DE2033485A1 - Control device for hydraulic systems - Google Patents

Description

R. 9907
My / Fu 3.7.70

Attachment to

Patent and utility license application

R O BE RT B O SG H GMBH, Stuttgart

Control equipment for hydraulic systems '

The invention relates to a control device for one of one Pressure medium source-fed hydraulic consumer, with a control slide, which is a working line leading to the consumer locked in a neutral position, with in two working positions the pressure medium source or a return, and which influences a control line> assigned to a switching valve for the return line of the pressure medium flow coming from the pressure medium source is.

From the German Offenlegungsschrift 1 507 164, Fig. 2, one is Control device known, in the connecting plate of the pressure medium coming from a pump from a. Switching valve directly in a return can be passed as long as it does not have a V / egeventil flows to a consumer. In this control device, an unintentional actuation of a directional control valve

■ - 2 -

109883/0908

BATH ORIGINAL

- 2 Robert Bosch GmbH R. 9907

Stuttgart

Load lowered even when the pump is switched off. In In many cases, however, it is desirable to prevent such a lowering of a load as long as the pump is not delivering pressure medium.

Furthermore, from US Pat. No. J5 299 902, a control _device with a plurality of control slides is known which controls the return flow from the consumers as a function of the pressure in the inlet to avoid cavitation. An additional, pressure-medium-operated valve is used for this purpose, which only fulfills this function. A changeover valve is missing in this device.

'The object of the invention is with a control device with Switching valve the lowering of a load by unintentional actuation of a directional control valve when the hydraulic pump is not delivering to a safe and easy way to prevent.

This is achieved according to the invention in that the switching valve is switched into a return channel of a control slide and a dieeen return channel for the consumer flow having a lack of control current blocking closure member.

Particularly advantageous configurations of the subject matter of the invention result from the subclaims and the description.

An exemplary embodiment of the subject matter of the invention is shown in the drawing. This shows in

Fig. 1 shows an embodiment of the control device in simplified representation, in

Fig. 2 is a side view of the connecting plate of the control device according to Fig. 1, in

FIG. 5 shows a longitudinal section through the connection plate according to I-I in Fig. 2.,

109883/0 9 08

■ BAD ORIGFNAL

Robert Bosch GmbH R. 9907

Stuttgart

The control device 10 according to the exemplary embodiment in FIG. 1 consists of a connection plate 11, a Bloekventil 12 for a single-acting “consumer 13 and an end plate l4.

To explain the connection plate 11 is at the same time on the Figures 2 and 3 referenced. The connection plate 11 has a housing 15 * a conventional pressure relief valve in a first bore 16 17 records. The pressure relief valve 17 ensures one Inlet connection l8 from a return connection 19. In the housing 15 A second bore runs perpendicular to a first bore 16 21, which penetrates a first chamber 22 and a second chamber 23. The first chamber 22 is connected to the return connection 19. In a closing member 24 of a switching valve 25 is guided in a sealed and sliding manner in the second bore 21. A spring 26 pushes this Closing member 24 into an initial position delimited by a spring ring 27, in which it is connected to a first piston-like section 28 the inlet connection 18 separates from the first chamber 22. Also locks the closing member 24 in the starting position with a second section 29 the second chamber 23 from the first chamber 22.

"From the space 31 accommodating the spring 26, a control channel leads in a flange surface 33 · The space 31 also stands over an im Inside the closing member 24 arranged throttle 34 with the zu * « running connection 18 in connection, which in turn also leads into the flange surface 33. _A pump 35 conveys pressure medium from a container 36 into this inlet connection 18. It also leads into the Flange surface 33 of the connecting plate a return channel 37 connected to the second chamber 23

The Black valve 12 shown in simplified form in FIG. 1 acts it is a valve of the usual type for controlling a single-acting valve Consumer 13 »A control slide 39 of the block valve

109883/0908 Ί

Robert Bosch GmbH 'R. J90T

Stuttgart

12 has three positions, namely neutral 41, raising 42 and lowering K ~ 5, in order to hydraulically shut off a consumer connection 44, with; to connect to an inlet channel 45 or to a return channel -46. In addition, the control slide 39 blocks a control channel 47 for the switching valve 25 in the raise 42 position, while it opens it in the neutral 41 and lower 43 positions. The inlet channel 45, the return channel 46 and the control channel 47 run in the block valve 12 from a flange surface 49 adjoining the connection plate 11. These channels 45, 46, 47 are connected in the planar surface 48 to the corresponding channels 18, 37, 32 in the connection plate 11. The inlet channel 45 and the return channel 46 are blocked in the flat surface 49 by stopper 51.

The end plate 14 is on the planar surface 49 .de: s Bl ^ ckventris .12 flanged and v / eist an outlet channel 52,; de.r the 'control channel 47 of the block valve 12, relieved to the container 36.

The throttle 34, the control channels 52, 47 and the AualaBkanäl '52 together form the control line 53 of ^the switching valve 2.5.

The operation of the device is as follows:

With the valve spool 39 is the block valve 12 in the _r ge recorded neutral position 41, the consumer 13 is hydraulically locked and the control channel 47 is controlled open. Promotes the 'pump 35 pressure medium into the inlet port 18 so flows through the control line 53 ein'Steuerstrom to the container 36. The pressure drop at the throttle JTK holding the changeover valve .25 open and the major part of the Druckmittelstroni & s from the pump 35 flows via the Return connection 19 to container 36.

109883/090 8

BAD ORSQfNAL

Robert Bosch GmbH R. 9907

Stuttgart $ r

If the control slide 39 is brought into the lifting position 42, then the control line 53 is interrupted, whereby the switching valve 25 closes the connection to the return 19. Thus flows Pressure medium from the inlet channel 45 to the consumer 13 ».

By moving the control slide 39 to the lowering position 43 the pressure medium flowing back from the consumer 13 is passed into the return channel 37 and into the chamber 23 of the connecting plate 11. As long as the pump 35 is delivering pressure medium, the switching valve is open and the pump 35 is relieved to the container 36, while a small control current via the control line 53 into the End plate 14 and there to the container 36 flows. Simultaneously controls the closing member 24 connects from the chamber 23 to the return port 19 and the load on the consumer can be reduced will.

However, if the pump is switched off and the control spool 39 is now unintentionally brought into the lowering position 43, no control oil flow flows via the control line 53. The spring 26 holds the closing member 24 of the switching valve 25 in the initial position, .in which it with its section 29 the chamber 31 from the return connection 19 separates. Thus, when the pump is switched off, there is an unintentional Lowering process on consumer 13 is not possible.

BAD ORSGiNAt. 109883/0908

Claims (3)

■ - 6 - .- ■ "■■■ Robert Bosch GmbHR. 9907 Stuttgart. Expectations: IJ control device for one fed by a pressure medium source hydraulic consumer ^ with a control slide., which shuts off a working line leading to the consumer in a neutral position, in two working positions with the pressure medium source or a return and which influences a control line that connects a switching valve to the return line of the from the pressure medium source coming pressure medium flow is assigned, characterized in that the switching valve (25) in a return channel (46, 37) of a control slide (39) switched is and a return channel (46, 37) for the consumer flow in the absence of control flow closing member (24). 2. Control device according to claim 1, characterized in that the closing member (24) of the Umsehaltventils (25) by a spring (26) loads an initial position in which it with a piston-like section (29) the return channel (37) separates from the return connection (19) while it is in the working position connects these together. BATH 109883 ^ / 0908 ■ -. τ - 3. Control device according to claim 1 or 2, characterized in that that the control device is designed as a multiple arrangement of control valves, and that the / switchover valve (25) together with a pressure relief valve (17) are arranged in a connection plate (XL). k. Control device according to one of Claims 1 to ~ 5 _3, characterized in that the control device with the switch valve (25) which shuts off the return duct (46, 57) in a combine harvester is assigned to the consumer which actuates a cutting table. BAD ORSGINAL