EP2541071A2 - Valve assembly for a hydraulic control system - Google Patents

Abstract

The arrangement has a pressure connection (P) connected with a pressure supply, and a tank connection (T) connected with a return pipe. Two load connections (A, B) are connected with hydraulic loads (11), and separate valves (1-4) e.g. 3/3-way valves, control the connection of the load connections with the pressure connection and the tank connection. Another separate valve e.g. 2/2-way valve, connects the pressure and tank connections. The separate valve is closed when the connection between one of the load connections and the pressure connection is opened. The hydraulic loads are formed as hydraulic cylinder or hydraulic motor. An independent claim is also included for a method for operating a hydraulic system.

Description

The present invention relates to a valve assembly for a hydraulic control system for controlling a hydraulic consumer, having a pressure port for connection to a pressure supply, a tank port for connection to a return line, and two load ports for connection to the terminals of the hydraulic consumer.

Such valve assemblies are commonly used in hydraulic control systems to control the supply to and drain from a hydraulic consumer. In conventional hydraulic control systems, a 4/3-way proportional valve is usually used to control the movement of the hydraulic consumer in both directions.

However, such hydraulic control systems with a single valve for controlling the hydraulic consumer have significant losses due to the mechanical coupling of inlet and outlet control edge. In the case of oppressive loads, unnecessary throttling losses occur at the outflow edge, and vice versa with pulling loads, throttling losses at the inlet edge. Farther are also the Ansteuerkanten mechanically coupled for both directions of movement and therefore can not be adapted to the application situation.

The reduction of these throttling losses are therefore used in the present invention resolved control edges. Instead of a common valve in each case a separate valve for controlling the inlet and outlet of the hydraulic consumer and / or the two directions of movement of the hydraulic consumer is used.

It is an object of the present invention to further improve such a valve arrangement with resolved control edges, in which at least two separate valves are used to control the connection of the two consumer connections with pressure connection and tank connection.

According to the invention, this object is achieved by a valve arrangement according to claim 1.

The present invention shows a valve assembly for a hydraulic control system for driving a hydraulic consumer, with a pressure port for connection to a pressure supply, a tank port for connection to a return line, and two load ports for connection to the terminals of the hydraulic consumer. At least two separate valves are provided for controlling the connection of the two consumer connections with pressure connection and tank connection. According to the invention, the valve assembly further comprises a valve for connection of pressure port and tank port.

By means of the valve according to the invention for connecting the pressure connection and the tank connection, an "open center" function is made possible, which connects the pressure connection and tank connection as long as there is no volumetric flow demand for the hydraulic consumer. This allows a more flexible use of the invention Valve arrangement and improves the drive options. In particular, it is possible to connect several valve assemblies in series.

The system of resolved control edges also makes it possible to control the individual control edges separately from each other and / or to design or dimension different to adapt the cross sections and to minimize the flow losses.

Advantageously, the valves for connection of pressure connection and tank connection are at least partially separately and optionally controlled differently.

Alternatively or additionally, at least partially different valves may be used for the valves for connecting the pressure connection and the tank connection, in particular differently dimensioned valves.

In a preferred embodiment of the present invention, the valve for connecting pressure port and tank port is designed as a separate valve. The "open center" function is thus not integrated in the valves for connecting the two consumer connections with pressure connection and tank connection, but executed separately.

In particular, a 2/2-way valve can be used for the valve for connecting the pressure connection and tank connection.

The present invention is advantageously used for controlling hydraulic consumers with two directions of movement. In this case, the valve arrangement is designed so that it can connect both consumer connections with the pressure connection or the tank connection, depending on the desired direction of movement.

Advantageously, the present invention is used in valve assemblies with resolved control edges, in which for connecting the first consumer terminal another valve is used with the pressure connection than for connecting the second consumer connection to the tank connection and / or wherein a second valve is used to connect the second consumer connection to the pressure connection than to connect the first consumer connection to the tank connection. As a result, the inlet and the outlet for the consumer can be controlled or executed separately.

Furthermore, it can be provided that a different valve is used to connect the first consumer port to the pressure port than to connect the second consumer port to the pressure port and / or to connect the first consumer port to the tank port, a different valve is used to connect the second consumer port with the tank connection. As a result, the two directions of movement of the hydraulic consumer can be controlled or executed separately.

In a particularly preferred embodiment, separate valves are used for all connections between the two consumer connections and pressure connection and tank connection, that is, a total of four valves for connecting the two consumer connections with pressure connection and tank connection.

In particular, 2/2-way valves can be used according to the invention for the valves for connecting the consumer connections with pressure connection and tank connection.

Alternatively, however, only two valves can be used to connect the consumer connections with pressure connection and tank connection. If a consumer is to be controlled with two directions of movement, two 3/3-way valves are advantageously used for this purpose.

Advantageously, the valve arrangement according to the invention comprises a control which closes the valve for connection of pressure port and tank port when the connection between one of the consumer ports and the pressure port is opened. Conversely, when all connections between one of the consumer ports and the pressure port are closed, the controller opens the pressure port and tank port connection valve. Furthermore, the controller can equally account for the connections between the load ports and the tank port.

The actuation of the valves of the valve arrangement according to the invention can be carried out both hydraulically, as well as electrically.

In a preferred embodiment, the control of the valves for connection of the consumer connections with pressure connection and tank connection and / or the valve for connection of pressure connection and tank connection takes place hydraulically.

In a first embodiment, the valves for connection of the consumer connections with pressure connection and tank connection and / or the valve for connection of pressure connection and tank connection can be controlled in each case via a separate valve associated therewith. For this purpose, for example, in each case a 3/3-way valve can be used. In particular, it may be provided that the valves for connecting the consumer connections with pressure connection and tank connection are each controlled via a separate valve associated with them. Furthermore, it can be provided that the valve for connection of pressure connection and tank connection is controlled via a separate valve associated with it.

In a second embodiment, the valves for connecting the consumer connections with pressure connection and tank connection and / or the valve for connection of pressure connection and tank connection are at least partially controlled jointly.

In particular, the valves for connection of the consumer connections with pressure connection and tank connection can be controlled at least partially together become. In particular, the control can take place via two separate valves, which each control a direction of movement of the hydraulic consumer.

Furthermore, it can be provided that the valve for connection of pressure port and tank port is controlled together with the valves for connecting the load ports with pressure port and tank port.

In particular, the valve arrangement can be designed so that the control terminal of the valve for connection of pressure connection and tank connection with one or more control lines for driving the valves for connecting the load ports with pressure port and tank port is in communication. Advantageously, the control connection of the valve for connecting the pressure connection and the tank connection is in this case connected to a plurality of control lines for activating the other valves, furthermore advantageously with all control lines. Advantageously, the connection takes place via one or more check valves. In this way can be ensured by the hydraulic control that the valve for connection of pressure port and tank port opens when all other valves are closed, and closes when one of the other valves opens.

The present invention further includes a hydraulic control system having a valve assembly as described above.

Furthermore, the present invention includes a hydraulic system with a valve assembly or with a hydraulic control system as set forth above. The hydraulic system advantageously comprises at least one hydraulic pump for providing a hydraulic pressure at the pressure connection of the valve arrangement, and a return line for connection to the tank connection of the valve arrangement. Furthermore, the hydraulic system according to the invention comprises a consumer whose inlet and outlet are connected to the two load ports of the valve assembly.

Advantageously, the valve assembly according to the invention is used with a consumer with two directions of movement. The consumer may be in particular a translational or rotary consumer. In particular, the hydraulic consumer may be a hydraulic cylinder or a hydraulic motor.

The hydraulic control system may comprise a further valve arrangement, which is connected in series with the valve arrangement according to the invention. By means of the valve according to the invention for connecting the pressure connection and the tank connection, such a series connection is possible since in the neutral position of the valve arrangement according to the invention hydraulic pressure flows from the pressure connection to the tank connection and thus further to the further valve arrangement.

In a preferred embodiment, the valve arrangement is also a valve arrangement according to the invention with dissolved control edges and a valve for connecting the pressure connection and the tank connection. However, it may also be a conventional valve.

The present invention further includes an implement having a hydraulic system as described above. In particular, it may be a movable working device. For example, the implement according to the invention may be an earthmoving device, a handling device and / or a crane.

Advantageously, the inventive hydraulic control system is used to control a working equipment of the implement. In particular, it is possible to control a hydraulic cylinder or a hydraulic motor of the working equipment. For example, a hydraulic cylinder for lifting a boom or hydraulic motor for driving a slewing gear or a winch can be controlled.

The present invention further includes a method of operating a hydraulic system as set forth above. According to the invention, the valve is closed to connect pressure port and tank port, when the connection between one of the consumer ports and the pressure port is opened. Advantageously, the operation of the hydraulic system takes place here as already described above with regard to the valve arrangement according to the invention.

The present invention will now be described in more detail with reference to embodiments and drawings.

Fig. 1:

Ein erstes Ausführungsbeispiel eines erfindungsgemäßen Hydrauliksystems mit einer erfindungsgemäßen Ventilanordnung und

Fig. 2:

ein zweites Ausführungsbeispiel eines erfindungsgemäßen Hydrauliksystems mit einer erfindungsgemäßen Ventilanordnung.

Showing:

Fig. 1:

A first embodiment of a hydraulic system according to the invention with a valve arrangement according to the invention and

Fig. 2:

A second embodiment of a hydraulic system according to the invention with a valve arrangement according to the invention.

The present invention enables a particularly efficient distribution of the volume flows to a consumer. For this purpose, resolved control edges are used. In addition, an "open center" function is integrated with another seat valve. The invention can thus minimize the pressure losses of the returns of the consumer. For example, different size seat valves for the inlet and the outlet of the hydraulic consumer can be used for this purpose. Simultaneously with the opening of the orifice to the inlet, the "open center" orifice closes to restrict the volume flow.

At the in Fig. 1 and 2 The exemplary embodiments shown, the inlet and outlet control edges are not carried out as usual as 4/3-way valve, but as a single control edges in the form of 2/2-way valves. This results in a number of four 2/2-way valves, two each for the two consumer connections A and B, that is for each of the consumer connections each a valve for the inlet and a valve for the flow.

The "open center" function is implemented via an additional 2/2-way valve, which is closed at a volumetric flow demand of the hydraulic consumer. This makes it possible to connect valve sections in series.

The system of dissolved control edges makes it possible to use different valves and / or to control inlet and outlet edges or directions of movement of the hydraulic consumer separately from each other. As a result, the cross sections can be adapted and flow losses can be minimized.

In the following, the embodiments will now be described in more detail:

In the FIGS. 1 and 2 shown valve assemblies according to the invention serve to control a hydraulic load 11. In the exemplary embodiment, this is a hydraulic cylinder. Alternatively, however, a hydraulic motor could also be activated.

The hydraulic consumer 11 has two connections, which form the inlet or outlet depending on the direction of movement. Furthermore, a hydraulic pump 10 is provided, which provides hydraulic pressure for operating the hydraulic consumer 11, as well as a tank 12, to which hydraulic fluid can flow back. The valve arrangement according to the invention now has two consumer ports A and B for connection to the terminals of the hydraulic consumer 11, a pressure port P for connection to the hydraulic pump 12 and a tank port T for connection to a return line leading to the tank. The individual connections can also be designed in the form of a plurality of connections connected in parallel.

In the valve assembly according to the invention is a valve assembly with dissolved control edges, so that the two consumer terminals A and B and both directions of movement of the consumer via separate valves and thus not mechanically interconnected control edges are controlled. For this purpose, four valves 1 to 4 are present in the embodiment, wherein valve 1, the pressure port P to the first consumer port A, valve 2, the tank port T with the first consumer port A, valve 3, the pressure port P to the second consumer port B and valve 4, the tank port T. connects to the second consumer terminal B. In each case 2/2-way valves are used as valves.

Alternatively to the in FIG. 1 arrangement shown with four valves for controlling the two load ports could also be an arrangement with only two separate valves are used. In such an arrangement, either the two consumer connections could then be controlled separately, or the two directions of movement of the hydraulic consumer. For example, two 3/3-way valves could be used for this purpose.

The use of separate valves for controlling the two consumer connections or directions of movement allows for a separate and possibly different control of the valves, and on the other hand, the use of different sized valves. These two options can be used both individually and combined to adapt to the particular application and thus to reduce losses.

In particular, the valve or the valves which connect or connect the first consumer connection A to the pressure connection P and the tank connection T can be designed differently from the valve or the valves connecting the second consumer connection B to the tank connection T and the pressure connection P . connect. In particular, different valve cross sections can be used. Alternatively or additionally, it may be provided that the valve or valves which actuate a first direction of movement of the hydraulic consumer be designed differently from the valve or valves which actuate a second direction of movement. In particular, you can again different sized valves and in particular valves are used with different cross sections.

According to the invention, a further valve 5 is now provided which connects the pressure port P to the tank port T. The valve 5 is designed as a separate valve to the other valves. As a result, there is a further separate control edge, via which a direct connection between the pressure connection and the tank connection can be established.

Through the valve 5, an "open center" function can be realized, which connects pressure port and tank connection with each other when the two consumer ports are disconnected from the pressure port and vice versa. Advantageously, a corresponding control is provided for this purpose. Advantageously, the controller is designed so that the valve 5 closes when one of the valves for connecting the pressure port opens with one of the two load ports, so as to throttle the flow.

At the in FIGS. 1 and 2 shown embodiments of the valve arrangement according to the invention, the valves 1 to 5 are hydraulically controlled. For this purpose, a hydraulic pump 13 is provided in each case, which provides the control pressure required for this purpose.

At the in FIG. 1 shown embodiment, a separate control valve SV1 to SV5 is provided for each of the valves 1 to 5. As a control valve while 3/3-way valves are used. In the FIG. 1 shown arrangement thus allows a separate control of all valves. The control valves SV1 to SV5 can be electrically controlled, for example.

Furthermore, the control valves SV1 to SV5 can also be integrated in the valves 1 to 5, so that in each case two-stage valves are used.

At the in FIG. 2 shown embodiment, however, only two control valves SV1 'and SV2' are used to control the valves 1 to 5. The control valve SV1 'controls the valves 1 and 4, that is, the connection of the first consumer port A to the pressure port and the connection of the second consumer port B to the tank port. The second control valve SV2 'controls, however, the valves 2 and 3, that is, the connection of the second consumer port to the pressure port and the connection of the first consumer port to the tank port. The first control valve SV1 'thus controls the first direction of movement, in which the terminal A of the consumer is pressurized, while hydraulic fluid from the second terminal B flows. The control valve SV2 ', however, controls the opposite direction.

The control valves SV1 'and SV2' for controlling the valves 1 to 4 are now also used to control the valve 5 to connect the pressure port and tank port. For this purpose, the control terminal of the valve 5 via check valves 16 with the control lines for controlling the valves 1 to 4 in connection. The check valves 16 ensure that the respective highest control pressure is applied to the control terminal of the valve 5. The valve 5 is thereby automatically closed when one of the valves 1 to 4 is opened.

A corresponding control of the valve 5 for the connection of pressure connection and tank connection would also be in the in FIG. 1 embodiment shown conceivable by dispensing with the control valve SV5 and the control terminal of the valve 5 is connected via check valves to the control lines for the valves 1 to 4.

Claims (14)

Valve arrangement for a hydraulic control system for controlling a hydraulic consumer (11), comprising a pressure connection (P) for connection to a pressure supply, a tank connection (T) for connection to a return line, and two consumer connections (A, B) for connection to the connections of the hydraulic consumer,
wherein at least two separate valves (1, 2, 3, 4) are used to control the connection of the two consumer connections (A, B) with pressure connection (P) and tank connection (T),
characterized,
that the valve arrangement comprises a valve (5) for connecting the pressure port (P) and tank connection (T). Valve arrangement according to claim 1, wherein the valve (5) for connecting pressure port (P) and tank port (T) is designed as a separate valve. Valve arrangement according to claim 1 or 2, wherein a different valve is used to connect the first consumer port (A) to the pressure port (P) than to connect the second consumer port to the tank port (T) and / or to connect the second consumer port (B ) with the pressure port (P) is used a different valve than for connecting the first consumer port (A) to the tank port (T) and / or wherein for connecting the first consumer port (A) to the pressure port (P) another valve is used when a different valve is used to connect the second consumer port (B) to the pressure port (P) and / or to connect the first consumer port (A) to the tank port (T) than to connect the second consumer port (B) to the tank port ( T). Valve arrangement according to one of the preceding claims, wherein for the valves (1,2,3,4) for connection of the consumer connections (A, B) with pressure connection (P) and tank connection (T) and / or for the valve (5) for connection from pressure port (P) and tank port (T) 2/2 way valves are used. Valve arrangement according to one of the preceding claims with a control which closes the valve (5) for connection of pressure port (P) and tank port (T) when the connection between one of the consumer ports (A, B) and the pressure port (P) is opened , Valve arrangement according to one of the preceding claims, wherein the valves (1,2,3,4) for connecting the consumer connections (A, B) with pressure connection (P) and tank connection (T) and / or the valve (5) for connection of pressure connection (P) and tank connection (T) are hydraulically controlled. Valve arrangement according to claim 6, wherein the valves (1,2,3,4) for connection of the consumer connections (A, B) with pressure connection (P) and tank connection (T) and / or the valve (5) for connection of pressure connection (P ) and tank connection (T) are each controlled by a separate valve associated with them (SV1, SV2, SV3, SV4, SV5). Valve arrangement according to claim 6, wherein the valves (1,2,3,4) for connection of the consumer connections (A, B) with pressure connection (P) and tank connection (T) and / or the valve (5) for connection of pressure connection (P ) and tank connection (T) are at least partially controlled jointly, wherein the control advantageously via two separate valves (SV1 ', SV2') takes place, which each control a direction of movement of the hydraulic consumer (11). Valve arrangement according to one of claims 6 to 8, wherein the control connection of the valve (5) for connection of pressure connection (P) and tank connection (T) with one or more control lines for driving the valves (1,2,3,4) for connecting the Consumer connections (A, B) with pressure connection (P) and tank connection (T) is in communication, advantageously via one or more check valves (16). Hydraulic control system or hydraulic system with a valve arrangement according to one of the preceding claims. Hydraulic control system or hydraulic system according to claim 10, wherein the valve arrangement according to one of the preceding claims is connected in series with a further valve arrangement. Working device with a hydraulic system according to claim 10 or 11, which is advantageously a traveling working device. Working apparatus according to claim 12, wherein the hydraulic control system is advantageously used to control a working equipment of the working device, further advantageously for controlling a hydraulic cylinder or a hydraulic motor of the working equipment. A method of operating a hydraulic system according to claim 10 or 11, wherein the valve for connection of pressure port (P) and tank port (T) is closed when the connection between one of the consumer ports (A, B) and the pressure port (P) is opened.

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