JPS5939602B2 - hydraulic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention provides at least two control slide valves for supplying pressure medium to two actuators and a supply conduit arranged in all control slide valves, which is used as a normal working pressure. The present invention relates to a hydraulic control device having a high primary pressure and a device for limiting a secondary pressure that is low compared to this primary pressure.

Hydraulic control devices with devices for limiting secondary pressure are known.

In this case, each directional control valve has one or two
Two additional pressure limiting devices are provided.

When such a control device is installed, for example, in a forklift truck, it is difficult to find an easily accessible position for the actuating lever of the individual directional control valve block as well as for the additional secondary pressure limiting device.

In addition to this difficulty of assembly, the cost of the necessary piping increases.

Furthermore, the known control device is uneconomically constructed because an additional valve is required for each actuator connection with a secondary pressure limiting device.

The object of the invention is to provide a hydraulic control device of the type mentioned at the outset, which avoids the above-mentioned disadvantages and can be constructed as simply as possible.

According to the invention, this problem is solved in that the device for limiting the secondary and secondary pressures has an electromagnetically operated, proportionally operated pressure control valve, which is connected to the supply line and the return line. electrical circuit connected in the hydraulic connection circuit between the pressure control valves and in which each control slide valve is assigned an electric switch, which switch is connected to the magnet of the pressure control valve. and one switch is connected to the
The solution is that an electric circuit section is connected that runs parallel to the other switch, and that this electric circuit section has a member connectable in series with the magnet, which changes the resistance of this electric circuit section. It was done.

In this way, the control device is not only constructed at low cost but is also suitable for assembly, which was not possible with conventional control devices of the same type.

Particularly advantageously, secondary pressure limiting devices can be used simultaneously for a number of directional control valves.

In the example, the directional control valve is operated by only one proportional pressure control valve of the proportional action type, and for each control slide valve,
This is because only simple switches and resistors are required which offer many possibilities as to the arrangement.

The outlay for conduits for connecting the control device is therefore significantly reduced.

A further advantage is that the proportionally operated pressure control valve also reduces the neutral circulation pressure and that the control device can therefore be made smaller.

The invention will now be explained with reference to the illustrated embodiment.

The control device 10 includes a connecting plate 11, four directional control valves 12,
13, 14, 15, and an end plate 16.

Each directional control valve 12, 13, 14, 15 has a control slide valve 17, 18, 19, 20 which all connect in parallel to the supply conduit 2.
1 and all are returned from supply 22 to 2
3 is connected within a neutral circulation circuit 24 guided by 3.

A main valve 25 is arranged in the connection plate 11 and is connected between the supply line 21 or the neutral circuit 24 and the return 23 .

The main valve 25 is precontrolled by a pressure limiting valve 26 .

A proportionally acting pressure control valve 27 is connected in parallel to the pressure limiting valve 26, which pressure control valve 27 can likewise pre-control the main valve 25.

A pressure limiting valve 26 and a pressure control valve 27 are arranged in the connecting plate 11 .

The pressure control valve 27 has a proportionally operated magnet 28,
This magnet 28 is connected in an electrical circuit 29 with a power source 30 .

The electric circuit 29 further includes a first electric switch 3.
1 is located, and this switch 31 is connected to the control slide valve 17.
is assigned to.

In parallel to the first switch 31 , a second switch 32 assigned to the control slide valve 18 is arranged in the electrical circuit 29 .

Both control slide valves 17,18 belong to the high pressure primary pressure, which is used as the so-called normal working pressure.

A third or fourth switch 33, 34 is assigned to the third and fourth control slide valves 19,20.

The third switch 33 is located in the electric circuit 29 in series with the first and second switches, and when the third switch is operated, the first potentiometer 35 is placed in the electric circuit 29. This potentiometer 35 is located in a first electrical circuit section 36 which runs parallel to the first and second switches 31,32.

Correspondingly, a second parallel electrical circuit section 37 with a potentiometer 38 is assigned to the fourth switch 34 .

Correspondingly, the third and fourth control slide valves 19.20 are
That is, because of the second action, it belongs to the secondary pressure, which is a lower working pressure than the primary pressure.

Pump 39 supplies pressure medium from tank 40 to the control device.

The mode of operation of the control device 10 is as follows.

If all control slide valves 17, 18, 19, 20 occupy the illustrated neutral position, no current flows through the magnet 28 of the proportional pressure control valve 27.

The pressure control valve 27 therefore does not load the precontrolled main valve 25 and the pressure limiting valve 26 at all.

A low neutral circulation pressure therefore results, independent of the number of directional control valves 12, 13, 14, 15.

If the control slide valve 17 is actuated, the first switch 31 closes the electrical circuit and the magnet 2B is energized.

In this case, the proportionally operated pressure control valve 27 is controlled to a pressure value greater than the pressure value regulated by the pressure limiting valve 26.

The actuator controlled by the control slide valve 17 is therefore protected by the primary pressure regulated in the pressure limiting valve 26.

This is because secondary pressure does not act.

If the control slide valve 18 is actuated accordingly, the associated actuator is also protected by the primary pressure.

If the third control slide valve 19 is operated, the magnet 2
8 is connected to the electric circuit 29 in series with the potentiometer 35.

Now, depending on the adjustment of the potentiometer 35, the electrical circuit 29
A low current flows in the pressure control valve 27 and therefore in the magnet 2.
8 controls the pressure proportional to the current.

Said secondary pressure regulated in the potentiometer 35 is used for the actuator controlled by the control slide valve 19.

If the control slide valve 20 is actuated accordingly, the secondary pressure is determined by the potentiometer 38.

It is particularly advantageous if the electrical circuit is constructed in such a way that if the control slide valves 17 or 19 belonging to the -voltage and the secondary pressure are actuated at the same time, priority is given to the secondary pressure.

In this case, the actuator, which is supplied with a high primary pressure, is protected by the check valve 41.

In the case of the control device shown, the potentiometer 35.3
8 is very easily and perfectly accessible, so that when assembling the control device care must be taken only to ensure that the actuating levers of the directional control valves 12, 13, 14, 15 are virtually accessible. All you have to do is pay.

Naturally, a series of changes to the illustrated control device 10 are possible without departing from the spirit of the invention.

Therefore, instead of a potentiometer, it is of course also possible to use permanently adjusted resistors or other components.

Additionally, voltage fluctuations and/or
Another circuit with transistors, diodes, etc. can be connected to the potentiometer to compensate for heating.

Naturally, the secondary pressure can be selected differently for each control slide valve.

Furthermore, the switch can also be configured to be able to control different secondary pressures for each actuator connection of a single directional control valve.

Furthermore, it is also advantageous to provide a proportional pressure control valve not as a pre-control valve as shown, but as the main valve itself.

Further variations are also possible.

[Brief explanation of the drawing]

The drawing shows a schematic wiring diagram of a hydraulic control device according to the invention. 10...control device, 11...connection board,
12,13゜14.15... Directional control valve, 17
, 18, 19° 20... Control slide valve, 21...
... Supply conduit, 22 ... Supply section, 23 ...
... Return, 24 ... Neutral circulation circuit, 25.
...Main valve, 26...Pressure limiting valve, 27
...Pressure control valve, 28...Magnet, 29
...Electric circuit, 30...Power supply, 31.
32, 33, 34... switch, 35...
... Potentiometer, 36, 37... Electric circuit section, 38... Potentiometer.

Claims (1)

Claims: At least two control slide valves for supplying the 12 actuators with pressure medium, a supply conduit assigned to all control slide valves, and a high pressure primary pressure serving as the normal working pressure. and a device for limiting a secondary pressure at a pressure lower than this primary pressure, wherein said device for limiting the secondary pressure and the secondary pressure operates electromagnetically. It has a proportionally operated pressure control valve 27 which connects the supply conduit 21 and the return 23.
connected in a hydraulic connection circuit between the
Electrical switch 3 for each control slide valve 12.14
1.33 is assigned and the switch 31.33 is connected to the magnet 28 of the pressure control valve 27.
an electrical circuit section 3 connected within the switch 33 and extending parallel to the switch 31 on the other hand;
6 is connected to the secondary pressure of the hydraulic type 2, characterized in that the electric circuit section has a member connectable in series with the magnet 28, which changes the resistance of this electric circuit section. 2. Hydraulic control device according to claim 1, characterized in that a potentiometer (35) is connected in the electric circuit section (36) of the associated control slide valve (19). 3 The proportional action type pressure control valve 27 and the pressure control valve 2
A pressure limiting valve 26 connected in parallel to 7 is configured as a valve for pre-controlling a main valve 25 connected in the hydraulic connection circuit between the supply line 27 and the return 23. A hydraulic control device according to claim 1 or 2, wherein: 4. The switch 33 of the control slide valve 19 belonging to the secondary pressure has priority over the switch 31 belonging to the primary pressure, and both control slide valves 17, 19 have a check valve 41 for protecting the actuator. Hydraulic control device with two parallel-connected control slide valves according to any one of claims 1 to 3. 5 Control device 10 controls all control slide valves 12, 1314
．． Any one of claims 1 to 4, comprising a neutral circulation circuit 24 controlled by 15
Hydraulic control device as described in . 6- A plurality of switches 31, 32 belonging to the secondary pressure are arranged in parallel with each other, and a plurality of switches 33, 34 belonging to the secondary pressure are arranged in parallel with each other, and the switches 31, 32 belonging to the primary pressure are arranged in parallel with each other.
Hydraulic control device according to any one of claims 1 to 5, which is located in the electrical circuit 29 in series with the hydraulic control device. 7 A main valve 25 , a pressure limiting valve 26 and a proportionally operated pressure control valve 27 are arranged in the connecting plate 11 . A hydraulic control device according to any one of claims 1 to 6. 8 Electric circuit 29 connects all control slide valves 17, 18°1
9. Hydraulic type according to any one of claims 1 to 7, which is closed in the neutral position of 20 and in which the pressure limiting valve 26 defines the primary pressure. Control device.