EP2657178B1 - Hydraulic system of a mobile working machine - Google Patents

Description

The invention relates to a hydraulic system of a mobile work machine, in particular an industrial truck, with a pump for common supply of a hydraulic steering device and a comprehensive at least one consumer working hydraulics, wherein in a delivery line of the pump, a priority valve for preferential supply of the steering device is arranged by means of a delivery branch line communicates with the steering device and with a delivery branch line to the working hydraulics.

In mobile machines, such as industrial trucks, a pump is used to jointly supply a hydraulic steering device and a working hydraulics, which usually includes several consumers. In order to ensure sufficient supply of the steering device with pressure medium during actuation of the steering device, a priority valve is arranged in the delivery line of the pump. The priority valve is in this case via a delivery branch line with the steering device and via a further delivery branch line with the working hydraulics in combination. If the pump in the sole operation of the steering device and non-driven consumers of the working hydraulics provides a need for the steering device excess flow delivers, it can flow through the priority valve connected to the working hydraulics Förderzweigleitung and to an undesirable operation of the load of the working hydraulics and thus lead to an undesired movement of a load handled by the consumers.

From the DE 10 2010 048 890 A1 a generic hydraulic system of a mobile work machine is known in which a pump is provided for the common supply of a hydraulic steering device and a comprehensive at least one consumer working hydraulics. In a delivery line of the pump, a priority valve for preferential supply of the steering device is arranged. The Priority valve is connected by means of a delivery branch line with the steering device and with a delivery branch line to the working hydraulics.

The DE 10 2008 052 079 A1 discloses a hydraulic system of a mobile work machine, in which a pump is provided which supplies a lifting drive, a tilt drive and possibly existing additional consumers with pressure medium. The linear actuator is controllable by means of a control valve, wherein in a guided from the control valve to the lifting drive connection channel a aufsteuerbares load-holding valve is arranged. A safety valve controls a guided to an input pressure compensator load pressure signaling line and a discharge line of the load-holding valve to prevent movements of the lifting drive in a safety position on the discharge of the load pressure signaling line and a shut-off of the discharge line.

The present invention has for its object to provide a hydraulic system available, can be effectively prevented with the unwanted consumer movements of the working hydraulics.

This object is achieved in that a safety device is provided which an undesired operation of the consumer Working hydraulics prevented, the safety device comprises a arranged in the run to the working hydraulic Förderzweigleitung shut-off valve device which is controlled in non-actuated consumers of the working hydraulics in a locked position and in a control of the load of the working hydraulics in an open position aufsteuerbar. With a shut-off valve device according to the invention, which is arranged in the conveying branch line arranged from the priority valve to the working hydraulics, undesired consumer movements of the working hydraulics can be avoided in a simple and effective manner. For non-actuated consumers of the working hydraulics, the shut-off valve device is in a blocking position and blocks the connection of the pump to the working hydraulics. In this way it is achieved that in a sole actuation of the steering device by the shut-off by means of the shut-off valve branch line unwanted movements of the consumers of the working hydraulics by a need of the steering device excess, excess flow of the pump can be prevented.

According to an advantageous embodiment of the invention, the shut-off valve device is designed as a pilot-operated shut-off valve, wherein acting in the direction of the blocking position control pressure chamber of the shut-off valve by means of a pilot valve at non-driven consumers of the working hydraulics of the pending in the delivery branch line delivery pressure of the pump and a control of the consumer Working hydraulics can be relieved to a container. By acting on acting in the direction of the blocking position control pressure chamber of the check valve of the pending in the delivery branch line pressure is achieved in a simple manner that the check valve is acted upon sole operation of the steering hydraulics and non-driven consumers of the working hydraulics in the blocking position and shuts off the delivery branch line. By relieving the pressure acting in the direction of the blocking position control pressure chamber of the check valve can be controlled by the pending in the delivery branch line delivery pressure of the pump in a flow position in a simple way when controlling the load of the working hydraulics, the check valve.

With particular advantage, the pilot valve has a first control position, in which the control pressure chamber of the check valve is connected to the delivery branch line, and a second control position, in which the control pressure chamber is connected to the container, wherein the pilot valve is acted upon by means of a spring device in the first control position and can be acted upon by means of an actuating device in the second control position. With such a pilot valve is achieved in a simple manner that the pilot valve connects the control pressure chamber in the non-actuated state with the delivery branch, so that in the non-actuated state of the pilot valve, the check valve is acted upon in the blocking position. In this way, a high reliability of the hydraulic system according to the invention is further achieved, since in the non-actuated state of the pilot valve by the acted upon in the blocking position check valve an undesirable movement of the consumers of the working hydraulics is avoided and prevented. When driving the load of the working hydraulics, the pilot valve can be operated in the second control position by controlling the actuator of the pilot valve in a simple manner to aufzusteuern by relieving the control pressure chamber to the container the check valve.

The actuating device of the pilot valve can be designed as a solenoid according to one embodiment of the invention.

With particular advantage, according to a preferred embodiment of the invention, the actuating device is designed as a control pressure surface, which communicates with a control pressure leading control pressure supply line. With a hydraulic actuation of the pilot valve by a control pressure of the hydraulic system, a simple operation of the pilot valve can be achieved.

According to an advantageous development of the invention, the safety device comprises a safety valve, by means of which the control pressure surface leading to the control pressure surface is relieved to a container at non-controlled consumers of the working hydraulics and the control pressure supply line to a control pressure source is connected to a control of the consumers of the working hydraulics. With such a safety valve can be easily actuated by the discharge of the control pressure line by means of the safety valve and the associated operation of the pilot valve in the first control position, the shut-off valve in the locked position to uncontrolled consumers of the working hydraulics by blocking the Förderzweigleitung an undesirable consumer movement the working hydraulics to prevent. If a desired consumer movement is to be performed, by means of the safety valve, the control pressure supply line can be acted upon by the control pressure generated by the control pressure source, so that the pilot valve is acted upon in the second control position to aufzusteuern the shut-off valve device in the open position.

Preferably, the further safety valve is arranged in the control pressure supply line, wherein the safety valve has a first control position in which the control pressure supply line is relieved to a container and has a second control position in which the control pressure supply line is connected to the control pressure source, wherein the safety valve by means of a spring device in the first control position is acted upon and by means of an electrical actuating device, in particular a solenoid, in the second control position can be acted upon. With such a safety valve, a high level of operational reliability is achieved because in the de-energized state of the safety valve by the discharge of the control pressure supply line, the shut-off valve device is acted upon in the blocking position and thus undesirable consumer movements of the working hydraulics can be prevented.

According to a preferred embodiment of the invention, a control valve throttling in intermediate positions is provided for the actuation of each consumer of the working hydraulics, which control valve can be actuated by means of a control device connected to the control pressure supply line. With a hydraulic actuation of the control valves of the working hydraulics by a drive pressure generated by the control pressure line by means of a control device, the reliability of the hydraulic system is further increased, as achieved in the de-energized state of the safety valve by relieving the control pressure supply line in a simple manner that with relieved control pressure supply line no actuation of Control valves of the working hydraulics can be done and thus unwanted movements of the consumers of the working hydraulics are made impossible. The safety valve thus continues to effectively prevent unwanted consumer movements of the working hydraulics can occur due to uncontrolled actuation of the control valves.

According to a preferred embodiment of the invention, the pump is designed as adjustable in the flow rate pump, wherein the flow rate of the pump is controlled by means of a control device controlling control valve device which is controlled by a load pressure signal of the steering device or the working hydraulics, wherein the safety device comprises a further safety valve , By means of which a load pressure signal leading load pressure signal line is relieved in non-actuated steering device and non-driven consumers of the working hydraulics and when operating the steering device and / or upon activation of the consumer of the working hydraulics in the load pressure signal line pending load pressure signal is passed to the control valve means of the pump. Such a load-sensing-controlled pump increases at a pending in the load pressure signal line load pressure signal at a control of the steering device and / or the control of a consumer of the working hydraulic flow rate to produce in the delivery line a delivery pressure to a predetermined control pressure difference higher than the Load pressure of the consumer is. By relieving the guided to the control valve means of the pump load pressure signal line by means of the further safety valve is achieved in such a pump in an effective manner that the flow rate of the pump is not increased in non-actuated steering device and non-driven consumers of the working hydraulics and thus the pump in a setting remains at the flow rate zero, so that unwanted consumer movements of the working hydraulics are prevented and made impossible.

For this purpose, the further safety valve is arranged in a guided from the load pressure signal line to a container branch line and has a flow position and a blocking position, wherein the safety valve is acted upon by a spring means in the flow position and by means of an electrical actuator, in particular a solenoid in the blocking position can be acted upon. With such a further safety valve is achieved in a simple manner that in the de-energized state, the load pressure signal line of the steering device and the working hydraulics with pressure medium supplying pump is relieved to the container. In this way, a high reliability of the hydraulic system according to the invention is further achieved, since in the de-energized state of the safety valve by relieving the control valve to the pump designed as a variable displacement pump, an increase in the flow rate Pump is prevented and thus unwanted movements of the consumers of the working hydraulics are made impossible.

According to an advantageous embodiment of the invention, a further pump is provided for additional supply to the consumer of the working hydraulics, which is designed as adjustable in the flow rate pump, the flow rate of the pump is controlled by means of a control device controlling control valve device controlled by a load pressure signal of the working hydraulics is, wherein the safety device comprises an additional safety valve, by means of which a load pressure signal leading load pressure signal line is relieved at non-actuated consumers of the working hydraulics and when driving the load of the working hydraulics the pending in the load pressure signal line load pressure signal is passed to the control valve means of the other pump. With such a further load-sensing-regulated variable displacement pump, in particular in the case of large industrial trucks which have a high flow rate requirement of the working hydraulics, the delivery flow requirement of both pumps can be covered when the consumers of the working hydraulics are activated. By relieving the guided to the control valve means of the further pump load pressure signal line is achieved in such a pump in an effective manner that the flow rate of the other pump is increased only at a desired control of consumers of the working hydraulics, so that unwanted consumer movements of the working hydraulics prevented and made impossible become.

The additional safety valve is expediently arranged in a branch line guided from the load pressure signal line to a container and has a flow position and a blocking position, wherein the additional safety valve is acted upon by a spring device in the flow position and by means of an electrical actuator, in particular a solenoid in the Lock position can be acted upon. With such a safety valve is achieved in a simple manner, which is relieved in the de-energized state, the load pressure signal line to the container. In this way, a high reliability of the hydraulic system according to the invention is further achieved, since in the de-energized state of the safety valve by relieving the control valve to the further pump designed as a further pump an increase in the flow rate The pump is prevented and thus unwanted movements of the consumers of the working hydraulics are made impossible.

According to an advantageous embodiment of the invention, an electronic control device is provided for controlling the safety device, which is for determining the actuation of the steering device with a steering sensor device of the steering device in combination. With such an electronic control device, which detects an actuation of the steering device with the steering sensor sensor device, the safety valve can be controlled in an easy manner upon actuation of the steering device to by supplying the control device of the steering device and the working hydraulics pump by the load pressure of the actuated steering device to achieve a corresponding control of the pump to increase the flow rate.

With particular advantage, the electronic control device determines, based on electrical control signals of the control valves of the working hydraulics, a control of the consumers of the working hydraulics. On the basis of the electrical control signals of the control valves can be determined by the electronic control device in a simple manner, a desired actuation of the load of the working hydraulics to allow by a corresponding control of the safety device, the desired actuation of the consumer.

Figur 1

einen Hydraulikschaltplan eines erfindungsgemäßen Antriebssystems,

Figur 2

einen Ausschnitt der Figur 1 in einer vergrößerten Darstellung Und

Figur 3

einen Ausschnitt der Figur 2 in einer vergrößerten Darstellung.

Further advantages and details of the invention will be explained in more detail with reference to the embodiments illustrated in the schematic figures. This shows

FIG. 1

a hydraulic circuit diagram of a drive system according to the invention,

FIG. 2

a section of the FIG. 1 in an enlarged view And

FIG. 3

a section of the FIG. 2 in an enlarged view.

In the FIG. 1 is a hydraulic circuit diagram of a hydraulic system according to the invention shown a mobile machine, such as an industrial truck.

As a consumer, the hydraulic system comprises a hydraulic steering hydraulic system L and a working hydraulic system A, which as a rule comprises several consumers. In the illustrated embodiment, only one consumer of the working hydraulics A is shown.

To supply the consumers, the hydraulic system has two pumps 1, 101. The pump 1 is provided for the common supply of the steering hydraulic L and the working hydraulics A. The pump 101 supplies only the working hydraulics A with pressure medium. The pumps 1, 101 are driven by a non-illustrated drive machine, for example, designed as a diesel engine internal combustion engine.

The pumps 1, 101 are in each case designed as pumps which are adjustable in the delivery volume or the delivery quantity and which are operated in the open circuit in the illustrated embodiment and are in communication with a container 2 on the input side. The pump 1 delivers into a delivery line 3 and the pump 101 into a delivery line 103, which are connected to corresponding consumers.

For controlling the direction of movement and the speed of movement of the consumer, a control valve 5, 105 throttling in intermediate positions is provided in each case. The control valve 5 for controlling the hydraulic steering device L is designed, for example, as Lenkorbitrol, which is actuated by means of a steering wheel 5a.

The control valves 105 for controlling the consumers of the working hydraulics A are designed as directional control valves. The control valves 5, 105 each have a neutral position in which the consumer lines routed to the consumers are shut off. The control valves 5, 105 have, in corresponding control positions, an orifice plate formed by the opening width and thus the released opening cross-section. Furthermore, pressure compensators DW can be arranged downstream or upstream of the metering orifice on the control valves 5, 105.

The control valves 105 of the working hydraulics A are electro-hydraulically actuated. To actuate the control valves 105 in the corresponding control positions electrically actuated pilot valves 110a, 110b are provided as drive means 110 which are connected on the input side to a control pressure supply line 120 and generate a hydraulic actuation pressure for actuating the control valve 105 when driven from a pending in the control pressure supply line 120 control pressure ,

The control pressure supply line 120 communicates with a control pressure source 121 which is constituted by a control pressure pump 122. In the illustrated embodiment, the control pressure source 121 further includes a pressure medium reservoir 123, which is associated with the control pressure supply line 120.

In the delivery line 3 provided for the common supply of the steering device L and the working hydraulics A pump 1, a priority valve P is arranged for the preferred supply of the steering device L with pressure medium. From the priority valve P is a delivery branch line 3a to the control valve 5 of the steering device L and a delivery branch line 3b to the control valves 105 of the working hydraulics A out.

The delivery line 103 of the pump 101 is guided to the control valves 105 of the load of the working hydraulics.

The pumps 1, 101 designed as variable-displacement pumps are each designed as a load-sensing controlled pump and provided with a control valve device 6, 106, for example a demand flow control valve, which is controlled by one of the delivery pressure signal of the pump 1 or 101 and the highest load pressure signal Consumer formed signal difference is controlled.

The control valve device 6, 106 actuates an adjusting device 7, 107 formed by an actuating piston device, by means of which a delivery volume adjusting device 8, 108 controlling the delivery volume of the pump 1, 101 can be actuated, for example an inclination adjustable swash plate of a pump 1, 101 designed as a swash plate pump is adjustable.

The adjusting device 7, 107 is acted upon by means of a - for example, designed as a spring device - control device in the direction of a maximum delivery volume and thus in the direction of increasing the delivery volume of the pump 1, 101. In addition, a control pressure space acting in the direction of an increase of the adjusting device 7, 107, in which the spring device is arranged, can be connected to a delivery side of the pump 1, 101.

For acting on the adjusting device 7, 107 in the direction of the minimum delivery volume and thus in the direction of reducing the delivery volume of the pump 1, 101, a second control pressure chamber counteracting the control pressure chamber with the spring device is formed on the adjusting device 7, 107.

This second control pressure chamber communicates with a control line 10, 110, which is guided to the control valve device 6, 106.

The control valve device 6, 106 is formed in the illustrated embodiment as a load-sensing control valve or demand flow control valve in a first control position, the control line 10, 110 to increase the flow rate of the pump 1, 101 with a leading container 2 to the container 11, 111 combines. In a second control position for reducing the delivery rate of the pump 1, 101, the control valve device 6, 106 connects the control line 10, 110 with the delivery side of the pump 1, 101.

The control valve device 6, 106 is acted upon by a in a delivery pressure signal line 50 and 51 pending delivery pressure signal of the pump 1, 101 in the direction of the second control position. In the direction of the first control position, the control valve device 6, 106 is acted upon by a control spring 15, 115, whose bias corresponds to a set control pressure difference, and the highest load pressure of the driven consumers acted upon.

The tap of the control valve means 6, 106 actuated load pressure of the driven consumer takes place in the region of the control valves 5, 105. For this purpose, upon actuation of the corresponding control valve 5, 105 in the direction of Control position of the downstream of the corresponding orifice pending load pressure of the consumer in a load pressure signal line 20 of the steering device L and a load pressure signal line 21 of the hydraulic system A reported and forwarded.

The load pressure signal line 21 of the working hydraulics A, in which is present at a control of one or more consumers of the working hydraulics A, the highest load pressure of the driven consumer is guided to the control valve means 106 of the pump 101 to the admission. In order to achieve in the pump 1, which is provided for the common supply of the steering hydraulics L and the working hydraulics A, a control of the control valve means 6 of the highest load pressure of the driven consumers, a selector valve means 45 is provided, for example, a shuttle valve, the input side with the load pressure signal line 20 of the steering device L and the load pressure signal line 21 of the working hydraulics A is in communication and at the output of a load pressure signal line 22 is connected, which is guided to the control valve device 6 of the pump 1 to the admission.

The hydraulic system according to the invention has a safety device S, which avoids and prevents unwanted actuation of the consumers of the working hydraulics.

The safety device S comprises a shut-off valve device 130 arranged in the conveying branch line 3b. The shut-off valve device 130 is controlled in non-activated consumers of the working hydraulics A or on sole actuation of the steering hydraulics L and non-actuated consumers of the working hydraulics A into a blocking position in order to shut off the conveying branch line 3b to prevent inadvertent actuation of the consumers of the working hydraulics A by the pump 1. When controlling the consumers of the working hydraulics A, the shut-off valve device 130 can be opened in an open position in order to achieve a supply of the consumers via the pump 1.

The shut-off valve device 130 is designed as a pilot-operated shut-off valve 131, which - as in connection with the Figures 2 and 3 is apparent - is acted upon by means of acting in the direction of a blocking position control pressure chamber 132 in the blocking position. In the control pressure chamber 132 may continue in a blocking position acting spring device 133 may be arranged. Acting in the direction of the blocking position control pressure chamber 132 of the check valve 130 is acted upon by a pilot valve 134 at non-driven consumers of the working hydraulics A pending in the delivery branch line 3b delivery pressure of the pump to pressurize the check valve 131 in the blocking position. When controlling the load of the working hydraulics A, the control pressure chamber 132 to the container 2 can be relieved by means of the pilot valve 134, so that the check valve 131 of the present in the delivery branch line 3b delivery pressure, which is present at a acting in the direction of the open position control surface of the check valve 131, is turned on in a flow position.

For this purpose, the pilot valve 134 is connected to a control line 135 branching off from the delivery branch line 3b upstream of the check valve 131 and a discharge line 136 led to the container 2.

The pilot valve 134 has a first control position 134a, in which the control pressure chamber 132 of the check valve 131 to the control line 135 and thus the delivery branch line 3b upstream of the check valve 131 is connected to actuate the check valve 131 in the blocking position. In a second control position 134b of the pilot valve 134, the control pressure chamber 132 of the check valve 131 is connected via the drain line 136 to the container 2 to aufzusteuern the check valve 131 in the open position. The pilot valve 131 is acted upon by means of a spring device 137 in the first control position 134a and actuated by means of an actuating device 138 in the second control position 134b.

The actuating device 138 is formed in the illustrated embodiment as a hydraulic control pressure surface which is connected to the control pressure supply line 120.

In order to achieve actuation of the check valve 131 in the blocking position for non-actuated consumers of the working hydraulics A by actuation of the pilot valve 134 in the first control position 134a, the safety device S comprises a safety valve 140. With the safety valve 140 is at non-actuated consumers of the working hydraulics the control pressure supply line 120 guided to the actuator 138 configured as the control pressure surface Container 2 relieved and when controlling the load of the working hydraulics A, the control pressure supply line 120 connected to the control pressure source 121.

The safety valve 140 is arranged for this purpose in the control pressure supply line 120 and has a first control position 140a, in which the control pressure supply line 120 is relieved to the container 2. In a second control position 140b of the safety valve 140, the control pressure supply line 120 is connected to the control pressure source 121. The safety valve 140 is acted upon by means of a spring device 141 in the first control position 140a and acted upon by an electrical actuator 142, such as a solenoid, in the second control position 140b.

The safety device S further comprises a further safety valve 150, by means of which the load pressure signal line 22 of the pump 1 is relieved when the steering device L is not actuated and the driven hydraulics A are not actuated, and when the steering device L is operated and / or when the load of the working hydraulics is actuated A in the load pressure signal line pending load pressure signal to the control valve device 6 of the pump 1 is performed.

The further safety valve 150 is arranged in a guided from the load pressure signal line 22 to the container 2 branch line 151 and has a flow position 150a, in which the load pressure signal line 22 is relieved to the container 2, and a blocking position 150b, in which the connection of the load pressure signal line 22 to Container 2 is shut off. The further safety valve 150 is acted upon by means of a spring device 152 in the flow position 150 a, in which the load pressure signal line 22 is relieved to the container 2. When unloaded load pressure signal line 22, the control valve means 6 of the pump 1 is acted upon in the direction of a reduction of the flow rate and the pump 1 is in a setting with the flow rate zero. The further safety valve 150 is acted upon by means of an electrical actuator 153, for example a solenoid in the blocking position 150b, in which the load pressure signal in the load pressure signal line 22 of the driven consumer, the control valve device 6 of the pump 1 in the direction of increasing the flow rate of the pump 1 applied.

The safety device S further comprises an additional safety valve 160, by means of which the load pressure signal leading load pressure signal line 21 of the pump 101 is relieved at non-driven consumers of the working hydraulics A and at a control of the load of the working hydraulics A pending in the load pressure signal line load pressure signal to the control valve means 106 of another pump 101 is guided.

The additional safety valve 160 is arranged in a guided from the load pressure signal line 21 to the container 2 branch line 161 and has a flow position 160a, in which the load pressure signal line 21 is relieved to the container 2, and a blocking position 160b in which the connection of the load pressure signal line 21 to Container 2 is shut off. The additional safety valve 160 is acted upon by means of a spring device 162 in the flow position 160a, in which the load pressure signal line 21 is relieved to the container 2. With unloaded load pressure signal line 21, the control valve means 106 of the pump 101 is acted upon in the direction of a reduction of the delivery rate and the pump 101 is in a setting with the delivery rate zero. The further safety valve 160 is acted upon by means of an electric actuator 163, such as a solenoid, in the blocking position 160b, in which the load pressure signal of the controlled consumer in the load pressure signal line 21, the control valve means 106 of the pump 101 is acted upon in the direction of increasing the flow rate of the pump 101.

The electrically operable safety valves 140, 150, 160 of the safety device S are actuated by means of an electronic control device, not shown, which is operatively connected to a steering sensor device 170 to determine the operation of the steering device L upon actuation of the steering wheel 5a by an operator. The electronic control device is also connected to actuating elements, not shown, for example, joysticks, in conjunction, by means of which the control means 110 of the control valves 105 of the working hydraulics A for actuation of the control valves 105 are controlled. Based on the control signals of the actuating elements and thus the control signals of the control valves 105, an actuation of the actuating elements by the operator and thus a desired control of the load of the working hydraulics A can be determined in this case.

• Sofern die Lenkungseinrichtung L und die Verbraucher der Arbeitshydraulik A nicht angesteuert sind, sind die Sicherheitsventile 140, 150, 160 der Sicherheitseinrichtung S nicht angesteuert und befinden sich in der ersten Steuerstellung 140a bzw. den Durchflussstellungen 150a, 160a.

The hydraulic system with the securing device S according to the invention operates as follows:

• If the steering device L and the consumers of the working hydraulics A are not activated, the safety valves 140, 150, 160 of the safety device S are not actuated and are located in the first control position 140a or the flow positions 150a, 160a.

By relieving the control pressure supply line 120 in the flow position 140a of the safety valve 140, the pilot valve 134 of the check valve 131 is acted upon in the first control position 134a, so that the check valve 131 is acted upon in the blocking position. By relieving the control pressure supply line 120, furthermore, no actuation of the control valves 105 by means of the control device 110 is possible.

The safety valves 150, 160 located in the flow-through positions 150a, 160a ensure, by relieving the load pressure signal lines 21, 22, that the pumps 1, 101 are set to the flow rate zero and remain in this position.

If only the steering device L is actuated by an operator, the actuation of the steering device L can be detected on the basis of the sensor signal of the steering sensor device 170. In such an operating state, only the safety valve 150 is actuated by the electronic control device, so that the safety valve 150 is acted upon in the blocking position 150b in which the load pressure of the steering device L present in the load pressure signal line 21 acts on the control valve device 6 and the pump 1 in the direction of a Increase of the flow rate is adjusted. By means of the priority valve P, a supply of the steering device L is ensured with the required by the steering device L flow. If the pump 1 deliver a consumption of the steering device L exceeding flow, it can not flow to the control valves 105 of the working hydraulics A and the unintentional movement of the load of the working hydraulics A on the non-actuated safety valve 140 in the blocking position shut-off valve device 130 and a load handled by consumers. With the shut-off valve device 130 located in the blocking position, an undesired actuation of the consumers of the working hydraulics can thus be avoided when the steering device L is operated alone.

If an intentional actuation of the consumers of the working hydraulics A is performed by an operator by actuation of the actuation elements, the safety valves 140, 150, 160 are actuated by the electronic control device, so that the safety valve 140 is acted on in the second control position 140b and the safety valves 150 , 160 in the blocking positions 150b, 160b are acted upon.

By the safety valve 140 actuated in the second control position 140b, the control pressure supply line 120 is connected to the control pressure source 121, so that a control pressure for actuating the corresponding control valve 105 can be generated by a control of the drive device 110.

The pending in the control pressure supply line 120 control pressure acts on the pilot valve 134 of the check valve 131 in the second control position 134 b, in which the control pressure chamber 132 of the check valve 131 is relieved to the container 2.

The safety valves 150, 160 located in the blocking position 150b, 160b enable the load pressure of the controlled consumer present in the load pressure signal line 21 to act on the control valve device 6 of the pump 1 and the control valve device 106 of the pump 101 and both pumps 1, 101 in the direction an increase in the flow rate can be adjusted. The flowing from the pump 1 via the priority valve P in the delivery branch line 3b flow applied to the check valve 131 of the shut-off valve 130 in the open position and controls the shut-off valve 130, so that the consumers of the working hydraulics A of both pumps 1, 101 are supplied with pressure medium.

If, during actuation of the consumers of the working hydraulics A, the steering device L is actuated at the same time, the preferred supply of the steering device with pressure medium from the pump 1 is ensured by means of the priority valve P, wherein the excess of the pump 1, the demand of the steering device L exceeding flow through the delivery branch line 3b and the open shut-off valve device 130 is the consumers of the working hydraulics A available.

Claims (14)

1. Hydraulic system of a mobile work machine, in particular an industrial truck, having a pump (1) for the common supply of a hydraulic steering device (L) and working hydraulics (A) comprising at least one consumer, a priority valve (P) for the preferred supply of the steering device (L) being arranged in a delivery line of the pump (1) and being connected to the steering device (L) by means of a delivery branch line (3a) and to the working hydraulics (A) by a delivery branch line (3b), characterized in that a safety device (S) is provided which prevents undesired actuation of the consumers of the working hydraulics (A), the safety device comprising a shut-off valve device (130) which is arranged in the delivery branch line (3b) led to the working hydraulics (A) and which, when the consumers of the working hydraulics (A) are not activated, is controlled into a blocking position and, when the consumers of the working hydraulics (A) are activated, can be opened into an open position under control.
2. Hydraulic system according to Claim 1, characterized in that the shut-off valve device (130) is formed as a pilot-controlled shut-off valve (131), a control pressure chamber (132) of the shut-off valve (131), acting in the direction of the blocking position, by means of a pilot control valve (134) when the consumers of the working hydraulics (A) are not activated being pressurized by the delivery pressure from the pump (1), present in the delivery branch line (3b), and, when the consumers of the working hydraulics (A) are activated, the said control pressure chamber (132) can be depressurized to a container (2).
3. Hydraulic system according to Claim 2, characterized in that the pilot control valve (134) has a first control position (134a), in which the control pressure chamber (132) of the shut-off valve (131) is connected to the delivery branch line (3b), and a second control position (134b), in which the control pressure chamber (132) is connected to the container (2), the pilot control valve (134) being loaded into the first control position (134a) by means of a spring device (137) and can be loaded into the second control position (134b) by means of an actuating device (138).
4. Hydraulic system according to Claim 3, characterized in that the actuating device (138) is formed as a switching solenoid.
5. Hydraulic system according to Claim 3, characterized in that the actuating device (138) is formed as a control pressure surface which is connected to a control pressure supply line (120) carrying a control pressure.
6. Hydraulic system according to Claim 5, characterized in that the safety device (S) comprises a safety valve (140) by means of which, when the consumers of the working hydraulics (A) are not activated, the control pressure supply line (120) led to the control pressure surface of the pilot control valve (134) is depressurized to a container (2) and, when the consumers of the working hydraulics (A) are activated, the control pressure supply line (120) can be connected to a control pressure source (121).
7. Hydraulic system according to Claim 6, characterized in that the safety valve (140) is arranged in the control pressure supply line (120), the safety valve (140) having a first control position (140a), in which the control pressure supply line (120) is depressurized to a container (2), and having a second control position (140b), in which the control pressure supply line (120) is connected to the control pressure source (121), the safety valve (140) being loaded into the first control position (140a) by means of a spring device (141) and, by means of an electric actuating device (142), in particular a switching solenoid, can be loaded into the second control position (140b).
8. Hydraulic system according to one of Claims 5 to 7, characterized in that in order to actuate each consumer of the working hydraulics (A), a control valve (105) throttling in intermediate positions is provided, which can be actuated by means of an activation device (110) connected to the control pressure supply line (120).
9. Hydraulic system according to one of Claims 1 to 8, characterized in that the pump (1) is constructed as an adjustable delivery rate pump, the delivery rate of the pump (1) being controlled by means of a control valve device (6) which controls an actuating device (7) and which is controlled by a load pressure signal from the steering device (L) or the working hydraulics (A), the safety device (S) comprising a further safety valve (150), by means of which a load pressure signal line (22) carrying the load pressure signal is depressurized when the steering device (L) is not actuated and the consumers of the working hydraulics (A) are not activated, and, in the event of actuation of the steering device (L) and/or in the event of activation of the consumers of the working hydraulics (A), the load pressure signal present in the load pressure signal line (22) is led to the control valve device (6) of the pump (1).
10. Hydraulic system according to Claim 9, characterized in that the further safety valve (150) is arranged in a branch line (151) led from the load pressure signal line (22) to a container (2) and has a flow position (150a) and a blocking position (150b), the safety valve (150) being loaded into the flow position (150a) by means of a spring device (152) and can be loaded into the blocking position (150b) by means of an electric actuating device (153), in particular a switching solenoid.
11. Hydraulic system according to one of Claims 1 to 10, characterized in that for the purpose of additionally supplying the consumers of the working hydraulics (A), a further pump (101) is provided, which is constructed as an adjustable delivery rate pump, the delivery rate of the pump (101) being controlled by means of a control valve device (106) which controls an actuating device (107) and which is controlled by a load pressure signal from the working hydraulics (A), the safety device (S) comprising an additional safety valve (160) by means of which, when the consumers of the working hydraulics (A) are not activated, a load pressure signal line (21) carrying the load pressure signal is depressurized and, when the consumers of the working hydraulics (A) are activated, the load pressure signal present in the load pressure signal line (22) is led to the control valve device (106) of the further pump (101).
12. Hydraulic system according to Claim 11, characterized in that the additional safety valve (160) is arranged in a branch line (161) led from the load pressure signal line (21) to a container (2) and has a flow position (160a) and a blocking position (160b), the additional safety valve (160) being loaded into the flow position (160a) by means of a spring device (162) and can be loaded into the blocking position (160b) by means of an electric actuating device (163), in particular a switching solenoid.
13. Hydraulic system according to one of Claims 1 to 12, characterized in that in order to activate the safety device (S), an electronic control device is provided which, in order to determine the actuation of the steering device (L), is connected to a steering sensor device (170) of the steering device (L).
14. Hydraulic system according to Claim 13, characterized in that the electronic control device determines activation of the consumers of the working hydraulics (A) by using electric activation signals of the control valves (105) of the working hydraulics (A).

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