DE102007016519A1 - Axial piston hydraulic motor, has high pressure and low pressure connections separated from each other from side of formation of rotatable part of valve plate to another side of formation of non-rotatable part of valve plate - Google Patents

Abstract

The motor has a displacement volume with a valve plate, about which a part is rotatable opposite to other part. The valve plate includes a curved opening, which connects a cylinder chamber with both high pressure and low pressure connections (11, 12) that are separated from each other from a side of formation of a rotatable part of the valve plate to another side of formation of a non-rotatable part of the valve plate. A non-rotatable formation is presented in a position to check whether the cylinder chamber is either large or small.

Description

I. Technical Background

The Torque adaptation of conventional axial piston machines based on change in the displacement volume, by angular adjustment of the swash plate. This "displacement control" costs a lot of power and needs a heavy hydraulic device, which responds slowly, is lossy and expensive. In addition, an unfavorable angle leads to loss of efficiency, which a moment change by more than a factor of 3 is problematic becomes.

• 1. So beschreibt bereits die FR 1303925 eine zeitgesteuerte Pumpe, die man auch als Motor verstehen kann. Demnach wird dem Hochdrucköl Niederdrucköl beigemischt, wenn der Versorgungsdruck den Arbeitsdruck übersteigt. Die Ventilplatte, mit den üblichen zwei Verbindungsöffnungen zwischen Zylinderkammern und Druckanschlüssen, hat einen drehbaren Außenring, der die Öffnungen an ihrer Außenseite umgrenzt. In die Öffnung zum Hochdruckanschluß mündet ein zweiter Niederdruckanschluß. Beide sind voneinander durch eine Ausformung am Außenring, die zur Innenseite der Öffnung reicht, getrennt. Der Ring kann über eine äußere Verzahnung gedreht werden, wodurch die Ausformung das Aufnahmeverhältnis zwischen Hoch- und Niederdrucköl (das Drehmoment) ändert. Das geht schnell und braucht wenig Kraft; der Änderungsbereich ist etwa zweimal so groß wie bei Verstellmotoren. Es funktioniert aber nur in einer Drehrichtung, was für die meisten Anwendungen, wofür Hydromotoren in Frage kommen, ein prohibitiver Nachteil ist.
• 2. In der WO 97/31185 ist die ganze Ventilplatte drehbar, wodurch sich Niederdrucköl ohne extra Anschluß und in beiden Drehrichtungen beimischen lässt. Parallel damit aber werden die Zylinder in der Leerphase mit dem Anschluß zur Pumpe verbunden – und stoßen dort auf einen Gegendruck, der den Wirkungsgrad reduziert und den Motor bereits bei Spreizungsfaktor 2 zum Stehen bringt.
• 3. Allerdings handelt die WO primär vom Austausch von Druck gegen Strom in einem Transformator: Ein Eingangsstrom mit bestimmten Druck wird in einen Ausgangsstrom mit anderem Druck umgewandelt, wobei Ein- und Ausgangsdruck sich unabhängig voneinander ändern können. Die Ventilplatte hat drei Öffnungen, mit Anschluß respektive zur Pumpe, Tank und Verbraucher. Drehung der Platte verbindet die Zylinderkammer kurzer oder länger mit diesen Anschlüssen, und variiert den Ausgangsdruck zwischen Eingangsdruck und Tankdruck. Der Nachteil: Ein Motor braucht einen Transformator dazu.
• 4. Die US 6176684 beschreibt eine Axialkolbenmaschine mit drehbarer und zugleich, aber unabhängig davon, verstellbarer Schrägscheibe. Auch ein solcher Motor wird, aus vorgenannten Gründen, gegenüber herkömmlichen Verstellmotoren eher im Nach- als im Vorteil sein.

These disadvantages do not exist with "timing" at the same displacement volume: The torque can be changed by the cylinder chamber during the oil consumption longer or shorter to connect with the high and the low pressure port, but the proposals in this respect have been primarily pumps, and are only conditionally, according to the motto "reverse pumps", transferable to engines:

• 1. That's how the FR 1303925 a timed pump, which can also be understood as a motor. Accordingly, low pressure oil is added to the high pressure oil when the supply pressure exceeds the working pressure. The valve plate, with the usual two communication openings between cylinder chambers and pressure ports, has a rotatable outer ring which bounds the openings on its outer side. In the opening to the high pressure port opens a second low pressure port. Both are separated from each other by a molding on the outer ring, which extends to the inside of the opening. The ring can be rotated via an outer toothing, whereby the shape changes the recording ratio between high and low pressure oil (the torque). This is fast and needs little power; The range of change is about twice as large as with variable displacement motors. However, it only works in one direction of rotation, which is a prohibitive disadvantage for most of the applications that hydromotors are suitable for.
• 2. In the WO 97/31185 the whole valve plate is rotatable, whereby low pressure oil can be added without extra connection and in both directions of rotation. In parallel, however, the cylinders are connected in the idle phase with the connection to the pump - and encounter there a back pressure, which reduces the efficiency and brings the engine already at a spreading factor 2 to a halt.
• 3. However, the WO is primarily about the exchange of pressure against electricity in a transformer: An input current with a certain pressure is converted into an output current with a different pressure, whereby input and output pressures can change independently. The valve plate has three openings, with connection respectively to the pump, tank and consumer. Rotation of the plate connects the cylinder chamber shorter or longer with these ports, and varies the outlet pressure between inlet pressure and tank pressure. The disadvantage: A motor needs a transformer to do so.
• 4. The US 6176684 describes an axial piston machine with rotatable and at the same time, but independently, adjustable swash plate. Also, such an engine will, for the reasons mentioned above, compared to conventional adjusting motors rather in the aftermath as an advantage.

For the supply or transformation of hydraulic energy So timing offers significant advantages over Displacement control. For the use of this Energy, however, the previous concepts are not serious Alternative for the axial piston adjusting motor.

II. Presentation of the invention

It It is therefore an object of the invention to provide an axial piston motor without the Disadvantages of both conventional adjusting motors as well as known To develop timers - an axial piston motor So with constant displacement volume and yet far adjustable torque, low loss, with optional direction of rotation and without extra pressure connection.

The Task is solved in the claim. Accordingly, it is not the valve plate opposite the swash plate (or vice versa), but the one separating bridge between the valve openings rotatable relative to the other with respect to the rotor axis. The solution is based on a few implementation examples explain.

In the I is the outer ring ( 2 ) of the valve plate ( 1 ) around its inner part ( 3 ) rotatable. It defines a circular valve opening ( 4 ) on its outer side ( 5 ), and has a shape ( 7 ), which are on the inside ( 6 ) enough. The almost continuous arc of the valve opening is only of the shape ( 8th ) at the non-rotatable part of the valve plate - where the cylinder chamber reaches either its largest (A) or its smallest (B) volume. The outer ring is, via an external toothing ( 9 ), preferably by an electric motor ( 10 ), turned. The position of the shaping shifts ( 7 ) within the valve opening, and the intake ratio of high and low pressure oil changes: the torque.

In the II The rotatable part of the valve plate encloses the valve opening, whereby this is also rotatable. The former shape ( 7 ) is here the bridge to the co-rotating inner part of the plate. Non-rotatable is here only the former shape 8th , Incidentally, the same applies as for the I ,

For all variants applies that the largest torque spread is achieved when the pressure connections ( 11 / 12 ) close to the non-rotatable shape 8th are located.

The invention is applicable to motors with swash plate, with inclined axis and according to the floating cup principle, such as in the NL 1019736 described.

The III show an example of the longitudinal average of an application with a swash plate: the shaping 8th is fixed in the position A, the shaping 7 is in position B, ie where the cylinder chamber at the largest resp. are the smallest. The valve opening on the chamber side ( 18 ) is narrower than the opening on the side of the push connections ( 19 ), so that the local current velocity is not too high. As a result, the separating surfaces between the rotatable and non-rotatable part of the valve plate ( 20 / 21 ) not vertical, but angled on the bottom plate ( 22 ) and presses the force with which the valve plate between the rotor and bottom plate is clamped, at the same time the rotating and non-rotating parts together and keeps the game between the two so low that may well form a lubricating film of oil, but larger losses are avoided. A precaution is recommended whereby the outer ring remains centered exactly around the rotor axis as the two formations approach each other; for example by a rib ( 23 ), in a groove ( 24 ) runs in the underlying floor slab.

The second III shows how the rotary part of the valve plate is rotated via an external toothing of an electric motor; the average DD 'corresponds to the I and II , Preferably, the electric motor and the peripheral apparatus find themselves wholly or largely in the cavity ( 25 ) of the constant motors place.

A (not shown) sensor on the output shaft ( 26 ) informs a computer ( 27 ) on differences between actual and induced driving speed, which then controls the electric motor to fix them. This constant adjustment is known from adjusting motors, except that here the displacement volume at a given pressure, but the pressure at a given volume is continuously adjusted.

For the sake of completeness, it should be noted that the above-described invention is also applicable as a pump by applying mechanical energy across the axis (FIG. 27 ) and above the high pressure port ( 11 or 12 ) is delivered to the consumers. It will provide the greatest working pressure when the formations ( 7 and 8th ) where the cylinder chamber reaches its largest and smallest volume. By shifting the shape ( 7 ), the high pressure port is also connected to increasing cylinder chamber. The effective working volume of the pump is reduced by this; the working pressure is adjustable like the torque in the engine variant.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - FR 1303925 [0002]
• - WO 97/31185 [0002]
• - US 6176684 [0002]
• NL 1019736 [0009]

Claims (1)

Axial piston hydraulic motor with fixed displacement volume, with a valve plate, a part of which is rotatable relative to the other part, characterized in that - the valve plate has only one, arcuate, opening connecting the cylinder chamber with both the high pressure and the low pressure port; - These connections are separated on one side by a formation of the rotatable, on the other side of a formation of the non-rotatable part of the valve plate from each other; - The non-rotatable formation is located at a location where the cylinder chamber is either the largest or the smallest.