JPH08319864A - Overheat preventing/controlling device for engine - Google Patents

Abstract

PURPOSE: To sink the temp. gradually to the specified appropriate level while the engine is left operating and prevent the engine from overheat by shifting the stopping position of a rack for adjustment of the fuel injection amount to the specific position where the amount decreases from the maximum. CONSTITUTION: When a water temp. sensor 1 or an oil temp. sensor S2 senses the specified overheat alert temp. while the engine 1 is in the high rating operating condition, a controller 6 emits a command signal to an output adjusting solenoid 4 and its plunger 8 is moved to C position, i.e., the low rating output position. Therefore, the left-hand stopping position of a rack 2 shifts to the right where the fuel injection amount decreases. As a result, the cooling water temp. of the engine 1 or the working oil temp. of the hydraulic system can be sunk gradually to the specified appropriate level while the engine 1 is left operating according to the low rating output curve, and the engine 1 can be prevented from overheat while the working efficiency is ensured good.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes an engine including a fuel injection pump including a rack for adjusting a fuel injection amount applied to a construction machine and the like, and a hydraulic system driven by the engine. The present invention relates to an engine overheat prevention control device.

[0002]

2. Description of the Related Art Generally, a construction machine such as a hydraulic excavator is supplied with hydraulic oil by a diesel engine including a fuel injection pump including a rack for adjusting a fuel injection amount, and a hydraulic pump driven by the engine. And a hydraulic system that is activated. In addition to the governor, an engine of this type equipped with an output adjusting solenoid, a controller for controlling the operation of the solenoid, and the like is known. The governor acts on the rack of the fuel injection pump to control the amount of fuel just enough so that the engine can maintain a predetermined rotation speed regardless of the load. The output adjustment solenoid is operated and controlled by the controller so as to regulate the movement of the rack in the fuel increasing direction and regulate the rack stop position where the fuel injection amount is maximum. Thereby, the rotation of the engine is controlled according to the predetermined rated output line. The driver's cab is provided with an accelerator dial, and by operating it, a desired engine speed is selected according to the work of the machine.

[0003]

When a construction machine having an engine constructed as described above is operated in an overload or high temperature environment, the cooling water temperature (engine cooling water temperature) or hydraulic oil temperature ( In some cases, the oil temperature of the hydraulic oil in the hydraulic system rises, exceeds its allowable value, and becomes overheated. If the operator determines that the overheat condition is relatively light, the engine speed is reduced by operating the accelerator dial to perform work with a light load as much as possible, and if it is determined to be relatively severe, It is unavoidable to lower the cooling water temperature or the hydraulic oil temperature to an appropriate temperature, for example, by putting the engine in a no-load high idle state. Although it is unavoidable for the operator to take such a measure, the operating efficiency is lowered and it is inefficient, and improvement is desired.

An object of the present invention is to provide a novel engine overheat prevention control device capable of preventing the engine and the hydraulic system from overheating while ensuring the operating efficiency.

[0005]

In order to achieve the above object, according to the present invention, a rack for adjusting a fuel injection amount of a fuel injection pump and a fuel injection by restricting movement of the rack in a fuel increasing direction. An engine equipped with solenoid means for defining the stop position of the rack where the amount is maximum and a controller for controlling the operation of the solenoid means, and a hydraulic pump driven by the engine supplies hydraulic oil to operate the engine. And a controller that controls the stop position of the rack when the cooling water temperature of the engine or the oil temperature of the hydraulic oil reaches a predetermined overheat warning temperature, to the position where the fuel injection amount becomes maximum. From the maximum to a predetermined position where the solenoid is moved to a predetermined position, the engine overheat prevention control device is characterized by: It is subjected.

[0006]

In the present invention, when the temperature of the cooling water of the engine or the temperature of the hydraulic oil reaches a predetermined overheat warning temperature, the controller sets the rack stop position of the fuel injection pump from the position where the fuel injection amount becomes maximum to the maximum position. The solenoid means is operated and controlled so as to move to a predetermined position where the number decreases. Therefore, in the range where the cooling water temperature or the hydraulic oil temperature is appropriate, the solenoid means defines the rack stop position at the position where the fuel injection amount is maximum, so that the engine follows the high rated output diagram (output 100%). Get up and running. However, when the engine cooling water temperature or the hydraulic oil temperature reaches the predetermined overheat warning temperature, the rack stop position is moved from the position where the fuel injection amount is maximum to the predetermined position where the fuel injection amount is less than the maximum, The engine operates according to the low rated power diagram (power is 90% as an example). As is clear from the above operation, even if the engine should be alerted to overheat, it is possible to prevent overheat while continuing the operation without stopping the machine. That is, in the present invention, it is possible to prevent the engine and the hydraulic system from overheating while ensuring the operating efficiency.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an engine and hydraulic system overheat prevention control device improved according to the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, reference numeral 1 indicates an engine, which is mounted on a construction machine such as a hydraulic excavator (not shown). Number 2 indicates a rack for adjusting the fuel injection amount of a fuel injection pump (not shown) mounted on the engine 1. The rack 2 is provided in the fuel injection pump so as to be movable in the left and right directions in the figure. When the rack 2 moves to the left in the figure, the fuel injection amount increases, and when it moves to the right, the fuel injection amount decreases and moves to the rightmost side. Then, the fuel injection amount becomes zero and the engine 1 is stopped. The fuel injection pump is a so-called in-line injection pump, which is well known to those skilled in the art, and a description thereof will be omitted. Reference numeral 4 is an output adjusting solenoid that constitutes a solenoid means, and regulates the movement of the rack 2 in the fuel injection amount increasing direction to define the stop position of the rack 2 at which the fuel injection amount becomes maximum, and It has a function of stopping the engine 1 by moving it to the rightmost. The operation of the output adjustment solenoid 4 is controlled by the controller 6.

Reference numeral 3 is a hydraulic system provided in a hydraulic excavator and known to those skilled in the art, and hydraulic oil is supplied and operated by a hydraulic pump 5 driven by the engine 1. Although not shown, the hydraulic system 3 includes a remote control valve controlled by an operation lever and a control valve operated by a secondary pilot pressure supplied from a pilot pump (driven by the engine 1) via the remote control valve. An actuator (a working machine cylinder such as a bucket, an actuator such as a traveling hydraulic motor, a swing hydraulic motor, or the like) that operates by supplying hydraulic oil from the hydraulic pump 5 by the operation of the control valve is provided.

To the controller 6, a starter switch,
Signals are input from a water temperature detector S1 that detects the water temperature of the engine 1 and an oil temperature detector S2 that detects the oil temperature of the hydraulic oil of the hydraulic system 3. The output adjusting solenoid 4 has a plunger 8 which can move to the left and right. The plunger 8 is provided with a mark B indicating a high rated output position, a mark C indicating a low rated output position, and a mark D indicating an engine stop position at predetermined intervals from right to left in the drawing. . Reference numeral 9 is a rotatably supported lever, and the right end of the plunger 8 and the left end of the rack 2 are positioned at one end sides with respect to the support shaft of the lever 9 so as to face and abut each other. Reference numeral 10 is an air-fuel ratio adjusting solenoid, which has a plunger 12 movable left and right. A retainer 12a is provided at the end of the plunger 12. The presser 12a is provided to restrain the movement of the lever 9 in the fuel increasing direction so as to reduce the fuel injection amount when the supply pressure of a turbocharger (not shown) mounted on the engine 1 is low. . The lever 9 is constantly urged counterclockwise by a spring (not shown) so that one end of the lever 9 contacts the left end of the rack 2.

From the controller 6 to the output adjusting solenoid 4
To the reference fixed mark A, the plunger 8 causes the high rated output position where the mark B on the plunger 8 matches, the low rated output position where the mark C matches, and the engine where the mark D matches. The operation is controlled so that they are respectively positioned at the stop positions. Number 14 schematically shows a part of the governor. The governor 14 is attached to the left end portion of the camshaft 16 of the fuel injection pump and is constantly pressed against the flyweight 18 by a flyweight 18 and a governor spring (compression coil spring) 20 that rotate integrally with the camshaft 16 and is movable in the left-right direction in the drawing. The riser 22 supported by
The governor spring 20 is provided with a governor lever 26 and a stop collar 28 which constantly act via a spring receiver 24 so as to increase or decrease the spring force. The governor lever 26 is rotatably supported, one end of which acts on the spring receiver 24, and the other end (not shown) of which is also connected to an accelerator dial (not shown). The accelerator dial provided in the driver's cab can be operated in, for example, 10 steps, and the connection relationship with the governor lever 26 is defined so that one end of the governor lever 26 rotates counterclockwise as the operation amount increases. ing.

The stop collar 28 is movably supported in the left-right direction in the drawing, and its right end is locked to the riser 22 so as to be constantly urged to the right by the spring force of the governor spring 20. . The stop collar 28 is the riser 2
2 is always urged to the left by a spring (not shown) so as to be always locked with 2. At the left end of the stop collar 28, the maximum torque adjusting screw 30 and the output adjusting screw 3 are provided.
2 are provided. When the stop collar 28 is moved to the right, first, the right end of the output adjusting screw 32 comes into contact with the torque spring (leaf spring) 34 provided in association therewith, and the spring force of the torque spring (leaf spring) 34 is resisted. Then, when further moving to the right, the right end of the maximum torque adjusting screw 30 contacts the stopper 36 and its movement is blocked. Number 3
Reference numeral 8 denotes a lever rotatably supported, one end of which is engaged with a sleeve 40 integrally provided on the rack 2.
The other end is engaged with a sleeve portion provided on the riser 22. Therefore, when the riser 22 moves to the right in the drawing, the rack 2 moves to the left in the drawing, that is, in the direction in which the fuel injection amount increases, and when it moves to the left, the rack 2 moves to the right in the drawing.
That is, the fuel injection amount moves in the direction of decreasing.

As is apparent from the above structure, the centrifugal force of the flyweight 18, which is rotationally driven by the camshaft 16 of the fuel injection pump, always causes the fuel to be reduced in the riser 2 direction.
2 and the lever 38 to act on the rack 2. on the other hand,
The spring force of the governor spring 20 always acts on the rack 2 via the riser 22 and the lever 38 in the direction of increasing the fuel. Therefore, the engine is controlled to rotate at a constant rotation speed in which the centrifugal force of the flyweight 18 and the spring force of the governor spring 20 are balanced.

Next, the operation of the apparatus configured as described above will be described. When the starter switch is switched from the OFF position to the Acc (accessory) -ON position,
The signal is input to the controller. The controller outputs a command signal to the output adjusting solenoid 4 based on this input signal, and causes the plunger 8 of the output adjusting solenoid 4 to move to B
Position, ie, high rated output position. When the starter switch is operated to the START position, the engine 1
Will start. Next, when the accelerator dial is set to a predetermined step position on the increasing side (a predetermined number of rotations is selected), the governor lever 26 rotates a predetermined amount in the counterclockwise direction in the figure to move to the high (high) idle side. To be done. Governor spring 2
Since the spring force of 0 increases and the riser 22 is moved to the right, the rack 2 is moved in the fuel increasing direction via the lever 38, and the rotation speed of the engine 1 is increased. The centrifugal force of the flyweight 18 increases as the rotation speed increases. as a result,
Since the riser 22 is moved leftward against the spring force of the governor spring 20, the rack 2 is moved in the fuel reducing direction via the lever 38. In this way, the predetermined rotation speed is maintained when the centrifugal force of the flyweight 18 and the spring force of the governor spring 20 are balanced.

When the load further increases in this state, the number of revolutions decreases, so that the riser 22 moves to the right. Riser 2
The stop collar 28 also moves to the right via 2. Then, the output adjusting screw 32 contacts the torque spring 34. When the load further increases, the output adjusting screw 32 pushes and bends the torque spring 34, and when it further moves, the maximum torque adjusting screw 30 abuts against the stopper 36 and its movement is blocked. In this operation, even if the left end of the rack 2 is moved to the left to the maximum and the lever 9 is rotated clockwise in FIG. 1, it does not contact the right end of the plunger 8. That is, the movement of the rack 2 in the fuel increasing direction is restricted only by the stopper 36. This rack stop position corresponds to the control position on the high rated output line (output 100%) shown in FIG.

As described above, in the state where the engine is operated in accordance with the high rated output, the water temperature detector S1 or the oil temperature detector S2 of the hydraulic oil indicates that the cooling water temperature of the engine 1 or the hydraulic oil temperature of the hydraulic system 3 is predetermined. When it detects that the overheat warning temperature of the
Is input to The controller 6 outputs a command signal to the output adjusting solenoid 4 based on this input signal, moves the plunger 8 of the output adjusting solenoid 4 to the C position, that is, the low rated output position, and positions it (the position shown in FIG. 1). As a result, the stop position on the left side of the rack 2 is
The position is the right position where the injection amount is smaller than the high rated output position where the fuel injection amount is maximum (the movement of the rack 2 in the fuel increasing direction is restricted by the right end of the plunger 8). This rack stop position corresponds to the control position on the low rated output line (90% output in this embodiment) shown in FIG. After that, the operation of the engine 1 is controlled according to this low rated output line. As a result, the cooling water temperature of the engine 1 or the operating temperature of the hydraulic system 3 can be gradually decreased to an appropriate temperature while operating the engine 1 according to the low rated output line, and overheating of the engine 1 can be ensured while ensuring operating efficiency. It can be prevented.

Water temperature detector S1 or hydraulic oil temperature detector S
When 2 detects that the cooling water temperature of the engine 1 or the hydraulic oil temperature of the hydraulic system 3 has dropped to a predetermined temperature which is an appropriate temperature lower than a predetermined overheat warning temperature, this signal is input to the controller 6. The controller 6 outputs a command signal to the output adjustment solenoid 4 based on this input signal, moves the plunger 8 again to the high rated output position, and positions it. After that, the operation of the engine 1 is controlled according to this high rated output line. As described above, the engine 1 operates according to the high rated output line when the cooling water temperature or the hydraulic oil temperature is at an appropriate temperature, and the low rated output line when the cooling water temperature or the hydraulic oil temperature reaches the overheat warning temperature. Therefore, it is possible to avoid overheating while operating the machine by automatically controlling so as to operate in accordance with two stages. When the starter switch is turned off, the operation of the controller is stopped and the command signal to the output adjusting solenoid 4 disappears. Therefore, the plunger 8 is automatically set to the maximum right position by the action of the built-in spring. It is moved to the engine stop position. Since the rack 2 is moved to the fuel injection amount zero position, the engine 1 is surely stopped.

Although one embodiment of the overheat prevention control device for the engine and the hydraulic system according to the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the present invention. Can be modified or modified.

[0018]

According to the engine and hydraulic system overheat prevention control apparatus constructed according to the present invention, even when the engine and hydraulic system are in a state where an overheat should be warned, the machine can continue to operate without stopping. Since it is possible to prevent overheating, it is possible to prevent overheating of the engine and the hydraulic system while ensuring operating efficiency.

[Brief description of drawings]

FIG. 1 is a simplified diagram of an engine and hydraulic system overheat prevention controller improved in accordance with the present invention.

2 is a diagram showing an output characteristic of an engine equipped with the control device shown in FIG. 1;

[Explanation of symbols]

 2 Rack 4 Output adjustment solenoid 6 Controller 8 Plunger 9 Lever 14 Governor 16 Camshaft 18 Flyweight 20 Governor spring 22 Riser 26 Governor lever 28 Stop collar 30 Maximum torque adjustment screw 32 Output adjustment screw 34 Torque spring 36 Stopper 38 Lever 40 Sleeve S Water temperature Detector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keiji Numata Keiji Numata 4-10-1 Yoga, Setagaya-ku, Tokyo Inside New Caterpillar Mitsubishi Corporation (72) Yoshihiko Hayashi 4-10-1 Yoga, Setagaya-ku, Tokyo Inside New Caterpillar Mitsubishi Corporation

Claims (1)

[Claims] 1. A rack for adjusting a fuel injection amount of a fuel injection pump, and solenoid means for restricting a movement of the rack in a fuel increasing direction to define a stop position of the rack at which the fuel injection amount becomes maximum. An engine having a controller for controlling the operation of the solenoid means, and a hydraulic system in which hydraulic oil is driven by a hydraulic pump driven by the engine to operate the engine are provided. When the oil temperature of the hydraulic oil reaches a predetermined overheat warning temperature, the solenoid means is operated to move the stop position of the rack from the position where the fuel injection amount is maximum to the predetermined position where the fuel injection amount is less than the maximum. An overheat prevention control device for an engine, characterized by controlling.