EP2038553B1 - Cylinder piston arrangement for a fluid pump or a fluid motor - Google Patents

Description

TECHNICAL AREA

The invention relates to a cylinder-piston arrangement according to the preamble of claim 1. Cylinder-piston arrangements of this type are represented on the relevant market, in particular as high-pressure water pumps.

An essential area of application for pumps of this type is the pressure delivery of water loaded with foreign substances, in particular also abrasive granules. Above all, high-speed machines with high working pressures in the range of a few hundred to a thousand bar are required. The energetic as well as the volumetric efficiency is therefore of great importance.

STATE OF THE ART

From the document DE2914694 a cylinder piston unit is known which comprises a pulsating working space. The cylinder-piston unit comprises a sealing hose that is axially expandable and inside which the pulsating working space is located.

DESCRIPTION OF THE INVENTION

The object of the invention is therefore to create pumps or Fluid motors that are characterized by high efficiencies of the aforementioned type and by a long service life. The solution to this problem according to the invention is determined by the features of claim 1.

Further developments and variants, including those that cannot be implemented in every case, result from features and combinations of features or combinations of subclaims, possibly including optional features or combinations of features.

Axial expansion hose diaphragm pistons with internal working space provide the basis for a robust construction with high wear resistance, even when operating with abrasive fluids. However, for constructional reasons, relatively large dead spaces must generally be observed, which adversely affects the volumetric efficiency. It is precisely this problem that is solved with the invention, namely with the aid of dead space displacement bodies. Overall, the invention thus enables a largely optimized type of construction.

BRIEF DESCRIPTION OF THE FIGURES

Fig.1

einen Teil-Axialschnitt einer Hochdruckpumpe mit einem als Axialdehnungs-Schlauchmembrankolben ausgebildetem Arbeitskolben, mit dem ein in den Arbeitsraum eingreifender und an der oszillatorischen Antriebsbewegung teilnehmender Totraum-Verdrängungskörper gekuppelt ist;

Fig.2

einen zu Fig.1 ähnlichen Teil-Axialschnitt, ebenfalls mit einem als Axialdehnungs-Schlauchmembrankolben ausgebildeten Arbeitskolben sowie mit einem Totraum-Verdrängungskörper, der jedoch in der Pumpe gestellfest angeordnet ist und infolge der oszillatorischen Antriebsbewegung des Arbeitskolbens relativ zu diesem in den innenliegenden Arbeitsraum des Axialdehnungs-Schlauchmembrankolbens eingreift;

Fig.3

einen zu Fig.2 ähnlichen Teil-Axialschnitt, ebenfalls mit einem als Axialdehnungs-Schlauchmembrankolben ausgebildeten Arbeitskolben mit innenliegendem Arbeitsraum sowie mit einem gestellfesten Totraum-Verdrängungskörper, jedoch mit andersartigem Strömungsweg des Arbeitsfluids;

Fig.4

einen zu Fig.3 ähnlichen Teil-Axialschnitt, ebenfalls mit einem als Axialdehnungs-Schlauchmembrankolben ausgebildeten Arbeitskolben mit innenliegendem Arbeitsraum sowie mit einem gestellfesten Totraum-Verdrängungskörper, jedoch mit andersartigem Strömungsweg des Arbeitsfluids und mit ebensolcher Ventilanordnung, insgesamt resultierend in einem weiter reduzierten Totraumvolumen;

Fig.5

ein Zeitdiagramm des Förderdruckes p (bar) für einen Arbeitskolben einer volumetrischen Pumpe über der Zeit t (msec), und zwar für eine Konstruktion ohne Totraum-Verdrängungskörper; und

Fig.6

ein Diagramm entsprechend Fig.5, jedoch für eine Konstruktion mit Totraum-Verdrängungskörper. Diese letztere Darstellung gilt grundsätzlich nicht nur für bewegliche, mit dem Arbeitskolben gekuppelte Totraum-Verdrängungskörper (siehe Fig.1), sondern ebenso für gestellfest ruhende und durch Bewegung des Arbeitsraumes in diesen eingreifende Totraum-Verdrängungskörper (siehe Figuren 2 bis 4). Dies kommt insbesondere bei Einsatz von Axialdehnungs-Schlauchmembrankolben in Betracht.

Fig.7

eine Ventilkonstruktion, insbesondere für Auslassventile

The invention is further explained with reference to the exemplary embodiments shown schematically in the drawings. It shows:

Fig. 1

a partial axial section of a high-pressure pump with a working piston designed as an axial expansion hose membrane piston, with which a dead space displacement body engaging in the working space and participating in the oscillatory drive movement is coupled;

Fig. 2

one too Fig. 1 Similar partial axial section, also with a working piston designed as an axial expansion hose membrane piston and with a dead space displacement body, which, however, is fixed to the frame in the pump and engages as a result of the oscillatory drive movement of the working piston relative to the latter in the internal working space of the axial expansion hose membrane piston;

Fig. 3

one too Fig. 2 Similar partial axial section, also with a working piston designed as an axial expansion hose membrane piston with an internal working space and with a dead space displacement body fixed to the frame, but with a different flow path of the working fluid;

Fig. 4

one too Fig. 3 Similar partial axial section, also with a working piston designed as an axial expansion hose membrane piston with an internal working space and with a dead space displacement body fixed to the frame, but with a different flow path of the working fluid and with the same valve arrangement, resulting overall in a further reduced dead space volume;

Fig. 5

a time diagram of the delivery pressure p (bar) for a working piston of a volumetric pump over time t (msec), namely for a construction without a dead space displacer; and

Fig. 6

a diagram accordingly Fig. 5 , but for a construction with a dead space displacer. This latter representation basically does not only apply to movable dead space displacement bodies coupled to the working piston (see Fig. 1 ), but also for dead space displacement bodies which are fixed to the frame and which intervene in them through movement of the work space (see Figures 2 to 4 ). This is particularly important when using axial expansion hose membrane pistons.

Fig. 7

a valve construction, especially for exhaust valves

DETAILED DESCRIPTION OF THE INVENTION

In the execution according to Fig. 1 is a working piston provided with an axial expansion hose membrane (shown in the top dead center position and hereinafter referred to briefly as ASK) at its lower end with an oscillating drive device AVO shown here only schematically by a downward-pointing arrow. The upper end of the axial expansion hose membrane piston ASK is arranged fixed to the frame and surrounds an inlet valve EV, which is fed via inlet channels EK and is designed as a check valve. The downwardly extending, hollow-cylindrical section Z of the axial expansion hose diaphragm piston is mounted in an axially displaceable manner in a housing bore GB with a lubrication (not shown here). An oscillating working space AR is formed in the interior of the axial expansion hose membrane piston ASK, from which a coaxial delivery channel FK leads to an outlet valve AV, which is also designed as a check valve, and to an outlet channel AK.

A substantially cylindrical dead space displacement body TK1 is connected to the axial expansion hose diaphragm piston ASK on the side of the working space AR, which is shown here in the top dead center position and obviously has a significant reduction in the effective dead space.

To determine the mode of operation of this construction is based on the representation already given in the Figures 5 and 6 to fall back on.

There the time diagram shows in Fig. 5 a slowed increase in the delivery pressure p for a working piston of a volumetric pump for a construction without a dead space displacer. The pressure drop at the end of the delivery cycle is correspondingly slowed down. Both mean a significant reduction in the delivery volume related to the piston stroke, ie the volumetric efficiency. The reason for this is the compressibility of the working fluid in the dead space.

In contrast, according to Fig. 1 dead space displacer TK1 engaging in the working space AR Fig. 6 illustrated steepening of the pressure rise as well as the pressure drop, overall a significant improvement in volumetric efficiency.

When executed according to Fig. 2 A dead space displacement body TK2a is provided which is fixed to the frame, but which in turn is due to the arrangement of the working space AR within the axial expansion hose membrane piston ASK and thus because of the relative movement between the axial expansion hose membrane piston ASK and the dead space displacement body TK2a given by the pump drive AR intervenes and brings about a similar improvement in volumetric efficiency. However, the reduction of the moving mass due to the dead space displacement body TK2a fixed to the frame is particularly advantageous here.

Inlet valve EV and outlet valve AV are analogous to the version according to Fig. 1 formed, however, the connection between the working space and the outlet valve is provided by a longer coaxial channel KOK in the dead space displacement body TK2a and in the inlet valve EV. The associated reduction in dead space displacement can be kept within reasonable limits.

This embodiment is particularly advantageous in that the displacement body TK2a has an internal flow and an outside flow around the working fluid with a flow deflection in an opening or end region of the dead space displacement body TK2a. Among other things, A particularly intensive flushing of the work area AR and the valves with regard to the accumulation of residues and contaminants, but also of compression-reducing air inclusions after longer downtimes.

When executing after Fig. 3 a dead space displacement body TK2b which is fixed to the frame is again provided, with the corresponding dynamic advantages. At the same time However, by eliminating a comparatively long coaxial channel connected to the working space AR, the dead space displacement volume is maximized. The fluid outlet takes place from the work area AR via cross bores BQ immediately below the inlet valve EV and a short and therefore practically harmless longitudinal channel LK.

When executing after Fig. 4 a dead space displacement body TK2c with fixed frame is also provided with the corresponding dynamic advantages. In addition, however, a compression-inactive arrangement of the outlet valve AV is provided at the end of an outlet coaxial channel AKOK on the working space side, which ensures optimum dead space displacement.

In addition, according to a valve construction Fig. 7 point out, which is particularly suitable for exhaust valves AV. Here, a valve body VK designed as a partial spherical shell is pivotably mounted about the center of the ball relative to a correspondingly shaped valve seat. At the same time, however, a longitudinal guide by means of a swivel guide SF and a centering member ZG is also required. The latter is connected to the valve body VK by a tight-elastic snap lock SV, so that relatively light and vibration-damping material can be considered for the swivel guide SF. In view of the swiveling mentioned, the inner bore of the swivel guide is weak Toroidal with a suitable sliding seat for the centering member ZG. Such a construction has proven itself due to its high stability and wear resistance.

Claims (9)

1. Cylinder-piston arrangement (10) for a volumetrically acting fluid pump or a fluid motor, with at least one axial expansion hose membrane piston (ASK), which defines at least one internal pulsating working space (AR), characterized in that at least one dead space displacer (TK1, TK2a , TK2b, TK2c, VK) is provided, which is in operative connection with the pulsating working space (AR) and wherein the dead space displacer (TK1, TK2a, TK2b, TK2c, VK) is designed such that the effective dead space in the working space (AR) is reduced and a steepening in the time course of the pressure rise as well as the pressure drop is effectuated compared to a cylinder-piston arrangement without dead space displacer.
2. Cylinder-piston arrangement (10) according to claim 1, characterized in that the dead space displacer (TK1, TK2a, TK2b, TK2c) is formed as a dead space displacer (TK1, TK2a, TK2b, TK2c) that reaches in the pulsating working space (AR).
3. Cylinder-piston arrangement (10) according to claim 1 or 2, characterized in that for the dead space displacer (TK2a, TK2c), an internal flow and an external flow (KOK, LK, AKOK) by a working fluid with a flow deflection are provided in an opening region or an end region of the dead space displacer (TK2a, TK2c).
4. Cylinder-piston arrangement (10) for a fluid pump or a fluid motor, with at least one axial expansion hose membrane piston (ASK), which defines at least one internal, pulsating working space (AR), according to one of the preceding claims, characterized in that at least one inlet valve (EV) and/or a corresponding outlet valve (AV), being designed as a multi-seat lift valve, is arranged in a fluid flow, and in that at least one fluid space (FR) is formed in the area between seats (S1, S2) of this valve, which can be reversed by the valve lift between closure and passage.
5. Cylinder-piston arrangement (10) according to claim 4, characterized in that at least some of the seats (S1, S2) of the multi-seat lift valve have sealing lines or sealing surfaces running in a common spherical surface (KF), at least substantially.
6. Cylinder-piston arrangement (10) according to Claim 4 or 5, characterized by at least one valve body (VK) which can be reversed between the closure and the passage, which has at least one sealing surface built as a spherical surface (KF), at least substantially or at least approximately, and which is movably mounted relative to at least one sealing line or sealing surface.
7. Cylinder-piston arrangement (10) according to claim 6, characterized in that the valve body (VK) is movably mounted about a pivot axis or a corresponding pivot point which runs through the centre of the spherical surface (KF), at least substantially or at least approximately.
8. Cylinder-piston arrangement (10) according to claim 6 or 7, characterized in that a pivot bearing of the valve body (VK) comprises a holder cooperating with a convex or concave curved guide member and in that a preferably elastically deformable snap closure (SV) is provided between the valve body (VK) and the pivot bearing.
9. Cylinder-piston arrangement (10) according to claim 1, characterized in that the dead space displacer (TK2a, TK2b, TK2c) comprises the valve body (VK) or in that a further dead space displacer is provided which is in operative connection with the pulsating working space (AR) and which comprises the valve body (VK).

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