CN108302222B

CN108302222B - Valve assembly for dual circuit-summation (Summiruding)

Info

Publication number: CN108302222B
Application number: CN201810027007.0A
Authority: CN
Inventors: T.魏克特
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-01-12
Filing date: 2018-01-11
Publication date: 2020-06-16
Anticipated expiration: 2038-01-11
Also published as: CN108302222A; DE102017200418A1

Abstract

The invention relates to a valve assembly for use in a hydraulic drive system having two hydraulic circuits. According to the invention, a first fluid flow path (20) is formed in a first position (41) of the first control slide (11), which extends from a first pump port (P1) through a first throttle (22) to a second pump port (P2), wherein the first pump port (P1) is fluidically connected to a first control chamber (21), wherein a first control port (LS 1) is fluidically connected to a second control chamber (31).

Description

Valve assembly for dual circuit-summation (Summiruding)

Technical Field

The invention relates to a valve assembly for use in a hydraulic drive system having two hydraulic circuits.

Background

Such hydraulic drive systems are known, for example, from DE 102006053897 a1 and DE 102011111416 a 1. Each of the two hydraulic circuits has a pump, which supplies pressure fluid in parallel to a plurality of associated actuators. A pressure balance is assigned to each actuator, so that the movement speed of the actuator can be set substantially independently of an external load. The two hydraulic circuits are connected to each other by a valve device in such a way that the pump of one hydraulic circuit can also supply pressure fluid to the actuator of the other hydraulic circuit. The valve device mentioned can comprise a pressure balance for enabling a load-independent adjustment of the hydraulic drive system.

Disclosure of Invention

The valve assembly according to the invention has the advantage that it is particularly simple to construct. It is particularly compact in design, wherein it can be integrated into conventional valve bodies with little effort. In particular, simple channel guidance can be realized in the valve body, which requires few bores. It is possible to dispense entirely with external fluid lines which are used only for the valve arrangement according to the invention.

A valve assembly is proposed, having a housing and a first and a second control slide valve, wherein the first control slide valve is received in the interior of the housing in a movable manner in the direction of a longitudinal axis, wherein the second control slide valve is received in the interior of the first control slide valve in a movable manner in the direction of the longitudinal axis, wherein the first control slide valve defines, together with the second control slide valve, a first and a second control chamber whose volumes can be adjusted opposite one another by a movement of the second control slide valve relative to the first control slide valve, wherein the first control slide valve and the second control slide valve together form a first and a second throttle, which can be adjusted jointly by a movement of the second control slide valve relative to the first control slide valve, wherein the valve assembly has a first and a second pump connection and a first and a second control connection, wherein the first control slide is able to assume a first, a second and a third position relative to the housing, wherein the third position is arranged between the first and the second position, wherein the first position of the first control slide forms a first fluid flow path which extends past the first throttle means to the second pump connection starting from the first pump connection, wherein in the first mentioned position the first pump connection is fluidically connected to the first control chamber, wherein the first control connection is fluidically connected to the second control chamber. The second control slide thus forms the pressure balance explained above. The first control slide forms a directional valve in order to be able to establish the desired connection between the mentioned interface and the pressure compensator. The valve assembly is provided for use with a pressure fluid, which is preferably a liquid and at most preferably hydraulic oil. The fluid connections to the first and to the second control chamber are preferably configured to be switchable. In the case of the use of the first control slide, at most the corresponding changeover is preferably effected.

In an intermediate position of the second control slide valve, it can be provided that both the first and the second throttle are blocked, wherein in a movement of the second control slide valve, in which movement the first control chamber expands, only the first throttle is opened, and wherein in a movement of the second control slide valve, in which movement the second control chamber expands, only the second throttle is opened. The second control slide forms with the first throttle element a pressure balance which is active if pressurized fluid is to be supplied from the first pump connection to the second pump connection. The second control slide forms with the second throttle device a pressure balance which is active if pressurized fluid is to be supplied from the second pump connection to the first pump connection. The very complex directional valve provided in DE 102011111416 a1 is therefore no longer necessary. At the same time, the second control slide valve causes: fluid flow in a direction opposite to the desired flow direction is not possible.

Provision can be made for the second control port to be locked in the first position of the first control slide. In particular, the fluid connection between the second control port and the first pump port is thereby interrupted. This can interfere with the function of the second hydraulic circuit, the highest load pressure of which is preferably applied to the second control interface.

It can be provided that the second position of the first control slide forms a second fluid flow path which extends from the second pump connection via the second throttle to the first pump connection, wherein in the second position mentioned the second pump connection is fluidically connected to the second control chamber, wherein the second control connection is fluidically connected to the first control chamber. Thereby, pressure fluid can be delivered from the second pump connection to the first pump connection. In this case, the second throttle element assumes the function of the pressure compensator.

Provision can be made for the first control port to be locked in the second position of the first control slide. In particular, this interrupts the fluid connection between the first control connection and the second pump connection, which would interfere with the function of the first hydraulic circuit, the highest load pressure of which is preferably applied to the first control connection.

It can be provided that the first pump connection can be connected to the second control connection via a first check valve, wherein the first check valve allows only a fluid flow from the first pump connection to the second control connection. The pressure at the first pump connection can thus be taken into account when determining the highest load pressure for the pressure regulation of the pump in the second hydraulic circuit. This preferably only takes place if pressure fluid is to be supplied from the second pump connection to the first pump connection. The aforementioned connection is preferably only present in the second position of the first control slide valve.

It can be provided that the second pump connection can be connected to the first control connection via a second check valve, wherein the second check valve allows only a fluid flow from the second pump connection to the first control connection. In this way, the pressure at the second pump connection can be taken into account when determining the highest load pressure for the pressure regulation of the pump in the first hydraulic circuit. This preferably only takes place if pressure fluid is to be supplied from the first pump connection to the second pump connection. The aforementioned connection is preferably present only in the first position of the first control slide valve.

Provision can be made for the first and second pump connections to be locked in the third position of the first control slide. Thereby interrupting fluid exchange between the first and second pump interfaces without depending on the position of the second control spool valve.

Provision can be made for the first and second control ports to be locked in the third position of the first control slide. In this way, the mutual influencing of the pressure regulation in the first and in the second hydraulic circuit is interrupted if no pressure fluid is to be exchanged between the circuits mentioned.

It can be provided that the second control slide is force-loaded in the direction of its neutral position by means of at least one spring. The pretension of the at least one spring mentioned is preferably so low that it does not substantially influence the hydraulic function of the valve assembly. This is achieved thereby: the second control slide valve is in the neutral position in the third position of the first control slide valve. The pressure regulating function of the second control slide valve is thus started as soon as possible after the first control slide valve has moved into the first or second position.

It goes without saying that the features mentioned above and yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone without leaving the scope of the invention.

Drawings

The invention is explained in detail below with the aid of the figures.

Fig. 1 shows a wiring diagram of a hydraulic drive system with a valve assembly according to the invention;

FIG. 2 shows a roughly schematic half-section of a first embodiment of a valve assembly according to the invention and

fig. 3 shows a longitudinal section through a second embodiment of the valve assembly according to the invention.

Detailed Description

Fig. 1 shows a wiring diagram of a hydraulic drive system 50 with a valve assembly 10, 10' according to the invention. The hydraulic drive system 50 comprises a first and a second

hydraulic circuit

51, 52, which are fluidically connected to each other via the valve assemblies 10, 10' in such a way that the two

circuits

51, 52 can each be supplied with pressure fluid by means of two pumps 53.

The two

hydraulic circuits

51, 52 are substantially identical in design. They preferably each comprise a plurality of hydraulic actuators 55, which are each configured, for example, as hydraulic cylinders or as hydraulic motors. Each

circuit

51, 52 has a pump 53 which draws pressure fluid from a tank 54 and feeds it into an associated pump line 60, to which an associated actuator 55 is connected in parallel. The hydraulic fluid returning from the actuator 55 flows back into the tank 54. All tank symbols in fig. 1 preferably represent the same tank 54. The pressure fluid is preferably a liquid and at most preferably a hydraulic oil.

A continuously adjustable third throttle 57 and a pressure compensator 56 are connected between the pump line 60 and the actuator 55. With which third throttling 57 the speed of movement of the associated actuator 55 can be adjusted. The third throttle 57 is preferably a component of a directional valve (not shown) with which the direction of movement of the associated actuator 55 can also be adjusted.

The pressure balance 56 is constructed in accordance with US 5305789. They regulate the pressure downstream of the associated third throttle 57 to the pressure in the associated control line 59. In addition, the maximally open pressure compensator establishes a connection between the pressure downstream of the third throttle 57 and the control line 59, so that the highest load pressure of all the associated actuators 55 is loaded in the control line 59. It is to be noted that this maximum load pressure can also be determined by means of a switching valve cascade (wechselventilkaskakakakadaden). Furthermore, a pressure balance can be used which adjusts the pressure drop at the third throttle 57 to a predetermined value.

The pumps 53 preferably have adjustable displacement volumes, wherein they are designed, for example, as axial piston pumps. The respectively associated pump regulator 58 regulates, by regulating the displacement volume, the delivery pressure of the pump 53, for example, to a value which is higher than the pressure in the associated control line 58 by a predetermined pressure difference. The pump regulator 58 can additionally limit the power required for driving the associated pump 53.

The valve assembly 10, 10' has a first and a second pump connection P1, P2 and a first and a second control connection LS1, LS 2. The pump or

control lines

60, 59 of the first hydraulic circuit 51 are connected to the first pump port P1 and the first control port LS 1. The pump or

control lines

60, 59 of the second hydraulic circuit 52 are connected to the second pump connection P2 and the second control connection LS 2.

Fig. 2 shows a roughly schematic half-section of a first embodiment of a valve assembly 10 according to the invention. The valve assembly 10 has a housing 13, which is designed, for example, in the form of a valve disk (ventilschebe) which forms a valve body (Ventilblock) together with a further valve disk. However, it is also possible to have a one-piece valve body in which further valve elements, in particular the pressure balance and a third throttle (56, 57 in fig. 1), are accommodated. The valve assembly 10 has first and second control valve slides 11, 12. The first control slide 11 is received in a preferably cylindrical bore 15 of the housing 13 in a movable manner in the direction of the longitudinal axis 14. The bore 15 is provided with a plurality of annular grooves 16 which are arranged side by side distributed along the longitudinal axis 14. The first control slide 11 also has a plurality of annular grooves 17 on its outer circumferential surface, which are arranged side by side distributed along the longitudinal axis 14. The

annular grooves

16, 17 are matched to one another in such a way that, depending on the position of the first control slide 11 relative to the housing 13, a fluid connection is produced as explained below.

In the intermediate position 43 of the first control slide valve 11, which is shown in fig. 2, the first and second pump connections P1, P2 and the first and second control connections LS1, LS2 are locked by the first control slide valve 11. Thus, no pressure fluid exchange takes place between the first and second hydraulic circuits via the valve assembly 10, independent of the position of the second control slide valve 12. If the first control slide 11 is moved to the right into the first position 41 starting from the middle position 43 in fig. 2, the first fluid flow path 20 is activated, wherein the second fluid flow path 30 is blocked. The first control port LS2 is locked, the first control port LS1 being connected to the second pump port P2 via the second check valve 33. The second check valve 33 in this case allows only a fluid flow from the second pump connection P2 to the first control connection LS 1. As a result, if the pressure at the second pump port P2 is higher than the remaining load pressure in the first hydraulic circuit 51, the pressure at the second pump port P2 acts on the first control port LS 1. Furthermore, the first control interface LS1 is connected to the second control chamber 31 in the first position 41.

If the first control slide 11 is moved to the left into the second position 42 starting from the middle position 43 in fig. 2, the second fluid flow path 30 is activated, wherein the first fluid flow path 20 is blocked. The first control port LS1 is locked, wherein the second control port LS2 is connected to the first pump port P1 via the first check valve 23. The first non-return valve 23 can only allow a fluid flow from the first pump connection P1 to the second control connection LS 2. As a result, if the pressure at the first pump port P1 is higher than the remaining load pressure in the second hydraulic circuit 52, the pressure at the first pump port P1 acts on the second control port LS 2. Furthermore, the second control interface LS2 is connected to the first control chamber 21 in the second position 42.

The second control slide valve 12 is received in the interior of the first control slide valve 11 so as to be movable in the direction of the longitudinal axis 14. The second control slide defines, together with the first control slide 11, a first and a

second control chamber

21, 31, which are arranged on opposite longitudinal ends of the second control slide 12. As a result, when the second control slide valve 12 is moved relative to the first control slide valve 11, the volumes of the first and

second control chambers

21, 31 are adjusted in opposition to one another. The second control slide valve 12 has a first and a second

annular groove

24, 34, which are arranged next to one another in the direction of the longitudinal axis 11. The first annular groove 24 forms, together with an annular groove or a radial bore in the first control slide 11, a continuously adjustable first throttle element 22. The second annular groove 34 forms, together with an annular groove or a radial bore in the first control slide 11, a continuously adjustable second throttle means 32. In the intermediate position of the second control slide valve 12 shown in fig. 1, the first and

second throttle devices

22, 32 are blocked. If the first control chamber 21 is enlarged starting from the intermediate position, the first throttle 22 is opened, wherein the second throttle 32 remains blocked. If the second control chamber 31 is enlarged starting from the intermediate position, the second throttle 32 is opened, wherein the first throttle 22 remains blocked. The hydraulically effective cross sections of the first control slide in the first and in the

second control chamber

21, 31 are preferably of identical design, so that the higher of the two pressures there determines in which direction the second control slide 12 moves.

The first annular groove 24 is connected to the first control chamber 21 via a first passage 25 in the second control slide 12. Furthermore, the first annular groove 24 is connected to the first pump port P1 in the first position 41 of the first control slide valve 11. The pressure upstream of the first throttle 22 is loaded in the first control chamber 21. In the second position 42 of the first control slide 11, the connection between the first annular groove 24 and the first pump port P1 is blocked, wherein the first control chamber 21 is connected to the second control port LS 2.

The second annular chamber 34 is connected to the second control chamber 31 via a second passage 35 in the second control slide 12. In addition, the second annular groove 34 is connected to the second pump port P2 in the second position 42 of the first control slide valve 11. The second control chamber 31 is loaded with pressure upstream of the second throttle. In the first position 41 of the first control slide 11, the connection between the second annular groove 34 and the second pump port P2 is blocked, wherein the second control chamber 31 is connected to the first control port LS 1.

By adjusting the first control slide valve 11 into the first position 41, pressure fluid can flow from the first pump port P1 to the second pump port P2 as long as the pressure at the first pump port P1 is higher than the pressure at the second pump port P2. The pressure fluid flows along the first fluid flow path 20 starting from the first pump connection P1 via the second additional throttle 26, further via the first annular groove 24, further via the first throttle 22 to the second pump connection P2. The pressure drop at the first throttle 22 occurs in such a way that the pressure in the first control chamber 21, i.e. the pressure upstream of the first throttle 21, is in equilibrium with the pressure in the second control chamber 31, i.e. the pressure at the first control connection LS 1. The free cross section of the first additional throttle means 26 is defined by the position of the first control slide 11 in the housing 13. It determines how much pressure fluid flows from the first pump port P1 to the second pump port P2.

If the pressure at the second pump port P2 now rises above the pressure at the first pump port P1, for example due to an external load on the hydraulic drive system, the second check valve 33 opens. As a result, the pressure at the first control port LS1 rises to the pressure at the second pump port P2. This causes the second control slide valve 12 to move to the left in fig. 2 for a short time, so that the first fluid flow path 20 is blocked and therefore fluid exchange between the first and second

hydraulic circuits

51, 52 is prevented. However, the pump regulator of the first pump subsequently causes the pressure at the first pump port P1 to be higher than the pressure at the first control port LS1 for a short time by a predetermined pressure difference. As a result, the pressure at the first pump port P1 is again greater than the pressure at the second pump port P2. Accordingly, the first fluid flow path 20 is opened again.

By adjusting the first control slide valve 11 into the second position 42, pressure fluid can flow from the second pump port P2 to the first pump port P1. The operating principle of the hydraulic pressure corresponds to the operating principle described above for the first position 41, with the following explanations: parts which are respectively designated as "first" are interchanged with parts which are respectively designated as "second", wherein the first and second

pilot slide valves

11, 12 are excluded here.

Fig. 3 shows a longitudinal section through a second embodiment of a valve assembly 10' according to the invention. The second embodiment is identical to the first embodiment with regard to its hydraulic function. The differences in the design of the geometry are explained below, with reference being made in the remaining respects to the embodiment in relation to fig. 1 and 2. In fig. 1 to 3, identical or corresponding parts are denoted by the same reference numerals.

The second control slide 12 is biased into its intermediate position, in which the first and second throttle means 22, 32 are blocked, by means of two springs 61, which are embodied, for example, as helical springs. The prestress of the spring 61 is designed to be so low that it has almost no influence on the function of the hydraulic pressure. The spring initially causes the second control slide valve 12 to be in the pressure-free state and to be in the intermediate position in the third position of the first control slide valve 11.

The first and

second passages

25, 35 each comprise a narrow gap 62, which is arranged between the first and

second control slide

11, 12. In the first and second

annular grooves

24, 34, a strongly swirling flow may occur. By means of the gap 62: these turbulence currents cause pressure fluctuations in the first and in the

second control chamber

21, 31, which adversely affect the above-described pressure regulation.

Furthermore, a separate locking screw 63 is to be noted, with which the first control slide 11 is locked on the front side. This simplifies the installation of the second pilot spool 12 and the spring 61.

Furthermore, the connection of the first and second control interfaces to the first control slide 11 is carried out with a more space-saving design. The first and second load pressure connections LS1, LS2 are formed by an annular groove 66 in the housing 13. A fluid connection to the first or

second control chamber

21, 31 is only established if the annular groove 66 covers the associated radial bore 65 in the second control slide 12. A fluid connection to the first or second pump connection P1, P2 is only established if the annular groove 66 covers the associated annular groove 64 in the first control slide 11.

The first control slide 11 can be moved in the direction of the longitudinal axis 14 by applying a pressure to the interior of the control cover 70. The two control covers 70 are arranged at opposite longitudinal ends of the first control slide 11. In each case a spring 71 with an associated spring retainer 72 is arranged in the control cover 70, with which the first control slide 11 is biased into the intermediate position. Furthermore, an adjustable stop 73 is provided, with which the movement distance of the first control slide 11 is defined.

List of reference numerals

P1 first pump interface

P2 second pump interface

LS1 first control interface

LS2 second control interface

10 valve assembly (first embodiment)

10' valve assembly (second embodiment)

11 first control slide valve

12 second control slide valve

13 casing

14 longitudinal axis

15 bore in housing

16 annular groove on the housing

17 annular groove on the outer side of the first control slide valve

20 first fluid flow path

21 first control room

22 first throttle mechanism

23 first check valve

24 first annular groove

25 first channel

26 first additional throttle mechanism

30 second fluid flow path

31 second control room

32 second throttle mechanism

33 second check valve

34 second annular groove

35 second channel

36 second additional throttle mechanism

41 first position of first control slide valve

42 second position of the first control spool valve

43 third position of first control slide valve

50 hydraulic driving system

51 first hydraulic circuit

52 second hydraulic circuit

53 pump

54 tank

55 actuator

56 pressure balance

57 third throttling mechanism

58 pump regulator

59 control line

60 pump pipeline

61 spring

62 gap

63 locking bolt

64 annular groove

65 radial drilling

66 annular groove

70 control cover

71 spring

72 spring retainer

73 stop

Claims

1. Valve assembly (10) having a housing (13) and a first and a second control slide (11, 12), wherein the first control slide (11) is received in the interior of the housing (13) so as to be movable in the direction of a longitudinal axis (14), wherein the second control slide (12) is received in the interior of the first control slide (11) so as to be movable in the direction of the longitudinal axis (14),

wherein the first pilot slide valve (11) and the second pilot slide valve (12) together define a first and a second control chamber (21, 31), the volumes of which can be adjusted in opposition to each other by a movement of the second pilot slide valve (12) relative to the first pilot slide valve (11),

wherein the first control slide (11) forms together with the second control slide (12) a first and a second throttle mechanism (22, 32) which can be adjusted jointly by a movement of the second control slide (12) relative to the first control slide (11),

wherein the valve assembly (10) has a first and a second pump connection (P1, P2) and a first and a second control connection (LS 1, LS 2), wherein the first control slide valve (11) can assume a first, a second and a third position (41, 42, 43) relative to the housing (13), wherein the third position (43) is arranged between the first and second position (41, 42),

wherein a first position (41) of the first control slide (11) forms a first fluid flow path (20) which extends from the first pump port (P1) via the first throttle (22) to the second pump port (P2), wherein in the first mentioned position (41) the first pump port (P1) is fluidically connected to the first control chamber (21), wherein the first control port (LS 1) is fluidically connected to the second control chamber (31).

2. The valve assembly of claim 1, wherein the valve body,

wherein in an intermediate position of the second control slide (12) both the first and the second throttle means (22, 32) are blocked, wherein in a movement of the second control slide (12), in which movement the first control chamber (21) expands, only the first throttle means (22) opens, and wherein in a movement of the second control slide (12), in which movement the second control chamber (31) expands, only the second throttle means (32) opens.

3. A valve assembly according to claim 1 or 2,

wherein the second control connection (LS 2) is locked in the first position (41) of the first control slide valve (11).

4. A valve assembly according to claim 1 or 2,

wherein a second position (42) of the first control slide (11) forms a second fluid flow path (30) which extends from the second pump port (P2) via the second throttle (32) to the first pump port (P1), wherein in the second mentioned position (42) the second pump port (P2) is fluidically connected to the second control chamber (31), wherein the second control port (LS 2) is fluidically connected to the first control chamber (21).

5. A valve assembly according to claim 1 or 2,

wherein the first control connection (LS 1) is locked in the second position (42) of the first control slide valve (11).

6. A valve assembly according to claim 1 or 2,

wherein the first pump connection (P1) is connectable to the second control connection (LS 2) via a first check valve (23), wherein the first check valve (23) allows only a fluid flow from the first pump connection (P1) to the second control connection (LS 2).

7. A valve assembly according to claim 1 or 2,

wherein the second pump connection (P2) is connectable to the first control connection (LS 1) via a second check valve (33), wherein the second check valve (33) allows only a fluid flow from the second pump connection (P2) to the first control connection (LS 1).

8. A valve assembly according to claim 1 or 2,

wherein in a third position (43) of the first control slide valve (11) the first and second pump ports (P1, P2) are locked.

9. A valve assembly according to claim 1 or 2,

wherein in a third position (43) of the first control slide (11) the first and second control interfaces (LS 1, LS 2) are locked.

10. A valve assembly according to claim 1 or 2,

wherein the second control slide (12) is force-loaded in the direction of its neutral position by means of at least one spring (61).