DD293866A5 - ADJUSTMENT DEVICE FOR HUB VOLUME CHANGE HYDROSTATIC PISTON MACHINES - Google Patents

Abstract

The invention relates to an adjusting device for Hubvolumenaenderung hydrostatic piston machines whose motion converter is actuated by actuating piston of a hydraulic servo circuit, wherein the control takes a separately actuated pilot valve. Application finds this adjusting device for hydrostatic piston engines, for example, axial piston machines with veraenderbarem displacement, which can be used as a continuously adjustable pumps or motors in open hydraulic circuits. According to the present invention, a pilot piston is force-connected to an actuator piston of the motion converter by a caliper, and the cylinder chamber accommodating the actuator piston is hermetically separated by membrane-type sealant into a section for the caliper spring with connection to the atmosphere, and into sections communicating with a leak chamber. axial piston; Motion converter; Sealant, membranous; Circulation, open; Leckoelraum; Meszfeder; Engine; Pilot valve; Pump; Servo circuit; Actuating piston; Cylinder space}

Description

For this 2 pages drawing

Field of application of the invention The invention relates to an adjusting device for Hubvolumenänderung hydrostatic piston machines whose Movement converter of actuating piston of a hydraulic servo circuit is operated / controlled, the control by a

operated separately pilot valve.

Application finds this adjusting device for hydrostatic piston machines, such as axial piston machines, with

changeable lifting volume, which can be used as continuously variable pumps or motors in open hydraulic circuits

Characteristic of the known state of the art Are known pressure and StromregeleinrichUingen for adjustable pumps (DE-OS 3143074), whose actuating piston via a Two-edge control valve to be powered by Arbeltskreis. This two-edge control valve is directly via a control line

with the working group and via a flow control valve and another line connected to this indirectly. The latter line is protected by a differential pressure valve and a proportional pressure valve, whereby the exact

Metering of the pressure medium flow and the required pressure at the consumer, d. H. of the circuit to be fed Hydromotors, is guaranteed. The illustrated structural design of such control devices does not allow independent of the pressure and current

direct proportional continuous adjustment of the motion converter via the pilot piston.

Furthermore, a control device for Hubvolumenverstellung of axial piston machines is known (DE-OS 3814188),

which has a pilot valve for controlling the actuating piston and thus of the motion converter. The servo circuit is from a

Supply-driven kgumpe supplied, which has a connection to a multi-function valve connection, which the said Pilot valve is connected upstream. About a pressure compensator is a match between the pressure of the feed pressure pump and the work pump, which

is also connected via a branch line to the pilot valve. With this control device an over-zero control of

Axial piston machines are allowed in closed circuit, which are available due to the door control purposes High pressure can be small and massearm dimensioned. This structural design of a control device has the disadvantage that when changing the leak pressure in Measuring spring chamber of the device, caused by a change in viscosity or by system-dependent leakage current resistances

between device and tank, the desired control characteristic is faulty or malfunctioning.

Object of the invention

The invention intends to provide an adjusting device for hydrostatic Kolbenrrtaschinen, which ensure the rational design and thus cost-effective production of the same with high positioning accuracy when using a two-edge control valve, wherein the pilot piston of the control valve is designed for different types of actuation.

Explanation of the essence of the invention

The object of the invention is to secure at a control device for hydrostatic piston engines a direct proportional hydraulic command input by acting on the integrated pilot piston of the actuator and seal it hermetically against a leakage oil chamber of the piston engine.

According to the invention, this object is achieved by means of non-positive connection of a pilot piston with a control piston of the motion converter by a measuring spring, wherein said actuator piston receiving cylinder chamber is hermetically separated by elastic sealing means in a section for the measuring spring with connection to the atmosphere, and in other separate sections, which are connected to a leakage oil space.

In an advantageous embodiment d'eser hermetic separation of the actuating piston is supported in addition to the measuring spring for frictional engagement additionally by a compression spring on a further sealant fixed to the housing.

In addition, it is favorable for functional reasons to connect the portion of the cylinder space for the measuring spring via a channel with the atmosphere and assign this a filter.

Furthermore, the hermetically separated by sealant other portions of the cylinder chamber are connected via holes with the leakage oil chamber of the piston engine.

Finally, the elastic sealing means for separating the cylinder space can advantageously be formed as bellows or membrane and connected by vulcanization or gluing hermetically sealed with control piston, pilot piston and the housing wall of this cylinder chamber.

This adjusting device according to the invention ensures the direct hydraulic control of the pilot piston over its effective area and prevents the build-up of opposing forces on the other end face of this pilot piston, which is arranged in the Zyiinderraum. A negative force influencing the adjusting process on the pilot piston is prevented by the hermetically separated portion of the cylinder space for the measuring spring, which has a channel provided with a filter connection to the atmosphere.

This sensitive area of the pilot piston is kept away by discharging via boreholes to a leakage oil space. By means of low-friction elastic sealing means an absolute separation of the leakage oil space from the cylinder space is secured for the measuring spring and thus allows the use of cost-effective two-edge spools as a pilot piston for command input via a direct force for continuous adjustment of hydrostatic pumps and motors.

embodiment

The invention is explained in more detail below with reference to an exemplary embodiment, wherein the drawings represent the following:

1: the schematic representation of an adjusting device for hydrostatic axial piston pumps FIG. 2: the enlarged view of a pilot piston according to the invention from FIG. 1 as a longitudinal section.

Shown is a hydrostatic axial piston pump with rotating cylindrical body 1, the axially movable working piston 2 are supported on a motion converter 3 designed as a cradle. This motion converter 3 is positively or non-positively connected to actuator piston 4.5, wherein a spring 6 holds the motion converter 3 at rest, as shown in the drawing in Fig. 1, on pivot position zero or near zero.

A directional control valve 7 integrated in the housing of the axial piston pump controls the hydrostatic servo circuit 8, wherein external control oil flow 14 is supplied to the directional control valve 7 or the control piston 4. As can be seen in Fig. 2, the directional control valve 7 has a pilot piston 9 with two control edges 10,11 and a front-side active surface 12, which rests on a bore 13der the control oil flow and thus an axial force is generated. Such a control oil flow for the purpose of command input is realized by means of a remote control valve, not shown, so that the voltage applied via a further bore 14 control oil flow of the servo circuit 8 is released at the control edge 10 of the line 15 of this servo circuit 8 and the actuating piston 4 is applied.

In Figure 2, the pilot piston 9 assumes a position which releases the control edge 11 and the line 15 connects with a leakage oil chamber 23, whereby the zero position of the motion converter 3 is secured.

The pilot piston 9 works in this case via a measuring spring 16 with the larger diameter adjusting piston 5 frictionally together. In a section 17 a of a cylinder chamber 17 for the actuating piston 5, a further compression spring 18 is arranged, which bears against the actuating piston 5 and an elastic Dichtrmpel 19 a, this secures against axial displacement and additionally assumes a support function for these elastic sealing means 19,19s.

These sealing means 19,19a separate the cylinder chamber 17 hermetically from the leakage oil chamber 23 of the axial piston pump and thus there is no leakage-pressure-dependent influencing of the end face 24 of the pilot piston as a disturbing variable to the opposite effective surface 12.

Named sealing means 19 is in this case designed as a bellows and the sealing means 19 a as a membrane, which are connected by vulcanization or gluing hermetically sealed with the actuating piston 5 and the pilot piston 9 and the housing wall of the cylinder chamber 17.

Section 17a here has a connection to the atmosphere via a channel 20 with built-in filter 21, while sections 17b, 17c of this cylinder space 17 are connected via bore 22, 22a to the leakage oil space 23 of the axial piston pump.

Upon actuation of the directional control valve 7, that is, his pilot piston 9 by means of the remote control valve via the bore 13, the Control edge 10 is released, in which the pilot piston 9 is displaced against the force of the measuring spring 16. Thus, adjusting oil passes the Servo circle 8 via the line 15 to the actuator piston 4 and moves it against the force of the spring 6 with entrainment of the Movement converter 3. This pivoting of the motion converter 3 causes the desired change in the stroke volume of the axial piston pump,

whereby the opposite actuating piston 5 is moved against the measuring spring 16 and the compression spring 18. With simultaneous force-displacement of the pilot piston 9 whose control edge 10 interrupts the supply of control oil via the line 15 to

Control piston 4, whereby the motion converter 3 is clamped in the desired position / position. If the application of the active surface 12 of the pilot piston 9 is interrupted by means of control oil, then the measuring spring 16 presses the Pilot piston 9 back to the mechanical stop. In this position, the control edge 11 opens and makes connection of the line '.5 with the leakage oil chamber 23 ago. The spring 6 represents the Movement converter 3 on pivot position zero cder close to zero back.

Claims (5)

1. Control device for the stroke volume change of hydrostatic piston machines, for example of axial piston pumps whose motion converter is actuated / controlled by control pistons of a hydraulic servo circuit, wherein the control is effected by a separately actuated pilot valve, characterized in that a pilot piston (9) with an actuating piston (5) of Movement converter (3) by a measuring spring (16) positively connected and the actuating piston (5) receiving cylinder space (17) by elastic sealing means (19,19a) is hermetically separated in a portion (17 a) for the measuring spring (16), which Has connection to the atmosphere, as well as in other separate sections (17b, 17c), which are connected to a leakage oil chamber (23). 2. Setting device according to claim 1, characterized in that in addition to the measuring spring (16) for the frictional engagement of the adjusting piston (5) additionally by a compression spring (18) via the sealing means (19 a) fixed to the housing. 3. Adjusting device according to claim 1, characterized in that the portion (17 a) of the cylinder space (17) for the measuring spring (16) via a channel (20) is connected to the atmosphere having a filter (21). 4. Setting device according to claim 1, characterized in that by means of sealing means (19,19a) hermetically separated further portions (17 b, 17c) via bores (22,22a) with the leakage oil space (23) of the piston engine are connected. 5. Setting device according to claim 1 to 4, characterized in that the elastic sealing means (19,19a) are formed as bellows or membrane and by vulcanization or gluing hermetically sealed with the actuating piston (5) or pilot piston (9) and the housing wall the cylinder space (17) are connected.