JP2000289977A - Engine accelerator limiting device in hydraulic work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine accelerator limiting device limiting an engine rotation control possible region by an accelerator control mechanism below predetermined number of rotation automatically when a temperature of hydraulic fluid is lowered. SOLUTION: This engine accelerator limiting device A is constituted by a rotation limiting part 10 attached to an accelerator control mechanism 9 to limit an engine rotation control possible region by the accelerator control mechanism 9 below predetermined number of revolutions when the accelerator control mechanism 9 is operated and a hydraulic fluid temperature detection part 11 which detects that a temperature of hydraulic fluid sucked by a hydraulic pump 2 is below a predetermined temperature and outputs an operation signal to the rotation limiting part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine accelerator used in a hydraulic working machine driven by a hydraulic pump driven by a hydraulic pump driven by an engine whose rotation speed is controlled by an accelerator control mechanism. It relates to a restriction device.

[0002]

2. Description of the Related Art When a working machine of this kind is used in a cold region, the viscosity of the working oil increases with the temperature of the working oil in the early stage of use, so that the engine speed increases. Therefore, even if the discharge oil amount of the hydraulic pump is increased, a large amount of hydraulic oil cannot be allowed to flow through the hydraulic line, and the hydraulic line or various valves are adversely affected.

For this reason, when using this type of working machine in a cold region, the operator of the working machine must take care that the engine does not rotate at high speed until the oil temperature rises to a predetermined temperature. Was operating. However, it is troublesome for the operator to operate the accelerator control mechanism with such caution, and the rotation of the engine may be excessively increased, which may adversely affect the hydraulic piping or various valves.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine for automatically limiting the engine rotation controllable area by an accelerator control mechanism to a predetermined number of revolutions or less when the temperature of hydraulic oil is low. It is an object of the present invention to provide an accelerator limiting device to solve the above problem.

[0005]

Means for Solving the Problems To achieve the above object, an engine accelerator limiting device for a hydraulic working machine according to the present invention is configured as follows.

An engine accelerator limiting device A attached to a hydraulic working machine driven as a driving hydraulic source by using a discharge oil of a hydraulic pump 2 driven by an engine 1 whose rotation speed is controlled by an accelerator control mechanism 9. A rotation limiter attached to the accelerator control mechanism for limiting an engine rotation controllable region by the accelerator control mechanism to a predetermined number of rotations or less during operation thereof; and a temperature of hydraulic oil sucked or discharged by the hydraulic pump 2. And an operating oil temperature detecting section for detecting that the temperature is below a predetermined temperature and outputting an operating signal to the rotation limiting section.

In the engine accelerator limiting device for a hydraulic working machine according to the present invention having the above-described configuration, when the hydraulic oil temperature detecting section detects that the temperature of the hydraulic oil sucked by the hydraulic pump is equal to or lower than a predetermined temperature, the detection is performed. According to the result, the rotation limiter is operated, and the engine rotation controllable region by the accelerator control mechanism is automatically limited to a predetermined number of rotations or less.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an engine accelerator limiting device in a hydraulic working machine according to the present invention will be described below with reference to FIG. Representative examples of the hydraulic working machine to which the present invention is applied include a mobile crane, an aerial work vehicle, and the like. These hydraulic working machines are driven using a discharge oil of a hydraulic pump driven by an engine whose rotation speed is controlled by an accelerator control mechanism as a drive hydraulic pressure source.

In FIG. 1, reference numeral 1 denotes an accelerator control mechanism 9.
The engine 2 whose rotation speed is controlled by the engine 2 is a hydraulic pump that is rotationally driven by the engine 1 and sucks hydraulic oil from a hydraulic oil tank 3 via a suction oil passage 4 to control the drive of a hydraulic working machine. Pressure oil is supplied to the drive control valve means 5 via a pump oil passage 6. The drive control valve means 5 includes actuators 7 for driving the hydraulic working machine.
It comprises four-way three-position type directional control valves 5a to 5e for controlling supply and discharge of hydraulic oil to and from a to 7e, respectively. Each of the directional control valves 5a to 5e has a carry-over oil passage that communicates at its neutral position and is cut off at the switching position.
Is returned to the hydraulic oil tank 3. Each of the direction switching valves 5 a to 5 e has its P port connected to the pump oil passage 6 and its T port connected to the hydraulic oil tank 3. Further, a pair of control ports of each of the directional control valves 5a to 5e are connected to the corresponding hydraulic actuator 7a.
To 7e.

Reference numeral 9 denotes an accelerator control mechanism for controlling the rotation of the engine 1. An accelerator operation section 9a operated by an operator of the hydraulic working machine, and an engine rotation control operated by an operation signal from the accelerator operation section 9a. 9b.

Such an accelerator control mechanism 9 is provided in a hydraulic working machine to which the present invention is applied. The engine accelerator limiting device A in the hydraulic working machine of the present invention is A rotation limiting unit 10 that is attached and limits an engine rotation controllable area by the accelerator control mechanism 9 to a predetermined number of rotations or less during operation thereof;
The hydraulic pump 3 is configured with a hydraulic oil temperature detector 11 that detects that the temperature of hydraulic oil sucked by the hydraulic pump 3 is equal to or lower than a predetermined temperature and outputs an operation signal to the rotation limiting unit 10.

The rotation restricting section 10 of the accelerator rotation restricting device A is arranged in association with the accelerator control mechanism 9 so as to limit the engine rotation controllable area by the accelerator control mechanism 9 to a predetermined number of revolutions or less during operation. For example, an actuator (hydraulic or electric) that restricts the tilt of the speed adjusting lever 9b1 in the engine rotation control unit 9b of the accelerator control mechanism 9 toward the high-speed rotation side at a predetermined time or more may be used. In addition, the oil temperature detecting unit 11 in the accelerator rotation restricting device A sets the temperature of the hydraulic oil in the hydraulic oil tank 3, or in the suction oil passage 4, or the pump oil passage 6 to a predetermined temperature or lower (for example, 5 ° C. or lower). This is to detect that the rotation has been stopped and to output an operation signal for operating the rotation limiting unit 10.

Next, the operation of the engine accelerator restriction device A will be described. In the engine accelerator restriction device A, the hydraulic oil sucked by the hydraulic pump 2 (the hydraulic oil in the hydraulic oil tank 3 or the suction oil passage 4) or the temperature of the pump oil passage 6 is reduced. When the temperature becomes equal to or lower than a predetermined temperature (for example, 5 ° C. or lower), the operating oil temperature detecting unit 11 detects the temperature and outputs an operating signal to the rotation limiting unit 10. Then, the rotation limiting unit 10
Is activated, the engine rotation controllable region by the accelerator control mechanism 9 is automatically limited to a predetermined number of revolutions or less.

[0014]

As described above, the engine accelerator limiting device in the hydraulic working machine according to the present invention, which is constructed and operates as described above, automatically limits the engine rotation controllable region to a predetermined rotational speed or lower when the temperature of the hydraulic oil is lower than a predetermined value. Therefore, it is possible to prevent a large amount of hydraulic oil having increased viscosity from flowing into the hydraulic piping or various valves.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an engine accelerator restriction device in a hydraulic working machine according to the present invention.

[Explanation of symbols]

1; engine, 2; hydraulic pump, 3; hydraulic oil tank,
4; suction oil passage, 5; drive control valve, 5a to 5e; directional switching valve, 6; pump oil passage, 7a to 7e; hydraulic actuator, 8; carryover oil passage, 9; accelerator control mechanism,
9a; accelerator operation unit, 9b; engine rotation control unit, 9
b1: speed control lever, 10: rotation limiter, 11: hydraulic oil temperature detector, A: engine accelerator limiter.

Claims (1)

[Claims] 1. A hydraulic pump 2 driven by an engine 1 whose rotation speed is controlled by an accelerator control mechanism 9.
An engine accelerator limiting device A attached to a hydraulic working machine driven as a drive oil pressure source by using the discharge oil of the engine, wherein the engine oil limiting device A is attached to the accelerator control mechanism 9 and defines a region in which the engine controllable by the accelerator control mechanism 9 can be controlled by the accelerator control mechanism 9 during operation. A rotation limiting unit for limiting the rotation speed to not more than a rotation speed, and detecting that the temperature of the hydraulic oil sucked or discharged by the hydraulic pump is below a predetermined temperature and outputting an operation signal to the rotation limiting unit. An engine accelerator limiting device for a hydraulic working machine, comprising: a hydraulic oil temperature detection unit 11.