JP2003154963A - Rear wheel-drive type three-wheeled tending machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve straight running stability of a three-wheeled tending machine having a front wheel as a free wheel. SOLUTION: This rear wheel-drive type three-wheeled tending machine is provided with one front wheel 26 at a front part of a machine body frame 11, and two rear wheels, right and left, at a rear part of the machine body frame, so that working implement for treating field crops is installed on the machine body frame, with the right and the left rear wheels driven by an engine. The front wheel 26 is installed on a front fork 25, and the front fork is rotatably installed on a head pipe 21 in the machine body frame, so that the front wheel can be steered. A cam plate 82 having a cam groove 82a is provided on the head pipe 21, and a roller 86 to be engaged with the cam groove 82a is provided on the front fork 25. An elastic member 88 to energize the roller 86 toward the cam groove 82a is provided on the front fork 25. The roller 86 is thus engaged with the cam groove 82a when the front fork 25 is directed in a straight running direction.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving a rear wheel drive type three-wheel type management machine. Note that the management machine means an agricultural machine that performs management such as thinning, weeding, mowing, etc. that is carried out after seedling planting and harvesting. 2. Description of the Related Art As a rear wheel drive type three-wheel management machine having one front wheel and two rear wheels, for example, Japanese Patent Laid-Open No. 2001-299011.
The publication “Rear-wheel-driven three-wheel type management machine” (hereinafter referred to as “conventional technology”) is known. As shown in FIG. 2 of the same publication, the above-described conventional technique includes one front wheel 26 at the front portion of the fuselage frame 11 (the numbers are those cited in the publication; the same applies hereinafter). The left and right rear wheels 31,
In the rear-wheel drive type three-wheel management machine 10 that includes an engine 32 and drives the left and right rear wheels 31, 31 with the engine 32, the front wheel 26
Is attached to the front fork 25, and this front fork 25 is rotatably attached to the head pipe 21 of the fuselage frame 11, so that the front wheel 26 can be steered by the steering handle 34. While running the three-wheeled control machine 10 in the field (between the fences),
Agricultural crops growing on the straw can be processed with a work tool (not shown). [0004] By the way, the ridges and ridges of the field are not always flat, and there are foreign objects such as pebbles between the ridges. When the three-wheel management machine 10 travels straight in such a place, an external force that changes the direction acts on the front wheel 26 due to the front wheel 26 hitting the heels and pebbles or hitting the unevenness of the ridges. External force is transmitted from the front wheel 26 to the steering handle 34 via the front fork 25. As a result, the steering handle 34 is swung to the left and right, so that the operator needs to increase the steering force in order to maintain straight travel. Therefore, there is room for improvement to reduce the labor of the worker. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a technique capable of improving the straight running stability of a three-wheel type management machine having a front wheel as a free wheel. In order to achieve the above object, according to a first aspect of the present invention, one front wheel is provided at the front of the body frame, and two left and right rear wheels are provided at the rear of the body frame. , A rear-wheel drive type three-wheel management machine that attaches a work tool for processing crops to the machine frame and drives the left and right rear wheels with an engine. The front wheel is attached to the front fork, and this front fork is attached to the head pipe of the machine frame. In the rear wheel drive type three-wheel management machine that enables the front wheels to be steered by attaching to the head pipe or front fork,
A cam plate having a cam groove is provided, a rolling member that engages with the cam groove is provided on the front fork or the head pipe, and a resilient member that urges the rolling member to the cam groove side,
By providing the front fork or the head pipe, the rolling member is configured to engage with the cam groove when the front fork is directed in the straight direction. When the front fork is directed in the straight direction, the rolling member is engaged with the cam groove, and this engaged state is maintained by the resilient member. For this reason, the direction of the front fork in the straight direction can be maintained with respect to the body frame side. Furthermore, when an external force that changes the direction of the front wheel is transmitted from the front wheel to the front fork when the three-wheeled control machine travels straight, the cam groove and the The direction of the front fork in the straight traveling direction can be maintained until an external force that releases the engagement relationship with the rolling member is applied. Accordingly, it is possible to suppress the front fork from fluctuating from side to side when the three-wheeled management machine travels straight ahead. For this reason, it is possible to improve the straight running stability of the three-wheel type management machine with the front wheel as a free wheel, so that the labor of the operator can be reduced. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. "Before", "After",
“Left”, “right”, “upper”, and “lower” follow the direction seen from the operator. The drawings are to be viewed in the direction of the reference numerals. FIG. 1 is a left side view of a rear wheel drive type three-wheel type management machine according to the present invention. The rear-wheel drive three-wheel management machine 10 is
One front wheel 26 is provided at the front of the body frame 11, and two left and right rear wheels 31, 31 (only the left is shown in the figure, the same applies hereinafter) are provided at the rear of the body frame 11. The self-propelled working machine is provided with an engine 32 and a seat 33 on which an operator sits at the upper rear part and a steering handle 34 at the longitudinal center of the machine body frame 11. Hereinafter, the rear-wheel drive three-wheel management machine 10 is simply referred to as “management machine 10”. The mounting structure of the front wheel 26 is the airframe frame 1.
1 is provided with a head pipe 21,
The front fork 25 is rotatably attached to the front fork 25 and the front wheel 26 is rotatably attached to the front fork 25.
The front wheel 26 which is a free wheel can be steered. Rear wheel 31, 3
1, the left and right rear wheel transmission mechanism cases 63a and 63a are extended downward from the rear portion of the body frame 11, and the left and right rear wheels 31 and 31 are rotated below the rear wheel transmission mechanism cases 63a and 63a. It is attached as possible. The management machine 10 includes a work tool 40 for processing agricultural products and first, second, and third work auxiliary tools 51, 52, 52, and 5 for assisting the work tool 40 in the machine frame 11.
3, power transmission mechanism 61, continuously variable transmission 6
2, rear wheel transmission mechanisms 63, 63, forward / reverse transmission lever 71,
A brake pedal 72, an operation clutch lever 73, a swing operation lever 74, and an operator step 75 are provided. By operating the forward / reverse transmission lever 71 to switch the speed of the continuously variable transmission 62 or to switch between forward and reverse, the power of the engine 32 is transmitted to the power transmission mechanism 61, the continuously variable transmission 62, and the rear wheel transmission mechanism. The rear wheels 31 and 3 through 63 and 63
1, the traveling speed of the rear wheels 31, 31 can be switched, or can be switched between forward and reverse. The engine 3 is switched by switching the power transmission mechanism 61 by switching the working clutch lever 73.
The power of 2 can be transmitted to the work tool 40. By operating the swing operation lever 74, the work tool 40 and the first, second, and third work auxiliary tools 51, 52, 52, 53 are swung up and down with a transmission hydraulic cylinder (not shown),
It can be adjusted to the optimum height for processing crops. The work tool 40 is for harvesting, for example, crops. The work tool transmission case 41 extends forward from the rear side of the machine body frame 11 and the work tool transmission case 41.
Auxiliary case 42 extending horizontally in the left-right direction (back direction in the figure), left and right work arms 43, 43 extending downward from the auxiliary case 42, and work arms 43, 43
Left and right drive shafts 66 extending from the lower end of the drive shaft 66 and the drive shaft 6
It consists of left and right cutting blades 67 and 67 attached to the lower end portions of 6,66. The work tool transmission case 41 can swing up and down. 44 and 44 are auxiliary arms. The first work assisting tool 51 is a guide member that guides the crop just before the front wheel 26 toward the cutting blades 67 and 67 while guiding the crop so as not to get entangled with the front wheel 26. The left and right second work assisting tools 52, 52 cut the crops 67, 67
And a guide member that guides the rear wheels 31 and 31 so as not to get tangled. Third work aid 53
Is a guide member for guiding the crops toward the cutting blades 67, 67. FIG. 2 is a plan view of a rear wheel drive type three-wheel management machine according to the present invention, in which a front wheel 26 is disposed at the body center (machine body width center) CL, and left and right rear wheels 31 on the left and right sides of the machine center CL. ,
31 and left and right cutting blades 67, 67 are arranged, and the machine center C
Seat 33 and steering handle 34 on the left side of L
The engine 32, the power transmission mechanism 61 and the work tool transmission case 41 are arranged on the right side of the machine body center CL, and the power transmission switching lever 71, the brake pedal 72, the work clutch lever 73 and the swing operation lever 74 are steered. It shows that it has been arranged in the vicinity of the handle 34. FIG. 3 is a plan view of the front fork mounting structure and steering system according to the present invention. A more specific mounting structure of the front fork 25 is that the steering stem 22 is mounted on the head pipe 21 so as to be rotatable left and right on the steering center line St, a top bridge 23 is mounted on the upper end of the steering stem 22, and the lower end of the steering stem 22 is mounted. By attaching the bottom bridge 24 and attaching the top of the front fork 25 to the top bridge 23 and the bottom bridge 24, the head pipe 21.
A front fork 25 is attached so as to be rotatable left and right. The head pipe 21 and the steering stem 22 are concentric with respect to the steering center line St, and the front fork 25 is parallel. According to such a steering system 20,
By steering the top bridge 23 to the left and right via the steering rod 27 with the steering handle 34 (see FIG. 2), the front wheel 26 that is a steered wheel can be steered around the steering center line St. The present invention is characterized in that the steering system 20 is provided with a straight travel maintaining mechanism 80, and the front fork 25 is maintained in a state of direct travel by the straight travel maintaining mechanism 80. The straight movement maintaining mechanism 80 attaches a mounting plate 81 to the head pipe 21, attaches a cam plate 82 to the mounting plate 81 with bolts 83, 83, and attaches a swing arm 85 to the bottom bridge 24 of the head pipe 21 with a support shaft 84. The base end is attached so as to be able to swing left and right, and a roller 86 is attached to an intermediate portion of the swing arm 85 so as to be rotatable left and right by a support shaft 87. The cam plate 82 is a member having a semicircular shape in plan view centered on the steering center line St. The cam plate 82 has a substantially V-shaped cam groove 82a at the front end of the outer peripheral surface, and the cam groove 82a is formed on the outer peripheral surface. Arc surfaces 82b and 82b on the left and right sides
Have The cam groove 82a is on the fuselage center CL. On the other hand, the roller 86 as the rolling member is in a position where it can engage with the cam groove 82a when the front fork 25 is directed in the straight direction shown in the drawing. In this way, the cam plate 82 can be provided on the head pipe 21, and the roller 86 can be provided on the front fork 25. Further, in the straight movement maintaining mechanism 80, the tip of the swing arm 85 is attached to the bracket 91 via a tension spring 88 and a connecting rod 89. The bracket 91 is
This is a member extending rearward from the bottom bridge 24. In this way, the tension spring 88 as a resilient member for resiliently urging the roller 86 toward the cam groove 82a is used as the front fork 25.
Provided. The connecting rod 89 serves as an adjustment bolt that adjusts the spring force of the tension spring 88. FIGS. 4 (a) and 4 (b) are operational views of the straight movement maintaining mechanism according to the present invention. (A) is a figure corresponding to the said FIG. 3, Comprising: The state which orient | assigned the front fork 25 to the straight ahead direction is shown. In this state, the roller 86 is engaged with the cam groove 82a, and the swing arm 85 is repelled rearward by the tension spring 88 in order to maintain this engaged state. Therefore, the state in which the front fork 25 is directed straight can be maintained. Furthermore, the three-wheel type management machine 10 (see FIG. 1).
When an external force that attempts to change the direction of the front wheel 26 (see FIG. 1) is transmitted from the front wheel 26 to the front fork 25 when the vehicle travels straight, the cam groove resists the resilient force of the tension spring 88. Until the external force that removes the engagement relationship between the roller 82a and the roller 86 acts, the direction of the front fork 25 in the straight traveling direction can be maintained. Accordingly, it is possible to prevent the front fork 25 from fluctuating left and right when the three-wheel management machine 10 travels straight. For this reason, the three-wheel management machine 10
Therefore, it is possible to reduce the labor of the operator. FIG. 2B shows the front fork 25 by steering the steering handle 34 (see FIG. 2).
Indicates that he steered to the left. As the bottom bridge 24 swings counterclockwise in the figure, the support shaft 84 is also displaced counterclockwise in the figure. As a result, the swing arm 85 turns counterclockwise in the figure. Along with this, the roller 86 is also displaced. When the bottom bridge 24 swings counterclockwise by an angle θ or more, the roller 86 comes off the cam groove 82a and rides on the left arc surface 82b. After the straight movement maintaining mechanism 80 is released in this way, the front fork 2
5 can be freely steered. Front fork 2
The same applies when steering 5 to the right. In the above embodiment of the present invention,
The straight movement maintaining mechanism 80 may be a moderation mechanism (click mechanism) having a combined structure of the cam plate 82, the rolling member 86, and the resilient member 88. Accordingly, even if the rolling member 86 is provided on the head pipe 21 and the cam plate 82 is provided on the front fork 25, the operation and effect are the same.
The elastic member 88 may be provided on either the head pipe 21 or the front fork 25. Further, the mounting position of the cam plate 82 may be shifted backward. For example, the arc center of the cam plate 82 is shifted rearward from the steering center (rotation center of the front fork 25). Since the arc center of the cam plate 82 is decentered rearward from the steering center, the roller 86 has a resilient member when the steering angle is further increased after the roller 86 has moved out of the cam groove 82a and moved onto the arc surface 82b. A force of returning to the cam groove 82a side by the elastic force of 88 works.
Therefore, the straight running stability of the three-wheel type management machine 10 can be further improved. Furthermore, the rolling member 86 is not limited to a roller, and may be a ball, for example. The elastic member 88 may be any member that elastically rolls the rolling member 86 toward the cam groove 82a, and may be, for example, a compression spring in addition to the tension spring. Furthermore, the management machine of the present invention is suitable for a three-wheel type management machine (agricultural working machine for carrying out management such as thinning, weeding, mowing, etc. before harvesting after seedling planting). Alternatively, it can be applied to an equivalent low speed vehicle. Low speed vehicles (including agricultural machinery and transport vehicles)
Then, even if there is a click feeling on the steering wheel, there is no possibility of impairing the running feeling. The present invention exhibits the following effects by the above-described structure. According to the first aspect of the present invention, the rolling member is engaged with the cam groove when the front fork is directed straight, and this engagement state is maintained by the elastic member. The direction of the fork in the straight direction can be maintained. Furthermore, when an external force that changes the direction of the front wheel is transmitted from the front wheel to the front fork when the three-wheeled control machine travels straight, the cam groove and the The direction of the front fork in the straight traveling direction can be maintained until an external force that releases the engagement relationship with the rolling member is applied. Accordingly, it is possible to suppress the front fork from fluctuating from side to side when the three-wheeled management machine travels straight ahead. For this reason, it is possible to improve the straight running stability of the three-wheel type management machine with the front wheel as a free wheel, so that the labor of the operator can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a left side view of a rear-wheel drive three-wheel management machine according to the present invention. FIG. 2 is a plan view of a rear-wheel drive three-wheel management machine according to the present invention. FIG. 4 is a plan view of a front fork mounting structure and a steering system according to the present invention. FIG. 4 is an operation diagram of a straight travel maintaining mechanism according to the present invention.
21 ... Head pipe, 23 ... Top bridge, 24 ... Bottom bridge, 25 ... Front fork, 26 ... Front wheel,
DESCRIPTION OF SYMBOLS 31 ... Rear wheel, 32 ... Engine, 34 ... Steering handle, 40 ... Working tool, 80 ... Straight running maintenance mechanism, 82 ... Cam plate, 82a ... Cam groove, 84 ... Support shaft, 85 ... Swing arm, 86 ... Rolling member (Roller), 88 ... Elastic member (tensile spring).

Continued front page    F-term (reference) 2B043 AA03 AB07 AB11 AB15 BA02                       BB01 BB07 DA04 DB01 DC03                 3D011 AA03 AD01                 3D013 CE00 CF31 CF41                 3D034 BA00 BB04 BC03 BC16 BC30

Claims (1)

What is claimed is: 1. A front wheel is provided with a front wheel at a front portion of the machine body frame, two rear wheels are provided at a rear portion of the machine body frame, and a work tool for processing agricultural products is attached to the machine body frame. A rear-wheel drive three-wheel management machine that drives the left and right rear wheels with an engine, wherein the front wheel is attached to a front fork, and the front fork is rotatably attached to a head pipe of the fuselage frame. In the rear-wheel drive three-wheel management machine that is steerable, the head pipe or the front fork is provided with a cam plate having a cam groove, and the front fork or the head pipe is engaged with the cam groove. And a spring member that springs the rolling member toward the cam groove is provided on the front fork or the head pipe. A rear-wheel drive type three-wheel management machine characterized in that the rolling member is engaged with the cam groove when the shaft is directed in the straight direction.