Working machinery

Abstract

To provide a work machine that can prevent more fuel than expected from being supplied to a fuel tank.SOLUTION: A work machine comprises a fuel tank having: a tank body having an internal space for storing fuel; a cylindrical fuel supply cylinder penetrating an outer wall of the tank body so that a top opening is exposed to the outside of the tank body and a bottom opening is located in the internal space of the tank body; and an opening / closing member that opens and closes the bottom opening by moving up and down with buoyancy received from the fuel stored in the internal space of the tank body. The opening / closing member includes: a floating body that moves up and down along an outer peripheral surface of the fuel supply cylinder with buoyancy received from the fuel stored in the fuel tank; a lid body that is disposed below the floating body and the bottom opening and has a larger area than that of the bottom opening; and a connecting member for connecting the lid body to the floating body.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a work machine equipped with a fuel tank.

Background Art

[0002] Currently, many work machines operate by the driving force generated by an engine. In such a work machine, if it is driven with more fuel stored in the fuel tank than expected, fuel may overflow from the fuel filler due to an increase in pressure inside the fuel tank or vibrations during the operation of the work machine.

[0003] Therefore, in order to solve such problems, Patent Document 1 discloses a technique in which a plate that rotates by receiving buoyancy from the fuel in the fuel tank closes the lower surface of the fuel filler at a timing when a predetermined amount of fuel is supplied to the fuel tank.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the fuel tank described in Patent Document 1, since the plate is disposed at a position where the fuel supplied through the fuel filler directly hits, when the fuel is supplied vigorously, the fuel collides with the plate and the rotation of the plate is hindered. As a result, the problem remains that the fuel filler is not closed at an appropriate timing and more fuel than expected is supplied to the fuel tank.

[0006] The present invention has been made in view of the above-described actual situation, and an object thereof is to provide a work machine capable of preventing more fuel than expected from being supplied to the fuel tank.

Means for Solving the Problems

[0007] To achieve the above objective, the present invention provides a fuel tank for storing fuel. Ku In a work machine equipped with a fuel tank, the fuel tank comprises a tank body having an internal space for storing fuel, a cylindrical fuel supply pipe penetrating the outer wall of the tank body such that its upper opening is exposed to the outside of the tank body and its lower opening is located in the internal space of the tank body, and an opening / closing member that opens and closes the lower opening by moving up and down due to buoyancy from the fuel stored in the internal space of the tank body, wherein the opening / closing member moves along the outer surface of the fuel supply pipe due to the buoyancy received from the fuel stored in the fuel tank With the outer circumferential surface of the fuel supply cylinder surrounded The invention is characterized by comprising a floating body that moves up and down, a lid positioned below the floating body and the lower opening and having a larger area than the lower opening, and a connecting member that connects the lid and the floating body. [Effects of the Invention]

[0008] According to the present invention, it is possible to obtain a work machine that can prevent more fuel than intended from being supplied to the fuel tank. Other problems, configurations, and effects will be clarified by the following description of embodiments. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of a hydraulic excavator, which is a representative example of a work machine according to the present invention. [Figure 2] This is a perspective view of a fuel tank with the left side wall omitted. [Figure 3] This is an external view of the fuel supply cylinder. [Figure 4] This is an external view of the opening and closing mechanism. [Figure 5] This is a perspective view of the fuel supply cylinder with the opening / closing mechanism attached. [Figure 6] This is an external view of a level gauge. [Figure 7] This diagram shows the opening / closing members and level gauge that operate in conjunction with each other. [Modes for carrying out the invention]

[0010] Embodiments of the work machine according to the present invention will be described with reference to the drawings. Figure 1 is a perspective view of a hydraulic excavator 1, which is a representative example of the work machine according to the present invention. In this specification, front, back, left, and right directions are based on the viewpoint of the operator riding and operating the hydraulic excavator 1, unless otherwise specified.

[0011] The hydraulic excavator 1 comprises a lower traveling body 2 and an upper rotating body 3 supported by the lower traveling body 2. The lower traveling body 2 and the upper rotating body 3 are examples of the vehicle body. The lower traveling body 2 is equipped with a pair of left and right crawlers. When the rotation of the traveling motor (not shown) is transmitted and the pair of left and right crawlers rotate, the hydraulic excavator 1 moves. However, the lower traveling body 2 may be wheeled instead of having crawlers.

[0012] The upper slewing body 3 is rotatably supported by the lower traveling body 2. The upper slewing body 3 rotates relative to the lower traveling body 2 when the driving force of a slewing motor (not shown) is transmitted to it. The upper slewing body 3 mainly consists of a base slewing frame 5, a front work implement 4 mounted vertically rotatably at the center of the front end of the slewing frame 5, a cab (driver's seat) 7 located on the front left side of the slewing frame 5, and a counterweight 6 located at the rear end of the slewing frame 5.

[0013] The front work implement 4 includes a boom 4a supported on the upper slewing body 3 so as to be able to move up and down, an arm 4b supported at the tip of the boom 4a so as to be able to swing, a bucket 4c supported at the tip of the arm 4b so as to be able to swing, and hydraulic cylinders 4d, 4e, and 4f that drive the boom 4a, arm 4b, and bucket 4c. The counterweight 6 is for balancing the weight with the front work implement 4 and is a heavy object that has an arc shape when viewed from above.

[0014] The cab 7 has an interior space where an operator who operates the hydraulic excavator 1 rides. In the interior space of the cab 7, a seat on which the operator sits and an operating device that the operator sitting on the seat operates are arranged. Then, when the operator boarding the cab 7 operates the operating device, the lower traveling body 2 travels, the upper revolving body 3 revolves, and the front working machine 4 operates.

[0015] Further, the upper revolving body 3 supports the engine house 8. The engine house 8 is supported by the swing frame 5 behind the front working machine 4 and the cab 7 and in front of the counterweight 6. The engine house 8 has an interior space for housing components (for example, in addition to the engine 9, a heat exchanger, a cooling fan, a post-treatment device, a hydraulic pump, etc.) for operating the hydraulic excavator 1.

[0016] Furthermore, the upper revolving body 3 supports the fuel tank 10. The fuel tank 10 is supported by the swing frame 5 in front of the engine house 8 and on the right side of the cab 7. Also, the upper surface and the right surface of the fuel tank 10 are exposed to the outside of the upper revolving body 3. The fuel tank 10 stores fuel (for example, light oil). Then, the engine 9 generates a driving force for operating the hydraulic excavator 1 by burning the fuel stored in the fuel tank 10.

[0017] FIG. 2 is a perspective view of the fuel tank 10 with the left side wall omitted. FIG. 3 is an external view of the fuel supply cylinder 12. FIG. 4 is an external view of the opening and closing member 13. FIG. 5 is a perspective view of a state where the opening and closing member 13 is attached to the fuel supply cylinder 12. FIG. 6 is an external view of the level gauge 14. As shown in FIG. 2, the fuel tank 10 mainly includes a tank body 11, a fuel supply cylinder 12, an opening and closing member 13, and a level gauge 14.

[0018] As shown in FIG. 2, the tank body 11 generally has the outer shape of a rectangular parallelepiped. Further, the tank body 11 has an internal space 15 for storing fuel. Furthermore, the internal space 15 of the tank body 11 is defined by a top wall 16, a bottom wall 17, a front side wall 18, a rear side wall 19, a right side wall 20, and a left side wall (not shown). However, the specific shape of the tank body 11 is not limited to the example of FIG. 2.

[0019] A through-hole 21 penetrating in the thickness direction is formed in the top wall 16 defining the top surface of the internal space 15. And a fuel supply cylinder 12 is attached to the through-hole 21. Also, a through-hole 22 penetrating in the thickness direction is formed in the bottom wall 17 defining the bottom surface of the internal space 15. And a pipe (not shown) for supplying fuel to the engine 9 is connected to the through-hole 22. That is, fuel is supplied into the internal space 15 through the fuel supply cylinder 12 attached to the through-hole 21, and fuel flows out from the internal space 15 through the pipe connected to the through-hole 22.

[0020] As shown in FIG. 3, the fuel supply cylinder 12 has an outer shape of a cylindrical shape (more specifically, a circular cylindrical shape) with both end faces in the axial direction open. That is, the fuel supply cylinder 12 penetrates in the axial direction. Hereinafter, the opening on the upper surface side of the fuel supply cylinder 12 is denoted as "upper surface opening 23", and the opening on the lower surface side is denoted as "lower surface opening 24".

[0021] The fuel supply cylinder 12 penetrates the top wall 16 (outer wall) of the tank body 11. Also, the fuel supply cylinder 12 is extended in the vertical direction such that the upper surface opening 23 faces upward and the lower surface opening 24 faces downward. Also, the upper surface opening 23 is exposed to the outside of the tank body 11. On the other hand, the lower surface opening 24 is located inside the internal space 15 of the tank body 11. Furthermore, the upper surface opening 23 is opened and closed by a detachable cap (not shown) at the upper end of the fuel supply cylinder 12.

[0022] The fuel supply cylinder 12 is provided with projections 25a and 25b. The projections 25a and 25b protrude radially outward from the outer circumferential surface of the fuel supply cylinder 12. Furthermore, the projections 25a and 25b are arranged at equal intervals (180° intervals in this embodiment) in the circumferential direction of the fuel supply cylinder 12. In addition, the projections 25a and 25b are provided at the lower end of the fuel supply cylinder 12. That is, when the fuel supply cylinder 12 is installed in the through hole 21, the projections 25a and 25b are positioned within the internal space 15 of the tank body 11.

[0023] Furthermore, the projections 25a and 25b have tapered surfaces 26a and 26b that are inclined to decrease in protrusion amount toward the downward direction. On the other hand, the upper surfaces of the projections 25a and 25b are planes perpendicular to the direction of movement of the opening / closing member 13 (i.e., the vertical direction). However, the number of projections 25a and 25b is not limited to two; there may be one or three or more.

[0024] The opening / closing member 13 is positioned in the internal space 15 of the tank body 11. It opens and closes the bottom opening 24 by moving up and down, receiving buoyancy from the fuel stored in the internal space 15 of the tank body 11. More specifically, as the amount of fuel stored in the internal space 15 increases, the opening / closing member 13 moves upward to close the bottom opening 24. Conversely, as the amount of fuel stored in the internal space 15 decreases, the opening / closing member 13 moves downward to open the bottom opening 24. As shown in Figure 4, the opening / closing member 13 consists of a lid 27, a float 28, connecting members 29a and 29b, and closing members 30a and 30b.

[0025] The lid 27 has a disc-shaped outer form. Furthermore, the diameter of the lid 27 is set to be larger than the diameter of the bottom opening 24. In addition, the lid 27 is made of a material with a density greater than the fuel stored in the internal space 15. That is, the lid 27 is configured to sink into the fuel stored in the internal space 15.

[0026] The floating body 28 has a ring-shaped outer shape. The inner diameter of the floating body 28 is set to be larger than the outer diameter of the fuel supply cylinder 12. Furthermore, the floating body 28 is made of a material with a lower density than the fuel stored in the internal space 15. In other words, the floating body 28 is configured to float on the fuel stored in the internal space 15.

[0027] The connecting members 29a and 29b connect the lid 27 and the float 28. More specifically, the lower ends of the connecting members 29a and 29b are connected to the upper surface of the lid 27, and the upper ends are connected to the lower surface of the float 28. In addition, at least a portion of the connecting members 29a and 29b is located radially inward from the inner circumferential surface of the float 28. Furthermore, the connecting members 29a and 29b are arranged at equal intervals (180° intervals in this embodiment) in the circumferential direction of the lid 27 and the float 28. The number and arrangement of the connecting members 29a and 29b correspond to the protrusions 25a and 25b provided on the fuel supply cylinder 12.

[0028] Furthermore, the connecting members 29a and 29b are provided with grooves 31a and 31b (31a is not shown). The grooves 31a and 31b are formed by recessing the inner surfaces of the connecting members 29a and 29b. The grooves 31a and 31b extend in the vertical direction. In addition, the lower ends of the grooves 31a and 31b are closed by the cover 27, and the upper ends are closed by closing members 30a and 30b. The closing members 30a and 30b may be detachable from the connecting members 29a and 29b.

[0029] The opening / closing member 13 is configured to float as a whole on the fuel stored in the internal space 15. More specifically, the density (buoyancy) of the opening / closing member 13 is set such that the entire lid 27 sinks in the fuel and at least a portion of the floating body 28 is located above the liquid surface.

[0030] As shown in Figure 5, the opening / closing member 13 is attached to the lower part of the fuel supply cylinder 12. More specifically, with the lid 27 facing downwards and the float 28 upwards, and the connecting members 29a and 29b facing the projections 25a and 25b, the opening / closing member 13 is inserted from below upwards into the fuel supply cylinder 12. At this time, the connecting members 29a and 29b, guided by the tapered surfaces 26a and 26b, elastically deform so as to expand outwards, and the closing members 30a and 30b overcome the projections 25a and 25b. As a result, the projections 25a and 25b enter the grooves 31a and 31b, and the opening / closing member 13 is attached to the fuel supply cylinder 12.

[0031] However, the method of attaching the opening / closing member 13 to the fuel supply cylinder 12 is not limited to the example described above. As another example, the opening / closing member 13 may be attached to the fuel supply cylinder 12 with the blocking members 30a and 30b removed. Then, the projections 25a and 25b may be inserted into the grooves 31a and 31b, and the blocking members 30a and 30b may be attached to the connecting members 29a and 29b.

[0032] When the opening / closing member 13 is attached to the fuel supply cylinder 12, the lid 27 is positioned below the bottom opening 24. The lid 27 is also positioned so as to overlap the bottom opening 24 when viewed from the extending direction of the fuel supply cylinder 12. The floating body 28 is positioned above the lid 27 so as to surround the outer circumferential surface of the fuel supply cylinder 12. The connecting members 29a and 29b are positioned facing the projections 25a and 25b. The grooves 31a and 31b receive the projections 25a and 25b.

[0033] The opening / closing member 13 is guided by projections 25a and 25b that enter the grooves 31a and 31b, and moves (i.e., moves up and down) in the extending direction of the fuel supply cylinder 12. As shown in Figure 5(A), the lower end of the movement range of the opening / closing member 13 is the position where the projections 25a and 25b abut against the closing members 30a and 30b. At this time, the cover 27 separates from the lower end of the fuel supply cylinder 12, and the bottom opening 24 is opened. On the other hand, as shown in Figure 5(B), the upper end of the movement range of the opening / closing member 13 is the position where the cover 27 abuts against the lower end of the fuel supply cylinder 12. As a result, the bottom opening 24 is closed.

[0034] The level gauge 14 is used to allow the operator to recognize when a predetermined amount of fuel has been stored in the internal space 15 of the tank body 11. The level gauge 14 is located inside the fuel supply cylinder 12. As shown in Figure 6, the level gauge 14 mainly comprises a frame 32, a float 33, an indicator 34, and a guard member 35.

[0035] The frame 32 is formed into a cylindrical shape with an open top and sides by combining columnar members. The frame 32 is housed in the fuel supply cylinder 12. The frame 32 also supports the float 33 so that it can move vertically. Furthermore, the frame 32 supports the guard member 35 above the float 33.

[0036] The float 33 is supported at the bottom of the frame 32 so as to be able to move up and down. The float 33 is made of a material that is less dense than the fuel. That is, the float 33 moves up and down inside the fuel supply cylinder 12 by the buoyancy it receives from the fuel inside the fuel supply cylinder 12. More specifically, the float 33 rises as the amount of fuel in the fuel supply cylinder 12 increases and descends as the amount of fuel in the fuel supply cylinder 12 decreases.

[0037] The indicator 34 is a long, rod-shaped member that protrudes upward from the float 33. The indicator 34 moves up and down together with the float 33. As shown in Figure 6(A), when the float 33 is at the lower end of its range of motion, the upper end of the indicator 34 is retracted into the frame 32 (in other words, the fuel supply cylinder 12). On the other hand, as shown in Figure 6(B), when the float 33 rises to a predetermined position, the upper end of the indicator 34 protrudes upward from the upper end of the frame 32 (in other words, the upper opening 23 of the fuel supply cylinder 12).

[0038] The guard member 35 has a conical shape. The guard member 35 is fixed inside the frame 32 above the float 33 with its apex facing upwards. The guard member 35 guides the fuel supplied from above to an opening provided on the side of the frame 32. This prevents the fuel supplied to the fuel supply cylinder 12 through the upper opening 23 from directly hitting the float 33.

[0039] Figure 7 shows the opening / closing member 13 and level gauge 14 which operate in conjunction. When the liquid level of the fuel stored in the internal space 15 of the tank body 11 is below the bottom opening 24, the opening / closing member 13 is located at the lower end of its range of motion as shown in Figure 5(A), and the float 33 is located at the lower end of its range of motion as shown in Figure 6(A). That is, as shown in Figure 7(A), the bottom opening 24 is open and the indicator 34 is retracted into the fuel supply cylinder 12.

[0040] Fuel supplied into the fuel supply cylinder 12 through the upper opening 23 is supplied to the internal space 15 of the tank body 11 through the lower opening 24. After the liquid level in the internal space 15 reaches the position of the float 28, the opening / closing member 13 rises as the liquid level rises. After the liquid level in the internal space 15 reaches the lower opening 24, the liquid levels in the tank body 11 and the fuel supply cylinder 12 become equal. Furthermore, the float 33 rises as the liquid level in the fuel supply cylinder 12 rises.

[0041] As more fuel is supplied to the fuel supply cylinder 12, the tip of the indicator 34 protrudes above the top opening 23, as shown in Figure 7(B). However, at the moment the tip of the indicator 34 protrudes from the top opening 23, the cover 27 has not yet closed the bottom opening 24. Then, as more fuel is supplied to the fuel supply cylinder 12, the cover 27 comes into contact with the lower end of the fuel supply cylinder 12, closing the bottom opening 24.

[0042] The timing of the indicator 34 protruding and the timing of the lid 27 closing the lower opening 24 are determined by the length of the connecting members 29a, 29b or the indicator 34. In other words, it is desirable that the connecting members 29a, 29b (or the indicator 34) be set to a length such that the lid 27 closes the lower opening 24 after the indicator 34 has protruded from the upper opening 23. In other words, it is desirable that the connecting members 29a, 29b (or the indicator 34) be set to a length such that the indicator 34 protrudes from the upper opening 23 before the lid 27 closes the lower opening 24.

[0043] According to the above embodiment, for example, the following effects are achieved.

[0044] According to the above embodiment, the lid 27 sinks into the fuel stored in the internal space 15, and the float 28 moves along the outer surface of the fuel supply cylinder 12, so that the fuel flowing into the internal space 15 through the bottom opening 24 does not directly hit the opening / closing member 13. As a result, the bottom opening 24 is closed by the lid 27 at a predetermined timing, regardless of the force of the fuel supplied to the fuel supply cylinder 12. Consequently, it is prevented that more fuel than intended is supplied to the fuel tank 10.

[0045] Furthermore, according to the above embodiment, the projections 25a and 25b that enter the grooves 31a and 31b guide the vertical movement of the opening / closing member 13, so that the opening / closing member 13 moves up and down smoothly. In addition, the vertical movement of the opening / closing member 13 becomes even smoother when the projections 25a and 25b and the grooves 31a and 31b are arranged at equal intervals.

[0046] Furthermore, according to the above embodiment, by attaching the closing members 30a and 30b to the upper ends of the grooves 31a and 31b, the opening and closing member 13 is prevented from falling out of the fuel supply cylinder 12 even when the fuel level in the internal space 15 falls below the lower opening 24.

[0047] Also, as in the above-described embodiment, by protruding the indicator 34 before the lid 27 closes the bottom opening 24, it is possible to prevent the fuel supply from continuing even after the bottom opening 24 is closed. As a result, after the bottom opening 24 is closed, the amount of fuel remaining in the fuel supply cylinder 12 can be reduced more than before.

[0048] Furthermore, in the above-described embodiment, the hydraulic excavator 1 equipped with the crawler-type lower traveling body 2 has been described as an example of the working machine. However, the present invention is not limited to this, and for example, it may be applied to a hydraulic excavator equipped with a wheel-type lower traveling body. In addition, it can be widely applied to other working machines such as wheel loaders, dump trucks, and hydraulic cranes.

[0049] The above-described embodiments are examples for explaining the present invention, and the scope of the present invention is not intended to be limited only to those embodiments. Those skilled in the art can implement the present invention in various other ways without departing from the gist of the present invention. For example, the lid 27 is not limited to a circular shape, and any shape may be used as long as it is larger than the cross-sectional area of the bottom opening 24 and can close the bottom opening 24 when contacting the fuel supply cylinder 12.

Explanation of Reference Numerals

[0050] 1 Hydraulic excavator (working machine) 2 Lower traveling body (vehicle body) 3 Upper revolving body (vehicle body) 4 Front working machine 4a Boom 4b Arm 4c Bucket 4d, 4e, 4f Hydraulic cylinder 5 Swivel frame 6 Counterweight 7 Cab 8 Engine house 9 Engine 10 Fuel tank 11 Tank body 12 Fuel supply cylinder 13 Opening / closing member 14 Level Gauge 15 Interior space 16. Top wall (exterior wall) 17 Bottom wall 18 Front wall 19 Rear wall 20 Right side wall 21 Through hole 22 Through hole 23 Top opening 24 Bottom opening 25a,25b protrusion 26a, 26b Tapered surface 27 Lid 28 Floating bodies 29a, 29b Connecting members 30a, 30b Closure members 31a,31b Groove 32 frames 33 Floats 34 Indicators 35 Guard member

Claims

1. In a work machine equipped with a fuel tank for storing fuel, The aforementioned fuel tank is A tank body having an internal space for storing fuel, A cylindrical fuel supply pipe penetrates the outer wall of the tank body such that its upper opening is exposed to the outside of the tank body and its lower opening is located in the internal space of the tank body, The tank body has an opening / closing member that opens and closes the lower opening by moving up and down due to buoyancy from the fuel stored in the internal space of the tank body, The opening and closing member is A floating body that moves up and down along the outer surface of the fuel supply cylinder, surrounding the outer surface of the fuel supply cylinder, due to the buoyancy it receives from the fuel stored in the fuel tank, A lid positioned below the floating body and the lower opening, and having an area larger than the lower opening, It comprises a connecting member that connects the lid and the float. A work machine characterized by the following features.

2. A fuel tank for storing fuel, A work machine comprising an engine that generates driving force by burning fuel stored in the aforementioned fuel tank, The aforementioned fuel tank is A tank body having an internal space for storing fuel, A cylindrical fuel supply pipe penetrates the outer wall of the tank body such that its upper opening is exposed to the outside of the tank body and its lower opening is located in the internal space of the tank body, The tank body has an opening / closing member that opens and closes the lower opening by moving up and down due to buoyancy from the fuel stored in the internal space of the tank body, The opening and closing member is A floating body that moves up and down along the outer surface of the fuel supply cylinder due to the buoyancy it receives from the fuel stored in the fuel tank, A lid positioned below the floating body and the lower opening, and having an area larger than the lower opening, It has a connecting member that connects the lid and the float, The fuel supply cylinder has a projection that protrudes radially outward from the outer surface, The connecting member has a groove formed therein that receives the projection and extends in the vertical direction. A work machine characterized by the following features.

3. In the work machine described in claim 2, The connecting member is fitted with a closing member that closes the upper end of the groove. A work machine characterized by the following features.

4. In the work machine described in claim 2, The fuel supply cylinder has a plurality of protrusions at equally spaced positions in the circumferential direction, The opening and closing member has a plurality of connecting members, each having a groove formed thereon at a position facing each of the plurality of protrusions. A work machine characterized by the following features.

5. A fuel tank for storing fuel, A work machine comprising an engine that generates driving force by burning fuel stored in the aforementioned fuel tank, The aforementioned fuel tank is A tank body having an internal space for storing fuel, A cylindrical fuel supply pipe penetrates the outer wall of the tank body such that its upper opening is exposed to the outside of the tank body and its lower opening is located in the internal space of the tank body, The tank body has an opening / closing member that opens and closes the lower opening by moving up and down due to buoyancy from the fuel stored in the internal space of the tank body, The opening and closing member is A floating body that moves up and down along the outer surface of the fuel supply cylinder due to the buoyancy it receives from the fuel stored in the fuel tank, A lid positioned below the floating body and the lower opening, and having an area larger than the lower opening, It has a connecting member that connects the lid and the float, The system includes a float that moves up and down inside the fuel supply cylinder due to the buoyancy it receives from the fuel, and a level gauge having an indicator that protrudes from the top opening when the float has risen to a predetermined position. The connecting member is set to a length such that the lid closes the lower opening after the indicator protrudes from the upper opening. A work machine characterized by the following features.

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