JPH0352284Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is applied to an actuator hydraulic circuit in a construction machine such as a hydraulic power shovel, which is driven by a prime mover with a speed governor that is the power source of the construction machine. It is related to.

(Prior Art) The conventional example of the actuator hydraulic circuit is the fifth actuator hydraulic circuit.
As shown in the figure, hydraulic pumps c and c are driven by a prime mover a with a speed-governing mechanism b, which is the power source for construction machinery, and a plurality of switching operation valves are installed in the discharge pipes l and l of the hydraulic pumps c and c. d, d..., and a hydraulic actuator (not shown) is connected to each switching operation valve d to form an actuator hydraulic circuit that individually drives each hydraulic actuator by each switching operation valve d. The pilot lines l ₁ and l ₁ are connected to the discharge pipes l and l of the hydraulic pumps c and c,
The pilot lines l ₁ and l ₁ are connected to the valve chamber of the regulating cylinder b 1 of the speed regulating mechanism b by interposing check valves e, e and a pilot switching valve f, and each switching operation valve d is connected to the valve chamber of the regulating cylinder b ₁ of the speed regulating mechanism b. When the actuators are operated in the neutral open position as shown in FIG. Adjustment lever _b2 connected to rod ₁ moves to position A due to spring bias, and the prime mover a becomes idling at low speed, and one of the switching valves d is switched to apply hydraulic pressure to the actuator. During operation, the oil pressure in one or both of the discharge pipes 1 and 1 increases, and when the oil pressure reaches a set value, the pilot switching valve f is switched as shown in the figure, and the high oil pressure causes the speed regulating mechanism to be activated. The adjusting cylinder _b1 of b is activated, the adjusting lever _b2 is in position B, the prime mover a reaches the set rotation (speed), and the hydraulic pumps c and c are also operated at their rated operation to obtain the predetermined discharge pressure for driving the actuator. When the actuator is not operating, the prime mover automatically rotates at a low speed and the hydraulic pump is operated at low speed to save fuel and reduce noise, and the prime mover is automatically set when the actuator is operating, that is, when there is a load. The structure includes a prime mover control mechanism that returns the rotation speed to the rated operating speed of the hydraulic pump.

(Problems with the prior art) In the conventional actuator hydraulic circuit, the spool of the switching valve is switched from the neutral state to the actuator drive side, and after the actuator starts moving, the discharge piping reaches the set pilot pressure, and the rotational speed of the prime mover increases. To return to the rated value, the rotational speed of the prime mover increases while the actuator is operating, causing a speed change, and if the spool of the switching operation valve is rapidly switched, the rotation of the prime mover may not sufficiently start up. When the motor is not turned on, the full load may be applied and the motor may stop rotating. Furthermore, since the pilot switching valve for the control signal of the prime mover rotation speed is installed and arranged independently in the pilot line, there are problems such as the space required for the installation of the pilot switching valve. be.

(Purpose of the invention, means for solving problems) This invention is an invention to deal with the above-mentioned problems, in which a hydraulic pump is driven by a prime mover with a speed regulating mechanism of a construction machine power source. In an actuator hydraulic circuit in which a hydraulic pump drives a plurality of hydraulic actuators via each switching operation valve, a pilot valve that is linked to each switching operation valve is provided, and each pilot valve operates the actuator of the switching operation valve. The configuration includes a prime mover control mechanism that is switched to output a rated rotation control signal for the prime mover before switching to the actuator side, and that is switched to output a low speed rotation control signal for the prime mover when the actuator is switched to the inactive side. The spool in the operating valve for actuator hydraulic pressure switching has a slight stroke (a few strokes) when switching.
Focusing on the characteristic that the circuit is opened after the stroke (mm), a pilot valve that outputs a rotation control signal for the prime mover during a short stroke is attached to the operating valve, and the pilot valve is switched by the operating valve to control the rotation of the prime mover. This construction machine eliminates the above-mentioned problems by accelerating the generation of control signals and smoothing the switching to the rated operation of the prime mover, as well as improving the operating performance and reliability of the actuator as well as reducing fuel consumption and noise. To provide the actuator hydraulic circuit.

(Embodiment) Fig. 1 shows a first embodiment of the present invention. In the figure, 1 is a prime mover mounted on a construction machine and serving as a drive source. The prime mover 1 includes an adjusting cylinder 2a. A speed governor mechanism 2 is attached which automatically controls and sets the rotational speed (rotational speed) of the prime mover, which is configured by a speed governor lever 2b connected to the rod of the same adjustment cylinder. Engine 1
The output shaft 1b is connected to the input shaft 3a of the pilot hydraulic pump 3 and the input shaft 4a of the hydraulic pump 4 for driving the actuator, and the output shaft 4b of the hydraulic pump 4 is connected to the input shaft of the hydraulic pump 5 for driving the actuator. 5a, each hydraulic pump 3, 4, 5
It is used for driving.

Further, a hydraulic pipe 14 is connected to the hydraulic discharge side of the hydraulic pump 4, and the hydraulic pipe 14 is connected to a plurality of working hydraulic system actuators 24a, 24.
actuators 24a, 24b, 24 are connected to the hydraulic pipes 14 and connected to the tank lines _T4 .
Switching operation valves 34a, 34b, and 34c are provided for each hydraulic pump 5, and a hydraulic pipe 15 is connected to the hydraulic discharge side of the hydraulic pump 5, and the hydraulic pipe 15 is connected to a plurality of working hydraulic systems. actuator 2
5a, 25b, 25c, and is connected to the tank line _T5 , and is interposed in the hydraulic piping 15 to each actuator 25a, 25.
Switching operation valves 35a, 35b, 3 for each b, 25c
5c and 35d are arranged. When all of the switching operation valves are set to neutral as shown in the figure, the actuators connected to the hydraulic pump 4 and the tank line _T4 and the hydraulic pump 5 to the tank line _T5 become inoperative, respectively, and the respective switching operation valves become inoperative. When the hydraulic pumps 4 and 5 are switched, the discharge hydraulic pressure of the hydraulic pumps 4 and 5 is supplied to the actuators, and each actuator is individually switched and operated by each switching operation valve. Also, a check valve 17 is provided between the hydraulic pipes 14 and 15.
18 is an interposed communication pipe 16, which is connected to the tank line via a relief valve 19.
Connected to T ₆ .

Furthermore, the switching operation valves 34a, 34b, 34
Pilot valves 44a, 44b,
44c, 45a, 45b, 45c, and 45d are fixedly installed, and when the actuator of each of the switching operation valves is in the inoperative state as shown in the figure, all of the pilot valves are in the neutral closed position. ,
A pilot pipe 13 connected to the discharge side of the pilot hydraulic pump 3 and the valve chamber 2c of the regulating cylinder 2a of the speed regulating mechanism 2 communicates with each of the pilot valves and to the tank line _T5 . At the same time, when any of the pilot valves is switched by the switching operation valve, the pilot piping 13
The hydraulic pressure on the side of the hydraulic pump 3 rises to a set pressure at the relief valve 20, and the set pressure is applied to the valve chamber 2c of the speed regulating mechanism 2.
When each actuator is not in operation, that is, when the tank lines of the hydraulic pipes 14 and 15 are connected, the adjustment lever 2b of the speed governor mechanism 2 is held in position A, and the low-speed drive motor 1 is controlled by the speed controller. By switching the lever 2b to position B, the rotational speed is increased and automatically controlled to the rated rotational speed. Furthermore, each of the pilot valves 44a...
45d closes with a stroke shorter than the switching stroke of each of the switching operation valves 34a...35d, and before each switching operation valve switches the actuator to the load side, that is, before opening to the switching side, each pilot The configuration is such that the valve is switched and closed, and control of the prime mover 1 to the rated rotational operation is accelerated.

(Function) The first embodiment of the present invention shown in FIG. 1 has the above-described configuration, so that the prime mover 1 drives the hydraulic pumps 3, 4, and 5, and as shown in the figure, the hydraulic pumps 3, 4, and 5 are When all of the switching operation valves 34a...35d that drive and operate the hydraulic actuators 24a...25c are in the neutral actuator inoperative state, all of the pilot valves 44a...44d are accordingly set to the neutral open position. Because of this, hydraulic pump 4,
The oil discharged from the hydraulic pump 3 is discharged to the tank line T ₄ and T ₅ , and the oil discharged from the hydraulic pump 3 is discharged to the tank line T ₅ via the pilot piping 13 and each pilot valve 44a...45d. The oil pressure in the engine 13 is not increased, and the speed control lever 2b of the speed control mechanism 2 is held at position A by the spring bias, so that the motor 1 enters a low-speed rotation operation, that is, an idling state.

When one of the switching operation valves 34a...35d is switched to an operating state for driving the corresponding hydraulic actuator, the pilot valve provided therein is automatically switched to the closed position by switching the switching operation valve. Since the communication of the pilot piping 13 to the tank line T ₅ is cut off, the oil pressure on the hydraulic pump 3 side of the pilot piping 13 increases, and the high oil pressure reaches the set pilot pressure set by the relief valve 20. The speed governor lever 2b of speed governor 2 reaches
is switched to position B, the number of rotations (speed) of the prime mover 1 is increased, and it automatically operates at the rated rotation, and each hydraulic pump 3, 4, 5 is driven at the rated output of the prime mover 1, and the hydraulic pressure is increased. System actuators are operated at a specified speed.

Each of the switching operation valves 34a...35d requires a small stroke from the neutral actuator inoperative state to the port opening to the actuator, whereas each of the pilot valves 44a...45d
is immediately closed from the neutral open position, resulting in a short switching stroke in which the pilot valve completes switching before reaching the switching opening of each switching operation valve, and the pilot pressure in the pilot piping 13 increases quickly. In other words, the operation of the governor mechanism 2, that is, the increase in the rotation speed of the prime mover 1 is accelerated, and the prime mover 1 smoothly reaches the rated rotational operation, and the increase in the rotational speed of the prime mover 1, that is, its rated output, causes the hydraulic pump to operate at the rated rotation. The switching opening of the switching valve is synchronized so that the actuator is operated smoothly at a specified speed.

Furthermore, when the switching operation valve that had been switched is returned to the neutral actuator inoperative state, the pressure oil in the pilot piping 13 is discharged to the tank line _T5 and the pressure is reduced, and the speed control lever 2b of the speed control mechanism 2 is moved to the position. The prime mover 1 automatically rotates at a low speed when the actuator is switched to the rated speed, and the prime mover and hydraulic pump are switched to the rated rotation operation when the actuator is switched to operate, and the actuator operates smoothly. It is possible to prevent wasteful air blowing and operation, and the noise level is reduced.

(Other Embodiments) FIG. 2 shows a second embodiment of the present invention, in which each pilot valve 44a...
Pilot piping 13a with 45d interposed
is connected to the communication pipe 16 connected between the hydraulic pipes 14 and 15 on the discharge side of the hydraulic pumps 4 and 5, and the hydraulic pressure on the communication pipe 16 side is used as the pilot hydraulic pressure instead of the hydraulic pump 3 of the first embodiment. It is characterized by a configuration in which the hydraulic piping 14,
Sequence valves 51 and 52 are installed in the hydraulic pumps 4 and 5, which are the main oil pressure supply sources for each hydraulic system actuator. A part of the hydraulic pressure is made to a set pressure by the main relief valve 19 through the communication pipe 16, and is supplied to the pilot pipe 13a through the throttle 50 and used as the pilot pressure for the speed regulating mechanism 2. At the same time, the cost can be reduced by not using the pilot hydraulic pump 3 of the first embodiment, and since the structure of each pilot valve is the same as that of the first embodiment, the same operation and effect can be obtained. Furthermore, the sequence valves 51 and 52 are used to secure hydraulic pressure as a predetermined pilot pressure on the hydraulic discharge side of the hydraulic pipes 14 and 15, and are set at a low pressure. This is to obtain the lowest operating pressure at which the 2d can be operated against the spring bias.

FIG. 3 shows a third embodiment of the present invention, and compared to the first embodiment, it is possible to operate or switch one or both of the hydraulic actuators 24a' and 25a', which are the drive source for driving the construction machine. sometimes piping 13
In Fig. 1b, a predetermined pressure is generated by the pilot hydraulic pump 3 and the relief valve 20 before the spool stroke starts supplying pressure oil from the switching operation valve to the actuator, and the predetermined pressure becomes the pilot pressure. Similarly, the rod 2d of the speed regulating mechanism 2
is operated against the spring bias, the speed regulating lever 2b is switched to position B and stopped, and the prime mover 1 is brought into rated rotational operation, and at the same time, the main hydraulic pumps 3 and 4 are activated.
The set pressure of the main relief valve 19 that determines the upper limit of the discharge side oil pressure of the is increased by the pressure regulator 60,
Hydraulic actuators 24a', 25 when starting traveling
a', that is, a configuration that guarantees the motor starting torque, and when other hydraulic actuators 24b, 24c, 25b, 25c in addition to the hydraulic actuators 24a', 25a' for traveling are operated at the same time as traveling. , the same hydraulic pressure as that of the pipe 13b is generated in the pipe 13c, the set pressure increase of the main relief valve 19 is canceled, and the life of the hydraulic pressure of other hydraulic system actuators that are highly loaded is guaranteed. In the third embodiment as well, when one of the hydraulic actuators is switched by each switching operation valve, a desired pilot pressure is generated in the pipe 13b, and the speed governor 2 is operated to operate the prime mover 1 at the rated rotation. Each pilot valve operates in the same manner as in the first embodiment, and the same effects can be obtained. In addition, 61 and 62 in the figure are the pilot piping 13 on the side of the pilot hydraulic pump 3 and the piping 13b, 13c.
It is a diaphragm inserted in between.

The pressure oil supply passage to each hydraulic actuator of each switching operation valve and the passage opening area of each pilot valve attached to each switching operation valve in the first, second, and third embodiments are as follows: The relative relationship to the spool stroke is as shown in Fig. 4, where the vertical axis is the opening area A and the horizontal axis is the spool stroke St of the operating valve, the area of the pressure oil supply passage to the hydraulic actuator of the operating valve is A ₁ , The passage area of the pilot valve is indicated by A ₂ , and in the diagram 0<St ₁
<St ₂ <Fs and 0<St ₃ <St ₄ <Fs,
Incidentally, the closing stroke of the pilot valve passage is
St ₁ , St ₃ , the opening stroke of the pressure oil supply passage to the hydraulic actuator of the operating valve becomes St ₂ , St ₄ , and the above-mentioned effects can be obtained. Fs in the diagram
indicates the full stroke position of the operating valve spool.

(Effect of the invention) As described above, in the present invention, the hydraulic pumps 3, 4, 5 are driven by the prime mover 1 with the speed regulating mechanism 2, which is the power source of the construction machine, and the hydraulic pumps are used to control the switching operation valves 34a...35.
A plurality of hydraulic actuators 24a...2 via d.
In the actuator hydraulic circuit that drives the actuator 5c, a pilot valve 4 is linked to each of the switching operation valves.
4a...45d, each of the pilot valves is switched before the switching operation valve is switched to the actuator operating side to output a rated rotation control signal for the prime mover, and is switched when the switching operation valve is switched to the actuator non-operating side. Since the motor is equipped with a motor control mechanism that outputs a low-speed rotation control signal for the motor, the pilot valve is switched at the same time as the switching operation of the switching operation valve, and the pilot valve is switched and the adjustment is performed before the switching operation valve is opened. Along with the operation of speed gear 2, the rated rotational operation of the prime mover is accelerated, the prime mover is operated smoothly, and the rated rotational operation of each hydraulic pump and the operation of the hydraulic system actuator are synchronized to prevent speed changes of the actuator. It operates smoothly and has significantly improved operating performance and reliability. Therefore, it is also possible to efficiently prevent the prime mover and hydraulic pump from idling and operating.
This has the effect of significantly reducing the noise level.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram showing the first embodiment of the present invention, Fig. 2 is a hydraulic circuit diagram showing the second embodiment, and Fig. 3 is a hydraulic circuit diagram showing the second embodiment.
FIG. 4 is a hydraulic circuit diagram showing a third embodiment, FIG. 4 is a relative characteristic diagram of the strokes of the switching valve and pilot valve of the present invention, and FIG. 5 is a mechanical diagram of a hydraulic circuit showing a conventional example. 1: Prime mover, 2: Governor, 3, 4, 5: Hydraulic pump, 24a, 24b, 24c, 25a, 25
b, 25c: Hydraulic actuator, 34a, 3
4b, 34c, 35a, 35b, 35c, 35
d: Switching operation valve, 44a, 44b, 44c, 45
a, 45b, 45c, 45d: Pilot valve.

Claims (1)

[Scope of utility model registration request] In an actuator hydraulic circuit in which a hydraulic pump is driven by a prime mover with a speed regulating mechanism of a construction machine power source, and the hydraulic pump drives a plurality of hydraulic system actuators via each switching operation valve, the actuator is linked to each switching operation valve. A pilot valve is provided for each,
Each pilot valve is switched before the switching operation valve is switched to the actuator operating side to output a rated rotation control signal for the prime mover, and is switched when the actuator is switched to the non-operating side to output a low speed rotation control signal for the prime mover. An actuator hydraulic circuit for construction machinery, characterized by being provided with a prime mover control mechanism that outputs a signal.