JPH0444828Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an operating device for a hydraulically driven working machine equipped with a hydraulic pump driven by an engine.

(Prior Art) Conventionally, in hydraulically driven working machines equipped with engine-driven hydraulic pumps, such as hydraulic truck cranes or hydraulic aerial work vehicles, it has been difficult to operate the hydraulic actuator for work and the accelerator of the engine. There is an idea to improve work operability by linking these operations, and specific measures include, for example, the applicant's application (for example, Utility Application No. 1983).
51179), the switching operation of the directional switching valve of the working hydraulic actuator is generally linked to the accelerator operation via a mechanical means such as a cam mechanism or a link mechanism.

However, in cases where the switching operation of the hydraulic actuator for work and the accelerator operation of the engine are mechanically linked, the lever operation is relatively slow due to the effects of sliding resistance in the sliding connection. It tends to become heavy, and therefore there is room for improvement in terms of work operability.

(Purpose of the invention) The present invention is an attempt to solve the problems pointed out in the above-mentioned section of the prior art. By linking the switching operation of the actuator and allowing it to be performed by hydraulic pressure at the end of the switching operation, it is possible to realize a lever operation that is light and meets the operator's requirements, and improves work operability. The object of this invention is to provide an operating device for a hydraulically driven working machine as described above.

(Means for Achieving the Object) As a means for achieving the above object, the present invention provides a hydraulic pump driven by an engine and a predetermined working hydraulic actuator to provide pressure to the working hydraulic actuator. The connection is made through a directional control valve that has a neutral position where the oil supply is stopped and an operating range that enables the supply of pressure oil to the hydraulic actuator for the work, and the operation of the directional control valve allows the work to be performed. In an operating device for a hydraulically driven work machine that controls the operation of an actuator, an adjustment device that is appropriately displaced when hydraulic oil is introduced and acts to displace a governor lever for regulating the engine speed toward a high speed rotation side. and a hydraulic actuator for speed control, and the hydraulic actuator for speed control operates between the middle of the operation range and the end of the operation range when the directional control valve is switched from its neutral position to the end of the operation range. It is configured to be connected to the hydraulic pump via the directional switching valve.

(Function) In the present invention, while operating the directional switching valve that controls the hydraulic pressure supply to the hydraulic actuator for work from its neutral position to the end of the operating range, the directional switching is performed only between the middle and the end of the operating range. In conjunction with the operation of the valve, hydraulic oil is simultaneously supplied to the speed regulating hydraulic actuator in addition to the working hydraulic actuator.

Therefore, during the operating period from when the directional control valve is in its neutral position until the hydraulic pressure starts to be supplied to the regulating hydraulic actuator, the engine rotates at a low speed and the amount of oil supplied to the working hydraulic actuator is relatively small. In addition, since the amount of supplied oil increases or decreases in accordance with the amount of operation of the directional switching valve, it is possible to perform very slow control of the working hydraulic actuator by operating the directional switching valve.

On the other hand, if the operation amount of the directional control valve increases and exceeds the operating position where the hydraulic pressure supply to the regulating hydraulic actuator starts (in other words, the amount of supply from the worker to the working hydraulic actuator increases) (If a request is made to increase the work speed), hydraulic pressure is supplied to the hydraulic actuator for work and simultaneously to the hydraulic actuator for speed control, and the hydraulic actuator for speed control operates the governor lever. is displaced to the high speed rotation side. As a result, the engine speed increases, the amount of oil supplied to the working hydraulic actuator increases, the operating speed of the working hydraulic actuator increases, and normal load work becomes possible.

(Effect of the invention) Therefore, according to the operating device for a hydraulically driven working machine of the present invention, when the directional control valve is operated to control the operation of the working hydraulic actuator, the speed regulating hydraulic actuator is simultaneously controlled. Since the engine accelerator is adjusted by The practical effect is that the operation in conjunction with the accelerator operation can be easily performed with a smaller operating force, and the operability is further improved.

Furthermore, the engine accelerator adjustment using this regulating hydraulic actuator is not set over the entire operating range of the directional control valve, but only over a large operation amount range from the middle to the end of the operating range. , the engine rotation speed is maintained at a low speed in the small operation amount range of the directional valve, where the operator is thought to want to operate the working hydraulic actuator at very low speeds, and the directional valve, where the operator is expected to perform normal load work at high speeds. In the large operation amount range, the engine speed is raised by the regulating hydraulic actuator at the same time as the directional control valve is operated, and the only control that accurately reflects the operator's intentions is the directional control valve operation. This has the effect of further improving the operability of the hydraulically driven working machine.

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows a hydraulic circuit diagram of a hydraulically driven aerial work vehicle equipped with an operating device according to an embodiment of the present invention, in which reference numeral 1 indicates a first jack hydraulic cylinder; 3 is a hydraulic cylinder for the second jack, 3 is a hydraulic motor for rotating the work platform, 4 is a hydraulic cylinder for boom hoisting, 5 is a hydraulic motor for boom rotating, and 6 is a hydraulic cylinder for boom extension and retraction. Each of the motors corresponds to a working hydraulic actuator within the scope of the utility model registration claims. The working hydraulic actuators 1 to 6 are connected to a hydraulic pump 21 via directional control valves 11 to 16, respectively. The hydraulic pump 21 is driven by an engine 22 whose speed is controlled by a governor 28 controlling the amount of fuel supplied.

Further, the reference numeral 25 is a spring return type accelerator cylinder (corresponding to the speed regulating hydraulic actuator in the scope of the utility model registration claim),
When hydraulic oil is introduced into the oil chamber 25a, the accelerator lever 26, which extends and is connected to the rod 25b, is rotated in the direction of arrow A, and the oil chamber 25a is communicated with the tank side. The accelerator lever 26, which is compressed by the spring force of the spring 25c, can be rotated in the direction of arrow B. This rotational displacement of the accelerator cylinder 25 in the direction of arrow A-B is applied to the governor lever 29 of the governor 28 via the push-pull cable 27 in the direction of arrow C (high speed side).
and is transmitted as a rotational displacement in the direction of arrow D (low speed side). That is, the oil chamber 2 of the accelerator cylinder 25
By introducing hydraulic oil into 5a, engine 2
2 will be automatically accelerated.

It goes without saying that the governor lever 29 can also be operated directly manually, without relying on the accelerator cylinder 25.

Each of the above-mentioned directional switching valves 11 to 16 is composed of an 8-port, 5-position switching valve having the same passage configuration, and each has a first pressure port 4.
The hydraulic pump 21 is connected in parallel to the hydraulic pump 21 via a communication oil passage 51 connected to the hydraulic pump 21 .
In addition, each of the directional control valves 11 to 16 is
Taking the directional switching valve 11 as an example, this directional switching valve 11 has a second pressure port 42 and a third pressure port 4 in addition to the first pressure port 41.
3 and a tank port 44, of which the second pressure port 42 and the tank port 44 are connected to the extension side oil passage 35 of the working hydraulic cylinder 1.
and the third pressure port 4 to the contraction side oil passage 36.
3 can communicate with a regulating oil passage 37 connected to the oil passage 25a of the accelerator cylinder 25, respectively.

Specifically, on both sides of the neutral first valve position 11A (corresponding to the neutral position in the scope of the utility model registration claim) where only the second pressure port 42 is opened,
A second valve position 11B in which the working hydraulic cylinder 1 is extended and the third pressure port 43 is closed, and a third valve position 11B in which the working hydraulic cylinder 1 is contracted and the third pressure port 43 is closed. valve position 11C is arranged. Furthermore, this second valve position 11B and the third valve position 11
On both sides of C, there is a fourth valve position 11D where the extension operation of the working hydraulic cylinder 1 is continued and at the same time the third pressure port 43 communicates with the regulating oil passage 37 and the accelerator cylinder 25 is extended. , a fifth valve position 11E is arranged in which the third pressure port 43 communicates with the regulating oil passage 37 and the accelerator cylinder 25 is extended at the same time as the contraction operation of the working hydraulic cylinder 1 is continued. .

In this embodiment, the neutral position and the fourth valve position 11D or the fifth valve position 11E are
The entire range of movement of the spool (not shown) during this period corresponds to the operating range of the claimed utility model. In addition, "from the middle of the operating range to the end of the operating range" referred to in the claims for utility model registration means that the directional control valve 11 is completely moved from its second valve device 11B or third valve position 11C to the fourth valve position. This corresponds to the period until switching to 11D or 5th valve position 11E.

According to the directional control valve 11 having such a configuration, the valve position is changed to the first valve position 11 by operating the lever.
At the time when the valve position A is switched to the second valve position 11B or the third valve position 11C, the working hydraulic cylinder 1 can be operated, but the engine is not supplied with hydraulic pressure to the regulating hydraulic actuator 25. 22 is maintained at a low speed rotation (idle rotation speed). Therefore, under this condition, by appropriately operating the directional control valve 11 between the first valve position 11A and the second valve position 11B or third valve position 11C, it is possible to perform fine speed control of the aerial work vehicle. This is the result.

On the other hand, if the lever is further operated from this state and the directional control valve 11 is switched from the second valve position 11B or the third valve position 11C to the fourth valve position 11D or the fifth valve position 11E, the above-mentioned Hydraulic pressure continues to be supplied to the working hydraulic cylinder 1, and in addition, hydraulic oil is supplied to the accelerator cylinder 25 side. Therefore, the governor lever 29 is displaced to the high speed side (in the direction of arrow C) via the accelerator cylinder 25, and the increase in engine speed causes an increase in the amount of hydraulic oil (that is, an increase in the speed of the working hydraulic cylinder 1). This enables normal load operation.

As described above, in this embodiment, the operating operation of the working hydraulic cylinder 1 and the speed increasing operation of the engine 22 are linked via oil pressure. The operation force is not increased due to the resistance of the sliding portion as is the case when the operation is performed mechanically via a screw or the like, and the operation can be performed more easily with a smaller operation force.

Furthermore, in this embodiment, the directional control valve 11 is located at its first valve position 11A and at its second valve position 1A.
By appropriately operating between 1B and 3rd valve position 11C, it is possible to control the working cylinder 1 at a very low speed while maintaining the engine speed at a low speed. When further operating from the second valve position 11B or the third valve position 11C to set it to the fourth valve position 11D or fifth valve position 11E, the engine speed is automatically increased and the working cylinder 1 is It can operate at high speed and perform normal load operation.

That is, by doing as in this embodiment, the work operation of the working hydraulic cylinder 1 and the speed increasing operation of the engine can be performed by only a single operation of operating the directional control valve 11. In a configuration in which the engine speed is automatically increased only in the large operating amount range of the switching valve 11, it is usually recommended that the operator operate the operating lever in the increasing direction when he or she desires to work at higher speeds. Since it is natural, it can be said that it is a control method that corresponds to the intention of the worker, and the synergistic effect of these methods makes the operability or workability of the aerial work vehicle even better.

Note that the directional control valve 11 changes from the fourth valve position 11D or the fifth valve position 11E to the third valve position 11.
C, second valve position 11B or first valve position 1
When it returns to the 1A side, the regulating oil passage 37 is connected to the tank side via the drain oil passage 38, so
The engine 22 is again rotated at low speed. The throttle 46 provided in the drain oil passage 38 is connected to the accelerator cylinder 2.
When hydraulic oil is introduced to the 5 side, the pressure drop of the hydraulic oil is suppressed to enable operation of the accelerator cylinder 25, and conversely, when the hydraulic oil is discharged, the hydraulic oil is allowed to be discharged to the tank side.

Further, in this embodiment, the restrictor 46 provided in the drain oil passage 38 is configured with a fixed flow rate restrictor, but in other embodiments of the present invention, it is configured with a variable flow rate restrictor. Particularly in the case where the variable flow rate restrictor is configured as described above, it is possible to improve the operational stability by constantly interlocking the directional control valve 11 and the accelerator cylinder 25 in an appropriate state for the following reasons. It becomes possible. That is, the amount of hydraulic oil introduced into the regulating oil passage 37 via the directional switching valve 11 is increased as the amount of operation of the directional switching valve 11 increases. When is a fixed flow rate restrictor, the relationship between the amount of hydraulic oil flowing through this restrictor and the differential pressure before and after the restrictor is not a simple proportional relationship due to the nature of a fixed restrictor, so the amount and direction of operation of the accelerator cylinder are It is conceivable that it becomes difficult to match the operation amount of the switching valve (the amount of hydraulic oil introduced into the regulating oil passage 37). In such a case, if the throttle 46 is configured as a variable flow rate throttle and the throttle 46 is opened as the amount of expansion of the accelerator cylinder 25 increases, the operation of the accelerator cylinder 25 and the directional control valve 11 are always controlled. It is possible to interlock them in an appropriate state and stabilize their operation.

In the above embodiment, the directional switching valve is configured with 8 ports and 5 positions, but the present invention is not limited to this, and for example, 8 ports and 3 positions are configured.
Of course, even in the case of a positional switching valve, the same effects as the directional switching valve in the above embodiment can be obtained by appropriately setting the opening characteristics of each port.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram of a hydraulically driven working machine equipped with an operating device according to an embodiment of the present invention. 1 to 6...Hydraulic cylinder for work (hydraulic actuator for work), 11 to 16...Direction switching valve, 2
5...Accelerator cylinder (hydraulic actuator for regulating speed), 28...Governor.

Claims (1)

[Scope of utility model registration request] A hydraulic pump driven by an engine and a predetermined working hydraulic actuator are placed in a neutral position where the supply of pressure oil to the working hydraulic actuator is stopped, and a neutral position where pressure oil is supplied to the working hydraulic actuator. An operating device for a hydraulically driven working machine, which is connected via a directional switching valve having an operating range of is provided with a speed regulating hydraulic actuator which is appropriately displaced by the introduction of the engine speed regulating hydraulic actuator and acts to displace the engine speed regulating governor lever toward the high speed rotation side, and the speed regulating hydraulic actuator is configured such that the directional switching valve is It is configured to be connected to the hydraulic pump via the directional switching valve between the middle of the operating range and the end of the operating range when switching from the neutral position to the end of the operating range. An operating device for a hydraulically driven working machine, characterized by: