicle configured to be steerable by selecting from the front and rear wheel steering modes, and for front wheels that send pressure oil to a front wheel steering cylinder that steers the front wheels below a steering handle of the work vehicle An all-hydraulic steering unit and a rear-wheel all-hydraulic steering unit that sends pressure oil to the rear-wheel steering cylinder that steers the rear wheels are provided side by side. A switching means for switching the transmission system is provided.
The steering units for the front and rear wheels perform a steering operation corresponding to the rotation of the steering shaft corresponding to the transmission system selected by the switching means.

According to a second aspect of the present invention, in the configuration of the first aspect, the steering shaft is provided with a slide gear movable along the shaft and an operation means for sliding the gear, and the front wheel full hydraulic pressure is provided. The steering unit includes an input shaft for inputting rotation of the steering shaft and a driven gear integrated with the input shaft, and the input for inputting rotation of the steering shaft to the all-hydraulic steering unit for rear wheels. The switching means is configured to include a shaft and a driven gear integral with the input shaft, and the operating means meshes the slide gear with either or both of the front wheel driven gear and the rear wheel driven gear. By doing so, the front-rear wheel steering mode, the front-wheel steering mode, and the rear-wheel steering mode are switched.
Rotation transmission from the steering shaft is switched by engaging the slide gear with the driven gears for the front wheels and the rear wheels according to the operation of the operating means.

The four-wheel steering device for a work vehicle according to the present invention has the following effects.
In the invention according to claim 1, since the transmission of the rotation of the steering shaft to the steering units of the front and rear wheels is switched by the operation of the switching unit, the four-wheel steering device can be configured by a simple switching unit.

  The slide gear having the configuration according to claim 2 is arbitrarily switched between the three steering modes by meshing with the driven gears for the front wheels and the rear wheels in accordance with the operation of the operation means. Therefore, the four-wheel steering device can be easily configured by a gear mechanism.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a side view of a multi-purpose work vehicle showing an application example of the four-wheel steering device of the present invention. This multi-purpose work vehicle 1 is an example of a tractor for roadside work, and the left and right front wheels 2 and 2 and the left and right rear wheels 3 and 3 are supported on a monocoque frame so as to be steerable, and a general tractor configuration and front and rear In reverse, that is, the engine 4 is arranged at the rear of the aircraft, and the mission case 5 is arranged at the front of the aircraft. A driver's cab 6 is formed at the front of the machine body, and a loading platform 7 is formed at the rear part, and front and rear PTO shafts 8f and 8r are provided in front and rear of the machine body as working machine power. Install.

  A steering column 11 is provided on the cab 6 and a steering handle 11h is provided. For four-wheel steering, the front and rear wheel steering cylinders 12 and 13 are connected to the front or rear wheels via a hydraulic system described later. Provided corresponding to the part. In the handle column 11, as shown in the internal perspective enlarged front view of FIG. 2, a switching means 16 by a gear mechanism connected to the steering handle 11h is arranged in the lower part.

  More specifically, a steering shaft 11s integrated with the steering handle 11h is pivotally supported on the handle column 11, and a switching means 16 is connected to the lower end of the steering shaft 11s via a joint 11c. Install the units 14 and 15.

  As shown in FIGS. 3 and 4, respectively, the switching means 16 includes an input shaft 21 connected to the steering shaft 11s and two fully hydraulic steering units 14, 15 as shown in a side view of the gear structure and a cross-sectional view taken along line AA. Input shafts 24 and 25 for rotational input, and a slide gear 21g having a gear thickness that can be switched by a switch lever 22 for transmission to the two fully hydraulic steering units 14 and 15, two front and rear wheels. The driving gears 24g and 25g are used.

  The slide gear 21g is configured to be slidable to at least three shift positions along the input shaft 21 by the switching lever 22. The two driven gears 24g and 25g are configured integrally with the input shafts 24 and 25 that rotate and input to the two fully hydraulic steering units 14 and 15. The front wheel driven gear 24g and the rear wheel driven gear 25g are both engaged with one another, or one of them is engaged with the slide gear 21g according to the shift position of the slide gear 21g determined by the operation of the switching lever 22. The transmission between the steering shaft 11s and the two fully hydraulic steering units 14, 15 is switched.

  As shown in the hydraulic system diagram of FIG. 5, the four-wheel steering device having the above-described configuration is connected to the corresponding steering cylinders 12 and 13 as shown in the hydraulic system diagram of FIG. By switching the rotation transmission by the switching means 16 in the turning operation, the front wheel steering mode for steering the front wheels by receiving the steering inputs to the selected front-wheel and rear-wheel all-hydraulic steering units 14 and 15 respectively, and the rear wheels The required wheels can be steered by steering control of the steering cylinders 12 and 13 corresponding to the rear wheel steering mode for steering the front and rear wheels and the front and rear wheel steering mode for steering the front and rear wheels together. Therefore, the four-wheel steering device can be easily switched by a gear mechanism.

Next, a work vehicle having another configuration example will be described. The same members as those described above are denoted by the same reference numerals, and description thereof is omitted.
As shown in the side view of FIG. 6 and the main part plan view of FIG. 7, the work vehicle 31 a of another configuration example 1 transmits power from the rear-arranged engine 4 to the transmission 33 and the front mount mower 34. The rear wheels 3 and 3 are configured to be steerable. The transmission 33 is formed in a gate shape integrally with the front wheel transmission portion 35, and the gate shape is disposed in front of the front wheel 2 and 2, with the axle portion 2a of the front wheels 2 and 2 as the rear side. 34g is placed. The collector blower 32b has a cylinder lifting mechanism arranged between the front wheels 2 and 2 in the orthogonal direction.

  The work vehicle 31a having the above-described configuration can be arranged at the shortest distance from the mower 34 of the front mount, and can have a rotating body inside the machine. On the other hand, in the case of the conventional type, in the case of the axial flow type blower arranged on the rear side of the fuselage, the work width projects beyond the effective cutting width by projecting to the outside of the machine. Also, in terms of noise, there is a problem that a large noise load is unavoidable on the operator's ears and environment due to the exposure of the blower. However, the above configuration can solve such a problem.

  Next, a hydraulic circuit configuration according to another example of steering control will be described. As shown in the hydraulic system diagram of FIG. 8, the steering wheel is configured such that the front wheel steering is controlled by the front hydraulic steering unit 14 and the rear wheel steering is controlled by the solenoid valve 41. 11h is disengaged by the electromagnetic clutch 42, and when it is moving, the steering of 4WS, front steering (FWS), and rear steering (RWS) can be easily switched by one steering handle 11h. Specifically, only the front or the front and rear can be operated when the clutch is on, and only the rear can be operated when the clutch is off.

  In this case, the steering system for the rear wheels is supplied from the high pressure side of the HST 43 via the pressure reducing valve 44 for guaranteeing the closed circuit pressure, and the check valves 45 and 45 are provided at both outputs, respectively, so that the forward / backward movement can be achieved. It becomes possible.

It is a side view of the multipurpose work vehicle which shows the example of application of the four-wheel steering device of this invention. It is a see-through | perspective enlarged front view of a handle column. It is a gear structure side view of a switching means. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3. It is a hydraulic system diagram of a multipurpose work vehicle. 10 is a side view of a work vehicle of another example 1. FIG. It is a principal part top view of the working vehicle of FIG. It is a hydraulic system figure concerning another example of steering control.

Explanation of symbols

1 Multipurpose work vehicle (work vehicle)
2 Front wheel 3 Rear wheel 4 Engine 5 Mission case 6 Driver's cab 11 Handle column 11h Steering handle 11s Steering shaft 12 Front wheel steering cylinder 13 Rear wheel steering cylinder 14 Front wheel all hydraulic steering unit 15 Rear wheel all hydraulic steering unit 16 Switching means 21 Input shaft 21g Slide gear 22 Switching lever (operating means)
24,25 Input shaft 24g Front wheel driven gear 25g Rear wheel driven gear

Claims (2)

A front wheel steering mode for steering the front wheels of a work vehicle (1) having left and right front wheels (2) and left and right rear wheels (3), a rear wheel steering mode for steering the rear wheels, and the front and rear wheels together. A four-wheel steering device for a work vehicle configured to be steerable by selecting from front and rear wheel steering modes for steering,
A front-wheel all-hydraulic steering unit (14) for sending pressure oil to a front-wheel steering cylinder (12) for steering the front wheels (2) below the steering handle (11h) of the work vehicle (1), and the rear wheels (3) a rear wheel steering cylinder (13) for steering the rear wheel and a rear wheel fully hydraulic steering unit (15) for sending pressure oil to the rear wheel steering cylinder (13) and / or one of the front and rear wheel steering units (14, 15). A four-wheel steering apparatus for a work vehicle, characterized in that it is provided with switching means (16) for switching a transmission system from the steering shaft (11s). The steering shaft (11s) is provided with a slide gear (21g) movable along the shaft and an operation means (22) for sliding the gear (21g), and the all-hydraulic steering unit for the front wheels (14) includes an input shaft (24) for inputting rotation of the steering shaft (11s) and a driven gear (24g) integrated with the input shaft (24), and the all-hydraulic steering unit for the rear wheels. (15) includes an input shaft (25) for inputting rotation of the steering shaft (11s) and a driven gear (25g) integrated with the input shaft, and the operating means (22) allows the slide gear (21g). Is configured to mesh with both or one of the front wheel driven gear (24g) and the rear wheel driven gear (25g). It allows four-wheel steering system for a work vehicle according to claim 1, wherein the switch front and rear wheel steering mode, the front-wheel steering mode, the rear wheel steering mode.

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