JPH0714133U - Engine protector - Google Patents

Abstract

(57) [Summary] [Purpose] When the amount of cooling water in the radiator decreases, the engine drive is forcibly stopped to protect the engine. A level switch 31 for detecting a liquid level of cooling water in a radiator is provided, and the level switch 31 activates a contact 33 when the cooling water falls below a predetermined level. Then, the a contact 33A of the level switch 31 is arranged between the starter switch 26 and the fuel solenoid valve 18 and the starter motor. Then, when the cooling water decreases below a predetermined level, the a contact 33A is opened, the electromagnetic valve 18 is closed, and the supply of fuel to the engine is stopped. On the other hand, by closing the emergency switch 36, the engine can be driven even if the a contact 33A is opened.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an engine protection device preferably used for construction machines such as hydraulic excavators and hydraulic cranes.

[0002]

[Prior art]

 Generally, in construction machines such as hydraulic excavators, a diesel engine is used as a prime mover, and the fuel stored in a fuel tank is supplied to the engine through a fuel pipe.

Then, this engine burns the supplied fuel in a combustion chamber to generate a driving force, and for example, rotationally drives a hydraulic pump or the like, and the pressure oil discharged from the hydraulic pump is used for traveling or turning. They are operated by supplying them to a hydraulic motor for work, a hydraulic cylinder for work, etc.

Here, a case where a conventional engine protection device is applied to a hydraulic shovel will be described with reference to FIGS. 4 to 6.

In the figure, 1 is an undercarriage, and 2 is an upper revolving structure which is rotatably mounted on a lower traveling structure 1 through a revolving device (not shown) and constitutes a working machine body. Is composed of a revolving frame 3 and a cab 4, a machine room 5, and a counterweight 6 mounted on the revolving frame 3, and the counterweight 6 covers the entire upper revolving structure 2 with respect to a working device 7 described later. It is designed to be balanced.

Reference numeral 7 denotes a working device provided at the front part of the upper swing body 2. The working device 7 is a boom 8 provided at the front part of the swing frame 3 so as to be capable of being lowered and raised, and a tip end of the boom 8. It comprises an arm 9 that can be lifted up and down, and a backhoe type bucket 10 that is rotatably provided at the tip of the arm 9, and these boom 8, arm 9, and bucket 10 are boom cylinder 11 , The arm cylinder 12 and the bucket cylinder 13 respectively. Then, the working device 7 rotates the bucket 10 by the bucket cylinder 13 while raising and lowering the boom 8 and the arm 9 by the boom cylinder 11 and the arm cylinder 12 during the excavation work of the earth and sand, and the like by the bucket 10. Is to be drilled.

In FIG. 5, reference numeral 14 denotes a diesel engine placed in the machine room 5, and by driving the engine 14, a hydraulic pump or the like (not shown) is rotationally driven to discharge from the hydraulic pump. The supplied pressure oil is supplied to the traveling and turning hydraulic motors and the cylinders 11 to 13 to operate them.

Reference numeral 15 denotes a fuel tank, and the fuel for driving the engine 14 is stored in the fuel tank 15. Reference numeral 16 denotes a fuel pipe for circulating the fuel in the fuel tank 15 through the engine 14, and a fuel pump 17 as a fuel supply means, a fuel solenoid valve 18 as a valve means, and a fuel are provided in the middle of the fuel pipe 16. The injection valves 19 are sequentially connected. The fuel injection valve 19 is provided in the engine 14 and injects fuel controlled by the governor into the engine 14.

Here, the fuel pump 17 is driven and stopped in conjunction with the closing and opening of a starter switch 26, which will be described later, and the fuel solenoid valve 18 is operated by the electric circuit shown in FIG. It is controlled to open and close depending on whether it is closed or opened. When the starter switch 26 is closed, the fuel pump 17 is driven and the fuel solenoid valve 18 is opened, so that the fuel in the fuel tank 15 is supplied to the engine 14 through the fuel pipe 16. On the other hand, when the starter switch 26 is opened, the drive of the fuel pump 17 is stopped and the fuel solenoid valve 18 is closed to cut off the fuel pipe 16 and stop the supply of fuel to the engine 14. It is a thing.

Reference numeral 20 denotes a radiator as a cooling means attached to the engine. The radiator 20 is a pipe having a radiation fin inside, and the upper end thereof is an upper tank 20A and the lower end thereof is a bottom tank 20B. A reservoir tank 20C communicating with the upper tank 20A is connected to the outside. The upper tank 20A and the bottom tank 20B are connected to a water jacket 22 via a cooling pipe 21, and the radiator 20, the cooling pipe 21 and the water jacket 22 are filled with cooling water. The cooling water in the radiator 20 is cooled by cooling air from a cooling fan 23 fixed to the axial tip of the rotary shaft 14A of the engine 14.

Further, the water jacket 22 is formed so as to surround the outer periphery of a cylinder (not shown) of the engine 14, and is for cooling the engine 14. In the middle, cooling water is introduced through a cooling pipe 21. A water pump 22 for circulating the water jacket 22 and the radiator 20 is provided.

As described above, the cooling means of the engine 14 is constituted by the radiator 20 and the water jacket 22 and the like, and the cooling means effectively cools the engine 14, and the cooling water cools the water jacket 22 of the engine 14. When flowing, the cooling water absorbs heat from the engine 14, and the superheated cooling water is sent to the radiator 20 through the cooling pipe 21 by the water pump 24, and the cooling water sent to the radiator 20 is transferred to the engine. It is forcibly cooled by the cooling wind of the cooling fan 23 generated by the rotational force of 14 and is sent to the water jacket 22 again. By repeating this in sequence, the engine 14 is cooled.

Next, FIG. 6 shows an electric circuit for driving the engine.

In FIG. 6, reference numeral 25 denotes a battery installed in the machine room 5. The positive side of the battery 25 is connected to the starter switch 26, and the negative side is connected to the ground. The starter switch 26 is connected between the positive side of the battery 25 and the starter relay 27 and the fuel relay 29. When the starter switch 26 is closed, the fuel pump 17 is driven and the starter relay is started at the time of starting. 27 is closed, the starter motor 28 provided in the engine 14 is driven, and the engine 14 is started.

Reference numeral 29 denotes a fuel relay connected between the starter switch 26 and the fuel solenoid valve 18. The fuel relay 29 is switched by closing the starter switch 26 to excite the coil portion 29A. The portion 29B is closed, and the battery 25 and the solenoid portion 18A of the fuel electromagnetic valve 18 are connected.

Reference numeral 30 denotes a diode connected between the fuel relay 29 and the fuel solenoid valve 18, and the diode 30 supplies a constant current to the solenoid portion 18 A of the fuel solenoid valve 18.

In the prior art configured as described above, by closing the starter switch 26, the fuel pump 17 is driven and the fuel electromagnetic valve 18 is opened to supply the fuel from the fuel tank 15 to the engine 14. To do. On the other hand, the engine 14 is started by driving the starter motor 28.

[0018]

[Problems to be solved by the device]

 By the way, in the above-mentioned conventional technique, the cooling state of the engine 14 when the engine 14 is driven is monitored by providing the radiator 20 with a water temperature sensor for detecting the water temperature of the cooling water, and cooling the temperature detected by the water temperature sensor. The water temperature is displayed by a water temperature gauge or an alarm device (lamp, buzzer, etc.) in the cab 4.

For example, when the cooling water gradually leaks due to a small hole in the cooling pipe 21 or a crack in the radiator 20, the water temperature sensor indicates that the temperature of the cooling water decreases as the cooling water decreases. You can follow the rise sufficiently. Therefore, the water temperature sensor can reliably detect the leakage of the cooling water (abnormality of the cooling system) and notify the driver of the decrease in cooling efficiency.

However, if there is a large amount of cooling water leaking from the cooling pipe 21 or the water jacket 22 for some reason, the cooling water will decrease sharply, and the reduced cooling water will cool the engine 14 efficiently. Cannot be performed and the temperature of the cooling water rises sharply. However, the water temperature sensor cannot follow the rapid temperature rise of the cooling water, and the engine 14 abnormally overheats before the water temperature sensor detects an abnormal temperature. Therefore, in the worst case, there is a problem that the piston is burned in the engine 14 and the engine 14 is fatally damaged.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention forcibly stops the fuel supply to the engine to drive the engine when the cooling state of the engine deteriorates. It is intended to provide an engine protection device that can be stopped.

[0022]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, an engine protection device adopted by the present invention is provided in the middle of an engine provided with a cooling means for cooling with cooling water and a supply pipe for supplying fuel to the engine. Detecting the amount of cooling water of the cooling means and the valve means that opens between the time when the engine is started and the time when the engine is stopped, and closing the valve means when the amount of cooling water falls below a predetermined level, It consists of fuel stopping means for stopping the fuel supply to the engine.

[0023]

[Action]

 When the amount of cooling water of the cooling means is higher than a predetermined level, the valve means is continuously opened from the start to the stop of the engine, during which the fuel stop means does not operate and fuel is supplied to the engine. Can be supplied.

On the other hand, when the cooling water amount of the cooling means becomes lower than the predetermined level, the fuel stopping means detects the decrease of the cooling water amount and closes the valve means to supply the fuel to the engine. The engine is forcibly stopped, the engine is stopped even while the engine is running, and the engine start is prohibited before the engine is started.

[0025]

【Example】

 Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In the embodiments, the same components as those of the above-described conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, 31 indicates a float type level switch for detecting the level of the cooling water M in the radiator 20, and the level switch 31 is provided in the upper tank 20 A of the radiator 20. Here, as shown in FIG. 2, the level switch 31 has a switch main body 32 formed in a stepped cylindrical shape with a small diameter portion 32A on the lower side, and a small diameter portion 32A of the switch main body 32. Between the contact 33 composed of the contact 33A and the contact b 33B and the small diameter portion 32A of the switch body 32, the upper and lower parts are moved in correspondence with the liquid surface of the cooling water M, and the position of the liquid surface falls below a predetermined position. In order to attach the cylindrical float 34 that opens the a contact 33A of the contact 33 and closes the b contact 33B and the switch body 32 to the upper tank 20A, The upper tank 20A is substantially fixed to the plate portion of the tank 20A by means of welding or the like and has a socket 35 having an internal thread 35A on its inner peripheral surface.

The switch body 32 is located on the upper side and has a threaded portion 32B formed on the base end side. The threaded portion 32A is screwed into the female threaded portion 35A of the socket 35 and the tip end side of the small diameter portion 32A. Is provided with a large-diameter stopper portion 32C that holds the float 34.

The level switch 31 thus configured is mounted in the upper tank 20A of the radiator 20 by screwing the male screw portion 32B of the switch body 32 into the female screw portion 35A of the socket 35. When the cooling water M in the radiator 20 is detected, when the amount of the cooling water M decreases and falls below a predetermined position, the magnet 34A in the float 34 acts on the contact 33, and the a contact 33A is turned on. It is opened and the contact b 33B is closed. As a result, a detection signal indicating that the cooling water M has decreased below a predetermined level is output to an electric circuit for driving an engine, which will be described later.

Next, an electric circuit for driving the engine, which serves as an engine protection device according to this embodiment, will be described with reference to FIG.

Although the electric circuit for driving the engine shown in FIG. 3 is configured almost the same as the electric circuit for driving the engine described in the prior art, the starter switch 26, the fuel relay 29, and the starter relay are used in this embodiment. It is different in that a contact 33, an emergency switch 36, and an alarm lamp 37, which will be described later, are connected to the switch 27 and the level switch 31 respectively.

Here, the contact 33 of the level switch 31 is connected in series between the starter switch 26 and the fuel relay 29 (starter relay 27), and the a contact 33A of the contact 33 is closed (the b contact 33B is open). State), that is, when the liquid level of the cooling water M is high, the starter switch 26 and the fuel relay 29 are in conduction, while the a contact 33A is in the open state (b contact 33B is in the closed state), That is, when the liquid level of the cooling water is low, the starter switch 26 and the fuel relay 29 are cut off, while the alarm lamp 37 arranged in the operator's cab 4 is connected to the ground by the b contact 33B and lights.

Further, the emergency switch 36 is provided in the operator's cab 4 and electrically connected in parallel with the contact 33. By closing the emergency switch 36, the contact 33 a of the contact 33 is in an open state. However, the starter switch 26 and the fuel relay 29 are connected to bring the engine 14 into a driving state.

In the engine protector according to the present embodiment configured as described above, the amount of the cooling water M in the radiator 20 becomes lower than a predetermined level, and when this state is detected by the level switch 31, When the contact 33a of the contact 33 is opened (the contact 33b is closed), the starter switch 26 and the fuel relay 29 are electrically disconnected. As a result, even if the starter switch 26 is closed and the engine 14 is being driven, the current is prohibited from flowing from the battery 25 to the solenoid portion 18A of the fuel solenoid valve 18, and the fuel solenoid valve 18 is closed. To In this case, the fuel supplied to the engine 14 via the fuel pipe 16 can be shut off and the engine 14 can be automatically stopped.

Therefore, even if the leakage amount of the cooling water M is rapid and large, the float 34 of the level switch 31 can always follow the liquid level of the cooling water M in the upper tank 20A, and Before the cooling efficiency due to the decrease in the water amount of M is significantly impaired, the fuel electromagnetic valve 18 provided in the fuel pipe 16 can be closed to forcibly stop the engine 14. As a result, it is possible to reliably prevent the piston or the like in the engine 14 from being seized, and it is possible to reliably extend the life of the engine 14.

Further, since the b contact 33B is closed by the opening of the a contact 33A, when the engine 14 is stopped, the alarm lamp 37 is turned on to notify. As a result, the cause of the engine 14 being stopped during work and traveling is clarified, the repair / inspection point can be easily determined, and the maintainability can be significantly improved.

Further, in the engine protecting apparatus of this embodiment, the engine 14 automatically stops when the amount of the cooling water M becomes small even during excavation work, so that the stopped position is Movement is necessary in unstable places. Even in this case, by closing the emergency switch 36 provided in the driver's cab 4, the engine 14 can be driven to move from an unstable position to a stable place.

On the other hand, when the amount of the cooling water M in the radiator 20 decreases while the engine 14 is stopped (before starting), the contact 33 a of the contact 33 is open and the contact 33 A is located behind the contact 33. Since the starter motor 28 is connected, the starter motor 28 does not rotate even if the starter switch 26 is cranked. Moreover, since the fuel supply to the engine 14 is stopped by the fuel solenoid valve 18, the prohibition of starting the engine 14 can be prevented by a double safety measure.

Further, in this embodiment, a simple component such as a level sensor 31 and a socket 35 is added to the radiator 20, and wiring from the level sensor 31 is incorporated into an electric circuit for driving the engine as shown in FIG. As a result, an engine protection device that protects the engine 14 can be configured.

In the embodiment, the diesel engine 14 is described as an example of the engine, but the present invention is not limited to this and may be applied to a gasoline engine. Further, in the above-described embodiments, the hydraulic excavator has been described as an example, but the present invention is not limited to the hydraulic excavator and may be used in a hydraulic crane, a wheel loader, and the like.

Further, in the embodiment, the level switch 31 is provided not only in the upper tank 20A of the radiator 20 but also in the reservoir tank 20C shown in FIG. 1 so as to detect the amount of the cooling water M. Good.

Further, in the embodiment, the water level of the cooling water M in the radiator 20 is detected by the float type level switch 31, but a capacitance type level switch, an ultrasonic level switch or the like is used. Good.

[0042]

[Effect of device]

 As described above in detail, according to the present invention, the fuel stopping means causes the valve means to be closed when the amount of the cooling water in the cooling means for cooling the engine falls below a predetermined level. The fuel supply to the engine is automatically stopped and the engine is forcibly stopped before the cooling efficiency of the cooling means is significantly reduced. As a result, it is possible to surely protect the engine.

On the other hand, when the fuel stop means detects that the amount of cooling water is small at the time of starting, it is possible to prohibit the starting of the engine.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a fuel supply system to an engine and a cooling system thereof according to the present embodiment.

FIG. 2 is a vertical cross-sectional view showing a level switch provided in an upper tank of a radiator.

FIG. 3 is a circuit diagram showing an electric circuit for driving an engine according to the present embodiment.

FIG. 4 is a perspective view showing a hydraulic excavator to which a conventional engine protection device is applied.

FIG. 5 is a configuration diagram showing a fuel supply system to an engine and a cooling system thereof according to a conventional technique.

FIG. 6 is a circuit diagram showing an electric circuit for driving an engine according to a conventional technique.

[Explanation of symbols]

 14 Diesel engine 15 Fuel tank 16 Fuel piping 17 Fuel pump 18 Fuel solenoid valve 20 Radiator 31 Level switch 33 contacts 33A a contact 33B b contact 36 Emergency switch 37 Alarm lamp

Claims (1)

[Scope of utility model registration request] 1. An engine provided with a cooling means for cooling with cooling water, and valve means provided in the middle of a supply pipe for supplying fuel to the engine, the valve means being opened between the start and stop of the engine. And a fuel stop means for detecting the amount of cooling water of the cooling means, closing the valve means when the amount of cooling water falls below a predetermined level, and stopping the fuel supply to the engine. Protector.