EP2157319B1 - Hydraulic device for a hydro motor - Google Patents

Description

The invention relates to a hydraulic control according to the preamble of patent claim 1.

Such hydraulic controls are used inter alia in agricultural vehicles, such as hydraulic plows, or in snowplows, deep hole drills, mobile cranes or the like, wherein in the shut-off neutral position of the three-position spool control valve, the hydraulic motor is hydraulically blocked as soon as it is against or under load in a certain position was brought. However, in such hydraulic controls, in particular in the vehicles mentioned above or in comparable applications, it is often necessary to be able to lift the hydraulic lock, possibly without adjustment of the hydraulic motor and when the pressure source is in operation, and to set a floating position, so to speak. However, since the hydraulic lock is also needed, no three-position slide control valve with non-shut or neutral open position can be used, but only for this additional function previously expensive hydraulic components are integrated into the hydraulic control to relieve at least one working fluid side of the hydraulic motor if necessary can , This may be, for example, a second three-position open spool valve control valve, or at least one external control, which adds additional and costly overhead. Another known possibility is to provide a four-position valve control valve from the outset, which has shut-off and non-blocking neutral positions. This, too, involves a great deal of effort, and may entail the disadvantage that the usable control strokes, e.g. in the case of a pressure control spool control valve, are shortened. Because it may need to be able to flow a considerable amount of pressure medium in the relief or floating position function.

At the EP0 786 598 A known hydraulic control is the respective, a working line in the branching off bypass line, hydraulically unlockable Check valve a shock valve, which is not selectively unlocked, but only opens in a pressure shock in the working line and degrades the pressure shock. Such a pressure shock can occur, for example, when the three-position slide control valve is in the shut-off zero position, and the hydraulically blocked hydraulic consumer is acted upon by external influence with a force that causes the pressure in the working line to rise above the set pressure of the shock valve. In the case of a vehicle, this may occur, for example, when a component that can be adjusted by the hydraulic consumer strikes an obstacle while the vehicle is driving.

The invention has for its object to provide a hydraulic control of the type mentioned, the active relief of at least one working fluid side of the hydraulic motor with a three-position slide control valve with shut-off neutral position allows without costly additional hydraulic components.

This object is achieved with the features of claim 1.

According to the invention, at least one simple and cost-effective, eg hydraulically, non-returnable check valve is incorporated into the hydraulic control such that a relatively large cross-section can be opened to relieve at least one side of the hydraulic motor, for example to the reservoir. The control pressure used for hydraulic unlocking is usually present in the hydraulic control anyway and only needs to be brought to the corresponding hydraulic pilot operated check valve. Incidentally, in such hydraulic controls already often for other reasons, a check valve in this interesting area of the hydraulic control to the basic equipment. This check valve can then be modified with negligible overhead either in a hydraulically releasable check valve or replace it with one, and then fulfills a useful dual function. As soon as at least one side of the hydraulic motor is to be relieved or a floating position has to be set in the hydraulically blocking neutral position of the three-position slide control valve, the at least one hydraulically releasable check valve is hydraulically unlocked to establish a direct working fluid connection from the working line to the reservoir. As a result, the three-position slide control valve receives a fictitious fourth switching position, so to speak. Alternatively, the check valve could be actively unlocked in other ways, for example by means of a magnet, with or without pilot pressure, or by hand. For optional hydraulic release is in a control pressure line between a Control pressure source and the hydraulically operated check valve arranged a solenoid switching valve, which is selectively operable to unlock the check valve (or the check valves for both sides). The control pressure line leads anyway usually in such hydraulic control permanently existing control pressure, which is for example about 25 bar. Alternatively, the required Entsperrdruck can be provided in other ways.

Suitably, the magnetic switching valve 2/2-magnetic switching valve with a black and white switching magnet, which switches when energized to passage and the check valves or hydraulically unlocked, however, shuts off in the de-energized state, so that the hydraulic motor is either hydraulically blocked, or in the other Control positions of the three-position slide control valve is hydraulically actuated without significant Abströmverluste.

To ensure that in operating conditions in which no hydraulic release of the check valves may occur, not accidentally or by leakage in an unlock line, which is connected to the control pressure line, unintentionally pressure is built up, it is expedient if the Entsperrleitung is connected via a throttle with the reservoir.

In a preferred embodiment with two working lines for the hydraulic motor both provided hydraulically releasable check valves via the then common solenoid switching valve with the control pressure source can be connected. Switches the solenoid valve to passage, then both check valves are unlocked to the reservoir at the same time.

In an expedient embodiment, the control pressure source comprises a pressure reducing valve fed by or from a pressure source of the hydraulic control, to which a substantially constant control pressure is adjustable, which is constantly available during operation of the hydraulic control, and, for example, also in proportional solenoid pressure pilot controls of the three-position sheer control valve is being used.

A particularly advantageous embodiment is characterized in that the two hydraulically releasable check valves for the two working lines of a hydraulic motor part of a between the three-position slide control valve and the hydraulic motor, z. B. for safety reasons, arranged secondary pressure limitation of the hydraulic motor. It already hereby existing components of the hydraulic control for the additional function of the active pressure relief of the hydraulic motor is used.

Since in the secondary pressure limiting anyway Nachsaug check valves are needed, which allow in the shut-off neutral position three-position slide control valve and responsive secondary pressure limiting the sucking of pressure medium, these Nachsaugrückschlagventile either replaced by hydraulically releasable check valves, or modified to corresponding check valves and interconnected accordingly, so that they can be unlocked via the magnetic switching valve.

In a further expedient embodiment with a secondary pressure limiting the hydraulic motor is between the respective hydraulically releasable check valve, a pressure relief valve, the z. B. may also have the function of a shock valve, and the three-position slide control valve, a load-holding valve disposed in each working line, which is hydraulically aufsteuerbar from upstream of the load-holding valve from the other working line. In the shut-off neutral position of the three-position slide control valve The hydraulic motor is hydraulically blocked and isolated by the load-holding valves of the three-position slide control valve. The secondary pressure limitation for one or both lines still responds in case of danger to z. B. to avoid a pressure surge or pressure increase above the maximum system pressure. Here, too, can be set on the unlocking of the check valves, a floating position or at least one working fluid side of the hydraulic motor optionally and actively relieve pressure. This unloaded hydraulic motor can then be adjusted for example by a coupling with another hydraulic motor of the other hydraulic motor.

In an expedient embodiment, the hydraulic motor is a double-acting differential cylinder.

Embodiments of the subject invention will be explained with reference to the drawing.

It shows Fig. 1 a block diagram of a hydraulic control S for here, for example, two hydraulic motors M, wherein the hydraulic control for the two hydraulic motors comprises different detailed solutions.

The hydraulic control S for the respective hydraulic motor M, for example, a double-sided acted upon (or unilaterally acted upon) differential cylinder for moving a load L is connected via pressure lines 1, 1 'to a pressure source P, not shown. The pressure source P is associated with a reservoir R, to which a return line 2 leads. The respective hydraulic motor M is connected to the pressure lines 1, 1 'and the return line 2 via, in the illustrated embodiment, two working lines 4, 5, and in each case a three-position slide control valve D. The three-position slide control valves D for the two hydraulic motors M can be shown as pressure-regulating proportional slide control valves with load pressure taps and a feed regulator 3 in the pressure line 1 '. Here are provided with proportional solenoids 15 actuatable Druckvorsteuerungen 16 for adjusting each three-position slide control valve D between three control positions, namely between two active control positions a, b and a shut-off neutral position 0, in which any connection between the working lines 4, 5 and the pressure line 1 ' or the return line 2 is blocked. The pressure pilot 16 may be connected to a control pressure source 17, for example, has a fed from the pressure source P pressure reducing valve, which sets a certain, substantially constant control pressure in a control pressure line 8, for example, about 25 bar, while the system pressure z. B. may be up to 230 bar or more.

The in Fig. 1 left hydraulic motor M is hydraulically blocked in the illustrated shut-off neutral position 0 of the left three-position slide control valve D. Nevertheless, it is also possible to relieve even at least one working line 4, 5 of the hydraulic motor M, z. B. to set a floating position in which the hydraulic motor M, for example, by a coupling K from the other hydraulic motor M 'can be adjusted. For this purpose, at least one, or branch of both working lines 4, 5 bypasses bypass lines 2 'to the return line 2, and is connected to the node 6 at which the respective bypass line 2' branches off from the working line 4, 5 or in FIG Beipassleitung 2 ', each one in the flow direction to the reservoir R blocking, hydraulically releasable check valve 7 is provided.

The two check valves 7 are connected via an unlock line 9 and expediently a common solenoid switching valve 10 with a black / white switching magnet 11 to the control pressure line 8, which carries the control pressure source 17 held by the control pressure and to the possibly also the feedforward control 16 of the three-position Schierbersteuerventile D is connected.

The solenoid switching valve 10 is, for example, connected so that it is in the shut-off state shown in the de-energized state of the solenoid 11, set by a spring 12, and 11 is energized when energized solenoid 11 in the passage position in which the control pressure in the control pressure line 8 via the Entsperrleitungen 9 both check valves 7 hydraulically unlocked and the working lines 4, 5 depressurized to the reservoir. Appropriately, the magnetic switching valve 10 can only be energized in the shut-off neutral position 0 of the three-position slide control valve D. The Entsperrleitungen 9 for the two check valves 7 may be connected via a connection 13 with a throttle arranged therein 14 with the return line 2 in order to avoid leakage-induced pressure build-up.

The two check valves 7 for the in Fig. 1 For example, the left hydraulic motor M may be without any existing equipment components of the hydraulic control, e.g. B. suction valves N, as they are needed in some applications. These suction valves N are replaced here for the active pressure relief either by the hydraulically releasable check valves 7 or modified to these. Otherwise, the hydraulic control S could be supplemented by the correspondingly interconnected valves 7, 10. Alternatively (not shown), the respective check valve could be unlocked by a magnet, or by hand, with or without pilot pressure.

The in Fig. 1 right hydraulic motor M 'has in its hydraulic control S as a safety feature on a so-called secondary pressure limiting B on.

The secondary pressure limitation B serves, for example, to mitigate in the shown shut-off neutral position 0 of the right three-position spool control valve D caused by external influences on the hydraulic motor pressure surge, or to prevent pressure above a permissible pressure value. It could thus make the secondary pressure limiting B a so-called shock-valve function.

In the secondary pressure boundary B of each working line 4, 5 branches off a connecting line 19, 18 to the return line 2 from. In each connecting line 18 and 19, a pressure-controlled and spring-biased pressure relief valve 20 is included, which is aufsteubar from the shut-off position shown pressure-dependent to the return line 2 and the pressure in the working line 4, 5 limited. The two pressure relief valves 20 can be set to different response pressures. Optionally, only one working line 4, 5 or in the case of a unilaterally loadable hydraulic motor of the then single working line a secondary pressure limitation B is assigned.

Increases in the respective working line 5, 4, the pressure on the set pressure of the associated pressure relief valve 20, then this speaks to and the pressure is limited. Since the hydromotor possibly moves when the pressure limiting valve 20 responds, and the three-position slide control valve D can not supply pressure medium in the shut-off neutral position 0, a suction check valve N is provided in the secondary pressure limitation B which, if required, sucks pressure medium from the return line 2 leaves.

Appropriately, the two Nachsaugrückschlagventile N or possibly only one either to the hydraulically releasable check valves 7 are modified for the additional function of an active pressure relief of the hydraulic motor M in the shut-off neutral position 0 of the three-position slide control valve or modified by the hydraulically releasable check valves 7 and replaced accordingly the Unlock line 9 and the solenoid valve 10 connected. These are both cost-effective measures to be able to realize the additional function of the active pressure relief of the hydraulic motor M 'in the hydraulic control using the secondary pressure limitation B.

The hydraulically releasable check valves 7 of in Fig. 1 Right hydraulic motor M can be connected via the Entsperrleitungen 9 and the solenoid valve 10 to the control pressure line 8, and can be connected via the throttle 14 and the connection 13 directly to the return line 2.

In addition, here as an option in each working line 5, 4 a in the flow direction to the three-position slide control valve D blocking load-holding valve 21, 22 is arranged. The two load-holding valves 21, 22 are cross-connected via lines 23, 24 from the other working line 5 or 4 hydraulically unlocked when the three-position valve control valve D is adjusted in one of the control positions a, b.

The principle of providing a pilot operated check valve 7 and solenoid valve 10 for selectively hydraulically unblocking the check valve 7 could also be realized with a hydromotor having only one working line, or could be implemented in the secondary pressure limiter B for only one of the secondary check valves N.

Although the hydraulic control S only ever contains a three-position slide control valve D with shut-off neutral position 0 for the hydraulic motor M, M ', it works without significant additional effort as if per hydraulic motor M, M' a much more complex four-position valve control valve with shut-off and not shut-off Neutral positions or two interconnected three-position slide control valves, one with shut-off neutral position and one with open neutral position would or would be provided.

Claims (9)

1. Hydraulic control device (S) for at least one hydromotor (M, M') for moving a load (L) in particular in a vehicle, comprising a three-position slider control valve (D) operating with a blocked neutral position (O) within a working fluid circuit between the hydromotor (M, M') and a pressure source (P) associated to a reservoir (R), wherein between the three-position slider control valve (D) and the hydromotor (M, M') which is connected via one or two working lines (4, 5), a bypass line (2') branches off from the respective working line (4, 5) to the reservoir (R), in which bypass line (2') an unlockable check valve (7) is arranged which blocks in flow direction to the reservoir (R), characterised in that the respective check valve (7), at least in the blocking neutral position (O) of the three-position slider control valve (D), for an intended pressure relief of at least one working line (4, 5) can be unlocked in flow direction to the reservoir (R) selectively actively by hand, or by means of a solenoid or by control pressure hydraulically via a switchable solenoid valve (10) which is arranged in a control pressure line (8) between a control pressure source (17) and an unlocking line (9) extending to the check valve (7).
2. Hydraulic control device according to claim 1, characterised in that the solenoid valve (10) is a 2/2-way solenoid switching valve which is to be switched open for the control pressure in case of electric actuation of a black/white switching solenoid (10), which solenoid valve (10) is blocked in current-free condition and is then isolating the control pressure.
3. Hydraulic control device according to claim 1, characterised in that the unlocking line (9) arranged between the solenoid switching valve (10) and the check valve (7) is directly connected with the reservoir (R) via an aperture (14).
4. Hydraulic control device according to claim 1, characterised in that in case of two working lines (4, 5) for the hydromotor (M, M') two hydraulically unlockable check valves (7) are actuable by control pressure for the hydraulic unlocking by means of the solenoid switching valve (10) which is commonly arranged for both check valves (7).
5. Hydraulic control device according to claim 1, characterised in that the control pressure source (17) comprises a pressure reducing valve which is supplied with pressure by the or by a pressure source (P) of the hydraulic control device (S).
6. Hydraulic control device according to at least one of the preceding claims, characterised in that the respective, preferably hydraulically, unlockable check valve (7) is part of a secondary pressure limiting device (B) of the hydromotor (M, M'), which secondary pressure limiting device (B) is arranged between the three-position slider control valve (D) and the hydromotor (M, M').
7. Hydraulic control device according to claim 6, characterised in that the secondary pressure limiting device (B), in particular for a double-actuated hydromotor (M, M'), comprises two pilot pressure controlled pressure limiting valves (20) respectively to the reservoir (R), and two suction check valves (M) for sucking back pressure medium, preferably from the reservoir (R), and that in the secondary pressure limiting device (B) at least one suction check valve (N) is modified into the, preferably hydraulically, unlockable check valve (7) or is replaced by the, preferably hydraulically, unlockable check valve (7).
8. Hydraulic control device according to claim 6 and 7, characterised in that in each working line (4, 5) a load holding valve (21, 22) is provided between the respective check valves (7), the pressure limiting valves (20, and the three-position slider control valve (D), which load holding valve (21, 22) is hydraulically controlled to open from the respective other working line (5 or 4) upstream of the load holding valve (21, 22).
9. Hydraulic control device according to at least one of the preceding claims, characterised in that the hydromotor (M, M') is a double-actuated differential cylinder, and that, preferably, the hydromotor (M, M') when pressure relieved in the blocking neutral position (O) of the three-position slider control valve (D), is movable by means of another hydromotor (M', M).

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