DE102022203102A1 - Low-pressure unit for raising a pressure level in a hydraulic drive and system consisting of a low-pressure unit and a hydraulic drive - Google Patents

Abstract

The invention relates to a low-pressure unit (1) for raising a pressure level in a hydraulic drive (8). The low-pressure unit (1) has a tank pressure accumulator (2) for storing a hydraulic fluid with a desired pressure, a low-pressure accumulator (3) downstream of the tank pressure accumulator (2) for temporarily storing the fluid, and a hydraulic pump (4) driven by a motor (5). on. According to the invention, the tank pressure accumulator (2), the low-pressure accumulator (3) and the pump (4) are hydraulically coupled to one another via a connecting block (6), and the connecting block block (6) is designed such that the low-pressure unit (1) is connected via the connecting block (6 ) can be integrated or connected directly into/on a main control block of the hydraulic drive (8) or is integrated or connected into/on this.

Description

The invention relates to a low-pressure unit for raising a pressure level in a hydraulic drive according to the preamble of patent claim 1 and a system consisting of a low-pressure unit and a hydraulic drive according to the preamble of patent claim 8.

In conventional hydraulic drives, in order to raise/adjust a pressure level in a hydraulic drive, an additional external or separate unit is connected, which supplies a hydraulic fluid, in particular oil, with a correspondingly desired pressure level to the hydraulic drive. The use of an external unit requires the use of piping or tubing as a connecting element between the hydraulic drive and the separate unit for supplying the hydraulic fluid, which takes up additional space and thus reduces the compactness of the hydraulic drive. In addition, the pipe or hose connection represents an additional maintenance factor, as a constant, problem-free supply of fluid with the desired pressure level to the hydraulic drive must be ensured.

In contrast, the present invention is based on the object of providing a low-pressure unit for raising a pressure level in a hydraulic drive / servo-hydraulic axis, which eliminates the need for an additional external unit and the hoses / piping required as a result. Furthermore, a system consisting of a hydraulic drive and the low-pressure unit according to the invention is to be created, the pressure level of which is adjusted without an external unit.

The first task is solved by a low-pressure unit with the features of patent claim 1 and the second by a system with the features of patent claim 8. Advantageous refinements and developments of the respective invention are the subject of the subclaims.

The invention relates to a low-pressure unit for raising a pressure level in a hydraulic drive. The low-pressure unit has a tank pressure accumulator for storing a hydraulic fluid with a desired pressure, a low-pressure accumulator downstream of the tank pressure accumulator for temporarily storing the fluid, and a hydraulic pump driven by a motor. The tank pressure accumulator, the low-pressure accumulator and the pump are hydraulically coupled to one another via a connection block and the connection block is designed in such a way that the low-pressure unit can be integrated directly into/on a main control block of the hydraulic drive via the connection block or can be connected to it integrated or connected.

In other words, a hydraulic fluid is stored in a tank pressure accumulator, which can be transported using a motor-driven hydraulic pump into a low-pressure accumulator, in which the fluid is then temporarily stored. The low-pressure unit consisting of the tank pressure accumulator, the low-pressure accumulator and the pump has a further connection block/coupling block to which the above-mentioned components are connected/connected. Furthermore, the components are hydraulically coupled/connected to one another via this connection block, that is, the hydraulic fluid flows via the connection block between the tank pressure accumulator, low-pressure accumulator and pump components. The connecting block can be connected to a hydraulic drive or integrated/installed directly into it.

This low-pressure unit with a tank pressure accumulator, a low-pressure accumulator and a pump, which are hydraulically coupled to one another using a connecting block that can be connected to a hydraulic drive, enables a compact arrangement of the components for increasing the pressure level within the hydraulic drive. Through direct integration or a direct connection/connection of the entire low-pressure unit into/to the hydraulic drive, an external unit for pressure level adjustment and additional hoses or pipes for connecting an external unit to the hydraulic drive are no longer necessary. Ultimately, installation space, effort and costs can be saved.

In a further aspect of the invention, the connecting block of the low-pressure unit has a flange surface with hydraulic interfaces for connecting the low-pressure unit to the hydraulic drive, in particular to the main control block of the hydraulic drive.

In other words, a surface of the connection block, via which the tank pressure accumulator, low-pressure accumulator and pump components are connected to one another, is designed as a flange surface/connecting surface/coupling surface. This flange surface has hydraulic interfaces/connections that represent outputs and inputs of the hydraulic circuit of the low-pressure unit. A connection of the low-pressure unit to the hydraulic drive, in particular to the main control block of the hydraulic drive, takes place via the interfaces of the flange surface, whereby the hydraulic (pressure) circuit / low-pressure circuit of the low-pressure unit is connected to the hydraulic (pressure) circuit of the hydraulic drive. Due to the direct/immediate connection via the interfaces on the flange surface of the low-pressure unit, additional hose or pipe connections are no longer necessary.

In a further aspect of the invention, the low-pressure unit has a plurality of (switching) valves, preferably in the form of solenoid valves, via the positions of which the low-pressure unit can be switched between operation as a closed system in which the pump supplies fluid/pressure medium at a desired pressure level conveyed from the tank pressure accumulator into the low-pressure accumulator, and can be switched to operation as an open system in which the pump conveys fluid from an externally connected tank into the low-pressure accumulator.

In other words, the low pressure unit can be operated as a closed system or as an open system. When operating as a closed system, the respective switching valves in the low-pressure unit are switched in such a way that the pressure medium is conveyed or can be conveyed from the tank pressure accumulator into the low-pressure accumulator via the pump driven by the motor. In an alternative operation of the low-pressure unit as an open system, the pressure medium is conveyed from an externally connected tank via the pump into the low-pressure reservoir of the low-pressure unit. The externally connected tank of the open system therefore replaces the tank pressure accumulator of the closed system.

For example, the tank pressure accumulator can be disconnected from the circuit (during operation) for any maintenance work/service activities and replaced by the external tank for a certain period of time. After the service work has been completed, the tank pressure accumulator can be switched on again, which decouples the external tank again. This advantageously ensures easier servicing compared to permanently closed systems. Switching between the closed and the open system can be implemented using a variety of valves. This switchover is preferably possible during operation of the low-pressure unit, that is, the switching processes between closed and open system operation or the (de)coupling of the tank pressure accumulator or the external tank are possible without switching off the system (the pump). Furthermore, the predominantly closed operation of the low-pressure unit makes it more difficult for the fluid/oil used as pressure medium to oxidize and also makes it more difficult for dirt (particles) to enter.

In a further preferred aspect of the invention, the low-pressure unit has a check valve which prevents the fluid from flowing back from the low-pressure accumulator to the pump.

In other words, a check valve, which is preferably located directly upstream of the low-pressure accumulator, ensures that the pressure medium conveyed by the pump does not flow back to it, thereby ensuring efficient transport of the fluid to the low-pressure accumulator.

In a further preferred aspect of the invention, the low-pressure unit has a controller, preferably designed as a two-point controller, which switches off the pump after reaching the desired pressure level in the hydraulic drive and / or switches on the pump when the pressure falls below a predetermined pressure level.

In other words, the pump of the low-pressure unit is preferably switched on and operated by the motor if the pressure level in the hydraulic drive falls below or falls below a certain value and is driven until a desired value of the pressure level is established. The pump remains switched off until the pressure level drops below the predetermined value again. As a result, the low-pressure unit is only operated as long as an adjustment of the pressure level is necessary, thereby saving energy. Furthermore, a more efficient and finer adjustment of the pressure level in the hydraulic drive is made possible.

In a further advantageous aspect of the invention, depending on the position of the plurality of valves, the tank pressure accumulator can be filled with fluid from the externally connected tank or the tank pressure accumulator and the low-pressure accumulator release fluid to the external tank or fluid from the tank pressure accumulator and the low-pressure accumulator is from can be accommodated in the externally connected tank.

Accordingly, by appropriately actuating/switching the valves, it is not only possible to switch between open and closed operation of the low-pressure unit, but also to empty the low-pressure accumulator and the tank pressure accumulator into the externally connected tank or to charge/store/feed the tank pressure accumulator with the Fluid from the external tank, depending on which function is desired. A reload of tank pressure memory is particularly necessary if the pressure of the pressure medium/fluid in the closed hydraulic (pressure) circuit has dropped (over time) or is too low. This advantageous embodiment of the low-pressure unit enables the pressure medium to be emptied/charged or replaced using the externally connected tank without the additional effort of stopping operations or through corresponding maintenance steps, since these steps can easily be initiated, preferably also during operation, only by switching the corresponding valves are.

In a further advantageous aspect of the invention, the low-pressure unit has an additional cooling unit and/or a filter unit and, depending on the position of the valves, is between operation as the closed system, in which the pump conveys fluid at a desired pressure level from the tank pressure accumulator into the low-pressure accumulator , and operation with a closed cooling circuit and/or a closed filter circuit consisting of the low-pressure accumulator, the pump and the cooling unit and/or the filter unit can be switched.

In other words, the advantageous embodiment of the low-pressure unit has a cooling unit/plate heat exchanger/cooler and/or filter unit that is connected to/is connected to the (pressure) circuit of the low-pressure unit. By appropriately switching the large number of valves, it is possible to create a closed cooling circuit and/or filter circuit via the (low-pressure) pump, with the help of which the fluid of the low-pressure circuit is cooled and/or filtered. If the low pressure in the system is too low, the cooling circuit and/or filter circuit is interrupted or decoupled and the low-pressure accumulator is filled again to its corresponding pressure level. Preferably, activating or deactivating the cooling circuit and/or filter circuit is possible during operation of the low-pressure unit. This means that no additional step of switching off or changing the corresponding components is necessary.

Since the low-pressure unit and thus also the cooling circuit or filter circuit integrated therein are, according to the invention, integrated/connected directly into/to the hydraulic drive or the servo-hydraulic axis, the fluid of the closed low-pressure circuit also cools the main control block of the hydraulic drive during operation of the cooling circuit. The cooled or filtered fluid can also be distributed in the axle by suction from the low-pressure circuit.

The invention further relates to a system consisting of a hydraulic drive and a low-pressure unit, in which the low-pressure unit is connected/integrated directly to/into a main control block of the hydraulic drive.

• 1 eine beispielhafte isometrische Vorderansicht einer Niederdruckeinheit, gemäß einem vorteilhaften Ausführungsbeispiel,
• 2 eine beispielhafte isometrische Rückenansicht der Niederdruckeinheit, gemäß dem vorteilhaften Ausführungsbeispiel aus 1,
• 3 einen hydraulischen Schaltplan der an einen hydraulischen Antrieb angeschlossenen Niederdruckeinheit gemäß einer vorteilhaften Ausführungsform und den Druckmittelstrom bei einem Betrieb als geschlossenes System,
• 4 einen hydraulischen Schaltplan der in 3 gezeigten Ausführungsform der Niederdruckeinheit und den Druckmittelstrom bei einem Betrieb als offenes System,
• 5 einen hydraulischen Schaltplan der in 3 und 4 gezeigten Ausführungsform der Niederdruckeinheit, und den Druckmittelstrom bei einem Befüllen des Tankdruckspeichers mit Fluid aus einem externen Tank,
• 6 einen hydraulischen Schaltplan der in den 3 bis 5 gezeigten Ausführungsform der Niederdruckeinheit und den Druckmittelstrom bei einem Entleeren des Tankdruckspeichers und des Niederdruckspeichers in den externen Tank,
• 7 einen hydraulischen Schaltplan der in den 3 bis 6 gezeigten Ausführungsform der Niederdruckeinheit mit einer zusätzlich angeschlossenen Kühleinheit und den Druckmittelstrom bei einem Betrieb eines integrierten Kühlkreislaufes.

The invention will now be explained in more detail using advantageous embodiments and with reference to the associated figures. The figures are only of a schematic nature and serve exclusively to understand the invention. It should be noted that the features of the individual embodiments are interchangeable with one another and can occur in any combination. Show it:

• 1 an exemplary isometric front view of a low-pressure unit, according to an advantageous embodiment,
• 2 an exemplary isometric rear view of the low-pressure unit, according to the advantageous exemplary embodiment 1 ,
• 3 a hydraulic circuit diagram of the low-pressure unit connected to a hydraulic drive according to an advantageous embodiment and the pressure medium flow when operating as a closed system,
• 4 a hydraulic circuit diagram of the in 3 shown embodiment of the low pressure unit and the pressure medium flow when operating as an open system,
• 5 a hydraulic circuit diagram of the in 3 and 4 shown embodiment of the low pressure unit, and the pressure medium flow when filling the tank pressure accumulator with fluid from an external tank,
• 6 a hydraulic circuit diagram in the 3 until 5 shown embodiment of the low pressure unit and the pressure medium flow when emptying the tank pressure accumulator and the low pressure accumulator into the external tank,
• 7 a hydraulic circuit diagram in the 3 until 6 shown embodiment of the low-pressure unit with an additionally connected cooling unit and the pressure medium flow when operating an integrated cooling circuit.

The present invention and the advantageous embodiment are described below with reference to the figures.

1 shows an exemplary isometric front view of the low-pressure unit 1 according to the invention, according to an advantageous exemplary embodiment. The low-pressure unit 1 has a tank pressure accumulator 2 and a low-pressure accumulator 3 on. The pressure medium stored in the tank pressure accumulator 2 is conveyed from the tank pressure accumulator by a pump 4 driven by a motor 5 and fed into the pressure circuit connected to it, in particular into the low-pressure accumulator 3 and temporarily stored in it. The components tank pressure accumulator 2, low-pressure accumulator 3 and pump 4 are hydraulically coupled or firmly connected to one another via a connection block 6, which is preferably cuboid-shaped here, whereby the hydraulic low-pressure circuit is formed.

2 shows the isometric back view of the in 1 shown low-pressure unit 1. In this view, a flange surface 7 can essentially be seen as a direct connection surface/contact surface with a hydraulic drive, preferably with a main control block of the hydraulic drive 8. A large number of interfaces are arranged on/on the flange surface 7, which are designed to connect the low-pressure circuit of the low-pressure unit 1 directly to the pressure circuit of the hydraulic drive 8.

3 shows a hydraulic circuit diagram of the low-pressure unit 1, which is directly connected to the hydraulic drive 8, according to an advantageous embodiment and the pressure medium flow when the low-pressure unit 1 is operated as a closed system. The low-pressure unit 1 has a tank pressure accumulator 2 for storing a fluid at a desired pressure. The pump 4 driven by the motor 5 pumps fluid from the tank pressure accumulator via open switching valves 9, 10 into the downstream low-pressure accumulator 3. When operating as a closed system, the further switching valves 11 and 12 are in the blocked state, so that an externally connected tank 13 is separated from the Low pressure circuit is decoupled and the fluid flows in the closed system. In this operation, as a closed system, a (spring-loaded) check valve 14 prevents the fluid from flowing back from the low-pressure accumulator 3 towards the pump 4. Furthermore, the low-pressure unit 1 has further (spring-loaded) check valves 15, 16 and the check valve 17, through which a possible leakage flow the pump 4 is discharged, preferably adjustable pressure relief valves 18, 19 and a pressure measuring device 20.

4 shows the hydraulic circuit diagram of the in 3 shown embodiment of the low-pressure unit 1 and the pressure medium flow when the low-pressure unit 1 is operated as an open system. All in the 3 The components of the low-pressure unit 1 shown are also shown in this figure. In this operation as an open system, the switching valves 9, 10 are still in the open position and the switching valve 12 is still in the blocked state. However, the switching valve 11 is now in the open position, whereby the pump 4 draws fluid from the external tank 13 and pumps it into the low-pressure tank 3. During this open operation of the low-pressure unit 1, service activities on the tank pressure accumulator 2 are possible without interrupting operation, since the tank pressure accumulator 2 is disconnected or decoupled from the low-pressure circuit in the open system. A leakage flow, which flows from a pump (not shown) of the hydraulic drive 8, can flow to the pump 4 via the open switching valves 9 and 10.

5 shows a hydraulic circuit diagram in the 3 and 4 shown embodiment of the low pressure unit 1, and the pressure medium flow when filling the tank pressure accumulator 2 with fluid from the external tank 13. The low pressure unit 1 can be switched during operation in such a way that the tank pressure accumulator 2 can be filled with new fluid / pressure medium from the externally connected tank 13 , if the pressure of the fluid in the tank pressure accumulator 2 is too low. Here, the switching valves 9, 11 and 12 are in an open state, whereas the switching valve 10 is blocked. Due to the open position of the switching valve 12, the hydraulic flow path between the external tank 13 and the tank pressure accumulator 2 is opened, whereby the pump 4 can pump fluid from the external tank 13 into the tank pressure accumulator 2.

6 shows a hydraulic circuit diagram in the 3 until 5 shown embodiment of the low-pressure unit 1 and the pressure medium flow when emptying the tank pressure accumulator 2 and the low-pressure accumulator 3 into the external tank 13. In order to drain / empty fluid with a possibly too low pressure from the low-pressure unit 1, in particular from the tank pressure accumulator 2 and from the low-pressure accumulator 3 , all switching valves 9, 10, 11 and 12 are open in open operation of the low-pressure unit 1, i.e. operation with the externally coupled tank 13. At the same time, fluid can be emptied from the tank pressure accumulator 2 and the low-pressure accumulator 3 into the external tank 13.

7 shows a hydraulic circuit diagram in the 3 until 6 shown embodiment of the low-pressure unit 1 with an additional cooling unit 21, which is connected to the low-pressure circuit, here downstream of the pump 4, as well as the pressure medium flow during operation of the integrated cooling circuit. The cooling circuit shown is integrated in the low-pressure unit 1 and also runs through the connected hydraulic drive 8. About the positions of the Switching valves 9 to 12 allow the cooling circuit to be switched on or decoupled in the closed system, ie the external tank 13 is decoupled during cooling. Compared to the operation of the low-pressure unit 1 as a closed system (see illustration in 3 ), the switching valve 9 is opened in a second position, which releases a fluid flow between the pump 4 and the integrated cooling circuit of the low-pressure unit 1. The positions of the remaining switching valves 10 to 12 do not differ from their respective positions in normal closed operation 3 .

Reference symbol list

1

Low pressure unit

2

Tank pressure accumulator

3

Low pressure accumulator

4

pump

5

engine

6

Connection block

7

flange surface

8th

hydraulic drive

9, 10, 11, 12

(switching) valve

13

external tank

14, 15, 16, 17

check valve

18, 19

Pressure relief valve

20

Pressure gauge

21

Cooling unit

Claims (8)

Low-pressure unit (1) for raising a pressure level in a hydraulic drive (8), with a tank pressure accumulator (2) for storing a hydraulic fluid with a desired pressure, a low-pressure accumulator (3) downstream of the tank pressure accumulator (2) for temporarily storing the fluid and with a hydraulic pump (4) driven by a motor (5), characterized in that the tank pressure accumulator (2), the low-pressure accumulator (3) and the pump (4) are hydraulically coupled to one another via a connecting block (6), the connecting block block (6 ) is designed such that the low-pressure unit (1) can be integrated directly into/to a main control block of the hydraulic drive (8) via the connecting block (6) or can be connected to it. Low pressure unit (1). Claim 1 , characterized in that the connecting block (6) has a flange surface (7) with hydraulic interfaces for connecting the low-pressure unit (1) to the hydraulic drive (8). Low pressure unit (1). Claim 1 or 2 , characterized in that the low-pressure unit (1) has a plurality of valves (9, 10, 11, 12), via the positions of which the low-pressure unit (1) switches between operation as a closed system in which the pump (4) supplies fluid a desired pressure level from the tank pressure accumulator (2) into the low-pressure accumulator (3), and operation as an open system in which the pump (4) conveys fluid from an externally connected tank (13) into the low-pressure accumulator (3). is. Low pressure unit (1). Claim 3 , characterized by a check valve (14), which prevents the fluid from flowing back from the low-pressure accumulator (3) to the pump (4). Low pressure unit (1). Claim 3 or Claim 4 , characterized by a two-point controller, which switches off the pump (4) after reaching the desired pressure level in the hydraulic drive (8) and / or switches on the pump (4) when the pressure falls below a predetermined pressure level. Low pressure unit (1) according to one of the Claims 3 until 5 , characterized in that , depending on the position of the valves (9, 10, 11, 12), the tank pressure accumulator (2) can be filled with fluid from the external tank (13) or the tank pressure accumulator (2) and the low-pressure accumulator (3) can supply fluid the external tank (13). Low pressure unit (1) according to one of the Claims 3 until 6 , characterized in that the low-pressure unit (1) has a cooling unit (21) and/or a filter unit and, depending on the position of the valves (9, 10, 11, 12), between operation as the closed system in which the pump (4 ) Fluid is conveyed at a desired pressure level from the tank pressure accumulator (2) into the low-pressure accumulator (4), and operation with a closed cooling circuit and/or a closed filter circuit consisting of the low-pressure accumulator (3), the pump (4) and the cooling unit (21 ) and/or the filter unit can be switched. System consisting of a hydraulic drive (8) and a low-pressure unit (1), preferably according to one of the preceding claims, in which the low-pressure unit (1) is connected/integrated directly to/into a main control block of the hydraulic drive (8).

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