Valve unit for a quick-changer and quick-change system

Abstract

The invention relates to a valve unit for the exclusive hydraulic actuation of the locking means of a mechanical quick-changer for attachments of a construction machine, wherein the valve unit comprises a feed pressure connector for applying the feed pressure, a first valve unit outlet for connecting an unlocking pressure line, a second valve unit outlet for connecting a locking pressure line, at least one discharge to the tank, and at least two switchable directional valves, with the feed pressure connector being connected or connectable to the second valve unit outlet via a serial connection of the at least two switchable directional valves.

Claims

1. A valve unit for the exclusive hydraulic actuation of the locking means of a mechanical quick-changer for attachments of a construction machine, wherein the valve unit comprises a feed pressure connector, a first valve unit outlet for connecting an unlocking pressure line, a second valve unit outlet for connecting a locking pressure line, at least one discharge to the tank, and at least two switchable directional valves, with the feed pressure connector being connected or connectable to the first valve unit outlet via a serial connection of the at least two switchable directional valves, and the valve unit comprises an integrated pressure store and/or a separate store connector for an external pressure store, with the internal pressure store and/or the external pressure store connector being connected or connectable to the second valve unit outlet.

2. A valve unit in accordance with claim 1, wherein the second valve unit outlet can only be connected to the feed pressure connector via a directional valve.

3. A valve unit in accordance with claim 1, wherein a pressure-reducing valve is provided at the feed pressure connector.

4. A valve unit in accordance with claim 1, wherein the at least two directional valves are electrically actuable.

5. A valve unit in accordance with claim 4, wherein the at least two directional valves are controllable via two separate control channels.

6. A valve unit in accordance with claim 1, wherein the at least two directional valves are different valve types.

7. A valve unit in accordance with claim 6, wherein the at least two directional valves include a poppet valve and a gate valve.

8. A valve unit in accordance with claim 1, wherein both directional valves are switched in the currentless state such that a connection of the feed pressure connector to the second valve unit outlet is present, both directional valves are in particular preloaded and switch into the second switching position in the currentless state.

9. A valve unit in accordance with claim 1, wherein the valve unit comprises one or more pressure sensors or connectors for external pressure sensors, with pressure sensors or connector points being provided for detecting the system pressure and/or the pressure at the first and/or second valve unit outlets.

10. A quick-change system having at least one quick-change adapter for installing an attachment and having at least one valve unit in accordance with claim 1.

11. A quick-change system in accordance with claim 10, wherein the quick-change adapter comprises a locking means and connectors for a locking pressure line and an unlocking pressure line, with the locking pressure connector being connected to the locking means via at least one check valve.

12. A quick-change system in accordance with claim 11, wherein the locking means include at least one hydraulic cylinder and the check valve is controllable for the release as required of a volume pressure backflow from the locking means.

13. A quick-change system in accordance with claim 12, wherein the check valve is hydraulically controlled with a hydraulic control line connected to the unlocking pressure line.

14. A construction machine having at least one valve unit in accordance with claim 1, wherein the valve unit is integrated in a superstructure of the construction machine.

15. The construction machine in accordance with claim 14, which is a hydraulic excavator.

16. A valve unit for the exclusive hydraulic actuation of the locking means of a mechanical quick-changer for attachments of a construction machine, wherein the valve unit comprises a feed pressure connector, a first valve unit outlet for connecting an unlocking pressure line, a second valve unit outlet for connecting a locking pressure line, at least one discharge to the tank, and at least two switchable directional valves, with the feed pressure connector being connected or connectable to the first valve unit outlet via a serial connection of the at least two switchable directional valves, and a first directional valve comprises two switching states, with the first switching state connecting the feed pressure connector of the valve unit to the second directional valve and the second switching state connecting the feed pressure connector to the second valve unit outlet.

17. A valve unit in accordance with claim 16, wherein the second directional valve comprises two switching states to release the connection of the first directional valve to the first valve unit outlet in a first switching state or to block it in a second switching state, ideally to block it in the direction of flow of the first valve unit outlet, such that a backflow from the first valve unit outlet via the second directional valve, and optionally the first directional valve, into the tank is possible, with the second directional valve preferably being connected to the tank via the first directional valve in the second switching state.

18. A valve unit for the exclusive hydraulic actuation of the locking means of a mechanical quick-changer for attachments of a construction machine, wherein the valve unit comprises a feed pressure connector, a first valve unit outlet for connecting an unlocking pressure line, a second valve unit outlet for connecting a locking pressure line, at least one discharge to the tank, and at least two switchable directional valves, with the feed pressure connector being connected or connectable to the first valve unit outlet via a serial connection of the at least two switchable directional valves, and a pressure shut-off valve is connected between the first directional valve and the second valve unit outlet and blocks the flow from the first directional valve to the second valve unit outlet when the pressure level at the second valve unit outlet exceeds a limit pressure, with the limit pressure preferably being able to be defined by the pressure at the second valve unit outlet and/or an adjustable pressure portion.

19. A valve unit for the exclusive hydraulic actuation of the locking means of a mechanical quick-changer for attachments of a construction machine, wherein the valve unit comprises a feed pressure connector, a first valve unit outlet for connecting an unlocking pressure line, a second valve unit outlet for connecting a locking pressure line, at least one discharge to the tank, and at least two switchable directional valves, with the feed pressure connector being connected or connectable to the first valve unit outlet via a serial connection of the at least two switchable directional valves, and the pressure shut-off valve opens the flow from the first directional valve to the second valve unit outlet when the pressure level at the first valve unit outlet exceeds a limit pressure, with the limit pressure preferably being able to be defined by the pressure at the first valve unit outlet and/or an adjustable pressure portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and properties of the invention will be explained in detail in the following with reference to an embodiment shown in the drawing. There are shown:

(2) FIG. 1: a hydraulic control of a quick-change adapter in accordance with the prior art; and

(3) FIG. 2: a hydraulic circuit diagram of the valve unit in accordance with the invention with a connected quick-change adapter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) The conventional design of a quick-change adapter or of the hydraulic circuit required for it in accordance with FIG. 1 was explained in detail at the beginning during the discussion of the prior art.

(5) FIG. 2 shows a hydraulic circuit diagram of the valve unit 10 in accordance with the invention. The valve unit 10 comprises a feed pressure inlet P as well as the two valve unit outlets A, B to which a likewise modified quick-change adapter can be connected. The valve unit 10 is only configured for the control and pressure supply of the quick-change adapter; for safety reasons, no further consumers should be controlled or fed by the valve unit 10.

(6) A restrictor 11 is provided at the inlet side in combination with the pressure-reducing valve 12 to be able to connect the valve unit 10 directly to the system pressure P of the construction machine. The system pressure P of the construction machine can thereby be restricted and regulated to the system pressure M within the valve unit 10 required for the operation of the quick-change adapter. The pressure-reducing valve 12 in particular allows a variable setting of the system pressure M.

(7) The valve unit outlet A serves the connection of an unlocking pressure line of the quick-change adapter, while the valve unit outlet B is intended for the connection of the locking pressure line. The constructionally simplified quick-change adapter is connected to these two connector points A, B and is made up of a hydraulic cylinder 30 for actuating a locking means and of the check valve 31. The unlocking pressure line A is connected to the rod side of the cylinder 30, while the locking pressure line B is connected to the base side. The check valve 31 in its normal position provides that no hydraulic medium can escape from the cylinder 30 at the rod side as long as no corresponding control command for the valve opening is applied at the check valve 31. The control of the check valve 31 takes place hydraulically in that a branch of the unlocking pressure line A is used as the control pressure. The connection of the valve unit in accordance with the invention can also take place in the reverse order.

(8) To achieve a certain redundancy or diversity in the hydraulic control of the quick-change adapter, the valve unit 10 is equipped with two directional valves 13, 14 which are electrically actuable via separate control channels. The first valve 13 is a 4/2-way directional valve and is connected at the inlet side to the outlet of the pressure-reducing valve 12, i.e. the system pressure M is applied to the inlet of the valve 13. The two switching states a, b of the directional valve 13 allow a connection of the system pressure M either to the valve inlet of the second directional valve 14 and thus indirectly to the unlocking pressure line A (switching state a) or alternatively to the valve unit outlet B for attaching to the locking pressure line (switching state b). The second directional valve which is designed as a 2/2-way directional valve therefore comprises two switching states a, b, with the outlet of the directional valve 13 being connected to the valve unit outlet A in a switching state a. In the second switching state b, the valve 14 only blocks the volume flow from the valve 13 to the valve unit outlet A; a backflow from the valve unit outlet A to the valve 13 is released, however.

(9) Both directional valves 13, 14 comprise a pilot valve having an electromagnetic actuation against spring pre-load so that if the electromagnet is not actuated both directional valves 13 14, remain, as shown in FIG. 2, in the second switching position b, b or are switched into this state. In this valve state, the system pressure M is applied to the valve unit outlet B for the locking pressure line to ensure a sufficient pressure level for the maintenance of the locking position of the hydraulic cylinder 30. In this state, the unlocking pressure line A is connected to the directional valve 13 via the directional valve 14, with the directional valve 13 ensuring a backflow of the unlocking pressure line A into the hydraulic tank T. It is thus sufficient for the locking actuation of the quick-change adapter to switch the directional valve 13 into the second switching state b.

(10) The system pressure M is also applied to the directional valve 14 in the first switching state a of the first directional valve 13. If the directional valve 14 is likewise in the first switching state a, the system pressure M is applied via both directional valves 13, 14 at the valve unit outlet A for the unlocking pressure and the quick-change adapter is unlocked by a pressurization of the ring chamber of the hydraulic cylinder 30.

(11) For technical safety reasons, a pressure shut-off valve 15 is additionally integrated between the directional valve 13 and the outlet of the locking pressure line B and interrupts the connection between the directional valve 13 and the outlet B if the pressure level of the locking pressure line B exceeds a specific limit value. In this case, the pressure of the locking pressure line B in conjunction with the adjustable pre-load of the spring of the pressure shut-off valve 15 serves as the limit value.

(12) Otherwise the flow from the directional valve 13 to the outlet B should be opened by the pressure shut-off valve 15 when the pressure level at the first valve unit outlet A exceeds a limit value. This is also necessary in order not to cause any pressure buildup when an unlocking is initiated. In this constellation, the pressure shut-off valve 15 acts redundantly with respect to the check valve 31 of the quick-change adapter.

(13) In addition, the valve unit 10 can comprise a pressure store 20 in order, on a failure of the hydraulic pump 1, to be able to compensate the drop thereby caused in the system pressure M so that the hydraulic cylinder 30 remains in the locked position. Possible pressure sensors 21, 22, 23 or measurement points can be integrated in the valve unit 10 for monitoring purposes, for instance, e.g. in the region of the system pressure M and also in the region of the unlocking pressure line A and the locking pressure line B.

(14) With respect to the design of the quick-change system in accordance with FIG. 1, the two valves 2, 3 shown there in the quick-change adapter can be dispensed with and only a check valve 31 can be attached to the locking pressure line B. For this purpose, the valve unit 10 is transposed in the superstructure of the construction machine, whereby more advantages arise with respect to the locking security and universal function of the quick-change adapter.

(15) The control valves 13, 14 used in the proposed valve unit 10 are configured as a gate valve (valve 13) and as a poppet valve (valve 14). A diversity in the valve arrangement results due to the different construction type and to the control of the two valves 13, 14 via separate channels. A simultaneous failure or a simultaneous malfunction of both valves 13, 14 as a result of a common cause (design error, etc.) is thereby precluded.

(16) These valves 13, 14 connected in series are furthermore designed such that when the quick-changer is locked, the pressure medium can only be sufficiently controlled with the aid of the valve 13. On the unlocking, in contrast, both valves 13, 14 have to be moved into the position required for this purpose, i.e. into the first switching position a, a. After the locking of the quick-change adapter, the valve 13 remains in the second switching position b, whereby the pressurization on the locking side (base side) of the cylinder 30 is still maintained and an unlocking can therefore not take place, not even if the valve 14 should stick in switching position a (unlock) or if it is jammed in this switching position. The locking system of the quick-change system is thus not only diverse, but also redundant.

(17) The locking redundancy in this respect results in this regard both from the interconnection of the control valves 13, 14 and from the positioning of the pressure restriction vale 15 which acts redundantly with respect to the check valve 31. The system is additionally still failsafe due to the fact that the system automatically switches into the safe state (locked) in the event of a defect. This is e.g. the case when a problem arises in the electrical system. In this case, the switching valves 13 and 14 would be switched into the currentless states (second switching positions b, b) due to the pre-load and the safe state (locked) would automatically be brought about.

(18) In summary, the disclosed valve arrangement 10 allows a redundant, diverse and also accident-proof interconnection of the quick-change adapter.