JPH031522B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic system used in a hydraulic shovel or the like, and particularly to a hydraulic control system having a logic valve for adding an attachment valve to a standard specification control system.

[Prior Art] Generally, a hydraulic control device equipped with a standard actuator in a hydraulic shovel or the like has pumps 1 and 2 driven by an engine, as shown in FIG. 1, and a switching valve 3 connected to the pump 1. ,4,5,
6 and 3 control valves 11 each having switching valves 8, 9, and 10 connected to the pump 2.
These control valves 7, 11 include a pressure generating circuit consisting of a throttle and a relief valve between the downstream of the center bypass passages 12, 13 via the plurality of switching valves and the tank passages 14, 15. Mechanism 1
6, 17 are provided, and this pressure generating mechanism 16,
The discharge amount of the pumps 1, 2 is controlled by applying pilot pressure generated by the switching valve upstream of the pump 17 to the control cylinders 18, 19.

When a hydraulic system having such a configuration is used to control a standard actuator, there are few problems with the control. However, in recent years, there has been a demand for attachments such as breaker specifications due to the versatility of hydraulic excavators, etc., and in order to cope with this, we have developed a 4-set control valve in which the 3-set control valve 1 is always equipped with a preliminary switching valve for attachment. The four control valves 7
Alternatively, the three control valves 11 may be replaced with four control valves, or the three control valves 11 may be modified to have four control valves as required. are doing.

[Problems to be Solved by the Invention] However, if a standby switching valve for the attachment is always provided as in the former case, one station is not required when the attachment valve is not used, and as in the latter case, three stations are controlled according to demand. If the valve is replaced with a four-set control valve or modified, there are problems such as the need for man-hours for replacing the control valves and restrictions on the installation layout.

The present invention was made in view of the above problems, and
The purpose is to use the switching valve for the standard actuator as is when an attachment valve is required, to removably dispose the attachment valve in any position, and to use the logic that is removably pre-assembled in the standard specification control valve. It is an object of the present invention to provide a hydraulic control device that can cope with attachment valve specifications by being configured with a valve.

[Means for Solving the Problems] In order to achieve the above object, a hydraulic control device according to the present invention provides a plurality of switching valves in parallel, and controls an actuator by a combination of turning on and off the switching valves. A standard actuator is provided with a pressure generation mechanism between the center bypass passage and the tank passage of a multiple control valve, and controls the pump discharge amount by a first pilot circuit branched from a circuit connecting the pressure generation mechanism and the center bypass passage. In the hydraulic control system, when using an attachment actuator other than the actuator, the same is included in the circuit connecting the most downstream switching valve of the multiple switching valves of the multiple control valves and the branch point of the first pilot circuit. A logic valve for opening and closing the circuit is removably provided, and a selector valve is connected to the switching valve for controlling the attachment actuator so as to turn on and off a second pilot circuit for controlling the opening and closing of the logic valve. The invention is characterized in that the attached attachment valve is removably provided in parallel with the multiple control valve at any position.

[Function] In the hydraulic control device of the present invention, the first pilot circuit branches between the logic valve and the pressure generation mechanism, which are interposed downstream of the center bypass passage via the most downstream switching valve of the multiple control valves. The pump discharge amount is controlled by the pilot pressure generated in the pump. When using an attachment valve, the second pilot circuit is turned on and off by a selector valve linked to the switching valve of the attachment valve, and the logic valve is opened and closed to control the pilot pressure of the first pilot circuit. , the pump discharge amount is controlled to suit the combined operation.

[Example] Hereinafter, FIGS. 2 to 4 showing examples of the present invention will be described in detail.

For convenience of explanation, the same parts as those in the conventional configuration shown in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 2, a logic valve 20 is connected in series between the center bypass passage 13 located upstream of the pressure generating mechanism 17 provided between the center bypass passage 13 of the control valve 11 and the tank passage 15, and the switching valve 10 located most downstream. This logic valve 20 and pressure generation mechanism 17 are interposed
A pump control port 21 provided between the two is connected to the control cylinder 19 via a first pilot circuit 22. Further, an attachment valve 23 arbitrarily disposed with respect to the control valve 11 is combined with a selector valve 25 in conjunction with its switching valve 24, and this supply passage 26 is connected to the discharge side of the pump 2, and the selector valve 25 is connected via a second pilot circuit 28 to a port 27 for opening and closing the logic valve 20.

In addition, FIG. 3 shows a pressure generating mechanism 17 in the control valve 11.
and details of the logic valve 20 attached, the valve member 29 fixed to the valve body 11a of the control valve 11 is provided with a pressure generating mechanism 17 and the logic valve 20, and the logic valve 20 is A poppet 30 having a throttle is inserted inside, and a plug 31 forming a port 27 and connecting to a second pilot circuit 28 to the attachment valve 23 is removably screwed to the rear of the poppet 30. There is. Further, when the poppet 30 moves against the spring 32, it connects the center bypass passage 13 and the control port 21. The pressure generating mechanism 17 is also provided with a relief poppet 33 that moves against a spring 35 due to the pressure of the control port 21, and this relief poppet 33 connects the control port 21 to the tank passage 15 via a throttle 34. do. The other configurations are omitted because they are well-known techniques.

What is shown in FIG. 4 is a control valve 11 from which the logic valve 20 is removed when the attachment valve 23 is not used, and the plug 31 of the logic valve 20,
The spring 32 and poppet 30 are removed, and a blind plug 31a is screwed into the valve member 29 in place of the plug 31.

Next, the operation of the present invention will be explained. First of all,
In FIG. 3 when the attachment valve 23 is added, when the switching valves 8, 9, 10 of the control valve 11 and the switching valve 24 of the attachment valve 23 are in the neutral position shown, the port 27 of the logic valve 20 is connected to the second The oil in the center bypass passage 13 is connected to the tank via the pilot circuit 28 and the selector valve 25, so it is at tank pressure. 17, and the pilot pressure before the throttle 34 that is generated when it flows from the pressure generating mechanism 17 to the tank acts on the control cylinder 19 via the first pilot circuit 22 to minimize the discharge amount of the pump 2. Close.

Now, when the switching valve 10 is switched from the neutral position shown in the figure to any direction position, the flow rate to the downstream center bypass passage 13 decreases according to the amount of movement of the spool of the switching valve 10, and the flow rate decreases according to this phenomenon flow rate. As a result, the pressure in the control port 21 decreases, and the discharge amount of the pump 2 increases in proportion to the decrease in pressure.

Therefore, when the switching valve 24 of the attachment valve 23 is switched from the neutral position shown in the figure to any direction position, the second pilot circuit 28 is disconnected from the tank and closed by the selector valve 25 that is linked to the switching valve 24. As a result, the logic valve 20 is in the closed position and the center bypass passage 13 is cut off.
The center bypass flow rate flowing into the pressure generating mechanism 17 becomes zero, and the pilot pressure generated in the control port 21 becomes even lower, so that the discharge amount of the pump 2 can be made the maximum discharge amount. Therefore, the maximum discharge amount of the pump 2 is determined when the supply flow rate from the supply passage 26 to the actuator via the switching valve 24 of the attachment valve 23 is secured, and when the switching valves 8, 9, and 10 of the control valve 11 are operated. Since the flow rate supplied to the actuator via these switching valves can also be ensured, combined operation of the control valve 11 and the attachment valve 23 is made possible.

In addition, when the attachment valve 23 is not required,
As shown in FIG. 4, the supply passage 26 connected to the pump 2 and the second pilot circuit 28 connected to the port 27 are cut off, and the logic valve 20
The main components are the plug 31 and the spring 3.
2. Remove the poppet 30, etc. to make it functionless, and then replace it with a spare plug 31.
By screwing a into the valve member 29, the valve member 29 having only the pressure generating mechanism 17 can be used as a fixed control valve 11 to meet standard actuator specifications.

[Effects of the Invention] As described above, according to the present invention, the logic valve can be easily and easily installed and removed depending on whether the attachment valve is required or not, thereby reducing the man-hours required for changing these specifications. Moreover, the manufacturing cost can be relatively low, and the attachment valve can be placed at any position without being restricted by installation space, so this device can be used in a wide range of applications.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional hydraulic control device, Fig. 2 is a circuit diagram showing an embodiment of the hydraulic control device of the present invention, and Fig. 3 is a schematic horizontal sectional view of the circuit diagram shown in Fig. 2. , FIG. 4 is a schematic horizontal sectional view showing the main parts in FIG. 3. 1, 2...pump, 3, 4, 5, 6, 8, 9,
10...Switching valve, 7,11...Control valve, 12,1
3... Center bypass passage, 14, 15... Tank passage, 16, 17... Pressure generation mechanism, 18, 1
9... Control cylinder, 20... Logic valve, 2
DESCRIPTION OF SYMBOLS 1... Pump control port, 22... First pilot circuit, 23... Attachment valve, 24...
...Switching valve, 25...Selector valve, 26...Supply passage, 27...Port, 28...Second pilot circuit, 29...Valve member, 30...Poppet, 31
...Plug, 31a...Mekura plug, 32,3
5...Spring, 33...Relief poppet, 34...
...Aperture.

Claims (1)

[Scope of Claims] 1. A pressure generating mechanism is provided between a center bypass passage and a tank passage of a multiple control valve in which a plurality of switching valves are provided in parallel and an actuator is controlled by a combination of turning on and off of the switching valves. In addition, in the standard actuator hydraulic control device that controls the pump discharge amount by a first pilot circuit branched from a circuit connecting the pressure generation mechanism and the center bypass passage, when using an attachment actuator other than the standard actuator, the above-mentioned A logic valve for opening and closing the circuit is removably provided in a circuit connecting the most downstream switching valve of the plurality of switching valves of the multiple control valve and the branch point of the first pilot circuit, and the logic valve for opening and closing the circuit is removably provided, and the logic valve for opening and closing the circuit is removably provided. An attachment valve, which is connected to a selector valve that is interlocked to turn on and off a second pilot circuit that controls opening and closing of the logic valve, is attached to the multiple control valve so as to be removable at any position. A hydraulic control device characterized by being installed in parallel.