JP2566443B2 - Fuel supply system for construction machinery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel supply system for an engine of a construction machine.

Prior Art FIG. 6 is a side view of a prior art wheeled shovel 1. In the figure, 2 is a lower traveling body of a wheel type shovel 1, 3 is an upper revolving structure, 4 is an engine, 5 is a fuel tank, 6 is a hydraulic oil tank, 7 is a counterweight, 8 is a swivel connecting portion, and 0-0 is The turning center, R ₁ is the rear single turning radius. FIG. 7 is a diagram showing a conventional fuel supply system 9.

Next, details of the conventional fuel supply system 9 will be described with reference to FIGS. 6 and 7. In the wheel type shovel 1, an upper revolving structure 3 is provided on a lower traveling structure 2 via a revolving connecting portion 8 so as to be revolvable, and an engine 4 and a fuel tank 5 are mounted on the upper revolving structure 3. Therefore, the fuel oil is fed from the feed side port 10 of the fuel tank 5 to the feed oil passage 1
1, oil is sent through the fuel pump and the injection pump 12. Then, the fuel overflow portion returns from the return side port 13 of the injection pump 12 to the fuel tank 5 via the return oil passage 14 and the return side port 15 of the fuel tank 5.

Problem to be Solved by the Invention When a wheel type shovel is used for work on a narrow site such as in an urban area or on a main road, if the turning radius of the rear end of the counterweight is large, the work becomes difficult or the above main line It blocks road traffic. Also, since various heavy equipment is mounted on the upper swing body,
The center of gravity was high and the stability of the car was poor. Further, since the fuel tank is arranged in the upper revolving structure, the fuel refueling position is high, and the fuel refueling position had to rise above the revolving structure at the time of refueling. Therefore, the fuel tank on the revolving structure has been relocated to the lower traveling structure, the engine mounting position has been arranged more toward the front side and the rear end turning radius has been reduced, and the center of gravity position of the vehicle body has been lowered and the fuel refueling workability has been improved. I am considering. However, when the fuel tank is installed in the lower traveling structure, the position of the engine mounted on the upper revolving structure is high, so fuel oil descent in the feed side oil passage, air entrapment, etc. occur,
There was a risk that the engine would start poorly and that engine stalls during work.

An object of the present invention is to solve the above problems and to provide a fuel supply system for a construction machine in which a fuel tank is arranged in a lower traveling structure and an engine is arranged in an upper revolving structure.

Means for Solving the Problems The means of the present invention taken to solve the above problems are a. The feed side port of the fuel tank arranged in the lower traveling structure and the swivel joint are connected via a check valve for preventing fuel oil descent to form a lower feed circuit. In addition, the swivel joint, the fuel pump for the engine, and the injection pump are communicated with each other through the upper feed circuit. Further, the fuel overflow return side port of the injection pump and the upper feed circuit are connected via a check valve, or the overflow return side port and the fuel tank are set to be communicable via a swivel joint, D. When the fuel oil in the fuel tank is supplied to the engine, the fuel oil can be prevented from falling, and the overflow fuel oil can be returned to the feed side circuit or the fuel tank.

Action a. A check valve is provided in the oil passage that connects the feed side port of the fuel tank and the swivel joint to form a lower feed circuit, whereby the feed circuit side that communicates with the engine from the fuel tank through the swivel joint is formed. It is possible to prevent the fuel oil from descending due to gravity and accompanying entrapment of air.

B. When the return port for fuel overflow in the injection pump and the upper feed circuit are connected via the check valve, the overflow fuel oil is sent to the upper feed circuit again without returning to the fuel tank. In this way, the overflow fuel oil is recycled and flowed directly to the upper feed circuit, so that this overflow circuit serves to assist the operation of the fuel pump.

C. When the return port for fuel overflow in the injection pump and the fuel tank are communicated with each other through the swivel joint, all the overflow fuel oil returns to the fuel tank through the swivel joint.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side view of a wheel type shovel 16 having a fuel supply system according to the present invention. In the figure, 17 is a lower traveling body, 18 is an upper swing body, 19 is a swing connecting portion, 20 is a fuel tank, 4'is an engine, and 7 is a counterweight. The rear end turning radius R ₂ of the wheel type shovel 16 is the rear end turning radius of the conventional wheel shovel 1.
The dimensions are smaller than R ₁ . FIG. 2 is a diagram showing a configuration around a fuel supply system in a portion A of FIG. In the figure, 21 is a fuel supply system according to the present invention, 22 is a swivel joint, and 23 is a swivel bearing. Third
The figure shows a fuel supply system 21 according to the present invention. In the figure, 24 is a swivel joint, and 25 and 26 are check valves.

Next, the configuration of the fuel supply system 21 according to the present invention will be described with reference to FIG. The feed side port 27 of the fuel tank 20 arranged in the lower traveling structure 17 and the swivel joint 24 were connected via a check valve 25 for preventing fuel oil lowering to form a lower feed circuit. Moreover, the swivel joint 24 and the engine fuel pump and injection pump 12 'are connected by the upper feed circuit 28. Further, the fuel overflow return side port 13 'of the injection pump 12' and the upper feed circuit 28 are connected via a check valve 26. When the fuel oil in the fuel tank 20 is supplied to the engine 4 ', the fuel oil can be prevented from falling and the overflow fuel oil can be returned to the feed side circuit 28.

Next, the function and function of the fuel supply system 21 according to the present invention will be described. The fuel oil is supplied to the feed side port 27 of the fuel tank 20, the oil passage 29, the check valve 25, the oil passage 30, the swivel joint 24's port A, oil passage B, C, port D, oil passage 28, fuel pump and injection pump 12. After that, oil is sent. Since the check valve 25 is provided in the lower feed circuit, the lowering of the fuel oil on the upper feed circuit 28 side due to gravity and the accompanying air entrapment are prevented. Also the injection pump 1
Return side port 13 'for fuel overflow at 2'
And the upper feed circuit 28 are connected via the check valve 26, the overflow fuel oil does not return to the fuel tank 20,
Oil is again sent to the upper feed circuit 28. In this way, the overflow fuel oil is recycled and flowed directly to the upper feed circuit 28, and this overflow circuit serves to assist the operation of the fuel pump.

FIG. 4 is a diagram showing another embodiment fuel supply system 31 according to the present invention. The fuel supply system 31 is different from the system 21 shown in FIG. 3 in that the fuel overflow return port 13 'in the injection pump 12' and the fuel tank 20 '.
The return-side port 32 is configured to be able to communicate with each other via the swivel joint 24. As a result, all the overflow fuel oil returns to the fuel tank 20 'through the swivel joint 24.

FIG. 5 is a diagram showing another embodiment of a fuel supply system 33 according to the present invention. The fuel supply system 33 differs from the system 21 in FIG. 3 in that an air bleeding circuit from the injection pump 12 'to the fuel tank 20' via the swivel joint 24 is provided. Reference numeral 34 is an air bleeding throttle portion provided in the air bleeding circuit.

As described above, in the fuel supply system according to the present invention, since the check valve for preventing the fuel oil lowering is provided in the lower feed circuit, the fuel of the lower traveling body is not mixed with the descending air of the fuel oil in the feed circuit. Fuel can be fed from the tank to the engine of the upper revolving structure. Furthermore, in a system in which the return port for fuel overflow in the injection pump and the upper feed circuit are connected via a check valve, the overflow fuel oil is directly recycled to the upper feed circuit, so that the minimum amount of fuel oil combustion is minimized. The amount of oil from the fuel tank
It can be sucked into the injection pump side via the swivel joint. As a result, the fuel oil is satisfactorily fed even when the self-sufficiency of the fuel pump is reduced during cold weather.

The turning radius of the rear end of the construction machine equipped with this fuel supply system is smaller than that of the conventional construction machine, and the center of gravity of the vehicle body is lowered to improve the vehicle body stability.
Fuel supply becomes easy.

Effects of the Invention A fuel tank on an upper swing structure of a construction machine is transferred to a lower traveling structure, and an engine mounting position is arranged on a more front side to reduce a rear end turning radius and lower a center of gravity position of a vehicle body. Improvements in fuel supply workability are taken into consideration. However, when the fuel tank is installed on the lower traveling structure, the position of the engine mounted on the upper revolving structure is high, so the fuel oil drops in the feed-side oil passage, air gets caught, and the engine starts. There is a risk that the product may become defective or that it may stall during work.

However, in the fuel supply system according to the present invention, since the lower feed circuit is provided with the check valve for preventing fuel oil drop,
Fuel can be fed from the fuel tank of the lower traveling structure to the engine of the upper revolving structure without lowering the fuel oil in the feed circuit and entrapment of air. Furthermore, in a system in which the return port for fuel overflow in the injection pump and the upper feed circuit are connected via a check valve, the overflow fuel oil is directly recycled to the upper feed circuit, so that the minimum amount of fuel oil combustion is minimized. The amount of oil can be sucked from the fuel tank to the injection pump side through the swivel joint. As a result, the fuel oil can be satisfactorily fed even when the self-sufficiency of the fuel pump is reduced in cold weather.

Therefore, in the construction machine equipped with the fuel supply system according to the present invention, the fuel supply function from the fuel tank of the lower traveling structure to the engine of the upper revolving structure is improved, the rear end turning radius of the upper revolving structure is reduced, and the center of gravity of the vehicle body is positioned. Improve degradation and refueling performance problems.

[Brief description of drawings]

FIG. 1 is a side view of a wheel type excavator having a fuel supply system according to the present invention, FIG. 2 is a view showing the configuration around the fuel supply system in the portion A of FIG. 1, and FIG. 3 is a fuel of the present invention. FIG. 4 is a view showing a supply system, FIGS. 4 and 5 are views showing a fuel supply system of another embodiment of the present invention, FIG. 6 is a side view of a conventional wheel shovel, and FIG. 7 is a conventional fuel supply system. FIG. 1,16 …… Wheel type excavator 2,17 …… Lower traveling structure 3,18 …… Upper revolving structure 4,4 ′ …… Engine 5,20,20 ′ …… Fuel tank 8,19 …… Swivel connection 9 , 21,31,33 …… Fuel supply system 12,12 ′ …… Injection pump 22,24 …… Swivel joint 25,26 …… Check valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Mitsunari 2-9-2 Kuchidanami, Asakita-ku, Hiroshima City, Hiroshima Prefecture Examiner Susumu Takagi

Claims (1)

(57) [Claims] 1. A construction machine in which an upper revolving structure is rotatably provided on a lower traveling structure via a revolving joint, an engine is mounted on the upper revolving structure, and an engine fuel tank is arranged on the lower traveling structure. A lower feed circuit is formed by connecting a feed side port of the fuel tank and a swivel joint via a check valve for preventing fuel oil descent, and the swivel joint, an engine fuel pump and an injection pump are connected to an upper part. And a fuel overflow communication side port of the injection pump and the upper feed circuit are connected via a check valve, or the overflow return side port and the fuel tank are connected via a swivel joint. Set so that the fuel oil in the fuel tank can be prevented from falling when it is supplied to the engine. Both construction machinery fuel supply system which is characterized by being configured to set possible return overflow fuel oil to the feed side circuit or the fuel tank.