DE102016117208A1 - Load-sensing drive system - Google Patents

Abstract

The invention relates to a load-sensing drive system (1) with a pump (2) and at least one of the pump (2) supplied with pressure medium double-acting consumer (5), in particular a differential cylinder, wherein for controlling each consumer (5) Control line valve (6) is provided and a pressure medium storage device (30) is provided, the connection with one of the respective control way valve (6) to a container (3) guided return line (8a, 8b) is controlled by means of a respective return valve (31a, 31b) , The return feed valve (31a, 31b) is acted upon in the direction of a discharge position (31c) only by the load pressure of the consumer (5) and a spring device (40a, 40b), wherein in the discharge position (31c) the associated return line (8a, 8b) is connected to the container (3), and is acted upon by the highest load pressure of the load (5) of the drive system (1) in the direction of a storage loading position (31d, 31e), in which the associated return line (8a, 8b) is connected to the pressure medium storage device (30 ) connected is.

Description

The invention relates to a load-sensing drive system with a pump and at least one of the pump with pressure medium supplied double-acting consumer, in particular a differential cylinder, wherein for controlling each consumer, a control valve is provided and a pressure medium storage device is provided, the connection to one of the respective control way valve to a container guided return line is controlled by means of a respective return valve.

Designed as load-sensing drive systems hydraulic drive systems are used in mobile machines. With load-sensing drive systems, the different load pressures of the various consumers can be provided with one pump. In the simultaneous control of several consumers with different load pressures, the pump is set to the highest load pressure of the driven consumers. At the consumers with a lower load pressure in each case a pressure compensator is arranged in the inlet side, which lower the system pressure supplied by the pump to the pressure required for the respective consumer. In this case, throttle losses occur at the inlet-side pressure compensators of the consumers.

In order to reduce these throttle losses at the inlet-side pressure compensators of the consumer, it is known in generic load-sensing drive systems to provide a pressure medium storage device whose connection is controlled by a guided from the respective control way valve to a container return line by means of a respective return valve. A generic load-sensing drive systems with a pressure medium storage device and return valves, which connects the pressure medium storage device with the corresponding return lines of the control way valves, is from the DE 10 2013 101 107 A1 known.

With the return valves, the return side of the corresponding consumer forming return line can be biased with the pressure of the pressure medium storage device and thus in the drain side forming the discharge line of the consumer, a back pressure can be generated. As a result, the pressure in the inlet side of the consumer is also raised by the pressure of the pressure medium storage device, so that the consumer is operated at a raised pressure level. As a result, the throttling losses at the pressure compensators arranged in the inlet side can be reduced during the simultaneous actuation of a plurality of consumers with different load pressures, and the throttling losses at the pressure compensators arranged in the inlet side can be at least partially recovered by loading the pressure medium storage device.

In the from the DE 10 2013 101 107 A1 known load-sensing drive system, the control path valves of the consumer each have a single return line and a single return feed valve, with which the connection of the return line with the pressure medium storage device or the container is controllable. The return feed valves are acted upon in each case by the current load pressure of the associated consumer and the pressure in the pressure medium storage device and a spring device in the direction of a discharge position, in which the associated return line is connected to the container, and of the highest load pressure of all consumers of the drive system in the direction of Memory loading position are acted upon, in which the associated return line is connected to the pressure medium storage device. The sum of the actual load pressure of the associated consumer and the pressure in the pressure medium storage device with the highest load pressure of the driven consumers is thus compared to the return feed valves. If the pressure drop across the pressure compensator (difference between highest load pressure of all consumers and current load pressure of the assigned consumer) is greater than the pressure in the pressure medium storage device when a consumer is actuated, the return feed valve is loaded into the storage charge position in which the return line of the consumer is connected to the pressure medium storage device is connected and thus the return side of the consumer forming the discharge side of the consumer is biased to the pressure level of the pressure medium storage device. In the storage loading position of the return valve, the pressure medium flowing away from the consumer in the return line is no longer conveyed into the container but into the pressure medium storage device. The pressure medium stored in the pressure medium storage device can be used in the drive system to supply a consumer or to drive the pump.

In the from the DE 10 2013 101 107 A1 known load-sensing drive system in which the control path valves of the consumer each have a single return line and a single return valve with which the connection of the return line with the pressure medium storage device or the container is controllable, no differential cylinder can be used as a consumer, the different piston surfaces have the two consumer sites. Such differential cylinders act as pressure booster, so that at the feedback valve of the consumer, the comparison of pressure in the pressure medium storage device with the pressure drop across the pressure balance ( Difference from highest load pressure of all consumers and current load pressure of the assigned consumer) is not valid for both directions of movement of the differential cylinder.

In the from the DE 10 2013 101 107 A1 known load-sensing drive system still can not be exploited the full potential of reducing the throttle losses at the arranged in the inlet side pressure compensators. Is at the DE 10 2013 101 107 A1 at a consumer, the return feed valve is acted upon in the storage loading position and pressure medium is conveyed from the return line of the consumer in the pressure fluid storage device, the pressure of the pressure fluid storage device is at the return line forming the outlet side of the consumer and at the same time increases the pressure in the inlet side of the consumer accordingly, for example, in a Gleichgangzylinder by the same amount. As a result, the actual load pressure reported to the consumer's feedback valve also increases. As a result, the return feed valve is acted upon rising load current of the associated consumer too early in the expiry position, in which the return line of the consumer is connected to the container and thus the connection to the accumulator means is switched off, since the return feed the DE 10 2013 101 107 A1 can not distinguish whether the current load pressure of the associated consumer comes through the load applied to the load or by the connection of the pressure of the pressure medium storage device to conditions.

The present invention has for its object to provide a load-sensing drive system of the type mentioned is available, which allows a simple structure and low construction costs to exploit the full potential of reducing the throttle losses of the arranged in the inlet side pressure compensators.

This object is achieved in that the return feed valve is acted upon in the direction of a drain position only by the load pressure of the consumer and a spring device, wherein in the outlet position the associated return line is connected to the container, and of the highest load pressure of the consumer of the drive system in Direction of a storage loading position is acted upon, in which the associated return line is connected to the pressure medium storage device. An inventive return feed valve thus forms a control valve that does not take into account the pressure in the pressure storage device. An inventive return feed valves thus does not compare the pressure of the pressure medium storage device with the pressure drop across the pressure balance of the consumer, but regulates a maximum pressure drop across the pressure compensator, the return feed ensures that a predetermined at the pressure compensator by a spring preload maximum pressure drop across the pressure compensator becomes. As a result, with a simple structure and low construction costs, the full potential of reducing the throttle losses on the pressure compensators arranged in the inlet side can be exploited.

With such a feedback valve designed as a control valve, according to an advantageous development of the invention, it is made possible for the pressure medium storage device to have at least two pressure medium reservoirs which have different pressure levels and the regenerative valve has a memory charging position for each pressure medium reservoir. From the feedback valve designed as a control valve, the return line of the consumer is always maximum accumulated, so that several pressure fluid accumulator can be connected to the return line with different pressure levels, as always formed by the feedback valve designed as a control valve, the return line to that pressure fluid reservoir, which is the next lower pressure level having.

According to an advantageous embodiment of the invention, the control path valve is provided with a first return line, which is connected in a first control position of the control valve to a second consumer side of the consumer, and provided with a second return line in a second control position of the control valve with a first side of the consumer Consumer is connected, wherein in the first return line, a first return valve is arranged, which controls the connection of the first return line with the pressure medium storage device or the container, and in the second return line, a second return valve is arranged, the connection of the second return line with the pressure medium storage device or controls the container. With a control way valve, which has its own return line for each consumer side, in each of which a separate return valve is arranged, it is possible with a simple structure and low construction costs, in a trained as a differential cylinder consumer having different piston surfaces on the two consumer sides, in two directions of movement of the differential cylinder to reduce the throttle losses at the pressure compensators by the respective return line is connected to the pressure medium storage device via the corresponding return feed. With separate return valves for both directions of movement of a differential cylinder, ie a separate return valve for each direction of movement of the differential cylinder, can easily throttle losses to the Pressure compensators are reduced in both directions of movement of the differential cylinder. The acted upon by the corresponding pressures control pressure surfaces on the respective return valve can hereby be adapted in a simple manner to the piston surfaces and thus to the area ratio of the differential cylinder to reduce the throttle losses at the pressure compensators for both directions of movement of the differential cylinder.

Further advantages and details of the invention will be explained in more detail with reference to the embodiment shown in the schematic figure.

In the figure is a circuit diagram of a load-sensing controlled, drive system according to the invention 1 presented a mobile machine.

The drive system 1 includes a pump adjustable in the delivery volume 2 , which is operated in the illustrated embodiment in the open circuit and the input side with a container 3 is in communication and on the output side in a delivery line 4 promotes to which several consumers are connected. In the illustrated embodiment is only a double-acting consumer 5 shown, which is designed as a differential cylinder.

To control the consumer 5 is a control valve throttling in intermediate positions 6 intended. The consumer 5 has a first consumer page 5a and a second consumer side 5b on. In the illustrated embodiment, the first consumer side 5a as the piston side and the second consumer side 5b designed as a piston rod side of the differential cylinder. The first consumer side 5a is by means of a first connection line 7a to the control way valve 6 connected. The second consumer side 5b is by means of a second connection line 7b to the control way valve 6 connected. The control way valve 6 is still to the support line 4 the pump 2 connected and to a first return line 8a and a second return line 8b connected, each with the container 3 keep in touch.

The control valve designed as a directional control valve 6 has a neutral position 6c on, in which the support line 4 the pump 2 , the return lines 8a . 8b and the consumer lines 7a . 7b are locked. In a first control position 6a the control way valve 6 is the support line 4 with the first consumer line 7a connected and the second consumer line 7b with the first return line 8a connected. In the first control position 6a is the second return line 8b shut off. In a second control position 6b the control way valve 6 is the support line 4 with the second consumer line 7b connected and the first consumer line 7a with the second return line 8b connected. In the second control position 6b is the first return line 8a shut off. The control way valve 6 points in the first control position 6a an orifice plate 10a on and is with a downstream of the orifice 10a arranged arranged not shown pressure compensator. The control way valve 6 points in the second control position 6b an orifice plate 10b on and is with a downstream of the orifice 10b arranged arranged not shown pressure compensator.

The on actuation of the control valve 6 in the direction of the first control position 6a downstream of the pressure compensator on the first consumer side 5a upcoming load pressure of the consumer 5 is in a load pressure signal line 20a reported and forwarded to a load pressure message line 21 of the load-sensing drive system 1 connected. Accordingly, upon actuation of the control path valve 6 in the direction of the second control position 6b the downstream of the pressure compensator on the second consumer side 5b Pending load pressure of the consumer in a load pressure signal line 20b reported and forwarded with the load pressure message line 21 connected is.

The downstream of the metering orifice 10a in the flow path from the delivery line 4 to the first consumer line 7a arranged pressure balance has a flow position and a blocking position. Towards the flow position, the pressure compensator is from the downstream of the metering orifice 10a impinging delivery pressure is applied. Towards the blocking position, the pressure compensator is acted upon by the highest load pressure of the driven consumers. The downstream of the orifice 10b in the flow path from the delivery line 4 to the second consumer line 7b arranged pressure balance has a flow position and a blocking position. In the direction of the flow position, the pressure compensator is from the downstream of the metering orifice 10b impinging delivery pressure is applied. Towards the blocking position, the pressure compensator is acted upon by the highest load pressure of the driven consumers.

When several consumers are actuated, there is a signal in the load pressure signaling line 21 the highest load pressure of the driven consumers to the flow rate of the pump designed as a variable displacement pump in the illustrated embodiment 1 to control. The pump 1 has to control the flow rate an adjusting device 25 on, for example, an inclination adjustable swash plate of an axial piston pump, which by means of a flow control valve designed as a demand flow control valve 26 is controllable. The flow regulator 26 is of that in the load pressure message line 21 controlled maximum load pressure of the driven consumers.

The drive system 1 is with a pressure medium storage device 30 provided, whose connection with that of the control way valve 6 to a container guided return lines 8a . 8b by means of return valves 31a . 31b is controlled.

In the illustrated embodiment, in the first return line 8a the control way valve 6 a first return valve 31a arranged, which is the connection of the first return line 8a with the pressure medium storage device 30 or the container 3 controls, and in the second return line 8b a second return valve 21b is arranged, which is the connection of the second return line 8b with the pressure medium storage device 30 or the container 3 controls.

In the illustrated embodiment, the pressure medium storage device comprises 30 at least two accumulator 30a . 30b that have different pressure levels.

The accumulator 30a is by means of the connection cable 35a to the first return line 8a between the control way valve 6 and the first return valves 31a connected and by means of the connecting cable 35b to the second return line 8b between the control way valve 6 and the second feedback valves 31b connected. In the connecting cables 35a . 35b are the check valves 36a . 36b arranged.

The accumulator 30b is by means of a connecting cable 50a on the output side to the first feedback valve 31a and by means of a connecting cable 50b on the output side to the second feedback valve 31b connected. In the connection cable 50a is a direction towards accumulator storage 30b opening check valve 51a arranged. Corresponding is in the connection cable 50b one towards the accumulator 30b opening check valve 51b arranged.

In the illustrated embodiment, the return valves 31a . 31b designed as shut-off valves, each having a flow position formed as a flow position 31c in which the associated return line 8a . 8b opened and thus with the container 3 is connected, and for each accumulator 30a . 30b a storage loading position 31d . 31e in which the associated return line 8a . 8b with the accumulator 30a or the accumulator 30b connected is.

In the expiration position 31c is the return line 8a respectively. 8b with the container 3 connected and the connection to the connecting line 50a respectively. 50b shut off. The storage loading position 31d in which the accumulator 30a can be loaded, is designed as a blocking position in which all connections are shut off. In the storage loading position 31e in which the accumulator 30b can be loaded is the return line 8a respectively. 8b with the connecting cable 50a respectively. 50b connected and the connection of the return line 8a respectively. 8b with the container 3 shut off. The storage loading position 31e is between the expiration position 31c and the storage loading position 31d arranged.

The return feed valves 31a . 31b are according to the invention in the direction of the expiration position 31c in each case only from the current load pressure of the consumer 6 and a spring device 40a . 40b applied. Toward the storage loading positions 31d . 31e are the return valves 31a . 31b from the highest load pressure of the consumers of the drive system 1 in charged. Opposite from the DE 10 2013 101 107 A1 known feedback valves are thus the feedback valves of the invention 31a . 31b not from that in the pressure medium storage device 30 applied pressure.

The first return valve 31a indicates the application of the current load pressure of the consumer 5 in the direction of the expiry position 31c a control pressure surface 41a on, by means of a control line 42a with the first consumer line 7a connected is. The first return valve 31a indicates that the loads of the drive system are subjected to the highest load pressure 1 in the direction of the storage loading positions 31d . 31e a control pressure surface 45a on, by means of a control line 46a with the highest load pressure of all load leading load pressure signaling line 21 of the load-sensing drive system 1 connected is.

The second return valve 31b indicates the application of the current load pressure of the consumer 5 in the direction of the expiry position 31c a control pressure surface 41b on, by means of a control line 42b with the second consumer line 7b connected is. The second return valve 31b indicates that the loads of the drive system are subjected to the highest load pressure 1 in the direction of the storage loading positions 31d . 31e a control pressure surface 45b on, by means of a control line 46b with the highest load pressure of all load leading load pressure signaling line 21 of the load-sensing drive system 1 connected is.

In the control lines 46a . 46b can throttle devices 49a . 49b , For example, screens, be arranged.

Not further shown further consumers of the drive system 1 are by means of appropriately constructed control valves 6 controllable and by means of the invention return valves 31a . 31b with the pressure medium storage device 30 connected.

In the drive system according to the invention 1 can with the two separate feedback valves 31a . 31b in the two return lines 8a . 8b of the consumer 5 and thus each a separate return valve 31a . 31b for each direction of movement of the consumer 5 In a simple way in a trained as a differential cylinder load for both directions of movement of the differential cylinder, the throttle losses are reduced to the inlet-side pressure compensators by the corresponding return valve 30a respectively. 30b the respective return line 8a respectively. 8b and thus the corresponding outlet side of the consumer with the pressure medium storage device 30 is connected. The control pressure surfaces acted upon by the corresponding pressures 41a . 45a at the return valve 31a and the control pressure surfaces acted upon by the corresponding pressures 41b . 45b at the return valve 31b can be adapted in a simple manner to the piston surfaces and thus to the area ratio of the differential cylinder in order to reduce the throttle losses at the inlet-side pressure compensators for both directions of movement of the differential cylinder.

The feedback valves according to the invention 31a . 31b form control valves that control the pressure in the pressure storage device 30 do not consider. The return feed valves 31a . 31b thus do not compare the pressure of the pressure medium storage device 30 with the pressure drop across the pressure balance of the consumer 5 but regulate in the operation of the consumer 5 a maximum pressure drop across the pressure compensator. Is the consumer moving 5 in a direction of movement, represents the respective in the outlet side of the consumer 5 arranged return valve 31a respectively. 31b sure that at the in the respective inlet side of the consumer 5 arranged pressure compensator a predetermined by a spring bias maximum pressure drop across the pressure compensator is not exceeded. As a result, the full potential of reducing throttle losses at the pressure compensators arranged in the inlet side can be exploited. With the feedback valves designed as control valves 31a . 31b It is also possible that the pressure medium storage device 30 at least two accumulator 30a . 30b may have, which have different pressure levels. In the operation of the consumer 5 is made by the feedback valves designed as control valves 31a . 31b the return line 8a respectively. 8b of the consumer 5 always maxed up and by means of the return valves 31a . 31b always the return line 8a respectively. 8b with that accumulator memory 30a . 30b connected, which has the next lower pressure level, so that in those the pressure fluid reservoir 30a . 30b is promoted, which has the next lower pressure level.

With the return valves according to the invention 31a . 31b can be in a load-sening drive system 1 the energy efficiency can be improved, since in the simultaneous operation of multiple consumers, the system-related losses caused by different load pressures on the consumers, partly in the pressure medium storage device 30 can be collected and in the pressure fluid storage device 30 stored pressure fluid can be made available to the drive system again.

With the two separate return valves 31a . 31b in the two return lines 8a . 8b , each with a return valve 31a respectively. 31b for a direction of movement of the consumer 5 is provided, the system-related losses mentioned in both directions of movement of designed as a differential cylinders consumers 2 be reduced.

With the return valves according to the invention 31a . 31b In addition, it is possible to exploit the full potential of reducing throttle losses at the pressure compensators located in the inlet side.

The feedback valves according to the invention 31a . 31b make it possible, more pressure fluid reservoir 30a . 30b to use, which have different pressure levels.

The invention is not limited to the illustrated embodiment, in which the control travel valve 5 two return lines 8a . 8b has, in each of which a separate return valve 31a . 31b is arranged. The control path valve may alternatively have only a single return line and a single return valve, which is controlled in the manner according to the invention.

In addition, the pressure medium storage device 30 only a single accumulator 30a exhibit. At the return valves 31a . 31b can then the memory loading position 31e and the connection for the connecting cable 50a omitted.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013101107 A1 [0003, 0005, 0006, 0007, 0007, 0007, 0027]

Claims (3)

Load-sensing drive system ( 1 ) with a pump ( 2 ) and at least one of the pump ( 2 ) pressurized dual action consumer ( 5 ), in particular a differential cylinder, wherein to control each consumer ( 5 ) a control way valve ( 6 ) is provided and a pressure medium storage device ( 30 ) is provided, whose connection with one of the respective control way valve ( 6 ) to a container ( 3 ) guided return line ( 8a ; 8b ) by means of a respective return valve ( 31a ; 31b ), characterized in that the return valve ( 31a ; 31b ) in the direction of an expiry position ( 31c ) in each case only by the load pressure of the consumer ( 5 ) and a spring device ( 40a ; 40b ) is acted upon, wherein in the expiration position ( 31c ) the associated return line ( 8a ; 8b ) with the container ( 3 ) and the highest load pressure of consumers ( 5 ) of the drive system ( 1 ) in the direction of a storage loading position ( 31d ; 31e ) is applied, in which the associated return line ( 8a ; 8b ) with the pressure medium storage device ( 30 ) connected is. Load-sensing drive system according to claim 1, characterized in that the pressure medium storage device ( 30 ) at least two accumulator ( 30a . 30b ), which have different pressure levels, and the feedback valves ( 31a ; 31b ) for each accumulator ( 30a ; 30b ) a storage loading position ( 31d ; 31e ) having. Load-sensing drive system according to claim 1 or 2, characterized in that the control-way valve ( 6 ) with a first return line ( 8a ) provided in a first control position ( 6a ) of the control valve ( 6 ) with a second consumer side ( 5b ) of the consumer ( 5 ), and with a second return line ( 8b ) provided in a second control position ( 6b ) of the control valve ( 6 ) with a first consumer side ( 5a ) of the consumer ( 5 ), wherein in the first return line ( 8a ) a first return valve ( 31a ) is arranged, the connection of the first return line ( 8a ) with the pressure medium storage device ( 30 ) or the container ( 3 ) and in the second return line ( 8b ) a second return valve ( 31b ) is arranged, the connection of the second return line ( 8b ) with the pressure medium storage device ( 30 ) or the container ( 3 ) controls.

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