CH705150A1 - Valve arrangement for hydraulic control system for controlling e.g. hydraulic cylinder for lifting extension arm of crane, has valve i.e. separate valve, connecting pressure connection and tank connection - 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 connection for connection to a pressure supply, a tank connection for connection to a return line, and two consumer connections for connection to the connections of the hydraulic consumer.

Such valve assemblies are used by default in hydraulic control systems to control the inlet to and the flow of 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 considerable 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. Furthermore, the control edges for both directions of movement are mechanically coupled and therefore can not be adapted to the application situation.

To reduce these throttle losses therefore resolved control edges are used in the present invention. 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.

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

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 arrangement furthermore comprises a valve for connecting the pressure connection and the tank connection.

The inventive valve for connecting pressure port and tank connection an "open center" function is enabled, which connects the pressure port and tank connection, as long as no volume flow demand for the hydraulic consumer is present. This allows a more flexible use of the inventive valve arrangement and improves the control 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 different design or dimension to adjust the cross sections and to minimize the flow losses.

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

Alternatively or additionally, at least partially different valves can be used for the valves for connecting pressure port and tank port, 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 is designed separately.

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

The present invention is advantageously used for controlling hydraulic consumers with two directions of movement. The valve assembly is designed in this case so that they can connect both consumer connections depending on the desired direction of movement with the pressure port or the tank port.

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

Furthermore, it can be provided that for the connection of the first consumer port to the pressure port another valve is used as for connecting the second consumer port to the pressure port and / or for connecting the first consumer port to the tank port another valve is used as the connection of the second consumer connection 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 for connecting the consumer connections with pressure connection and tank connection can be used. 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 assembly according to the invention comprises a controller, 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 take into account the connections between the consumer connections and the tank connection.

The control of the valves of the inventive valve assembly can be done 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 assigned to them. Furthermore, it can be provided that the valve for the connection of the pressure connection and the tank connection is also actuated via a separate valve assigned to it.

In a second embodiment, the valves for connecting the load ports with pressure port and tank port and / or the valve for connecting pressure port and tank port are at least partially controlled together.

In particular, the valves for connecting the consumer connections with pressure connection and tank connection can be controlled at least partially together. 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 consumer ports with pressure port and tank port.

In particular, the valve assembly can be designed so that the control port of the valve for connecting pressure port and tank port with one or more control lines for driving the valves for connecting the load ports with pressure port and tank port is connected. 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. This allows the hydraulic control to ensure that the valve opens to connect the pressure port and tank port when all other valves are closed and closes when one of the other valves opens.

The present invention further comprises a hydraulic control system with a valve assembly as described above.

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

Advantageously, the inventive valve assembly is used with a consumer with two directions of movement. The consumer can be in particular a translatory 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 because, 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, it is also in the further valve arrangement to a valve arrangement according to the invention with dissolved control edges and a valve for connection of pressure port and 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 for controlling a working equipment of the implement is used. 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 for connecting pressure port and tank port is closed 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.

[0037] In the following: <Tb> FIG. 1: <sep> A first embodiment of a hydraulic system according to the invention with a valve arrangement according to the invention and <Tb> FIG. 2: <sep> 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, differently sized 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 closes the "open center" orifice in order to restrict the volume flow.

In the embodiments shown in FIGS. 1 and 2, the inlet and outlet side control edges are not executed 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 for each of the two consumer ports A and B, that is, for each of the consumer ports each have a valve for the supply 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 the resolved 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 adjusted and flow losses can be minimized.

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

The valve arrangements according to the invention shown in FIGS. 1 and 2 are used to control a hydraulic consumer 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 inventive valve assembly 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 10 and a tank port T for connection to a tank leading to the return line. The individual connections can also be designed in the form of a plurality of connections connected in parallel.

In the inventive valve assembly is a valve assembly with resolved control edges, so that the two consumer ports 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 exemplary embodiment, wherein valve 1, the pressure port P with the first consumer port A, valve 2, the tank port T with the first consumer port A, valve 3, the pressure port P with the second consumer port B and valve 4, the tank port T. connects to the second load port B. In each case 2/2-way valves are used as valves.

As an alternative to the arrangement shown in Fig. 1 with four valves for controlling the two consumer connections and an arrangement with only two separate valves could be 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 load ports 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 connects or connect the first consumer port A to the pressure port P and the tank port T can be designed differently from the valve or the valves which have the second consumer port B with tank port T and pressure port P connects or connects. 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, again different sized valves and in particular valves with different cross sections can be used.

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

By 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.

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

In the embodiment shown in Fig. 1, 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. The arrangement shown in Fig. 1 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.

In the embodiment shown in Fig. 2, however, only two control valves SV1 and SV2 are used to control the valves 1 to 5. The control valve SVV controls the valves 1 and 4, ie the connection of the first consumer connection A to the pressure connection and the connection of the second consumer connection B to the tank connection. On the other hand, the second control valve SV2 controls the valves 2 and 3, that is to say the connection of the second consumer connection to the pressure connection and the connection of the first consumer connection to the tank connection. The first control valve SV1 thus controls the first direction of movement, in which the port A of the consumer is pressurized, while hydraulic fluid from the second port B flows. On the other hand, the control valve SV2 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 is connected via a shuttle valve 16 with the control lines for controlling the valves 1 to 4 in connection. The shuttle valve 16 ensures that the respective highest control pressure is applied to the control port of the valve 5. The valve 5 is thereby automatically closed when one of the valves 1 to 4 is opened.

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

Claims (14)

Valve arrangement for a hydraulic control system for controlling a hydraulic consumer (11), having 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 at least two separate valves (1, 2, 3, 4) are used to control the connection of the two consumer ports (A, B) with pressure port (P) and tank port (T), characterized in that the Valve assembly comprises a valve (5) for connection of pressure port (P) and tank port (T). 2. 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. 3. 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) a different valve is used as for connecting the first consumer port (A) to the tank port (T) and / or wherein for connection of the first consumer port (A) with the pressure port (P) another valve is used as for connecting the second consumer port (B) to the pressure port (P) and / or to connect the first consumer port (A) to the tank port (T) is used a different valve than for connecting the second consumer port (B) with the Tank connection (T). 4. Valve arrangement according to one of the preceding claims, wherein for the valves (1, 2, 3, 4) for connecting the load ports (A, B) with pressure port (P) and tank port (T) and / or for the valve (5) 2/2-way valves are used to connect pressure port (P) and tank port (T). 5. Valve arrangement according to one of the preceding claims with a controller, 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. 6. Valve arrangement according to one of the preceding claims, wherein the valves (1, 2, 3, 4) for connecting the load ports (A, B) with pressure port (P) and tank port (T) and / or the valve (5) for connection be hydraulically controlled by pressure port (P) and tank port (T). 7. Valve arrangement according to claim 6, wherein the valves (1, 2, 3, 4) for connecting the load ports (A, B) with pressure port (P) and tank port (T) and / or the valve (5) for connection of pressure port (P) and tank connection (T) are each controlled by a separate valve associated with them (SV1, SV2, SV3, SV4, SV5). 8. Valve arrangement according to claim 6, wherein the valves (1, 2, 3, 4) for connecting the load ports (A, B) with pressure port (P) and tank port (T) and / or the valve (5) for connection of pressure port (P) and tank connection (T) are at least partially controlled together, the control advantageously via two separate valves (SV1, SV2) takes place, which each control a direction of movement of the hydraulic consumer (11). 9. Valve arrangement according to one of claims 6 to 8, wherein the control connection of the valve (5) for connection of pressure port (P) and tank port (T) with one or more control lines for driving the valves (1, 2, 3, 4) for Connection of the consumer connections (A, B) with pressure connection (P) and tank connection (T) is in communication, advantageously via one or more check valves (16). 10. A hydraulic control system or hydraulic system with a valve assembly according to one of the preceding claims. 11. A hydraulic control system or hydraulic system according to claim 10, wherein the valve assembly according to one of the preceding claims is connected in series with a further valve arrangement. 12. Tool with a hydraulic system according to claim 10 or 11, wherein it is advantageously a movable working device. 13. Tool according to claim 12, wherein the hydraulic control system is advantageously used to control a working equipment of the implement, further advantageously for controlling a hydraulic cylinder or a hydraulic motor of the work equipment. 14. 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) opened becomes.