DE19605992A1 - Hydraulic control unit for bucket e.t.c. excavators using two six-way valves - Google Patents

Abstract

The output (15) from the first 6-way control valve (10) is connected to the input (14) of the second valve (30) and a priority valve (40) control pressure chamber (50) is linked via a nozzle (51) to the output side of a metering diaphragm (48). Chamber (50) is supplemented by a pressure governor valve (52). The second valve (30) input (14) is connected via flow valve (56) in nozzle form to the pressure source (65) and thus by-passes the priority valve (40) altogether. The valve (56) is integrated in the priority valve housing (45) and circuited directly between priority valve input (41) and second output (43). In a case involving extreme bucket loads during the accelerating swivel movement, pump (65) volume cuts back. Here nozzle valve (56) supplies the pressure required to sustain power cylinder (36) operation. The pump cuts out with decrease in load.

Description

The invention is based on a hydraulic control arrangement, which in particular on a mobile working device, e.g. B. a bag ger, is used and the characteristics from the generic term of claim 1.

Such a hydraulic control arrangement is from DE-OS 28 27 191 known. A hydraulic control arrangement with 6-way Control valves for hydraulic consumers becomes common referred to as throttle control, because when an Control valve between the inlet inlet and outlet gear running circulation channel is throttled to build to enable a print. In the known one Throttle control with hydraulic control system a priority valve is the primary output of the primary valve via an orifice plate with the inlet inlet of the first 6-way Control valve and the secondary output of the priority valve with connected to the inlet inlet of the second 6-way control valve. In the neutral position of both 6-way control valves can tel through this from the inlet inlet to the outlet aisle flows to the tank independently of the other 6-way control valve flow away. The priority valve of the hydraulic control arrangement According to DE-OS 28 27 191, if the second, subordinate consumers to be supplied with pressure medium are not operated should be arbitrarily placed in a stable position in whose input is connected to a channel downstream of the orifice plate and the total pressure flowing to the priority valve with the first consumer to be served first Available. With this hydraulic control arrangement so the primary hydraulic consumer with the whole amount of pressure medium flowing to the priority valve will. The priority valve ensures that the first 6-way control valve always with a minimum amount of pressure  tel flows. Even if the first, priority hydraulic Consumer is not operated, the second, subordinate hydraulic consumers only the remaining amount is available.

In contrast, the invention has for its object a hy Draulic control arrangement with the features from the preamble of claim 1 so that the operation of the two subordinate hydraulic consumer the entire er Most priority hydraulic consumers, especially if this is at rest, amount of pressure medium not required is available.

This object is inventively for a hydraulic control Arrangement with the features from the preamble of claim 1 solved in that the drain outlet of the first 6-way Control valve with the inlet inlet of the second 6-way Control valve is connected. Even with an inventive hydraulic control arrangement flows one through the opening voltage cross-section of the orifice plate and by the Priorityven til be maintained across the orifice pressure difference matched pressure medium quantity from the entrance of the priority valve whose primary output to the first 6-way control valve with which the priority hydraulic consumer is controlled. Of this However, the part of the pressure medium that does not come into operation of the primary hydraulic consumer is used to close running input of the second 6-way control valve and stands together with that coming from the secondary outlet of the priority valve Pressure medium quantity for the operation of the subordinate hydraulic Available to consumers. In particular, in the neutral position of the first 6-way control valve all of this flow of pressure medium also to the second 6-way control valve reach.

Advantageous configurations of a hydraulic system according to the invention rule can be found in the subclaims.

So it is provided according to claim 2 that a control pressure chamber of the Priority valve through a nozzle with an outlet of the orifice  is connected and that a pressure limiter to the control pressure chamber supply valve is connected. The pressure in this control pressure Raum works with a spring in the sense of increasing the opening cross section between the entrance and the primary exit of the Priority valve on a spool that is in the opposite direction, So in the direction of increasing the cross section between the input and the secondary output from a pressure before the measurement aperture is applied. When the print limit becomes effective control valve is the connection between the input and the The primary outlet of the priority valve is just open to the extent that that of the pressure in front of the orifice on the control piston of the Priori force generated by the spring force just above that of the force set at the pressure relief valve Control piston is located. This is particularly convenient if from the front hydraulic loads, large loads should be moved len. The training is especially for the slewing gear of an excavator dung expedient according to claim 2. For the operation of the nachrangi The hydraulic fluid is in each case opposite the hydraulic consumer available to maintain the pressure differential between the pressure set on the pressure relief valve and the pressure in front of the orifice plate is not required.

If the pressure medium source is a hydraulic pump, whose output during the acceleration phase of the priority hydraulic consumer movable heavy load below the priority amount, d. H. falls below the amount that falls on the orifice corresponds to a spring force on the priority valve generated pressure difference, so that to operate the subordinate hydraulic consumer available Reduce pressure medium volume to zero. This is conceivable, for. B. then when the hydraulic pump is capacity-controlled or together with a second hydraulic pump regulates the total output in order to to prevent choking an internal combustion engine. Only when the from priority hydraulic consumer moved heavy load on one corresponding to the reducing flow rate of the hydraulic pump Speed is accelerated, their load pressure would drop and thus the delivery rate of a power-controlled pump again  increase. Then would also operate the subordinate hy amount of pressure medium available to draulic consumers get bigger again.

A complete standstill of subordinate hydraulic consumption chers can be prevented by the fact that according to claim 3 Inlet inlet of the second 6-way control valve via a stream valve bypassing the priority valve with the pressure medium source is connected. Pressure fluid can also flow through the current valve then from the pressure medium source to the second 6-way control valve flow when there is no opening cross section between the entrance and the secondary output of the priority valve is available. In be the flow valve is a particularly simple nozzle, so not designed as a relatively expensive flow control valve.

An embodiment according to claim 3 with a flow valve in the bypass the priority valve also appears regardless of the Features of claim 1 in all tax arrangements with priority rity circuit advantageous in which for the operation of a subordinate hydraulic consumer even then a certain Pressure medium quantity should be available if the delivery quantity a hydraulic pump temporarily in the range or even below the requested for the priority hydraulic consumer Pressure medium quantity is. In particular, the bypass to the priori Action valve also for priority load sensing controls circuit applicable.

According to claim 5, the flow valve is preferably in the housing of the priority valve integrated and directly between the entrance and switched the secondary output of the priority valve.

An embodiment of a hydraulic according to the invention Control arrangement and a priority valve used therein shown in the drawings. Using these drawings the invention is now explained in more detail.

Show it

Fig. 1 shows the hydraulic control arrangement and

Fig. 2 shows the priority valve in a section through its longitudinal axis.

The hydraulic control arrangement according to FIG. 1 has a first 6-way control valve 10 with a housing 11 , which is provided with an inlet connection P and with a return connection T. A line 12 , which leads to a tank 13 , is connected to the return connection T. The designation 6-way control valve stems from the fact that this valve has, in a generally known manner, six control rooms which can be connected to one another in a certain way by means of a valve piston. In a middle neutral position of the control valve 10 , a control chamber 14 , which is referred to below as the inlet inlet, is largely unthrottled connected to a control chamber 15 , which is called the outlet outlet in the following. The inlet inlet 14 is di rectly connected to the inlet port P of the housing 10 . A pressure control chamber 17 connected to the inlet port P via a load holding check valve 16 , a control chamber 19 connected to a tank channel 18 starting from the return port T, a control chamber 19 ending in a first consumer port A1 and a second consumer port 20 leading to a second consumer port B2 of the valve housing 11 Consumer control room 21 are shut off from each other in the central neutral position of the control valve 10 . The valve piston of the control valve 10 can be moved from the neutral position to one side in a working position in which the two control rooms 17 and 20 and on the other hand the two control rooms 19 and 21 are connected to one another and the inlet inlet 14 and outlet outlet 15 from each other are separated. In a working position lying on the other side of the neutral position, the two control rooms 17 and 21 and the two control rooms 19 and 20 are connected to one another, while the inlet inlet and outlet outlet are likewise separated from one another. The valve piston of the control valve 10 is spring-loaded in the neutral position and hydraulically adjustable from the neutral position. A transition from the neutral position to the maximum stroke of the valve piston is divided into three phases. In the first phase, an area of positive overlap is run over, which ensures the tightness of the control rooms 17 , 19 , 20 and 21 in the neutral position. In a second area, the connection between the inlet inlet 14 and the outlet outlet 15 is gradually throttled, while the connections between the control rooms 17 , 19 , 20 and 21 are gradually opened. A residual stroke begins when the inlet inlet 14 is completely separated from the outlet outlet 15 .

Immediately to the housing 11 of the control valve 10 , the Ge housing 29 of a second 6-way control valve 30 is attached, which has the same six control rooms and the same connection possibilities among these control rooms as the control valve 10 . However, an inlet connection P and a return connection T are not present on the housing 29 of the control valve 30 . Rather, the inlet inlet 14 and via a load holding valve 16 and the pressure control chamber 17 to the outlet outlet 15 of the Steuererven valve 10 is connected. The tank channel 18 of the control valve 10 continues in the housing 29 of the control valve 30 . The tank control chamber 19 of the control valve 30 is connected to the tank channel 18 within the housing 29 .

At the control valve 30 , further control valves can be installed, the inlet inlet of which is connected to the outlet outlet of the valve before and through which a tank channel 18 also passes. In an end plate 31 , the drain outlet of the last valve is connected to the tank channel 18 .

From the two work connections A1 and B1 of the control valve 10 , two lines lead to a hydraulic motor 35 which , for. B. may drive the slewing gear of an excavator and the privileged to be able to be supplied with egg ner pressure medium quantity Q1, the a certain maximum pressure medium quantity Q1 _max , z. B. does not exceed 100 l / min.

From the work connections A2 and B2, two lines lead to a hydraulic cylinder 36 , which may be on the equipment of an excavator. The hydraulic cylinder 36 is a subordinate hydraulic consumer compared to the hydraulic motor 35 , since the supply of the hydraulic motor 35 with pressure medium has a certain priority over the supply of the hydraulic cylinder 36 with pressure medium.

To ensure the priority between the two hydraulic consumers 35 and 36 , a priority valve 40 is provided which has an input 41 , a primary output 42 and a secondary output 43 , which, as can be seen in FIG. 2, constructively spaced apart from one another Valve bore 44 circumferential annular spaces of a housing 45 are formed. The connections between the individual annular spaces 41 , 42 and 43 are made by a displaceable in the valve bore 44 Ven tilkolben 46 . A measuring orifice 48 is inserted between the control chamber 42 and a first external connection 47 of the valve housing 45 . The valve piston is acted upon in the direction of an enlargement of the opening cross section between the two control spaces 41 and 42 by a compression spring 49 and also by the pressure spring 49 containing the control pressure space 50 prevailing control pressure. The control pressure chamber 50 is connected to the external connection 47 via a nozzle 51 . In addition, a pressure relief valve 52 is connected to the Fe derraum 50 . The control pressure in the control pressure chamber 50 thus does not rise above the value set on the pressure relief valve 52 . In the direction of an enlargement of the opening cross-section between the control chamber 41 and the control chamber 43 , i.e. between the inlet and the primary outlet of the priority valve 40 , the valve piston 46 is acted upon by the pressure in the control chamber 42 , that is to say by the pressure upstream of the measuring orifice 48 , via the bores of the Valve piston and a damping nozzle 53 is passed into a second control pressure chamber 54 .

A channel 55 leads from the control chamber 43 through the housing 45 to the outside and forms a second external connection of the housing 45 . Via a nozzle 56 , a pressure connection 57 of the housing 45 , which cuts the control chamber 41 , and the channel 55 and thus the control chambers 41 and 43 are connected to one another regardless of the position of the valve piston 46 .

A line 58 leads from the connection 47 of the valve housing 45 to the inlet connection P of the 6-way control valve 10 . A line 58 leads from the connection 55 of the valve housing 45 to a connection P1 of the 6-way control valve 30 , which is connected to the inlet inlet 14 of this control valve. The pressure input 57 of the Ventilge housing 45 is connected to an adjustable hydraulic pump 65 which can be driven by an internal combustion engine 66 , Hy draulic oil sucks from the tank 13 and promotes this to the pressure input 57 of the valve housing 45 . The hydraulic pump 65 is controlled in terms of output or, together with any second hydraulic pump that may be present, is controlled in terms of total output. This is to prevent who the engine 66 is stalled. The maximum delivery rate of the hydraulic pump 65 , which of course also depends on the number of revolutions of the internal combustion engine 66 , is greater than the maximum amount of pressure medium provided for the operation of the hydraulic motor 35 and may, for. B. 200 l / min.

From the inflow of the priority valve 40 from the hydraulic pump 65 , the amount of pressure medium flows in accordance with the pressure drop existing between the pressure 57 and the secondary outlet 55 and subject to changes, a partial flow through the nozzle 56 . The remaining amount of pressure medium, the priority valve 40 preferably as long as the primary output 42 until a pressure difference occurs across the measuring orifice 48 , which speaks to the force of the compression spring 49 . Only when this pressure difference is present, an opening cross-section between the input 41 and the secondary output 43 is opened, so that additional pressure medium flows away from the priority valve 40 via the external connection 55 . The pressure difference corresponding to the Druckfe of 49 occurs at the orifice 48 when the maximum amount of pressure medium Q1 _max provided for the operation of the hydraulic motor 35 flows.

It is now assumed that both 6-way control valves 10 and 30 are in their central neutral position and that no further control valve is actuated. Then the pressure medium Q1 _{max flows} from the input 41 to the primary output 42 of the priority valve 40 and via the orifice plate 48 , the line 58 , the inlet port P of the control valve 10 , and via its inlet inlet 14 and outlet outlet 15 to the inlet inlet 14 of the control valve 30th A small amount of pressure medium flows via the nozzle 56 from the pressure inlet 57 to the secondary outlet 55 of the priority valve 40 . The remaining amount flows from the inlet 41 of the priority valve 40 to the secondary outlet 43 and together with the amount flowing through the nozzle 56 via the line 59 to the port P1 of the control valve 30 and from there also to the inlet inlet 14 of this valve. The entire amount of pressure medium delivered by the hydraulic pump 65 flows to the outlet outlet 15 of the control valve 30 , into the tank channel 18 and via the tank connection T of the control valve 10 back to the tank 13 .

If only the 6-way control valve 30 is actuated, the entire amount of pressure medium delivered by the hydraulic pump 65 is available for the operation of the hydraulic cylinder 36 .

When driving the hydraulic motor 35 and the associated slewing gear of an excavator, a large mass must be accelerated to who. The pressure in line 58 becomes so high that the pressure limiting valve 52 of the priority valve 40 responds. May z. B. be set to 300 bar and limits the pressure in the control pressure chamber 50 of the priority valve 40 to this value. The pressure in front of the orifice 48 is set to a value which is higher than the pressure set on the pressure limiting valve 52 by the force of the spring 49 . If the force of the spring 49 corresponds to a pressure difference of 15 bar, then a pressure of 315 bar is established upstream of the measuring orifice 48 . The aperture on the measuring 48 flowing pressure medium quantity is very small at first and increases with increasing speed of the rotating mechanism until the maximum amount of pressure medium flows Q1 _max over the orifice 48th With that the acceleration phase of the slewing gear is ended, the load pressure at the hydraulic motor 35 drops and the hydraulic motor maintains its speed. The difference between the quantity of pressure medium conveyed by the pump 65 and the quantity of pressure medium flowing through the orifice plate 48 passes via line 59 from the priority valve to the inlet inlet 14 of the 6-way control valve 30 . This remaining amount is available for the operation of the hydraulic cylinder 36 .

It may be that during the acceleration phase of the lathe, during which the load pressure is high, the power control of the hydraulic pump 65 responds and its stroke volume is reduced, so that this z. B. only promotes 70 l / min. Without the direct connection from the pressure inlet 57 to the secondary outlet 55 of the priority valve 40 via the nozzle 56 , an amount of pressure medium would be available for the operation of the hydraulic cylinder 36 at the beginning of the acceleration phase of the hydraulic motor 135 , which would be almost the delivery rate of the hydraulic pump 65 Corresponds to 70 l / min. The amount of pressure medium would decrease with increasing speed of the hydraulic motor 35 and then be zero if the speed of the hydraulic motor 35 corresponds exactly to the delivery rate of the hydraulic pump 65 in the amount of 70 l / min. Due to the then falling load pressure of the hydraulic motor 35 , the hydraulic pump 65 swings out. Until their delivery quantity exceeds the pressure medium quantity Q1 _max , no pressure medium would be available for the operation of the hydraulic cylinder 36 . Through the bypass leading through the nozzle 56, pressure medium flows through the line 59 to the inlet 14 of the 6-way control valve 30 even when the secondary outlet 43 of the priority valve 40 to the inlet 41 is shut off. However, the load pressure on the hydraulic cylinder 36 must then be lower than the pressure in the pressure inlet 57 of the priority valve 40 . This is the case until the end of the acceleration phase of the hydraulic motor 35 . At the end of the acceleration phase, the delivery rate of the hydraulic pump exceeds Q1 _max and then quickly reaches a high value. Now the Q1 _max is available for the subordinate hydraulic consumer 36, regardless of the load pressures, if the residual amount of pressure medium exceeds.

Claims (5)

1. Hydraulic control arrangement, in particular for a mo biles working device, with a pressure medium source ( 65 ) with a first 6-way control valve ( 10 ) with which a first hydraulic consumer ( 35 ) can be controlled, with a second 6-way Control valve ( 30 ) with which a second hydraulic consumer ( 36 ) can be controlled, each of the two 6-way control valves ( 10 , 30 ) having an inlet inlet ( 14 ) and an outlet outlet ( 15 ), which in one Neutral position are largely unthrottled, and each of the two hydraulic consumers ( 35 , 36 ) can be supplied with actuation of the respective 6-way control valve ( 10 , 30 ) via its inlet inlet ( 14 ) pressure medium, and with a priority valve ( 40 ), the primary output ( 42 ) via a measuring orifice ( 48 ) with the inlet inlet ( 14 ) of the first 6-way control valve ( 10 ) and the secondary outlet ( 43 ) with the inlet inlet ( 14 ) of the second 6 -Way control valve ( 30 ) is connected, characterized in that the drain outlet ( 15 ) of the most 6-way control valve ( 10 ) is connected to the inlet inlet ( 14 ) of the second 6-way control valve ( 30 ). 2. Hydraulic control arrangement according to claim 1, characterized in that a control pressure chamber ( 50 ) of the Prioritätsven valve ( 40 ) is connected via a nozzle ( 51 ) to an outlet of the measuring orifice ( 48 ) and that to the control pressure chamber ( 50 ) a pressure relief valve ( 52 ) is connected. 3. Hydraulic control arrangement, in particular according to claim 1 or 2, characterized in that the inlet inlet ( 14 ) of the second 6-way control valve ( 30 ) via a flow valve ( 56 ) bypassing the priority valve ( 40 ) with the Druckmit telquelle ( 65 ) is connected. 4. Hydraulic control arrangement according to claim 3, characterized in that the flow valve is a nozzle ( 56 ). 5. Hydraulic control arrangement according to claim 3 or 4, characterized in that the flow valve ( 56 ) in the housing ( 45 ) of the priority valve ( 40 ) is integrated and directly between the input's ( 41 ) and the secondary output ( 43 ) of the priority valve ( 40 ) is switched.