JP2003095292A - Fuel tank structure of farm work machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel tank structure of a farm work machinery, where an opening/closing operation of an openable cap can be smoothly performed even if a temperature changes. SOLUTION: On a filler opening 18A of a fuel tank 18, a boss part 22 on which the openable cap 23 can be screwed tightly is provided. A male screw part 22A and a female screw part 23A are formed on the boss part 22 and the openable cap 23, respectively. The cap 23 is formed of a phenol resin, and the boss part 22 is formed of a PE resin having a large linear expansion coefficient. A thread ridge shape of a screw start edge part 22a on the male screw part 22A is formed so as to have a small width along a pitch direction and a low thread height, in order to produce the thread ridge shape different from that of another part 22b.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel tank structure mounted on an agricultural work machine.

[0002]

2. Description of the Related Art In the structure of a fuel tank, an opening / closing cap for closing a fuel supply port and a boss portion provided on a fuel tank for screwing the opening / closing cap are usually made of the same material.
However, in general, since the opening / closing cap is gripped to perform the opening / closing operation, a strong operating force may act on the opening / closing cap, and there are cases where it is desired to use a material having high strength for the opening / closing cap. It is also conceivable to adopt a structure in which a relatively soft material is used for the opening / closing cap and elastically deforms even when it comes into contact with another object to reduce damage.

[0003]

As described above, when a material different from the boss portion of the fuel tank is used as the opening / closing cap, the opening / closing cap and the fuel tank boss portion may have different linear expansion coefficients. Then, when refueling after installing the opening / closing cap once, if the temperature is higher than that when the opening / closing cap is installed due to heat generated by the engine, etc., the opening / closing cap is screwed tightly. In some cases, opening and closing operations were difficult. An object of the present invention is to provide an agricultural work machine that does not reduce the sealing performance of the opening / closing cap while easily performing the opening / closing operation even when the temperature is higher than when the opening / closing cap is attached. The point is to provide a fuel tank structure.

[0004]

[Means for Solving the Problems] [Structure] A characteristic structure of a paddy working machine according to the present invention according to claim 1 is that a boss portion to which an opening / closing cap can be screwed is provided at a fuel filler port of a fuel tank, The male screw portion forming the attachment structure is formed of a resin having a larger linear expansion coefficient than that of the female screw portion, and the mountain shape of the screwing start end portion of the male screw portion is formed into a mountain line different from that of the other portion. The width along the direction is small and the thread height is low, and the operation and effect are as follows.

[Operation] When the opening / closing cap is screwed to the boss portion of the fuel tank, the first ridge located at the tip of the male screw portion becomes the portion where the engagement between the male screw portion and the female screw portion is most displaced. On the other hand, since the width along the pitch direction is small and the thread height is low, even if the male screw part having a large linear expansion coefficient expands, the first crest located at the tip of the male screw part. Engages in the first valley of the corresponding female screw portion without any discrepancy.

[Effect] Therefore, even when the male screw portion and the female screw portion have different expansion states, the opening / closing cap is not tightly tightened and the opening / closing operation is facilitated.

[Structure] A characteristic structure according to the present invention according to claim 2 is that a boss portion to which an opening / closing cap can be screwed is provided at a fuel filler port of a fuel tank, and a male screw portion forming the screwing structure is used as a female screw portion. In order to make the valley shape of the threaded end portion of the female threaded portion different from other portions, it is formed of resin having a larger linear expansion coefficient than that of the female threaded portion so that the width along the pitch direction is wide and the thread valley depth is large. Is formed in a deep state, and its action and effect are as follows.

[Operation and Effect] When the opening / closing cap is screwed to the boss portion of the fuel tank, the male screw portion and the female screw portion are located at the deepest portion of the female screw portion, which is the portion where the mesh is most displaced. Since the width along the pitch direction is large and the thread valley depth is deep with respect to one valley,
Even if the male screw portion with a large linear expansion coefficient expands, the first thread located at the tip of the male screw portion corresponds to the first female screw portion.
Engage in the valley without any discrepancy. Therefore, even when the male screw portion and the female screw portion have different expansion states, the opening / closing cap is not tightly tightened and the opening / closing operation is facilitated.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIGS. 1 to 3, a rice transplanter, which is an example of a paddy field working machine, has a multiple-row planting type planting apparatus 2 at a rear portion of a traveling machine body 1 via a link mechanism 3. A lift cylinder 4 using a hydraulic cylinder is provided, which is connected so as to be able to move up and down freely and raises the seedling planting device 2 with pressure oil supply and lowers the seedling planting device 2 by its own weight with oil drainage.

In the traveling vehicle body 1, a mission case 8 is connected to a front portion of a vehicle body frame 6 having a pair of left and right driving front wheels 7 for steering and a pair of left and right driving rear wheels 5 via an axle case 5A. It has a frame structure in which the front step 9 made of metal is connected in a cantilever shape facing forward, and the front section of the front step 9 and the front section of the mission case 8 are connected via a connection frame 10.

As shown in FIG. 1, a driving part 14 is provided in front of a driving part including a driver's seat 11, a steering wheel 12 and a driving step 13, and an engine 15 which is a main body of the driving part 14 is provided. Are mounted and fixed in a state of extending over the connecting frame 10 and the mission case 8. The prime mover 14 is covered with an engine bonnet 17, which covers the upper part of the prime mover 14 and the fuel tank 1.
It comprises an upper cover 19 for accommodating eight, a rear cover 20 for covering the rear part of the driving part 14, and a front cover 21 for covering the front part of the driving part 14.

Next, the fuel tank 18 will be described.
As shown in FIGS. 2 to 4, the fuel tank 18 is a blow molding product of PE resin, and has an oil supply port 18A and a gauge port 1 on the upper surface.
8B is formed and a supply hose nipple 1 is formed on the lower surface.
8C is attached. A boss portion 22 for attaching the opening / closing cap 23 is formed on the oil supply port 18A, and a male screw portion 22A for attaching the opening / closing cap 23 is engraved. On the other hand, flange portions 18D are integrally formed on the left and right side surfaces of the fuel tank 18, and the left and right flange portions 18D are formed.
Mounting seat surfaces 18d and 18d for a handle post (not shown) are formed on D and 18D. This mounting seat surface 18d,
18d is used to fix the fuel tank 18 to the machine body.

The screwing structure of the opening / closing cap 23 and the boss portion 22 will be described. As shown in FIG. 4, the boss portion 22 is formed by injection molding of PE resin, and is attached to the fuel tank 18 by using an adhesive or an adhesive means such as ultrasonic welding. On the other hand, the opening / closing cap 23 is made of phenol resin and has a female screw portion 23A formed on the inner surface.

The opening / closing cap 23 and the fuel tank 1 described above.
8. The coefficient of linear expansion in the boss portion 22 forming the oil supply port 18A is as follows depending on the material.
That is, the opening / closing cap 23 is 0.41 × 10 ⁻⁴ , the fuel tank 18 is 1.70 × 10 ⁻⁴ , and the boss portion is 3.43 × 10 ⁻⁴ .
^-4 , and there is a large difference in linear expansion coefficient between the opening / closing cap 23 and the boss portion 22. Therefore, if the temperature changes after mounting, the opening / closing cap is mounted when the opening / closing cap 23 is mounted. 23 was too tight, which made it difficult to operate.

Therefore, the following improvements have been made.
That is, as shown in FIG. 4 and FIG. 5, three male threads 22A are formed on the cylindrical surface of the boss 22, and the first mountain 22a formed on the tip of the boss 22 is The width of the mountain is narrower than the angle line, and the height of the mountain is low.
That is, the male screw portion 22A is formed into a trapezoidal screw,
As shown in FIG. 5, processing is performed over the inclined surface A and the front end surface B toward the front end side of the boss portion 22 in the first mountain. The machining amount is the second mountain 22 located on the base end side of one pitch.
The amount of processing is gradually reduced by multiplying by b, and processing is performed so as to be connected to another unprocessed mountain without a step. In order to show a specific processing amount, the male screw portion 22
The representative dimensions of A are clearly shown in FIG. Screw pitch a is 4m
m, the tip width b of the screw thread and the bottom width b of the valley are 1.5 mm,
The processing amount c on the inclined surface A is 0.15 mm, the processing amount d on the inclined surface C is 0.05 mm, and the processing amount e on the tip surface B is 0.1.
mm.

At room temperature, as shown in FIG. 6 (a), the male screw portion 22A and the female screw portion 23A appear in a normal screwed state, and when the temperature becomes high, the entire boss portion 22 expands. The processed inclined surface A of the first ridge 22a of the male screw portion 22A is in a state of being close to the first valley portion 23a located on the innermost side of the female screw portion 23A. In the state described above, the second ridge 22b of the male screw portion 22A
Second valley portion 2 of female screw portion 23A corresponding to the inclined surface C of
3b and the inclined surface D of the third crest 22c of the male screw portion 22A and the corresponding third valley portion 23c of the female screw portion 23A are in close contact with each other. The contact state on the inclined surface C is a line contact state extending from the tip end portion to the base end portion of the second crest 22b. By closely contacting the inclined surface C and the inclined surface D, the sealing property is maintained.

In the above embodiment, the case where the linear expansion coefficient of the male screw portion is larger than the linear expansion coefficient of the female screw portion has been described. On the contrary, when the linear expansion coefficient of the male screw part is small, it is best to take the following measures. In other words, three male threads 22A are formed on the cylindrical surface of the boss 22, and the third ridge 22c formed at the base end of the boss 22 has a width narrower than that of the other mountain peaks. Mold the mountain height to a low level. In addition, when the female screw portion is processed, the valley line of the valley located at the tip of the female screw portion 23A is made wide with a wide width along the pitch direction. This allows the opening / closing operation of the opening / closing cap to be performed without any discrepancy.

[Another Embodiment] (1) In the above-described embodiment, the angle line of the male screw portion 22A is changed to deal with the problem. However, as shown in FIG. 7, the first screw positioned at the innermost portion of the female screw portion 23A. The valley diameter portion 23a may be processed to have a wider width along the pitch direction and a deeper valley depth than the other valley diameter portions 23b. That is,
The inclined surface E and the bottom surface F of the first root diameter portion 23a are processed. For the processing on the inclined surface and the processing on the bottom surface, the amount of processing is gradually reduced from the first root diameter portion 23a to the second root diameter portion 23b to prevent a step from occurring, and when the inclined surface E is in close contact The same applies to the point where the above-mentioned inclined surfaces C and D are in close contact with each other. (2) In the embodiment described above, the open / close cap 23 is formed with the female screw portion and the boss portion 22 is formed with the male screw portion, but the open / close cap 23 may be formed with the male screw portion and the boss portion 22 may be formed with the female screw portion.

[Brief description of drawings]

[Figure 1] Side view of rice transplanter

[Fig. 2] Side view of the fuel tank

FIG. 3 is a plan view of the fuel tank.

FIG. 4 is an exploded vertical sectional view showing an opening / closing cap and a boss portion of a fuel tank.

FIG. 5 is a vertical cross-sectional view showing a state in which the first screw thread of the boss portion is processed into a chevron line different from other threads.

FIG. 6 is a vertical cross-sectional view showing a screwed state of an opening / closing cap and a boss portion of a fuel tank.

FIG. 7 is a vertical cross-sectional view showing a state in which the female screw portion of the opening / closing cap is processed.

[Explanation of symbols]

18 Fuel tank 18A Filling port 22 Boss 22A male screw part 23 Open / close cap 23A Female screw part

Claims (2)

[Claims] 1. A fuel tank is provided with a boss portion to which an opening / closing cap can be screwed, and a male screw portion forming the screwing structure is made of resin having a linear expansion coefficient larger than that of a female screw portion. In order to make the mountain shape of the screwing start end portion in the male screw portion into a mountain line different from other portions,
A fuel tank structure for agricultural work machines that has a small width along the pitch direction and a low thread height. 2. A fuel supply port of a fuel tank is provided with a boss portion to which an opening / closing cap can be screwed, and a male screw portion forming the screwing structure is formed of resin having a linear expansion coefficient larger than that of a female screw portion, In order to make the valley shape of the screwing end portion in the female screw portion a valley line different from other portions, the width of the agricultural machine is wide along the pitch direction and the depth of the screw valley is deep. Fuel tank structure.