DE3319533A1 - HYDRAULIC CONTROL SYSTEM FOR THE STEERING AND WORKING HYDRAULICS ON VEHICLES - Google Patents

Abstract

1. A hydraulic control system for the steering and other hydraulically energized equipment - including a controllable power lift (18, 19, 32) - of a motor vehicle, particularly of a tractor, the system comprising two hydraulic circuits serving to feed pressure fluid to the hydraulically operable devices, each circuit including its respective hydraulic pump (1, 2) and both being interconnectable by actuating a sequence valve (37), in which the hydraulic pump (1) of the first circuit is arranged to feed pressure fluid to a hydraulic power steering device (8) via an element (10) adapted to accord priority to supplying this device, in which any pressure fluid not required for steering is arranged to flow via one or more distributing valves (16) for the other consuming devices to the - subsequent - power lift (19), and in which the second hydraulic circuit's hydraulic pump (2) communicates, if pressure fluid is not required, via the sequence valve (37) with a pressure fluid reservoir (7), characterized in that a duct (50) of the second hydraulic circuit includes at least one distributing valve (52) which serves to feed pressure fluid to the other consuming devices, which is located between the hydraulic pump (2) and the sequence valve (37) and which is provided, like the other distributing valve (16), with a neutral passage, that the outlet of the first mentioned distributing valve's (52) neutral passage is connected via a nonreturn valve (53) to the inlet of the distributing valve (16) of the first hydraulic circuit, that the sequence valve (37) while normally connecting the outlet of the first-mentioned distributing valve's (52) neutral passage with the reservoir (7) closes this by-pass if either the distributing valve (16) of the first hydraulic circuit or a power-lift control valve (20) is actuated, that the power-lift control valve (20) is arranged to be actuated by a pilot valve (32), that the pilot pressure for the control valve (20) is also simultaneously transmitted to the sequence valve (37) so as to urge the latter towards its closing position, and in that the transmission of the pilot pressure to the sequence valve (37) is effected via a flow-inhibiting throttling member (throttling relief valves 44, 45).

Description

Klöckner-Humboldt-Deutz AG

5000 Cologne 80, May 19, 1983 D 83/28 AE-ZPB Da / B

Hydraulic control system

for the steering and working hydraulics

on vehicles

The invention relates to a hydraulic control system for steering and working hydraulics including a controllable power lift system on vehicles, in particular agricultural tractors, with two each connected to a hydraulic pump and hydraulic circuits that can be connected to one another by actuating a connecting valve for supplying hydraulic ones Consumer with pressure fluid, the steering hydraulics in the first hydraulic circuit from the hydraulic pump is supplied via an element that primarily supplies pressure fluid, and the element that is not required for the steering Amount of liquid to the downstream power lift via one or more directional control valves for other consumers flows in and the hydraulic pump in the second hydraulic circuit through the connecting valve when pressure fluid is not required is in communication with the reservoir.

A control system of this type has become known (oil hydraulics & Pneumatik 24 (1980) No. 11 ,, p. 810, Fig. 4), whereby the one hydraulic pump is connected to a flow divider that primarily supplies the steering hydraulics with hydraulic fluid. The residual current from the flow divider is fed to the power lift and is sufficient in terms of quantity for the

kner-Hurr.holdt-Dpu'z AG /λ\ίΓ%.Μ Wt ^

- 4 - 19.05

D 83/28

regulating operation of the same. The second hydraulic pump is directly connected to the storage tank via a connecting valve and to the hydraulic circuit via a check valve the first hydraulic pump in connection. When a directional valve is operated to supply one of the other consumers with hydraulic fluid, the switching valve is closed via a control pressure, so that the consumer through the merger of both hydraulic circuits, sufficient hydraulic fluid flows in. With this well-known Control system, however, the second hydraulic circuit can only be used in conjunction with the first hydraulic circuit, so that no separate use of the two hydraulic circuits, as is desirable in some cases, carried out can be.

The invention is based on the object, while avoiding the disadvantage described, a control system of the type mentioned at the beginning outlined genre to the effect that the two Hydraulic circuits in the control system can also be separated from one another for the supply of hydraulic ones, if required Available to consumers. It should also be ensured that the sequence valve responds to short control pulses the lift does not respond.

The object is achieved in that in the second hydraulic circuit in the line between the hydraulic pump and the sequence valve, one or more directional control valves are arranged to supply other consumers with hydraulic fluid and that in one of the pilot valve of the power lift to the connecting valve leading control lines at least one delay element for the on the connecting valve control pulses acting in the closing direction are provided.

- 5 - May 19, 1983

D 83/28

This measure ensures that both hydraulic circuits can also be used independently of each other. Even when operating the power lift on the first hydraulic circuit the second hydraulic circuit can be used for other consumers, since the power lift for the normal work process (control) is not used by the steering hydraulics Delivery rate of this hydraulic pump comes from.

In order to ensure that the greatest possible amount of pressure medium is always available to the power lift for regulation purposes, a further development is in progress the invention provides that the steering hydraulics for supplying pressure fluid via a priority valve is connected to the hydraulic pump. It is useful if the sequence valve is included in the control unit of the power lift is housed.

An embodiment of the invention is described in more detail below with reference to the drawing. The only representation Figure 3 shows schematically a control system according to the invention.

Two hydraulic pumps 1 and 2, which are preferably used as tandem pumps are carried out, are on the suction side via lines 3 or 4 and a filter 5 or 6 with the storage tank 7 for hydraulic fluid in connection. The hydraulic pump 1 supplies a first hydraulic circuit with steering hydraulics 8, which are connected via a priority valve 10 to a line 11 emerging from the hydraulic pump on the pressure side is. A line 12 leads from the priority valve 10 back to the storage container 7. The priority valve 10 is designed in such a way that it only supplies the hydraulic fluid quantity directly required for steering to the steering hydraulics. An outgoing line 13 from the priority valve 10 leads through a valve block 14 to a directional valve block

AKHD "'-' ■■ -" ■■

- 6 - 19.05.i9 ^ 3 ^aOO °

D 83/28

15, in which a directional control valve assigned to the first hydraulic circuit 16 is shown in simplified form. A regulating control device 18 for a power lift is attached to the directional control valve block 15 flanged, the lifting cylinder of which is denoted by 19.

Inside the regulating control device 18 is the line 13 coming from the directional control valve 16 with a control valve 20 connected on the input side. The control valve 20 is on the output side through a line 21 with a line 22 in Connection which is connected to the storage container 7 via a hydraulic fluid cooler 23 and a filter 24.

A line 25 branches off from the line 13 in the direction of flow upstream of the control valve 20, which by means of a control line 26 with one end face 27 of the control valve 20 and with a spring-reinforced check valve 28 a line 30 is in communication. The line 30 connects the lifting cylinder 19 of the power lift via a flow control valve 31 with a pilot valve 32 of the power lift system arranged in the reservoir 7. As a three-way valve The pilot valve 32 formed is also connected through a line 33 to the one loaded by a spring 34 Front side 35 of the control valve 20 in connection. The pilot valve 32 is controlled by a control linkage, not shown activated, which compares actual values of tensile force or position measured values with specified target values.

A connecting valve is also located in the control unit 18 of the power lift 37 housed, which is loaded on its one end face 38 in the closing direction by a spring 39 and the other end face 40 of which is connected to the line 13 by a line 41. The spring-side face 38 of the sequence valve 37 is connected to the line 33 by control lines 42, 43, wherein in the line 42 a check valve 44 and in the line 43 a

Klöckner-Humboldt-Deufz AG _

- 7 - May 19, 1983

D 83/28

Throttle member 45 is arranged. Of the connecting valve 37 designed as a two-way valve, one leads on the return side Line 46 to line 22. There is also a connection between line 43 and line 13 by means of a Line 47 in which a throttle member 48 is arranged.

The other hydraulic pump 2 is for supplying a second one The hydraulic circuit is connected on the pressure side by a line 50 and a valve block 14 to a directional valve block 51, wherein a single directional control valve 52 is shown in a simplified manner. in the direction of flow behind the directional valve block 51 is the line 50 via a check valve 53 to the line 13 of the first supplied by the hydraulic pump 1 Connected to the hydraulic circuit. In the flow direction upstream of the check valve 53 there is between the line 50 and the input of the sequence valve 37 a connection through a line 54.

During operation, the hydraulic pump 1 constantly conveys pressure fluid into the first hydraulic circuit, with the steering hydraulics is primarily supplied with hydraulic fluid. The priority valve 10 controls only the directly to Steering the required amount of hydraulic fluid to the steering hydraulics, while not steered for the rest of the time the full pressure medium flow is available to the other consumers, in particular this hydraulic circuit stands. If no other consumer is connected to the first hydraulic circuit, it flows from the steering Unneeded amount of hydraulic fluid through the line and the directional valve block 15 and through the control valve and the lines 21 and 22 back to the reservoir. When the power lift is switched on, the pilot valve is activated 32 when sinking impulses from the

Kl-xkner-Humboldt-DeijtzAG ZzArSkH ^ J

- 8 - May 19, 1983

D 83/28

The shown neutral position is moved to the right and, in the case of lifting impulses, to the left. With the latter effect builds in the line 33 via the line 47 and the throttle member 48, a control pressure supported by the Force of the spring 34 actuates the control valve 20 in the closing direction, so that through the line 25, the check valve 28 and the line 30 pressure fluid flows to the lifting cylinder 19. The lift or the lift is then lifted connected work device. If, on the other hand, the pilot spool 32 is moved to the right from the neutral position, the control line 33 is relieved of pressure, the control valve 20 being in the open position shown. At the same time, pressure fluid can flow out of the lifting cylinder 19 through the line 30 and the flow control valve 31, so that a lowering process takes place on the power lift or on the implement.

At the end face 40 of the sequence valve 37, the pressure present in the line 13 is constantly present, while at the same Face 38 when the pilot valve 32 is open, only the force of the spring 39 acts. The sequence valve 37 is located is thus in the closed position shown. When operating the power lift is "control" of the same Pilot valve 32 always only briefly out of the neutral position due to the short control times that occur moved in one direction or the other. However, these short movements of the pilot valve 32 are by no means sufficient off, on the end face 38 of the sequence valve 37 as a result of the throttle connected upstream as a delay element 45 to build up a control pressure which, supported by the force of the spring 39, is large enough to control the sequence valve 37 in the To influence the sense of closure. Only when the power lift is used for a long time, for example when lifting of an implement, the sequence valve 37 is as a result

Klöekner + Iumboldt-Deutz AG

- 9 - May 19, 1983

D 83/28

the pressure build-up on the end face 38, supported by the force of the spring 39, is moved into the closed position. Through this the return of the pressure fluid from the second hydraulic circuit fed by the hydraulic pump 2 is carried out the line 54, the connecting valve 37 and the lines 46, 22 to the reservoir 7 are blocked, and it flows Pressure fluid from the second hydraulic circuit through the check valve 53 into line 13 of the first hydraulic circuit. In this way, the first hydraulic circuit is provided with the additional one required to quickly lift out an implement Amount of pressure medium supplied.

Instead of the power lift, other consumers can of course also be connected via one or more directional control valves 16 the first hydraulic circuit can be connected. When controlling a directional control valve in this block, the Pressure medium in line 13 is shut off and fed to a consumer (not shown) = line 13 is behind the directional valve depressurized. The sequence valve 37 is then displaced in the closing direction by the force of the spring 39 and the discharge of the pressure medium from the circuit of the hydraulic pump 2 via the lines 54, 46 is shut off. The directional control valves 16, the flow rates of both hydraulic circuits are always available if directional control valves 52 are not activated are.

To the second hydraulic circuit supplied by the hydraulic pump 2 one or more consumers can be connected independently of the first hydraulic circuit via the directional control valves 52 can be switched on or off. So one of the can be connected to the second hydraulic circuit via one of the directional control valves 52 connected consumers can be, for example, a mower motor, while the lifting cylinder of the mower

D 83/28

is in communication with the first hydraulic circuit via one of the directional control valves 16. But it is also possible with Operation of the power lift via the first hydraulic circuit, for example, a hydraulic permanent consumer with the to operate the second hydraulic circuit via one of the directional control valves 52.

Claims (3)

Klöckner Humboldt-Deutz AG 5000 Cologne 80, May 19, 1983 D 83/28 DE AE-ZPB Da / B Claims Hydraulic control system for the steering and working hydraulics including an adjustable power lift system on vehicles, in particular agricultural tractors, with two Hydraulic circuits connected to one hydraulic pump each and which can be connected to one another by actuating a connecting valve for supplying hydraulic consumers with hydraulic fluid, where in the first hydraulic circuit of the Hydraulic pump, the steering hydraulics is supplied via an element that primarily supplies pressure fluid, and the The amount of fluid not required for the steering is sent to the downstream power lift via one or more directional control valves flows in for other consumers and the hydraulic pump in the second hydraulic circuit when it is not required The hydraulic fluid is in communication with the reservoir through the sequence valve, characterized in that in the second hydraulic circuit in the line (50) between the hydraulic pump (2) and the connecting valve (37) one or more directional control valves (52) for supplying other consumers with hydraulic fluid are and that in one of the pilot valve (32) of the power lift leading to the connecting valve (37) Control lines (42, 43) have at least one delay element (45) for the connection valve (37) in the closing direction acting control pulses is provided. KK ..- kner-Humboldt-Deiitz AG D 83/28 2. Control system according to claim 1, characterized in that the steering hydraulics (8) for supplying pressure fluid via a priority valve (10) is connected to the hydraulic pump (1). 05 3. Control system according to claims 1 and 2, characterized in that the sequence valve (37) with im Control unit (18) of the power lift is housed.