EP1985854B1 - Pump system - Google Patents

Description

The subject invention relates to a pump assembly having two pumps and a suction port and two pressure ports, wherein each of the two pressure ports is connected via a pressure line to a working space of one of the pumps and the pressure lines are connected via an AND valve, wherein by the AND valve respectively a pressure port is connected to the suction port.

In hydraulic circuits, manually operated piston pumps are often used to operate independently of an external source of energy, such as e.g. electric current to generate hydraulic volume flows. This usually happens as a primary energy generation, but also as an emergency operation of electrically operated pumps in case of power failure. The usual use of a single pump requires at least one valve to operate the hydraulic consumers in both directions of movement. However, the execution of the manual operation of this valve is often very expensive, since this is usually located under panels and therefore is not freely accessible.

The well-known actuation of hydraulic consumers in reversing units solves the problem of recycling the flow through an AND valve between the two consumer lines. However, especially in low-leakage mini-hydraulics often arises in such a hydraulic unlocking a problem that the caged pressure degrades only slowly in the lines and thus the And-valve does not switch as desired when reversing the impetus actually immediately. When operating the opposite side, therefore, there is a hydraulic short circuit via the and-valve. Only when the pressure on the primary side has diminished, the secondary side is ready for operation. An example of such a hydraulic circuit can be found in the EP 1 093 994 A2 in which the working chambers of a working cylinder are connected via pressure medium lines and check valves with a reversible pump, whereby the piston of the working cylinder can be moved in both directions depending on the direction of rotation of the pump. The check valves can be hydraulically unlocked via return lines and an and-valve - the unlocking takes place here directly by the acting hydraulic pressures.

It is therefore an object of the subject invention to provide a pump assembly and a method of operating such a pump assembly which allows easy, safe and rapid operation in both directions.

This object is achieved in that two unlockable check valves are provided which are each associated with one of the pumps, wherein a pilot-operated check valve with its blocking side to the pressure port of the other Pump and its opening side is connected to the suction port and for each unlockable check valve for unlocking an actuator is provided which can be activated by the associated pump. By actuating the pilot operated check valve (and thus the pressure reduction) by the pump, a hydraulic short circuit during reversing can be reliably avoided, thereby enabling easy, safe and rapid actuation in both directions.

Particularly advantageous pumps are used as pumps and in particular manually operated piston pumps. In this case, the actuating device is preferably activated by the piston of the piston pump.

Preferably, an actuating device comprises an activating means, which cooperates with the pump, and an unlocking means, which cooperates with a sealing element of the check valve, wherein particularly preferably as a means of activation, a plunger is provided, which projects into the working space of the piston pump and which is movably supported by the piston and the Piston pump is arranged entrainable. Such an arrangement is structurally particularly simple and compact. Alternatively, a sensor or an electrical switch can be provided as activating means.

A particularly simple and compact embodiment is obtained if the same plunger is provided as the activating means and as the unlocking means.

Alternatively, an electro-mechanical release of the check valve or a hydraulic or pneumatic cylinder may be provided as the unlocking.

A further structural simplification and a particularly compact arrangement result when a piston pump and the associated non-return valve are arranged in a common housing.

• Fig. 1 ein Hydraulikschema der gegenständlichen Erfindung,
• Fig. 2 und 3 eine bevorzugte Ausführung einer Betätigungseinrichtung und eines Details davon und
• Fig. 4 eine schematische und allgemeine Darstellung einer Betätigungseinrichtung.

The subject invention will be shown below with reference to the schematic, advantageous embodiments FIGS. 1 to 4 described. It shows

• Fig. 1 a hydraulic scheme of the subject invention,
• Fig. 2 and 3 a preferred embodiment of an actuator and a detail thereof and
• Fig. 4 a schematic and general illustration of an actuator.

In Fig. 1 is a working cylinder 30 with a piston 31 and two working spaces 35, 36 by a pump assembly 1, here a manually operable double piston pump, driven. For this purpose, the work spaces 35, 36 via lines 37 each with a pressure connection A, B of the pump assembly 1 connected. In the lines 37, a controllable check valve 33, 34 is arranged in each case, which are controlled via control lines 38, 39 each from the other pressure port A, B. This makes it possible that the piston 31 of the working cylinder 30 can be moved by applying a working space 35, 36 controlled at a working pressure in both directions. To this end, the pump arrangement 1 sucks in pressure medium via a suction connection S and a suction line 11 from a pressure medium reservoir 32.

The pump assembly 1 can be designed as a double-piston pump with two manually operable piston pumps 2, 3. Of course, any other suitable pump, in particular equivalent and a reversible single pump in question. In order to control the working cylinder 30, one of the two piston pumps 2, 3 is actuated in the illustrated example until the piston 31 has reached the desired position. Such a pump arrangement 1 is therefore particularly suitable as an emergency operation, e.g. for hydraulics of operating tables, suitable.

The working chambers 44 of the two piston pumps 2, 3 are connected via pressure lines 6, 7 with one of the two pressure ports A, B, respectively. In the pressure lines 6, 7 can be arranged between the associated pressure port A, B and the working chamber 44 of the associated piston pump 2, 3 each have a check valve 16, 17. The two pressure lines 6, 7 are connected via an and-valve 10, e.g. a shuttle valve or two-pressure valve, which is arranged here between the pressure ports A, B and the check valves 16, 17 connected. About this and valve 10 via the return line 18 in a known manner, the return of the flow rates from each one of the working spaces 35, 36 of the working cylinder 30 to the pressure medium reservoir 32, here via the suction line 11 and the suction port S, of course, provided a separate return line could be.

The working spaces 44 of the piston pumps 2, 3 thereby suck pressure medium, such as e.g. Hydraulic fluid, via the suction port S and suction lines 11 "in. In the suction lines 11", in the working chambers 44 of the piston pumps 2, 3 and check valves 23, 24 are usually arranged. In the embodiment shown, only one suction port S is provided and the suction lines 11 and return lines 18 all connect to this suction port S. Of course, but also separate suction lines 11, return lines 18 and / or multiple suction ports can be provided.

On the pressure side of the piston pumps 2, 3 may also be arranged a pressure limiting arrangement. In the exemplary embodiment shown, this comprises a connecting line between the two pressure lines 6, 7 in the two non-return valves 21, 22 against each other be arranged directed. Between the two check valves 21, 22 branches off a line to the suction port S, in which a pressure relief valve 20 is arranged. Thus, the working pressure of the pump assembly 1 can be limited upwards. Of course, any other suitable pressure limiting arrangement, eg also an adjustable, can be provided.

In order to prevent a hydraulic short circuit from occurring via the and-valve 10 as a result of the caged-in pressure in one of the pressure lines 6, 7 when the piston 31 of the working cylinder 30 is reversed, a mechanical unlocking via an actuating device 12, 13 is provided according to the invention. Each pressure line 6, 7 is connected via a pressure relief line 8, 9 with the suction port S. In each of the two expansion lines 8, 9, a pilot-operated check valve 4, 5 is arranged, which is associated with one of the two piston pumps 2, 3 respectively. Each unlockable check valve 4, 5 can be unlocked by an actuator 12, 13, which is activated by the associated piston pump 2, 3. The opening side 45 of the check valves 4, 5 is connected via a suction line 11 'respectively to the suction port S and the blocking side 46 via the expansion lines 8, 9 respectively with the pressure line 6, 7 of the other piston pump 2, 3, so that a mutual unlocking realized is. The actuating device 12, 13 is activated by the movement of the piston pump, preferably by the piston 42 of the piston pump 2, 3, as in Fig. 1 indicated and described in detail below.

The following will be briefly with reference to the Fig. 1 the function of the pump assembly 1 according to the invention described. When the piston pump 2 is actuated, eg as a foot pump manually with the foot, the check valve 16 opens in the pressure line 6 and the pilot operated check valve 34 in the line 37 to the working cylinder 30. At the same time, the pressure line 7 of the second piston pump 3 via the and-valve 10 for returning the volume flow from the working chamber 35 of the working cylinder 30 is connected to the suction port S and unlocks the pilot operated check valve 33 of the second conduit 37 via the high pressure in the first conduit 37. The piston 31 thus moves from the expanding working chamber 36 in the direction of the decreasing working space 35. If now the other piston pump 3 is actuated, then the direction is reversed, with both piston pumps 2, 3 of course not being able to be actuated simultaneously. Due to the still caged high pressure in the pressure line 6 but the And valve 10 remains in the previous position, so that the second piston pump 3 remains connected via the And-valve 10 with the suction port S and thus would pump into space (hydraulic short circuit over the And valve 10). A reversal of movement would therefore only be possible if the pressure in the pressure line 6 had decreased (slowly). To prevent this, the unlockable Check valve 5 of the second piston pump 3 during the idle stroke by the actuator 13, which is activated by the piston 42 here at the end of the stroke, unlocked, whereby the pressure line 6 is connected via the check valve 5 to the suction port S and the caged high pressure in the pressure line. 6 is dismantled immediately. The next stroke of the piston pump 3, the and-valve 10 is switched by the now high pressure in the pressure line 7 and the piston 31 can now be moved in the other direction.

As in Fig. 2 shown, the pump assembly 1 is advantageously arranged in a common housing 40, wherein, of course, a separate arrangement in different housings or housing parts is conceivable. In the housing 40 are thus the two piston pumps 2, 3, the and-valve 10, optionally the check valves 16, 17 and 23, 24, the pilot operated check valves 4, 5, optionally a pressure relief device, the lines 6, 7, 8, 9, 18, 11 and the actuators 12, 13 are provided. On the housing 40, the pressure ports A, B and the suction port S are further arranged. The individual components of the pump assembly 1 are in the housing 40 according to the hydraulic scheme of Fig. 1 connected with each other. The working chambers 44 of the piston pumps 2, 3 are here closed by a screw plug 49 through which the pistons 42 are performed. The pistons 42 may be guided in a guide bushing 47. Appropriate seals, for example on the locking screw 49, are of course provided. The pistons 42 can be automatically reset by a return spring 48 after each stroke. The two piston pumps 2, 3 can, as in Fig. 2 to be arranged side by side.

As actuating means 12, 13 for a mechanical unlocking in the illustrated preferred embodiment at the bottom of the working space 44 of a piston pump 2, 3, as activating means 61, a plunger 50 is movably arranged, as in the detailed view in Fig. 3 can be removed. For this purpose, the plunger 50 is arranged here in a housing opening 52 with a close fit in order to achieve a sealing effect. The plunger 50 extends with one end, preferably a few millimeters, into the working chamber 44 of the piston pump 2, 3. The other end of the plunger 50 is the opening side 45 of the check valve 2, 3 and the sealing element 51, here a ball, the pilot-operated check valve 4, 5 faces and is spaced from the sealing element 51. At the side facing away from the working space 44 of the plunger 50 and between the plunger 50 and the sealing element 51 acts here on the suction port S and the suction 11 of the pressure of the pressure medium reservoir 32. During normal operation of the piston pump 2, 3, the plunger 50 (depending on Dimensioning) are pressed by the force acting on the plunger 50 high pressure in the working space 44 in the direction of sealing element 51 and mechanically opens the check valve 4, 5, so that in addition to the return line 18 and a further return of the flow through the pilot operated check valve 4, 5 and the suction line 11 is given to the suction port S and the pressure medium reservoir 32, which of course does not affect the function of the pump assembly 1.

When reversing the plunger 50 is here taken at the end of the first idle stroke (see above) of the piston 42 from the piston 42 and pushed mechanically towards the sealing element 51 and thus unlocks the check valve 4, 5, whereby the locked high pressure in the pressure line 6, 7 can be safely removed via the check valve 4, 5. The plunger 50 is thus simultaneously the unlocking means 62 in this embodiment.

However, it is of course possible to form an actuating device 12, 13 with another suitable activating means 61 and / or unlocking means 62, as generally in Fig. 4 shown. For example, as an activating means 61, an electrical switch could be actuated by the piston 42. It could also be provided as an activating means 61 any inductive, capacitive or other suitable sensor arrangement which provides an activation signal. For example, could be arranged on the piston 42 or other suitable part of a permanent magnet, which cooperates with a fixed Hall sensor, and so activates the actuator 12, 13. The activating means 61 is actuated by the movement of the associated piston pump 2, 3. In principle, any suitable actuator, for example a mechanical adjusting element, an actuator of a linear motor or a hydraulic or pneumatic cylinder is suitable as the unlocking means 62. An electro-mechanical release of the check valve 4, 5 is conceivable. Thus, the sealing element 51 of the check valve 4, 5 could also be moved by an electromagnet. The activation means 61 can be activated at an arbitrary position, for example at the beginning, of the stroke of the piston 42 (eg in order to avoid an idle stroke at the beginning of the reversing). Likewise, the actuator 12, 13 instead of the piston 42 by another component of the piston pump 2, 3, for example, a piston rod 43, are activated.

Likewise, a control device 60, for example a microprocessor or a programmable logic controller, may be provided, which receives the activation signal from the activating means 61 and controls the unlocking of the check valve 4, 5 via the unlocking means 62, as in FIG Fig. 4 indicated by dashed lines.

The other components of the pump assembly 1, such as and-valve 10, optionally the check valves 16, 17 and 23, 24, optionally a pressure relief device and the lines 6, 7, 8, 9, 18, 11, are standard components of the hydraulic, so here it is omitted to describe their realization in detail. Likewise, the design and dimensions of these components and the effective pressures is a standard task for a person skilled in this field, which is why it is also omitted to further explanations.

Claims (12)

1. A pump arrangement with two pumps (2, 3) and a suction connection (S) and two pressure connections (A, B), wherein each of the two pressure connections (A, B) is connected via a pressure line (6, 7) to a working chamber (44) of one of the pumps (2, 3) and the pressure lines (6, 7) are connected via an AND-valve (10), wherein a pressure connection (A, B) is connected in each case by the AND-valve to the suction connection (S), characterised in that two unlockable non-return valves (4, 5) are provided, which are each assigned to one of the pumps (2, 3), wherein an unlockable non-return valve (4, 5) is connected with its locking side (46) to the pressure connection (A, B) of the respective other pump (2, 3) and via its opening side (45) to the suction connection (S), and that an actuation device (12, 13) is provided for each unlockable non-return valve (4, 5) for the purpose of unlocking, said actuation device being able to be activated by the assigned pump (2, 3).
2. The pump arrangement according to claim 1, characterised in that the pump is constituted as a piston pump (2, 3), preferably as a manually actuatable piston pump.
3. The pump arrangement according to claim 2, characterised in that an actuation device (12, 13) can be activated by the piston (42) of the piston pump (2, 3) .
4. The pump arrangement according to claim 1, 2 or 3, characterised in that an actuation device (12, 13) comprises an activation means (61), which cooperates with the pump (2, 3), and an unlocking means (62), which cooperates with a sealing element (51) of the non-return valve (4, 5).
5. The pump arrangement according to claim 4, characterised in that a tappet (50) is provided as an activation means, which tappet projects into the working chamber (44) of the piston pump (2, 3) and which is mounted in a movable manner and disposed so as to be capable of being driven by the piston (42) of the piston pump (2, 3).
6. The pump arrangement according to claim 4, characterised in that a sensor or an electrical switch is provided as an activation means (61).
7. The pump arrangement according to any one of claims 4 to 6, characterised in that a tappet is provided as an unlocking means (62), which tappet projects into the working chamber (44) of the piston pump (2, 3) and which is mounted in a movable manner and disposed so as to be capable of being driven by the piston (42) of the piston pump (2, 3).
8. The pump arrangement according to claim 7, characterised in that the same tappet (50) is provided as an activation means (61) and as an unlocking means (62).
9. The pump arrangement according to any one of claims 4 to 6, characterised in that an electro-mechanical unlocking means (62) is provided, which is provided for the electro-mechanical unlocking of the sealing element (51) of the non-return valve (4, 5).
10. The pump arrangement according to any one of claims 4 to 6, characterised in that a hydraulic or pneumatic cylinder is provided as an unlocking means (62).
11. The pump arrangement according to any one of claims 1 to 10, characterised in that a pump (2, 3) and the associated non-return valve (4, 5) are disposed in a housing (40).
12. The pump arrangement according to any one of claims 1 to 11, characterised in that all the components of the pump arrangement (1) are disposed in a housing (40).

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