JPS6011243B2 - Control device installed in Aburosho unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a hydraulic unit that operates an actuator by supplying the discharge of a constant displacement hydraulic pump driven by an engine through a directional control valve. The present invention relates to a control device that performs manual control.

First, an example of the basic hydraulic circuit of the above hydraulic unit will be explained with reference to FIG. The constant displacement hydraulic pump 2, which is a pressure oil source for the hydraulic cylinder 4, and the pilot hydraulic pump 6, which is a pressure oil source for the pilot valve 5, are both driven by the engine 1. The pressure oil discharged from the hydraulic pump 2 is controlled by switching the hydraulic pilot operating directional control valve 3.
It is supplied to the bottom side chamber or rod side chamber of the hydraulic syringe 4 to operate the hydraulic syringe 4. Pilot valve 5
is designed to be switched by swinging an operating lever 7, and by this switching, pressure oil from the hydraulic pump 6 is supplied to the pilot chamber of the directional switching valve 3, and the valve 3 is switched. Note that if the directional switching valve 3 is of a manually operated type, the pilot valve 5 is not necessary.

In such a hydraulic unit, it is troublesome to change the output rotation speed of engine 1 by operating the governor of engine 1, so especially in construction machinery such as hydraulic excavators, engine 1 is set to the maximum rotation speed and kept constant. I often leave it as is.

When a discharge pressure-discharge rate diagram of a constant discharge island type hydraulic pump is drawn, it becomes the POXQ line in FIG. 2.

The discharge flow rate of a constant displacement hydraulic pump varies only depending on the engine speed. Here, the discharge amount at the maximum engine speed is Q, and the maximum working pressure of the circuit is Po.
The maximum engine horsepower required to drive this hydraulic pump is greater than or equal to the horsepower Ha shown by the constant horsepower curve AXB. Now, at any given moment, the discharge pressure and discharge amount required to actually drive the hydraulic cylinder 4 are P, Q, respectively.
If so, the required horsepower is the horsepower Hc shown by the constant horsepower curve CYD. However, even in this case, in a conventional unit where the hydraulic pump continues to discharge the maximum discharge amount Qo, the consumed horsepower is He shown by the constant horsepower curve E,
Therefore, the difference between He and Hc becomes the horsepower loss. As mentioned above, in conventional hydraulic units, it is difficult to control the engine speed during actual operation, resulting in a considerable amount of horsepower loss.

The purpose of this invention is to eliminate the above-mentioned drawbacks. During actual operation, the flow rate required for the hydraulic circuit, that is, the operating signal of the directional control valve, is detected, and the engine governor, that is, the rotation speed, is controlled at any time by feedback of the flow rate. The system controls the horsepower consumption to bring it closer to the required horsepower.

Hereinafter, each embodiment of the present invention shown in FIGS. 3 and 4 will be described with reference to the pressure flow diagram in FIG. 2.

FIG. 3 shows an embodiment of a hydraulic unit in which a constant discharge type hydraulic pump and a hydraulic pilot operating direction variable valve are roughly combined.

Normally, the engine speed is controlled by swinging the throttle lever 8 in the direction of the arrow (to the 8' position) and operating the engine governor 11 via the links 9 and 10. In this embodiment, a single acting cylinder 12 is used in such a link mechanism.
are connected. The cylinder 12 can freely swing around a pin 13, and the pin 13 slides in the direction of the arrow in the elongated hole 14 when manually controlling the engine speed. Further, when automatically controlling the engine speed, the pin 13 is fixed at a predetermined position by the pin 15. The bottom chamber of the single-acting cylinder 12 includes a first
As shown by the dashed line in the figure, the pilot valve 5
A pilot pressure Pp taken out from the shuttle valve 28 is introduced. A spring 17 is provided in the rod chamber. When the operating lever 8 is in the neutral position, the link 10 is also in the neutral position, and when the rod 16 of the single-acting cylinder 12 is in the position where it can move all the way and the maximum flow rate is required, the pilot pressure Pp is at the maximum. becomes pressure, link 10
is in the maximum value dislocation layer and is set so that the engine speed is maximum. Assume that during operation, as shown in FIG. 2, P is required for the load pressure and Q is required for the discharge flow rate.

That point is point Y in the figure. In order to discharge a flow rate of Q, the operating lever 7 in FIG. 1 is swung to a predetermined position and the directional control valve 3 is switched by a predetermined pilot pressure Pp. The link 10 is extended by a predetermined length by the pilot pressure Pp, and accordingly, the link 10 is rotated by a predetermined angle, changing the rotational speed of the engine and bringing the discharge amount of the hydraulic pump to Q.
At this engine speed, the maximum engine horsepower is Q,
Horsepower Hg expressed by constant horsepower curve GH passing through point and point Po
It is.

Therefore, regardless of the discharge pressure P, the consumed horsepower at that time will not overload the engine, and the difference between the required horsepower and the consumed horsepower will be smaller than in the conventional system, and the loss of horsepower will be reduced accordingly. Of course, in an actual engine, the maximum number of revolutions (idling state) is limited, and the discharge flow rate Q3 corresponding to this is determined.
Therefore, at a flow rate of Q3 or less, loss of horsepower occurs as in the conventional case. On the other hand, there are cases where it is desired to operate the engine at a constant speed by fixing the throttle lever 8 at a predetermined position, as in the conventional case, without automatically controlling the engine speed as described above. it is conceivable that.

In this case, if the pin 15 is removed, when the pilot pressure Pp is generated, the housing 12a of the cylinder 12 escapes from the rod 16 in the direction of the elongated hole, and the link 10 is not affected. FIG. 4 shows an embodiment of a hydraulic unit in which a constant discharge type hydraulic pump and a manual directional valve are roughly combined, and the same reference numerals as in FIG. 3 represent the same or equivalent parts.

Normally, in the case of a manual directional control valve, the operating lever 18 is swung to move the link 19 and operate the spool 21 of the directional control valve 20.

In this embodiment, a cam 22 is provided between the link 19 and the spool 21, and a roller 24 rotatably attached to one end of a swinging bell crank 23 is in contact with the cam 22. I'm forced to. A roller 25 is rotatably attached to the other end of the bell crank 23, and this roller 25 is inserted into the elongated hole 9a formed in the link 9.
It's stuck in. The roller 25 is fixed to the innermost hole 9a by a removable pin 26. bell crank 23
A tension coil spring 27 is connected to the spring 2.
7, the roller 24 is always pressed against the cam 22. Now, when the operating lever 18 is swung from the neutral position shown in the figure, the cam 22 moves to the left or right depending on the stroke.
Push up the roller 24.

At the same time, the bell crank 23 is rotated clockwise, and the engine speed is increased via the link 10. Other operations are similar to the previously described embodiment. According to the invention described above, the following effects can be obtained.

That is, in a hydraulic unit using a constant displacement hydraulic pump, the engine can always be operated at close to the required rotation speed, thereby saving fuel costs. In addition, the hydraulic pump can be operated at close to the required discharge amount, so there is no heat loss due to throttling excess flow, and the oil cooler and the like can be downsized.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an example of a basic hydraulic circuit for operating an actuator, Fig. 2 is a pressure flow diagram of a constant displacement hydraulic pump, and Figs. 3 and 4 are various embodiments of the present invention. It is a block diagram which shows an example. 1... Engine, 2... Constant discharge type hydraulic pump, 3...
・...Hydraulic pilot operated directional valve, 4...Hydraulic cylinder, 5...Pilot valve, 7...
......Operation lever, 8...Throttle ring lever, 11...Governor, 12...Single acting cylinder, 18...Operating lever, 20. ...
... Directional switching valve, 22 ... Cam, 23 ... Bell crank, 24 ... Loaf. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A hydraulic unit comprising an engine having a governor, a constant displacement hydraulic pump driven by the engine, and an actuator actuated by the oil discharged from the hydraulic pump via a directional control valve. A detection means for detecting an operation signal of the directional control valve, and a control means for automatically controlling the governor of the engine based on the detection signal from the detection means, and the actuator is controlled by the operation of the directional control valve. A control device for a hydraulic unit, characterized in that the control device is configured to bring the output horsepower of the engine closer to the required horsepower when the engine is in operation.